bowers, todd allen. forest structure and health trends in

ABSTRACT Bowers, Todd Allen. Forest Structure and Health Trends in the Southern Appalachian Montane Spruce-fir and Northern Hardwood Ecosystems of the Black Mountains, North Carolina.

(Under the direction of Dr. Robert I. Bruck)

Spruce-fir forests of the Southern Appalachians are ice age relics currently existing now in

isolated montane islands at elevations above 1400 m. Decline in the spruce-fir ecosystem

throughout the region was shown following extensive surveys in high elevation red spruce

(Picea rubens Sarg.) and Fraser fir (Abies fraseri (Pursh) Poir.) forests conducted during the

1980’s. Following an observed decline in red spruce crown condition at lower elevations (1500

m) in the Black Mountains of North Carolina during the summer of 2001, it was deemed

necessary to conduct a new investigation to characterize trends in forest health in the spruce-fir

and adjacent northern hardwood forests.

Beginning in 2002, we undertook a new study in order to gain further information

relating to the observed decline by resurveying 28 permanent spruce-fir forest plots installed in

1985 at 1525, 1675, 1830, and 1980 m in the Black Mountains. Simultaneously, we established

a new system of 40 permanent plots to survey the northern hardwood forests in 9 areas

throughout the Black Mountains between 1220 and 1525 m. Following previous protocols in the

spruce-fir forest, and using a similar rubric in the northern hardwood forests, we measured live

and dead basal area, live and dead stem density, and assessed tree crown conditions for all

overstory species. Insect and disease occurrences were also recorded when found with special

attention given to balsam woolly adelgid (Adelges piceae Ratz.) on Fraser fir, hemlock woolly

adelgid (Adelges tsugae Annand) on hemlock, beech scale insect (Cryptococcus fagisuga

Lindinger) and cankers caused by Nectria coccinea var. faginata (Lohman, Watson and Ayers)

on beech, and low crown vigor or defoliation in oaks.

Individual plot assessments in the spruce-fir zone revealed a wide range of response over

the 17-year interim and while few results were statistically significant, several profound trends

were evident. Results show a large increase in live basal area at 1980 m for Fraser fir with a

corresponding large significant (p < 0.10) increase in live stem density of 3237 stems/ha from

1986 to 2003. While not statistically significant, a large rise in dead spruce at 1525 m and a

decrease in dead fir at 1980 m were also shown. Data suggests a rapid regeneration of dense and

healthy fir is currently underway at the highest altitudes, especially in areas of former severe

mortality and overstory collapse. However, the amount of progression towards a climax high-

elevation fir forest is highly variable and very patchy. A significant (p < 0.10) decline in crown

condition for spruce and fir continues to manifest, especially in mature trees at lower altitudes

(1525, 1675, and 1830 m). Causal factors behind the current trend in fir crown decline remain

unknown, as balsam woolly adelgid (Adelges piceae Ratz.) was not frequently encountered,

suggesting that adelgid populations are currently low. Long term recovery for Fraser fir is

uncertain as stems reach adelgid-susceptible age and size classes.

The northern hardwood forests of North Carolina, found up to approximately 1525 m,

where they give way to spruce-fir forests, exhibit a unique assemblage of many species endemic

to the Southern Appalachians. Common northern hardwood type canopy trees of the Black

Mountains include northern red oak (Quercus rubra var. borealis Michaux f.), chestnut oak (Q.

prinus L.), red maple (Acer rubrum L.), sugar maple (A. saccharum Marshall), American beech

(Fagus grandifolia Ehrh.), and eastern hemlock (Tsuga canadensis (L.) Carr.).

With the exception of red spruce and eastern hemlock, the northern hardwood forest

survey found most tree species in an excellent condition. Many feared emerging pathogens and

insects were not evident, however it is expected that they may have profound impacts on forests

throughout the region. The main value of this study is in the potential for long-term monitoring

of these sites and detection of disease onset and incipient mortality before epidemic levels are

achieved.

FOREST STRUCTURE and HEALTH TRENDS in the SOUTHERN APPALACHIAN MONTANE SPRUCE-FIR and NORTHERN

HARDWOOD ECOSYTEMS of the BLACK MOUNTAINS, NORTH CAROLINA

By

TODD ALLEN BOWERS

A thesis submitted to the Graduate Faculty of North Carolina State University

in partial fulfillment of the requirements for the Degree of

Master of Science

PLANT PATHOLOGY

Raleigh 2005

APPROVED BY:

________________________________ _________________________________ Dr. Tom Wentworth Dr. Larry Grand

________________________________ _________________________________ Dr. Shuijin Hu Dr. Robert Bruck

Chair of Advisory Committee

ii

DEDICATION

This paper is dedicated to my zealous summer field crew. Without their support I could not

have undertaken and completed a task of this magnitude. Thanks especially go out to Kerby

Smithson, Laura Vance, Matthew Cherry, Margaret Worthington, Maggie Schnieder, and

Jerome “Bill” Miller. The summers of 2002 and 2003 were priceless and thoroughly

enjoyable thanks to them. The endless amount of energy they put into this endeavor was

crucial towards making my project a success. I hope the work we did together will have a

positive lasting effect on the survival of the forests in our wondrous western North Carolina

Mountains. Additionally, the author wishes to thank Dr. Robert Ian Bruck for the

opportunity and inspiration to achieve this graduate degree at North Carolina State

University. I have cherished the years of mentorship he has provided me and many others

while I have been a student at NC State.

iii

BIOGRAPHY

Todd Allen Bowers was born on November 17th, 1968 in Oak Harbor, Washington as the

first son of Jerry Truhill and Karen Kennedy. Following his mother’s death in 1984, Todd

finished high school in South Lake Tahoe, California and joined the U.S. Navy. After two

years of training in Orlando, Florida and Idaho Falls, Idaho, he served aboard the nuclear

powered guided missile cruiser USS Truxtun (CGN-35). During the three years on board the

“Tommy T” his specialties were Reactor Operator and Electronics Technician. Following

two overseas deployments including Operation Desert Storm in 1991 and countless smaller

cruises, Todd was transferred to the Nuclear Propulsion Training Unit in Saratoga Springs,

New York. While there he led the training of students in the routine and casualty control

operations of a land based prototype propulsion system. Additionally, while serving as

Leading Petty Officer for Reactor Controls Division, Todd achieved the level of Engineering

Watch Supervisor. In 1995, Todd left the Navy after over eight and a half years of honorable

service with the rank of Petty Officer First Class and Enlisted Surface Warfare

Qualifications.

After several months of odd jobs and soul searching, including an epiphany in the

Adirondack Mountains, Todd matriculated into North Carolina State University in Raleigh,

North Carolina in the fall of 1996. During his four and a half years of undergraduate study,

he held several meaningful positions contributing to his college success. These jobs included

agriculture field and lab technician, Forest Health Monitor crew leader for the North Carolina

Division of Forest Resources, summer nature Camp Director for the City of Raleigh Parks

and Recreation, and as a barista for Caribou Coffee through the semesters. Somewhere in the

middle of campus life Todd met Becky Townsend and married her a year later. Immediately

iv

after graduating Summa Cum Laude with a BS in Natural Resources – Ecosystem

Assessment in 2000, Todd joined EcoScience Corp. in Raleigh.

While he was only with EcoScience for a year Todd gained an incredible amount of

experience in the field delineating wetlands, restoring streams, surveying for endangered

species, and performing many biological assessments of riverine and forest habitats.

However, the call back to school was too great and he enrolled again at North Carolina State

University to study spruce-fir forest health in the Southern Appalachians. This thesis is the

culmination of his work and studies in the Plant Pathology Department and research in the

Black Mountains of Yancey County, North Carolina. Todd now lives alone with his cat,

Gargles, in Raleigh where he has made his home for nine years. His hobbies include hosting

vegan potlucks, playing acoustic guitar, backpacking and hiking, bicycling, experiencing

Barefoot Manner, catching an infectious groove, cleaning streams, and speaking for the trees.

v

ACKNOWLEDGEMENTS

Funding for this research was provided by the USDA Forest Service Southern Global Change

Program and the Stanback Foundation of North Carolina. I wish to extend my gratitude to

these organizations for their contribution to the understanding of forest health in the Southern

Appalachians and for allowing me the financial means to undertake a graduate degree.

I would like to thank the entire Mt. Mitchell State Park staff and David Zietlow for allowing

us access to park facilities and joining the spirit of scientific pursuit.

I would like to thank my grandparents, Woody and Charlotte Cecil, for their support of all

my endeavors since starting college.

In addition to the multitude of individuals who directly contributed to the success of this

body of work, the author would like to thank the baristas at many fine coffee establishments

within the City of Raleigh. Gratitude and kudos go out Cup A Joe in Mission Valley, The

Third Place in Five Points, Global Village Organic Café on Hillsborough, and Café Cyclo in

Cameron Village. Many infusions of caffeine were needed to provide the inspiration to keep

working. Thanks for keeping the java flowing!

vi

TABLE OF CONTENTS

LIST OF TABLES........................................................................................................... VIII LIST OF FIGURES.............................................................................................................X

1. FOREST STRUCTURE TRENDS IN THE MONTANE RED SPRUCE-FRASER FIR ECOSYSTEM OF THE BLACK MOUNTAINS, NORTH CAROLINA. ................ 1

ABSTRACT...................................................................................................................................................... 1 1.1 INTRODUCTION................................................................................................................................... 2

1.1.1 Background.......................................................................................................................................................2 1.1.2 Site Location and Description.........................................................................................................................11

1.2 MATERIALS AND METHODS ................................................................................................................ 13 1.2.1 Original Plot Establishment ............................................................................................................................13 1.2.2 Field Sampling................................................................................................................................................13 1.2.3 Analysis ..........................................................................................................................................................17

1.3 RESULTS ................................................................................................................................................. 18 1.3.1 General Description of Weather and Plot Conditions.....................................................................................18 1.3.2 Live Stem Density ..........................................................................................................................................21 1.3.3 Dead Stem Density .........................................................................................................................................24 1.3.4 Live Basal Area ..............................................................................................................................................27 1.3.5 Dead Basal Area .............................................................................................................................................30 1.3.6 Crown Class Condition...................................................................................................................................34

Crown Class 1 34 Crown Class 2 37 Crown Class 3 39

1.3.7 Diameter Class Change per Species ...............................................................................................................41 Red Spruce 41 Fraser Fir 44 Yellow Birch 46

1.3.8 Disease and Insect Incidence ..........................................................................................................................49 1.4 DISCUSSION ........................................................................................................................................... 51

1.4.1 Current Status .................................................................................................................................................51 1.4.2 Comparison to “virgin” or undisturbed spruce-fir forest ................................................................................52 1.4.3 Comparison with Trends of Recent Studies....................................................................................................54 1.4.4 Analysis of Projected Values..........................................................................................................................56 1.4.5 Conclusions ....................................................................................................................................................58

1.5 ACKNOWLEDGEMENTS ...................................................................................................................... 61 1.6 LITERATURE CITED.............................................................................................................................. 62

2. EVIDENCE OF MONTANE FRASER FIR (ABIES FRASERI) AND RED SPRUCE (PICEA RUBENS) RECOVERY ON THE HIGH PEAKS AND RIDGES OF THE BLACK MOUNTAINS, NORTH CAROLINA. ................................................................ 66

ABSTRACT.................................................................................................................................................... 66 2.1 INTRODUCTION..................................................................................................................................... 67

2.1.1 Background.....................................................................................................................................................67 2.1.2 Site Location and Description.........................................................................................................................73

2.2 MATERIALS AND METHODS ................................................................................................................ 76 2.2.1 Original Plot Establishment ............................................................................................................................76 2.2.2 Field Sampling................................................................................................................................................76 2.2.3 Analysis ..........................................................................................................................................................79

2.3 RESULTS ................................................................................................................................................. 81 2.3.1 Individual Plot Assessments ...........................................................................................................................81

Plot B-44 Cattail Peak 81 Plot B-52 Potato Knob 81 Plot B-53 Balsam Cone 81

vii

Plot B-54 Mt. Mitchell 82 2.3.2 Stem Density ..................................................................................................................................................83 2.3.3 Basal Area ......................................................................................................................................................84 2.3.4 Crown Class Condition...................................................................................................................................85 2.3.5 Diameter Class Change...................................................................................................................................87

Fraser Fir 87 Red Spruce 88 Yellow Birch 89

2.3.6 Disease and Insect Incidence ..........................................................................................................................89 2.4 DISCUSSION ........................................................................................................................................... 91

2.4.1 Comparison to “virgin” or undisturbed fir forest ............................................................................................92 2.4.2 Comparison with Recent Studies....................................................................................................................93 2.4.3 Analysis of Projected Values..........................................................................................................................95 2.4.4 Conclusions ....................................................................................................................................................96

2.5 ACKNOWLEDGEMENTS ...................................................................................................................... 98 2.6 LITERATURE CITED.............................................................................................................................. 99

3. SPECIES COMPOSITION AND CROWN CONDITION OF NORTHERN HARDWOOD FORESTS OF THE BLACK MOUNTAINS, NORTH CAROLINA. . 103

ABSTRACT.................................................................................................................................................. 103 3.1 INTRODUCTION................................................................................................................................... 104

3.1.1 Background...................................................................................................................................................104 3.1.1 Site Location and Description.......................................................................................................................111

3.2 MATERIALS AND METHODS .............................................................................................................. 113 3.2.1 Site Selection and Plot Establishment...........................................................................................................113 3.2.2 Field Sampling..............................................................................................................................................115

3.3 RESULTS ............................................................................................................................................... 117 3.3.1 Mensuration Data and Evaluation of Each Plot Group .................................................................................117

Bald Knob Ridge 117 Buncombe Horse Range Ridge 118 Blue Ridge Parkway 119 Mt. Mitchell Trail 120 Locust Creek 121 Woody Ridge 121 Celo Ridge 122 Bowlens Creek 123 North Fork 124

3.3.2 Crown Class Condition of the Most Common Species.................................................................................125 3.4 DISCUSSION ......................................................................................................................................... 127

3.4.1 Current Status ...............................................................................................................................................127 3.4.2 Possible Outcomes and Potential Trends ......................................................................................................128 3.4.3 Conclusion....................................................................................................................................................130

3.5 ACKNOWLEDGEMENTS .................................................................................................................... 131 3.6 LITERATURE CITED............................................................................................................................ 132

viii

LIST OF TABLES

TABLE 1.1 LIVE STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC..................................................................................................................................................................... 21

TABLE 1.2 LIVE AND DEAD STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ASPECT, FOR RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC......................................................................................................................................... 24

TABLE 1.3 DEAD STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC. ............................................................................................................................................................. 25

TABLE 1.4 LIVE BASAL AREA WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC..................................................................................................................................................................... 28

TABLE 1.5 LIVE AND DEAD BASAL AREA WITH STANDARD ERROR, STRATIFIED BY ASPECT, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC......................................................................................................................................... 29

TABLE 1.6 DEAD BASAL AREA WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC..................................................................................................................................................................... 31

TABLE 1.7 CROWN CLASS 1 STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC......................................................................................................................................... 35

TABLE 1.8 CROWN CLASS 1 STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ASPECT, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC......................................................................................................................................... 36





TABLE 1.13 RED SPRUCE LIVE STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 41

TABLE 1.14 RED SPRUCE LIVE BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 42

TABLE 1.15 RED SPRUCE DEAD STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 42

TABLE 1.16 RED SPRUCE DEAD BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 42

TABLE 1.17 FRASER FIR LIVE STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 44

TABLE 1.18 FRASER FIR LIVE BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 45

TABLE 1.19 FRASER FIR DEAD STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 45

TABLE 1.20 FRASER FIR DEAD BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 45

ix

TABLE 1.21 YELLOW BIRCH LIVE STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. .................................................... 47

TABLE 1.22 YELLOW BIRCH LIVE BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 47

TABLE 1.23 YELLOW BIRCH DEAD STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. .................................................... 47

TABLE 1.24 YELLOW BIRCH DEAD BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. ......................................................... 48

TABLE 2.1 LIVE AND DEAD STEM DENSITY WITH STANDARD ERROR FOR FRASER FIR, RED SPRUCE, YELLOW BIRCH, AND THE TOTAL FOR ALL OVERSTORY SPECIES AT 1980 M (N=4)................................................................ 83

TABLE 2.2 LIVE AND DEAD BASAL AREA WITH STANDARD ERROR FOR FRASER FIR, RED SPRUCE, YELLOW BIRCH, AND TOTAL FOR ALL OVERSTORY SPECIES AT 1980 M (N=4)....................................................................... 84

TABLE 2.3 CROWN CLASS 1-4 STEM DENSITY WITH STANDARD ERROR FOR FRASER FIR, RED SPRUCE, YELLOW BIRCH, AND TOTAL FOR ALL OVERSTORY SPECIES AT 1980 M (N=4). .......................................................... 86

TABLE 3.1 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE BALD KNOB RIDGE PLOTS (N=5). ...................................................................................................... 117

TABLE 3.2 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE BUNCOMBE HORSE RANGE RIDGE PLOTS (N=4). ............................................................................... 118

TABLE 3.3 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE BLUE RIDGE PARKWAY PLOTS (N=6)................................................................................................. 119

TABLE 3.4 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE MT. MITCHELL TRAIL PLOTS (N=5). .................................................................................................. 120

TABLE 3.5 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE LOCUST CREEK PLOTS (N=5). ............................................................................................................ 121

TABLE 3.6 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE WOODY RIDGE PLOTS (N=2).............................................................................................................. 122

TABLE 3.7 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE CELO RIDGE PLOTS (N=3).................................................................................................................. 123

TABLE 3.8 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE BOWLENS CREEK PLOTS (N=5). ......................................................................................................... 123

TABLE 3.9 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE NORTH FORK PLOTS (N=5). ............................................................................................................... 124

x

LIST OF FIGURES

FIGURE 1.1 LOCATION OF MT. MITCHELL AND THE BLACK MOUNTAINS IN RELATION TO ASHEVILLE IN WESTERN NORTH CAROLINA. ..................................................................................................................................... 12

FIGURE 1.2 LOCATION OF THE 28 SURVEYED SPRUCE-FIR PLOTS THROUGHOUT THE BLACK MOUNTAINS. PLOTS ARE REPRESENTED BY YELLOW SQUARES.................................................................................................... 14

FIGURE 1.3 EXAMPLES OF CROWN CLASS 1-4 RATINGS ON SPRUCE AND FIR TREES.............................................. 16 FIGURE 1.4 RED SPRUCE MEAN LIVE STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION

AND ASPECT. ............................................................................................................................................... 22 FIGURE 1.5 FRASER FIR MEAN LIVE STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION

AND ASPECT. ............................................................................................................................................... 23 FIGURE 1.6 YELLOW BIRCH MEAN LIVE STEM DENSITY (STEMS/HA) FROM 1986 TO 2003 STRATIFIED BY

ELEVATION AND ASPECT. ............................................................................................................................ 23 FIGURE 1.7 RED SPRUCE MEAN DEAD STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION

AND ASPECT. ............................................................................................................................................... 26 FIGURE 1.8 FRASER FIR MEAN DEAD STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION

AND ASPECT. ............................................................................................................................................... 26 FIGURE 1.9 YELLOW BIRCH MEAN DEAD STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY

ELEVATION AND ASPECT. ............................................................................................................................ 27 FIGURE 1.10 RED SPRUCE MEAN LIVE BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND

ASPECT. ....................................................................................................................................................... 29 FIGURE 1.11 FRASER FIR MEAN LIVE BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND

ASPECT. ....................................................................................................................................................... 30 FIGURE 1.12 YELLOW BIRCH MEAN LIVE BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION

AND ASPECT. ............................................................................................................................................... 30 FIGURE 1.13 RED SPRUCE MEAN DEAD BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND

ASPECT. ....................................................................................................................................................... 32 FIGURE 1.14 FRASER FIR MEAN DEAD BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND

ASPECT. ....................................................................................................................................................... 33 FIGURE 1.15 YELLOW BIRCH MEAN DEAD BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION

AND ASPECT. ............................................................................................................................................... 33 FIGURE 1.16 A-F. CHANGE IN RED SPRUCE CROWN CLASS FOR EACH ELEVATION ZONE AND ASPECT.................... 36 FIGURE 1.17 A-F. CHANGE IN FRASER FIR CROWN CLASS FOR EACH ELEVATION ZONE AND ASPECT..................... 37 FIGURE 1.18 A-F. CHANGE IN YELLOW BIRCH CROWN CLASS FOR EACH ELEVATION ZONE AND ASPECT. .............. 38 FIGURE 2.1 LOCATION OF MT. MITCHELL AND THE BLACK MOUNTAINS IN WESTERN NORTH CAROLINA. .......... 75 FIGURE 2.2 HIGH ELEVATION SPRUCE-FIR PLOT LOCATIONS ALONG THE MAIN RIDGELINE OF THE BLACK

MOUNTAINS. ............................................................................................................................................... 77 FIGURE 2.3 EXAMPLES OF CROWN CLASS 1-4 RATINGS ON SPRUCE AND FIR TREES.............................................. 79 FIGURE 2.4A-D PERCENTAGE OF CHANGE IN FRASER FIR CROWN CLASS FROM 1986 TO 2003 FOR EACH PLOT AT

1980 M. ....................................................................................................................................................... 86 FIGURE 2.5 FRASER FIR LIVE BASAL AREA AND STEM DENSITY 1986 TO 2003 AT 1980 M FOR EACH 10-CM

DIAMETER CLASS (N=4). ............................................................................................................................. 87 FIGURE 2.6 RED SPRUCE LIVE BASAL AREA AND STEM DENSITY 1986 TO 2003 AT 1980 M FOR EACH 10-CM

DIAMETER CLASS (N=4). ............................................................................................................................. 88 FIGURE 3.1 LOCATION OF MT. MITCHELL AND THE BLACK MOUNTAINS IN WESTERN NORTH CAROLINA. ........ 112 FIGURE 3.2 NORTHERN HARDWOOD PLOT LOCATIONS IN THE VICINITY OF THE BLACK MOUNTAINS IN YANCEY

COUNTY, NORTH CAROLINA. .................................................................................................................... 114 FIGURE 3.3 CROWN CLASS RATINGS OF 10 MOST COMMON TREE SPECIES FOUND IN BLACK MOUNTAIN NORTHERN

HARDWOOD AND MONTANE OAK FORESTS. ............................................................................................... 125

1. Forest Structure Trends in the Montane Red Spruce-Fraser Fir Ecosystem of the Black Mountains, North Carolina.

ABSTRACT

Spruce-fir forests of the Southern Appalachians are ice age relics currently existing as




1980’s. In 2002-3, we resurveyed 28 permanent spruce-fir forest plots installed in 1985

between 1525 and 1980 m in the Black Mountains of North Carolina. Following previous

protocols, we measured live and dead basal area, stem density, and assessed tree crown

conditions for all overstory species. Insect and disease occurrences were also recorded when

found. Results show large increases in live basal area and live stem density at 1980 m for

spruce and fir populations, with a downward trend in the same parameters for spruce at lower

elevations. A large rise in dead spruce at 1525 m and a decrease in dead fir at 1980 m were

shown. Data suggests significant (p < 0.10) fir regeneration is occurring at 1980 m,

especially in areas of former severe mortality. However, significant (p < 0.10) decline in

crown condition for spruce and fir continues to manifest, especially in mature trees. Causal

factors behind the current trend in crown decline remain unknown, as balsam woolly adelgid

(Adelges piceae Ratz.) was not frequently encountered suggesting that adelgid populations

are currently low. Long term recovery for fir is uncertain as stems reach adelgid-susceptible

age and size classes.

2

1.1 INTRODUCTION

1.1.1 Background

The spruce-fir forest ecosystem of the Southern Appalachian Mountains, consisting primarily

of the dominant tree species red spruce (Picea rubens Sargent)1 and Fraser fir (Abies fraseri

[Pursh] Poiret), once covered much of southeastern North America and is considered a

remnant of the last ice age that ended approximately 18,000 years ago (Whittaker 1956;

White and Cogbill 1992). As the climate ameliorated since the ice age, the lowland spruce,

fir, and northern hardwood species gave way to deciduous forests. The montane spruce and

fir moved northward along the mountains and upward in the southern ranges, which had

sufficient altitude to provide the damp and relatively cold climate necessary for their survival

(Oosting and Billings 1951). The present range of red spruce extends northeast to Canada,

while Fraser fir is endemic to the Southern Appalachians (Busing et al. 1988). Contained

almost exclusively in the higher elevations of North Carolina and Tennessee, the spruce-fir

forest type exists in a region where harsh winter conditions coincide with hot and humid

summers. In the Southern Appalachians the montane spruce-fir forest type now covers

approximately 26,600 hectares (65,730 acres) above 1500 m (4920 ft) (DeSelm and Boner

1984; Adams and Eagar 1992; and Fernandez 1992).

Montane spruce-fir forest species are highly dependent on elevation and moisture

conditions in the Southern Appalachians, with an abrupt ecotone between dominance of

spruce-fir and hardwood species (White 1984). However, a few deciduous species continue

to thrive with increasing elevation. Above the hardwood zone dominated by oaks and

maples, red spruce and Fraser fir share dominance of the canopy and understory with a few

less common and smaller trees and shrubs, namely yellow birch (Betula lutea Michaux f.),

3

rhododendron (Rhododendron catawbiense Michaux and R. maximum L.), fire or pin cherry

(Prunus pensylvanica L. f.), striped and mountain maple (Acer pensylvanicum L. and A.

spicatum Lam.), and, at the highest elevations, mountain ash (Sorbus americana Marshall)

and hobblebush (Viburnum alnifolium Marshall) (Whittaker 1956; McLoed 1988). Red

spruce, as a dominant or codominant, usually makes its appearance at about 1375 m (4500 ft)

elevation, depending on topography, and may share the canopy with common hardwood

species such as American beech (Fagus grandifolia Erhart), sugar maple (A. saccharum

Marshall), eastern and Carolina hemlock (Tsuga canadensis L. [Carr.] and T. caroliniana

Engelm.), northern red oak (Q. rubra var. borealis [Michaux f.] Farwell), black birch (B.

lenta L.) and black cherry (P. serotina Ehrhart). With increasing altitude, Fraser fir gains

importance in the forest, until it becomes a codominant with spruce around 1700 m (5600 ft)

and finally by 1830 m (6000 ft) it may constitute 80 percent or more of the stand (Cain 1935;

Whittaker 1956). Above this altitude in the Black Mountains, Fraser fir dominates the ridges

and high peaks up to 2037 m (6684 ft), the elevation of Mt. Mitchell, the highest peak in

eastern North America.

Interest in forest health of Southern Appalachian spruce-fir was heightened following

studies in the early to mid 1980s that documented widespread forest deterioration in Europe

(Schutt and Cowling 1985; Nilsson and Duinker 1987; and Prinz 1987) and decline of red

spruce in the northeastern United States (Siccama et al. 1982; Hornbeck et al. 1986; Johnson

et al. 1986; and Vogelmann et al. 1988). The European studies were prompted by increased

levels of decline phenomena, which included simultaneous and rapid decreases of health and

vigor of many tree species with corresponding growth rate decreasing symptoms and

prevalence of new diseases (Schutt and Cowling 1985). Regional air pollution and acid

1 Floristic nomenclature follows Radford et al. 1968.

4

precipitation was believed to be contributing to declining crown condition in red spruce in

Vermont (Siccama et al. 1982), while climate change was theorized as a potential cause

behind poor growth patterns in New England and upstate New York (Hornbeck et al. 1986).

Decline in the southern spruce-fir forests, underway since the introduction of an exotic

insect, the balsam woolly adelgid (Adelges piceae Ratz.) in 1957 (Speers 1958; White 1984;

and Smith and Nicholas 1998), was hypothesized to be a result of a combination of factors.

The montane southern spruce-fir ecotype is one that has recently been considered to be

“living on the edge” as several factors that contribute to decline symptoms such as thin acidic

soils, harsh climate, acid deposition, and high ozone levels are constantly interacting to cause

stress on the trees.

Many regional studies, organized under the Forest Response Program of the National

Atmospheric Deposition Assessment Program (NAPAP), began in the mid 1980s to

document the myriad decline symptoms that were becoming evident in the montane forests

of the Great Smoky and Black Mountains (Busing et al. 1988; Bruck et al. 1989; Pitelka and

Raynal 1989; LeBlanc et al. 1992; and Nicholas et al. 1992). By 1987 a rapid deterioration

in the physical appearance of Southern Appalachian spruce-fir ecosystems was evident

across the region (Bruck et al. 1989). Along with these trends, the predominant cause behind

the wave of decline in spruce-fir forests, and pinpointing a common factor remained elusive

and controversial. Theories behind the decline syndrome ranged from competition (LeBlanc

et al. 1992), acid precipitation and air pollution (Bruck et al. 1989), soil acidification

(Cowling et al. 1988), severe winter weather conditions (Nicholas 1992), to blackberry

(Rubus spp.) encroachment (Busing et al. 1988; Pauley and Clebsch 1990). Even the term

“forest decline” is a considered a misnomer, with perhaps a more correct term being “forest

5

species decline” (Skelly 1992) since the terms “dieback”, “decline”, and “blight” neither

identify, nor even suggest, causal relationships (Houston 1992).

Measuring decline or even acknowledging its presence has proved to be problematic,

and considerable uncertainty existed within the scientific community as the roles of natural

and air pollution-related factors in the phenomenon of forest decline (Johnson 1992).

Supporters and skeptics of decline theories abound, lending support to advocates for forest

protection or denying claims that recent observations are not at all unusual or threatening.

Perhaps the greatest omission in some recent studies was consideration of the impact of the

balsam woolly adelgid (BWA), which was responsible for most of the mortality in spruce-fir

forests, particularly of Fraser fir at Mt. Mitchell, North Carolina (Pitelka and Raynal 1989;

Edmonds et al. 2000). Forest decline theory opponents are quick to point out that

photographs of recent “forest decline” and dead fir trees (especially on Mt. Mitchell) with

captions stating that air pollutants and acid rain as the factors of greatest importance are

misleading, because the actual damage was from adelgid attack (Skelly 1992).

An analysis by LeBlanc et al. (1992) concluded that the prevalence of individual tree

growth decline in red spruce populations in the Southern Appalachians was not greater than

historical levels for this species and region. Despite identifying the similarity to historic

trends, LeBlanc’s analysis could not determine if the causes of increased decline since 1950

differed from historical causes. Because this decline did not exceed estimates of historical

decline, the current decline trend was not considered anomalous. However, because the

episode of growth rate decline continued up to LeBlanc’s sampling year (1991), it was not

possible to determine the extent of the trend, but it was determined that the decline was not

6

related to tree age. Additionally, Bruck et al. (1989) found no symptoms of insect attack or

disease that may have been important contributors to red spruce decline.

Characterizing normal red spruce growth is important in determining if a deviation

from the norm exists. However, as is the case with many shade tolerant species, small red

spruce can be quite old and trees of the same size may have widely different ages (Oosting

and Billings 1951). Seedlings may exceed 20 years old and saplings may be more than 60

years old, concluding that there is little relation of size to age (Peart et al. 1992). Further

investigations by LeBlanc et al. (1992) sought to correlate red spruce decline with respect to

other parameters; however, no difference was found in prevalence of growth decline between

sub-populations that differed with regard to diameter at breast height (dbh), competitive

status, stand density, slope, aspect, or site exposure. Conversely, Bruck et al. (1989) found

that west facing slopes showed increased incidence of decline and increased suppression of

annual volume increment. Furthermore, McLaughlin et al. (1987) and LeBlanc et al. (1992)

rejected the hypothesis that red spruce radial growth rate decline might be due to competitive

effects.

Estimations of mortality or dieback have also proved to be problematic when applied

to forest or species decline, and efforts to find a single, reliable index of tree health or vigor

have remained unproductive. Percent standing dead is often used erroneously to illustrate the

decline of certain species. According to Peart et al. (1992), percent standing dead is not an

estimate of mortality rate nor can it easily be converted to such as it reflects a cumulative

result. Changes in mortality rates over time, for example, would not normally be detected

against background variation without large samples of trees monitored continuously for at

least several years, unless the changes were abrupt and dramatic. A tree population is

7

considered to be relatively steady over time if the total number in the population and its age

and size structure remain reasonably constant (Peart et al. 1992). But few studies have been

established to monitor changes in entire ecosystems over time. Problems in measuring vigor

(crown condition) exist mainly due to the variety of methods available and observer

inaccuracy and bias (Peart et al. 1992), which introduce error even when seasoned field

technicians perform the evaluations.

The spruce-fir ecosystem of the Southern Appalachian Mountains exists where few

species of plants, especially trees, can survive. Winters at higher elevations in these

mountains can be quite harsh, with punishing winds and ice frequently occurring. Due to

these conditions, red spruce and Fraser fir can thrive because few trees can compete with

them in this environment. The environmental conditions are highly variable to the point

where even the hardier plant species experience some stress, which may eventually lead to

decline symptoms. The degree to which trees are altered by stress is controlled in part by

their genetics and in part by the conditions of their immediate surroundings (Houston 1992).

Stresses such as extreme cold and drought can combine with many other factors such as

slope, aspect, and elevation to impact trees tremendously.

Trees on west facing slopes have shown increased incidence of decline symptoms,

and increased suppression of annual volume increment (Bruck et al. 1989), although crown

condition of red spruce was not believed to be related to aspect (Adams and Eagar 1992).

Aspect-related decline symptoms may be due to the fact that western facing slopes take the

brunt of the weather and pollution as air systems move from west to east over the mountains,

which are generally oriented north-east to south-west (Mohnen 1992). East facing slopes

tend to be drier as well, resulting in different moisture regimes on a given ridge. In the

8

Southern Appalachians, change in moisture supply has been linked to compositional changes

within montane spruce-fir, with red spruce and rhododendron dominance being more

prominent on drier sites, and fir, moss, and herb dominance being more prominent on the

moister sites (White and Cogbill 1992).

Climatic stresses may have also had an impact on the southern spruce-fir forests. In

contrast to Northern Appalachian forests, there is very little evidence of winter injury to

foliage in southern forests. Ice, snow, wind damage, and droughts are not uncommon, but

few studies have considered their role (Peart et al. 1992; Mohnen 1992). According to one

study in the Black Mountains of North Carolina (Bruck et al. 1989), between 1985 and 1989

annual mortality rates for red spruce ranged from 1.1 to 8.4 percent, although these values are

thought to be well within natural limits (Adams and Eagar 1992). Bruck et al. (1989)

speculated whether the increase in the number of dead trees per plot observed in 1985-6

would have continued in 1987 without the intervention of drought in 1986 and rime ice

damage during December 1986 and February 1987.

Elevation, a critical factor for competing species at higher altitudes, plays a role in

amplifying the effects of other stresses. Those trees at higher elevations are generally

exposed to greater amounts of wind, ice, acidic deposition, ozone and other air pollutants.

Elevation has been linked with decline but not necessarily as a causal factor. According to

LeBlanc et al. (1992) and Busing and Pauley (1994), the only factor found to be associated

with red spruce decline is elevation, but only as an inciting factor due to exposure to high

winds and ice (thinning shock) following fir mortality. The impact of fir mortality on red

spruce growth due to thinning shock may be greatest at 1980 m (6500 ft). The proportion of

trees that exhibited decreasing or slowed growth rate after 1967 was substantially greater

9

among trees growing at 1980 m than at lower elevations. Additionally, mortality of Fraser fir

was 12, 31, 38, and 55 percent of standing basal area in stands at 1525, 1675, 1830, and 1980

m (5000, 5500, 6000, 6500 ft) elevation stands respectively (LeBlanc et al. 1992).

Bruck et al. (1989) and Nicholas et al. (1992) carried out detailed multi-annual forest

surveys throughout the Southern Appalachians, including the Black Mountains of North

Carolina, in order to quantify the deterioration of the spruce-fir forests during the 1980’s.

While these surveys varied drastically in their approach, both studies concluded that a rapid

collapse of forest structure was in progress, but failed to determine the primary underlying

causes of the collapse. Several hypotheses were offered, including direct acidic deposition,

leaching of nutrients from and toxic levels of aluminum in the soil, infestation of the balsam

wooly adelgid, and severe weather events during the winter of 1986-7 (Cowling et al. 1988;

Bruck et al. 1989; Silver et al. 1991; and Nicholas 1992). Regardless of the causes and effect

mechanisms, the physical condition and structure of the montane ecosystems on and around

Mt. Mitchell had greatly deteriorated by 1987.

In the spring of 2001, an alarming observation by several scientists was made near

Mt. Mitchell State Park in North Carolina. Low altitude red spruce forests at 1500 m had

undergone a significant decline during the winter of 2000-2001. Initial meteorological data

analysis failed to indicate any unusual events over this period of time. More detailed

meteorological analysis at nearby Grandfather Mt. in North Carolina indicated a slow but

significant rise in mean temperatures from 1954 to 2000. Additionally, soil temperature and

moisture data taken from the summer of 2001 indicated a warming and drying of montane

soils relative to observations made in the 1980’s (Bruck, personal communication).

Historically, serious decline of red spruce had only been observed at the much higher

10

elevations of the montane spruce-fir forests of the Southern Appalachians above 1500 m

(Adams and Eagar 1992). Decline and high mortality in red spruce below 1500 m is a

somewhat new phenomenon in the Black Mountains, with little evidence to explain its

occurrence.

In order to gain an understanding of the recent change in Fraser fir and red spruce

health, we began a resurvey of the Black Mountain montane forests within and adjacent to

Mt. Mitchell State Park in May 2002, returning to plots used by Nicholas (1992) in the

1980s. To the best of our knowledge no recent surveys had been performed within the high

elevation spruce-fir ecosystem of the Black Mountains in approximately 14 years. In order

to characterize long term changes in forest structure and community dynamics another in-

depth survey was needed to ensure continuity of monitoring. We wished to quantify any

further deterioration or changes in spruce-fir forest composition and compare the new data to

existing historical data and forecasted trends. Additionally, we wished to evaluate the

present level of balsam woolly adelgid infestation on Fraser fir. We hypothesized several

trends would be evident including continued collapse of mature Fraser fir and red spruce, an

increase in density of young Fraser fir especially in smaller size classes, a decrease in mature

red spruce density due to thinning shock, and an increase of yellow birch at higher altitudes.

This study was accomplished through the cooperation of the North Carolina State University

(NCSU) Departments of Plant Pathology and Soil Science, and the USDA Forest Service

Southern Global Change Program. This paper reports the findings made during the resurvey

of those plots during the summers of 2002-3.

11

1.1.2 Site Location and Description

The Black Mountains are situated in western North Carolina, 40 kilometers northeast of the

city of Asheville NC, at approximately 35°35’ N, 82°15’ W (Figure 1.1). Mt. Mitchell, at

2037 m, is the highest peak in eastern North America and is only one of several high peaks

within the Black Mountain range. The bulk of the range, and thus our study area, is oriented

roughly north-south, extending from Celo Knob in the north to Black Mountain Gap in the

south (Figure 1.2). The Black Mountains are part of the Southern Appalachian and Blue

Ridge Mountain ecophysiographic zone, which extends northeast from northern Georgia to

northern Virginia. Approximately 15 percent of the high elevation spruce-fir forests of the

Southern Appalachians occur in the Black Mountains, with the majority of the remainder

occurring in the Great Smoky Mountains and the Balsam Mountains, which lie to the south

and west in Tennessee and North Carolina.

12

FIGURE 1.1 LOCATION OF MT. MITCHELL AND THE BLACK MOUNTAINS IN RELATION TO ASHEVILLE IN WESTERN NORTH CAROLINA.

13

1.2 MATERIALS and METHODS

1.2.1 Original Plot Establishment

In 1985 and 1986, a stratified, randomly located, system of 40 permanent plots was

established in the Black Mountains by Nicholas (1992) of the Virginia Polytechnic Institute

(VPI). Stratification factors included elevation (four classes: 1525, 1675, 1830, 1980 m, +/-

30 m [5000, 5500, 6000, 6500 ft +/- 100 ft]), exposure to prevailing winds, and topographic

type (ridge/slope/draw) with three replicates per stratal combination wherever possible.

Permanent plot size was a 20 x 20 m projected quadrangle (0.04 ha [0.10 ac]), corrected for

slope angle, and staked with PVC pipe in each corner to denote plot boundaries. The a priori

definition of the southern spruce-fir forest type used by Nicholas required that plots have at

least 25 percent spruce and/or fir present (live) or former (dead standing stems) canopy

coverage. Overstory strata were defined as woody stems with diameter at breast height (dbh)

≥ 5.0 cm. Measurements by species included dbh (to nearest mm), crown condition

evaluation (Class 1: 100-90% needles or leaves intact; Class 2: 90-50% intact; Class 3:49-1%

intact; and Class 4: dead), and disturbance symptomology (signs and symptoms of disease or

damage to stems and crowns) for every tree on each plot. Site data recorded at each plot

included elevation, slope percent, aspect, and topographic features.

1.2.2 Field Sampling The main sampling periods extended from the 18th of June to the 14th of September in 2002

and from the 29th of May to the 1st of August in 2003. We relocated and resurveyed 28 of the

original 40 VPI plots during the summers of 2002 and 2003. The locations of the 28

recovered plots throughout the Black Mountains are shown in Figure 1.2. Plots were found

14

using written directions, topographic maps, and hand drawn maps, when available. The

2002-3 surveys attempted to re-evaluate each plot according to the original methods.

FIGURE 1.2 LOCATION OF THE 28 SURVEYED SPRUCE-FIR PLOTS THROUGHOUT THE BLACK MOUNTAINS. PLOTS

ARE REPRESENTED BY YELLOW SQUARES.

15

Data recorded for each plot included location coordinates and elevation determined

by global positioning system (GPS) and/or USGS topographic map, slope percent, aspect of

plot face, live and dead basal area estimation using a forester’s prism, a list of woody and

herbaceous species within the plot, an estimation of dead woody debris present, a brief

description of the topography and groundcover, and an estimation of canopy closure

percentage. Plots that were damaged or vandalized were repaired (i.e. corner stakes

replaced) when necessary, making sure to correct for slope angles. A new set of written

directions as well as new hand drawn maps were made to augment GPS coordinates and

allow for ease in relocating for future surveys. Weather conditions during sampling were

noted and included temperature, precipitation (if in progress), cloud cover, and wind.

Resurveyed trees were identified by their tag number, measured for dbh to the nearest

mm, and evaluated for crown damage. Ingrowth trees (those that met the original size

criteria [≥ 5.0 cm-dbh) were assigned a number, tagged at the base, measured for dbh to the

nearest mm, and evaluated for crown damage. Each qualified tree within the plot was

evaluated on the 4-point scale equivalent to the one discussed above (Class 1: 0-10% crown

damage, Class 2: 11-50% crown damage, Class 3: 51-99% crown damage, and Class 4:

standing dead) to estimate individual decline or damage percentage of the crown (Figure

1.3). Every tree crown was assigned a position within the forest canopy (dominant,

codominant, intermediate, or suppressed) as determined by estimation of the canopy height.

Each tree bole and crown was visually examined for abnormalities such as decay, insect

infestation, fungi, excessive foliar chlorosis and/or necrosis, and crown and stem damage.

All qualitative observations were made by at least 2 technicians for each tree, with

16

occasionally a third technician consulted to confirm judgment in case of disagreement. All

data were subsequently entered into a spreadsheet for analysis.

Furthermore, on many sites, two soil samples (following NAPAP protocols) were

taken on each side of the plot along a common elevational gradient. On many of the same

sites, foliar samples of each dominant tree species were taken from the lower canopy when

possible. Samples were returned promptly to the laboratory at NCSU for processing and

chemical analysis. Analysis, results, and discussion of these samples will not be further

addressed in this paper.

FIGURE 1.3 EXAMPLES OF CROWN CLASS 1-4 RATINGS ON SPRUCE AND FIR TREES.

Class 1

Class 3 Class 4

Class 2

17

1.2.3 Analysis

Tree species considered for statistical analysis include red spruce (Picea rubens), Fraser fir

(Abies fraseri), and yellow birch (Betula lutea). Mountain-ash (Sorbus americana) and

rhododendron (Rhododendron maximum and R. catawbiense) although common, were

excluded due to the amount of prolific basal sprouting, low basal area contribution to the

total, and failure of each species to reach true canopy codominance in most cases. Plot level

calculations of live and dead basal area (m2/ha), live and dead stem density (stems/ha), and

crown class for each species were made for comparison with the previous survey. Raw data

from the 1985-6 survey were obtained from the previous investigators at VPI and compiled

to summarize the parameters listed above for each species at the plot level. Plots were then

paired for statistical analysis using paired t-testing (Battles et al. 2003) in order to determine

the statistical significance of the difference of each parameter mean as stratified by elevation

or aspect. Increment classes above 5 cm-dbh, in 10 cm-dbh increments, were made for

comparison and assessment of size distribution of each species.

18

1.3 RESULTS

1.3.1 General Description of Weather and Plot Conditions Throughout the summers of 2002 and 2003 we experienced a variety of weather events, with

seasons of highly variable humidity, precipitation, wind speed, and temperature. Weather

conditions were generally mild for summer at this latitude as midday temperatures ranged

from 7 C (45F) to 27 C (80F). Wind speeds varied from very light to damaging in isolated

locations during thunder storms. Sampling did not occur when there was probability of close

lightning strikes or when wind speed was high enough to be considered hazardous.

Precipitation was highly variable, depending mainly on the prevailing air systems, which

tend to bring in significant amounts of moisture to the Southern Appalachians in the summer.

The stand condition and vegetation of each plot varied tremendously for a supposed

single forest type and in fact was representative of several subtypes within the classification

of spruce-fir forest (Schafale and Weakley 1990). Over the entire span of the Black

Mountains we encountered sparse sites that had as few as 9 live standing trees (B-42 at 1850

m [6070 ft] with 6 live fir and 1 live spruce) to plots that contained a thick and regenerating

low canopy of 250 fir saplings (B-53 at 1950 m [6400 ft]). Rather than a continuous type or

subtypes of even aged forest we discovered a mosaic of forest types and conditions. The

types of conditions we observed can be categorized as severely damaged with most overstory

trees dead or dying, moderately damaged sites with some recently dead trees, healthy plots

with little change or some growth in overstory structure, and regenerating stands of dominant

trees under a mostly destroyed canopy.

Severely damaged sites were found at plots B-7, 8, 11, 42, and 47. Here crown

damage was extensive with most overstory conifers dead leaving the canopy at least 90

19

percent open. These sites appear to have either recently collapsed with no evidence of

regeneration or have not shown any recovery from a previous decline or mortality event.

Parameter trends include increases in dead stem density and dead basal area, with reductions

in live stem density and basal area from the previous survey in 1986. Most severely

damaged sites have a lush understory and groundcover ranging from rhododendron or dense

canes of blackberry to ferns and other low lying herbs such as Houstonia sp. L. and

Impatiens pallida Nuttall. For example plot B-11 is now a “graveyard” of recently dead

formerly dominant large red spruce trees with an incredibly thick layer of rhododendron.

Plot B-7 went from having 77 live and 28 dead firs in 1986 to 63 dead and 14 live but sickly

fir trees by 2002. The canopy at this site is mostly gone and the groundcover is lush with

ferns with few seedlings.

Moderately damaged sites were found at plots B-34, 44, 48, 49, 50, and 51. These

stands have trees that are exhibiting a generally declining condition. The understory, while

not thick and copious with seedlings, is recruiting live stems but at a slower rate than

dominant overstory trees are dying and falling. Some of this slow rate of regeneration may

be caused by shading of seedlings by blackberry. Characteristics of these stands are large

openings, sparse and patchy seedling and understory growth, many large and dead standing

and fallen trees throughout the plot, and generally poor canopy condition.

Plots that appeared stable in condition or what was determined to have slight changes

in stand parameters included B-4, 6, 12, 16, 22, 30, 33, 35, 36, 46, and 56. A common trend

for these plots was an increase in live basal area and a reduction in overall stem density and

dead basal area. The overstory spruces and firs tended to be large and exhibiting good vigor,

providing a mostly closed canopy. The understory was generally sparse but sometimes thick

20

with a few slowly growing intermediate sized or suppressed trees awaiting openings in the

canopy before realizing their full potential. Grasses and moss were the dominant type of

groundcover. Birches and maples were common as well as a high number of dying pin

cherries. These sites appear to be close to reaching a climax of healthy spruce-birch or

spruce-fir forest in the near future.

Plots with trends indicating rapid recovery with large amounts of regeneration under a

dead or dying overstory include B-17, 18, 40, 52, 53, and 54. These plots had high live stem

densities usually exceeding 3000 stems/ha giving evidence as vigorous recovery. Extreme

examples of this trend are plots B-52 and 53, both at 1980 m, where live fir densities rose

from 1,275 to 5,700 and 800 to 6,200 stems/ha respectively. Other parameter trends include

a reduction in dead stem density and basal area, and an increase in live basal area. These

plots were at higher elevations and were sites of recent severe mortality, creating an almost

completely open canopy. Fraser fir tends to be the primary contributor to sapling density on

these sites, with a minor amount of regenerating spruce. Sites like this should experience a

reduction in live stem density over the next two decades because of competition induced

mortality.

The following results are stratified by elevation zone (1525, 1675, 1830, and 1980 m)

and by aspect (east and west) where deemed applicable. We achieved a representative

resample of each elevation and aspect when possible. At 1525 and 1980 m we surveyed 4

plots each. At 1675 and 1830 m we resurveyed 7 and 13 plots respectively. Each parameter

trend is discussed in detail below.

21

1.3.2 Live Stem Density Total live stem density changes were noticeable for most elevation classes with the most

remarkable differences at the highest elevation zone (Table 1.1 and Figures 1.4-1.6).

Significant changes at 1980 m include mean total live stem density, which underwent a 385

percent increase from the previous survey in 1986. The bulk of this change at 1980 m can be

attributed to Fraser fir, which showed a large significant increase in live trees from 919 to

4156 stems/ha (p < 0.10) in 2003. At the same time red spruce increased noticeably at the

same elevation. This high-density increase can be attributed mainly to two of the four plots

that had very high amounts of fir recruitment with densities approaching and exceeding 6000

stems/ha. On the four plots at this elevation yellow birch was not found in the latest survey.

TABLE 1.1 LIVE STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR,

YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

Changes at the lower elevations were much less dramatic but show a few differing

trends. Stands at 1525 m showed a decrease in total live stem density from 869 to 706

stems/ha, attributed mainly to a 27 percent drop in red spruce density. One stand (B-11) in

particular at this altitude lost over two thirds of red spruce live stems. The influence of red

spruce live density drop was somewhat alleviated by slight increases in fir and birch

densities. Stands at 1675 m underwent the most noticeable reduction in total live stem

ELEVATION 1525 m 1675 m 1830 m 1980 m (N = 4 plots) (N = 7 plots) (N = 13 plots) (N = 4 plots) Live Stem Density (stems/ha)Year Sampled 1986 2003 1986 2003 1986 2003 1986 2003

Red SpruceFraser FirYellow Birch

Total

694 ± 1336 ± 6

69 ± 39

869 ± 92

506 ± 13713 ± 7

81 ± 46

706 ± 122

761 ± 15964 ± 32

486 ± 134

1539 ± 292

729 ± 187179 ± 87

361 ± 108a

1346 ± 335

479 ± 118683 ± 246169 ± 42

1619 ± 226

454 ± 110765 ± 214148 ± 36

1633 ± 287

75 ± 10919 ± 240

25 ± 25

1181 ± 288

275 ± 1884156 ± 1105b

0 ± 0

4556 ± 1088b

a. Significant from previous value at p < 0.05b. Significant from previous value at p < 0.10a. Significantly different from previous value at p < 0.05b. Significantly different from previous value at p < 0.10

22

density; however, most of this change was due to yellow birch. Yellow birch live density

significantly dropped 25 percent (p < 0.05) from the previous survey with lower densities in

all plots sampled. Red spruce live stem density was slightly less while fir density at this

elevation almost tripled, rising from 64 to 179 stems/ha. Stands at 1830 m overall showed a

slight increase in live stem density from the previous survey. The species differed in change

however, with small decreases for red spruce and yellow birch and a rise in mean fir density

from 683 to 765 stems/ha.

0

100

200

300

400

500

600

700

800

900

1000

1525 1675 1830 1980 East West

Elevation (meters) and Aspect

Den

sity

(ste

ms/

ha)

19862003

FIGURE 1.4 RED SPRUCE MEAN LIVE STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND ASPECT AT THE BLACK MOUNTAINS, NC.

23

0

1000

2000

3000

4000

5000

6000

1525 1675 1830 1980 East West


Den

sity

(ste

ms/

ha)

19862003

FIGURE 1.5 FRASER FIR MEAN LIVE STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION

AND ASPECT AT THE BLACK MOUNTAINS, NC.

0

100

200

300

400

500

600

700

800

900

1000

1525 1675 1830 1980 East West


Den

sity

(ste

ms/

ha)

19862003

FIGURE 1.6 YELLOW BIRCH MEAN LIVE STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION


When stratified by aspect, live stem density underwent many significant changes

from 1986 to 2003 (Table 1.2 and Figures 1.4–1.6). For east facing sites the mean total live

stem density increased by 71 percent from 1266 to 1775 stems/ha, despite significant

24

moderate drops in live stem density for red spruce and yellow birch (p < 0.05). The

pronounced rise in Fraser fir live density offset these reductions by significantly rising from

368 to 1064 stems/ha (p < 0.10). The majority of this rise in fir density is primarily due to

two east facing plots at 1980 m. For west facing sites there was also a general upward trend

in mean live stem densities, with only yellow birch showing a significant drop from 314 to

244 stems/ha (p < 0.10). West facing Fraser fir and red spruce live stem densities rose 27

and 36 percent, respectively.

TABLE 1.2 LIVE AND DEAD STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ASPECT, FOR RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

1.3.3 Dead Stem Density

Although few statistically significant changes occurred for each species and the overall total

from 1986 to 2003, there were some notable trends in mean dead stem density. The most

dramatic change occurred in the highest elevation plots at 1980 m (Table 1.3 and Figures 1.7-

1.9). Spruce, fir, and birch mean dead stem densities all dropped by roughly two-thirds at

this altitude. Fraser fir showed the greatest reduction in standing dead stems from 1163 to

288 stems/ha, however this is statistically insignificant. Plots at this elevation appeared to

have lost most of their previously dead stems as they have dropped out of the canopy.

p p p ASPECT East West East West (N = 19 plots) (N = 9 plots) (N = 19 plots) (N = 9 plots) Live Stem Density (stems/ha) Dead Stem Density (stems/ha)Year Sampled 1986 2003 1986 2003 1986 2003 1986 2003


Total

543 ± 80368 ± 162166 ± 43

1266 ± 145

436 ± 67a

1064 ± 387b

136 ± 36a

1775 ± 357

478 ± 178669 ± 204314 ± 113

1775 ± 270

650 ± 190b

850 ± 344244 ± 84b

1997 ± 472

88 ± 19239 ± 14588 ± 23

611 ± 153

109 ± 26154 ± 7432 ± 8a

345 ± 72

53 ± 30381 ± 11656 ± 27

664 ± 136

58 ± 29447 ± 15039 ± 21

622 ± 134a. Significant from previous value at p < 0.05b. Significant from previous value at p < 0.10a. Significantly different from previous value at p < 0.05b. Significantly different from previous value at p < 0.10

25

TABLE 1.3 DEAD STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

Results vary by species at the other elevation zones. Red spruce at 1525 m doubled

its standing dead stems in most of plots surveyed at this altitude and overall the mean

increased from 94 to 206 stems/ha. However at 1675 and 1830 m red spruce mean dead stem

density underwent very little change. No dead Fraser fir stems occurred at 1525 m due to

few live fir stems, thus dead stem recruitment, at this altitude. Conversely, the amount of

new standing dead fir trees at 1675 and 1830 m did increase, especially at the latter elevation

where fir is a codominant canopy species. Mean dead fir density at 1830 m rose from 252 to

413 stems/ha with many plots showing a doubling or more of its dead stems. Dead fir stem

increases on plots at this altitude are from a mix of dead older canopy trees and competition

induced mortality among saplings. As noted above and at the other remaining elevation

zones, yellow birch underwent a reduction in standing dead stems. Most notably, yellow

birch dead stem density significantly dropped by almost 75 percent from 106 to 27 stems/ha

at 1830 m (p < 0.05).

ELEVATION 1525 m 1675 m 1830 m 1980 m (N = 4 plots) (N = 7 plots) (N = 13 plots) (N = 4 plots) Dead Stem Density (stems/ha)Year Sampled 1986 2003 1986 2003 1986 2003 1986 2003


Total

94 ± 340 ± 06 ± 6

150 ± 42

206 ± 800 ± 00 ± 0

225 ± 78

89 ± 347 ± 7

93 ± 30

404 ± 76

129 ± 5161 ± 3379 ± 24

325 ± 76

65 ± 23252 ± 80106 ± 32

656 ± 108

60 ± 19413 ± 14227 ± 9a

587 ± 129

75 ± 741163 ± 631

31 ± 31

1406 ± 649

25 ± 25288 ± 9713 ± 12

338 ± 114a. Significant from previous value at p < 0.05a. Significantly different from previous value at p < 0.05

26

0

50

100

150

200

250

300

350

1525 1675 1830 1980 East West


Den

sity

(ste

ms/

ha)

19862003

FIGURE 1.7 RED SPRUCE MEAN DEAD STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION


0

400

800

1200

1600

2000

1525 1675 1830 1980 East West


Den

sity

(ste

ms/

ha)

19862003

FIGURE 1.8 FRASER FIR MEAN DEAD STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION


27

0

40

80

120

160

200

1525 1675 1830 1980 East West


Den

sity

(ste

ms/

ha)

19862003

FIGURE 1.9 YELLOW BIRCH MEAN DEAD STEM DENSITY (STEMS/HA) FOR 1986 AND 2003 STRATIFIED BY

ELEVATION AND ASPECT AT THE BLACK MOUNTAINS, NC.

When stratified by aspect very few statistically significant changes occurred in dead

stem density from 1986 to 2003 (Table 1.2 and Figures 1.7-1.9). The overall mean totals of

dead stems in the east underwent a marked decrease from 611 to 345 stems/ha, while west

facing sites only showed a slight decrease from 664 to 622 stems/ha. These trends mainly

follow the dead fir density change, which dropped 85 stems/ha in the east but rose by 66

stems/ha in the west. The response in dead fir density offset the minor changes in dead stems

from red spruce, which increased slightly on both aspects, and yellow birch, which decreased

significantly from 88 to 32 stems/ha (p < 0.05) on east facing sites.

1.3.4 Live Basal Area

Overall there is no statistically significant change in mean live basal area for any of the

species or the total when stratified by elevation (Table 1.4 and Figures 1.10-1.12). As with

live stem density, red spruce live basal area is on the decline at 1525 m from 50.2 to 43.4

28

m2/ha. This is primarily due to one collapsing stand (B-11) at this altitude. At the mid-

elevation stands (1675 and 1830 m) there were only slight increases, with the exception of a

slight decrease in red spruce live basal area from 34.4 to 31.7 m2/ha at 1675 m; all of these

differences, however, are not significantly different. Most plots at 1675 m actually showed

an increase in live basal area, but the drop in overall mean from 46.3 to 42.5 m2/ha was

primarily due to the collapse of red spruce on only one plot (B-47) at this altitude. At 1980

m Fraser fir showed a very substantial increase in basal area from 17.9 to 33.0 m2/ha mainly

due to the quadrupling of live stems ≥ 5 cm-dbh at this elevation. Vigorous regeneration of

fir saplings on two of the four plots at this altitude is responsible for this trend. Additionally,

yellow birch disappeared from the 1980 m plots since the previous survey in 1986.

TABLE 1.4 LIVE BASAL AREA WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

When stratified by aspect there were just a few significant differences in live basal

area as shown in Table 1.5 and Figures 1.10-1.12. On the east facing sites Fraser fir showed

a significant rise in mean live basal area from 4.0 to 10.1 m2/ha (p < 0.05). Fraser fir at the

west facing sites showed a moderate decrease from 18.1 to 13.0 m2/ha. Both of these trends

had fir mean live basal area approaching a similar value as the gap between east and west

facing decreased from 14.1 to 3.1 m2/ha. At the same time the gap between red spruce values

when compared by aspect shrank from 16.5 to 11.2 m2/ha as the mean of east facing sites

ELEVATION 1525 m 1675 m 1830 m 1980 m (N = 4 plots) (N = 7 plots) (N = 13 plots) (N = 4 plots) Live Basal Area (m2/ha)Year Sampled 1986 2003 1986 2003 1986 2003 1986 2003


Total

50.2 ± 10.00.0 ± 0.03.1 ± 1.8

59.4 ± 7.2

43.4 ± 5.50.0 ± 0.03.8 ± 2.2

54.4 ± 7.3

34.4 ± 8.40.7 ± 0.47.3 ± 1.6

46.3 ± 6.1

31.7 ± 6.11.1 ± 0.58.6 ± 2.6

42.5 ± 5.9

13.7 ± 3.412.5 ± 4.03.1 ± 0.9

32.4 ± 2.3

17.6 ± 4.312.9 ± 3.33.9 ± 1.1

37.2 ± 3.7

3.4 ± 1.517.9 ± 5.50.2 ± 0.1

23.7 ± 6.1

4.8 ± 2.533.0 ± 5.70.0 ± 0.0

41.3 ± 3.6

29

slightly dropped and the mean of west facing sites significantly increased (p < 0.05). Overall

live basal area rose more on east facing plots (4.4 m2/ha) than west facing plots (0.3 m2/ha),

however neither of them significantly.

TABLE 1.5 LIVE AND DEAD BASAL AREA WITH STANDARD ERROR, STRATIFIED BY ASPECT, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

0

10

20

30

40

50

60

70

1525 1675 1830 1980 East West


Bas

al A

rea

(m2/

ha)

19862003

FIGURE 1.10 RED SPRUCE MEAN LIVE BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND

ASPECT AT THE BLACK MOUNTAINS, NC.

ASPECT East West East West (N = 19 plots) (N = 9 plots) (N = 19 plots) (N = 9 plots) Live Basal Area (m2/ha) Dead Basal Area (m2/ha)Year Sampled 1986 2003 1986 2003 1986 2003 1986 2003


Total

27.9 ± 4.64.0 ± 1.53.5 ± 0.7

39.2 ± 3.7

26.6 ± 3.710.1 ± 3.3a

4.1 ± 0.9

43.6 ± 2.7

11.4 ± 5.418.1 ± 5.44.1 ± 1.6

36.9 ± 4.1

15.4 ± 6.1a

13.0 ± 3.45.5 ± 2.3

37.2 ± 5.5

4.4 ± 1.34.4 ± 1.71.5 ± 0.4

14.1 ± 2.5

6.9 ± 2.53.4 ± 1.50.8 ± 0.3

12.1 ± 2.9

1.1 ± 0.69.1 ± 3.20.4 ± 0.2

13.0 ± 2.4

1.9 ± 1.015.0 ± 4.50.4 ± 0.3

18.4 ± 3.6a. Significant from previous value at p < 0.05a. Significantly different from previous value at p < 0.05

30

0

10

20

30

40

50

60

70

1525 1675 1830 1980 East West


Bas

al A

rea

(m2/

ha)

19862003

FIGURE 1.11 FRASER FIR MEAN LIVE BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND ASPECT AT THE BLACK MOUNTAINS, NC.

0

10

20

30

40

50

60

70

1525 1675 1830 1980 East West


Bas

al A

rea

(m2/

ha)

19862003

FIGURE 1.12 YELLOW BIRCH MEAN LIVE BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION


1.3.5 Dead Basal Area There were no statistically significant differences between the 1986 and 2003 surveys for

dead basal area when stratified by elevation (Table 1.6 and Figures 1.13-15). One or two

plots at their respective elevation zone primarily affected large changes in mean dead basal

31

area. At 1525 m red spruce at plot B-11 went from 4.8 to 51.9 m2/ha standing dead, resulting

in a 330 percent increase in overall dead basal area from 3.1 to 14.3 m2/ha. Changes at other

elevations were much less dramatic in scope. The rise in red spruce dead basal area at 1675

m was primarily due to the influence of only one stand (plot B-47), which underwent an

increase of dead spruce basal area of over 400 percent. Overall, at this altitude, dead basal

area rose slightly due to increases from all species. At 1830 m the results per species were

mixed as red spruce and yellow birch means in dead basal area went down and the Fraser fir

mean increased from 5.8 to 10.7 m2/ha (Table 1.6). This increase in fir dead basal area

offsets the decreases in the other species causing a slight rise in overall mean dead basal area

at this altitude. At 1980 m the trend for all species is downward, causing a drop in the mean

dead basal area from 29.4 to 16.6 m2/ha. This decrease was mainly influenced by the 37

percent drop in the mean fir dead basal area at this altitude, made possible by a single stand’s

(plot B-52) loss of all its dead stems and a drop in dead basal area from 32.0 to 0 m2/ha.

TABLE 1.6 DEAD BASAL AREA WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

ELEVATION 1525 m 1675 m 1830 m 1980 m (N = 4 plots) (N = 7 plots) (N = 13 plots) (N = 4 plots) Dead Basal Area (m2/ha)Year Sampled 1986 2003 1986 2003 1986 2003 1986 2003


Total

3.1 ± 1.10.0 ± 0.00.1 ± 0.1

4.6 ± 0.7

14.3 ± 12.30.0 ± 0.00.0 ± 0.0

15.2 ± 12.0

2.6 ± 0.90.2 ± 0.21.3 ± 0.5

7.9 ± 0.7

6.4 ± 2.70.6 ± 0.31.7 ± 0.8

10.0 ± 2.5

3.2 ± 1.55.8 ± 1.71.7 ± 0.6

14.9 ± 2.5

2.8 ± 0.810.7 ± 3.60.5 ± 0.2

15.2 ± 3.4

5.2 ± 5.122.0 ± 5.00.4 ± 0.3

29.4 ± 4.7

2.5 ± 2.413.9 ± 5.00.1 ± 0.1

16.6 ± 5.6

32

0

5

10

15

20

25

30

1525 1675 1830 1980 East West


Bas

al A

rea

(m2/

ha)

19862003

FIGURE 1.13 RED SPRUCE MEAN DEAD BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND


0

5

10

15

20

25

30

1525 1675 1830 1980 East West


Bas

al A

rea

(m2/

ha)

19862003

FIGURE 1.14 FRASER FIR MEAN DEAD BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION AND


33

0

5

10

15

20

25

30

1525 1675 1830 1980 East West


Bas

al A

rea

(m2/

ha)

19862003

FIGURE 1.15 YELLOW BIRCH MEAN DEAD BASAL AREA (M2/HA) FOR 1986 AND 2003 STRATIFIED BY ELEVATION


When stratified by aspect there were no statistically significant differences in dead

basal area between 1986 and 2003 (Table 1.5 and Figures 1.13-15). Results for the east-

facing sites had mixed results as Fraser fir and yellow birch means decreased with the red

spruce mean increasing slightly. Overall, there was just a modest decrease in standing dead

basal area for all plots with an east aspect. Results for west-facing sites mainly showed an

increase in dead basal area for these sites. Fraser fir dead basal area increased by 40 percent

from 9.1 to 15.0 m2/ha, greatly influenced by two plots, B-7 and 8, that had an increase of

32.0 and 17.0 m2/ha in standing dead wood respectively. Red spruce on these sites showed a

slight increase while yellow birch remained unchanged. Overall the east-facing sites appear

to show a 14 percent decrease in dead basal area, while west-facing sites are displaying a 41

percent rise in this parameter, neither statistically significant.

34

1.3.6 Crown Class Condition

Crown class was evaluated on every tree with ≥ 5 cm-dbh. Classes 1-3 are made up of live

trees and cumulatively are the components of live stem density. The breakdown of live stem

density into these separate classes allowed us to see the trends occurring within this

parameter a bit more closely. The results for Class 4 trees, those considered dead, were

discussed above in the results of dead stem density.

Crown Class 1

When stratified by elevation, the density (stems/ha) of Crown Class 1 trees declined

significantly at the lower elevation zones (p < 0.10 at 1525 m and p < 0.05 at 1675 m) and

greatly increased at 1980 m (Table 1.7). Red spruce Class 1 density significantly declined in

the three lower elevation zones with only a slight increase at 1980 m (p < 0.10). Red spruce

underwent a reduction in Class 1 trees at every elevation (Figure 16 a-d). The most dramatic

drop in Class 1 red spruce trees was at 1525 m where density dropped from 550 to 188

stems/ha and from 70 percent in 1986 to 26 percent in 2003. This change was highly

influenced by a single plot (B-11) where red spruce was in rapid decline. Fraser fir Class 1

density change varied by elevation but showed a large (but not significant) increase from 525

to 2669 stems/ha at 1980 m (Table 1.7). This high density was mainly due to rapid fir

regeneration on two plots at this altitude. Figures 17 a-c display the drop in Class 1 trees as a

percentage of all standing fir at 1525-1830 m, while Figure 17 d shows the rise in Class 1 fir

at 1980 m. Change in yellow birch density was only significant (p < 0.05) at 1675 m, where

Class 1 trees dropped from 439 to 268 stems/ha (Table 1.7).

35

TABLE 1.7 CROWN CLASS 1 STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

When stratified by aspect (Table 1.8 and Figures 1.16-1.18), only Fraser fir shows an

increase in Class 1 density from 301 to 653 stems/ha on east facing sites. However, as a

percentage of standing trees (Figure 17e), fir shows very little change in Class 1 trees

illustrating that not all regeneration on these sites is in the least damaged crown condition.

Red spruce underwent a significant (p < 0.05) reduction in Class 1 trees from 466 to 188

stems/ha and yellow birch density dropped slightly on the same sites. All species, as well as

the total, displayed a decrease in Class 1 stem density on west facing sites with only yellow

birch having a significant (p < 0.10) reduction. This trend lowered the gap between east

facing and west facing sites from 348 stems/ha in 1986 to 38 stems/ha in 2003 as Class 1 tree

densities approached similar values.

ELEVATION 1525 m 1675 m 1830 m 1980 m (N = 4 plots) (N = 7 plots) (N = 13 plots) (N = 4 plots) Stem Density (stems/ha)Year Sampled 1986 2003 1986 2003 1986 2003 1986 2003


Total

550 ± 1206 ± 5

63 ± 38

681 ± 70

188 ± 43b

0 ± 081 ± 45

344 ± 78b

714 ± 16357 ± 30

439 ± 125

1343 ± 288

421 ± 108a

79 ± 38268 ± 85a

829 ± 228a

419 ± 105535 ± 225108 ± 30

1202 ± 213

217 ± 60b

319 ± 8598 ± 25

810 ± 175

69 ± 15525 ± 14313 ± 13

706 ± 150

88 ± 252669 ± 1093

0 ± 0

2863 ± 1115a. Significantly different from previous value at p < 0.05.b. Significantly different from previous value at p < 0.10.

36

FIGURE 1.16 A-F CHANGE IN RED SPRUCE CROWN CLASS FOR EACH ELEVATION ZONE AND ASPECT. TABLE 1.8 CROWN CLASS 1 STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ASPECT, OF RED SPRUCE,

FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

1525 meters N=4

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

1986

2003

1675 meters N=7

0

20

40

60

80

100

1 2 3 4

Crown Class

Perc

ent

1986

2003

1830 meters N=13

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

19862003

West Aspect N=9

0

20

40

60

80

100

1 2 3 4

Crown Class

Perc

ent

1986

2003

East Aspect N=19

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

1986

2003

1980 metersN=4

0

20

40

60

80

100

1 2 3 4

Crown ClassPe

rcen

t

1986

2003

a b

c d

e f

A S P E C T E a s t W e s t (N = 1 9 p lo t s ) ( N = 9 p l o ts ) S t e m D e n s i t y ( s t e m s /h a )Y e a r S a m p l e d 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

R e d S p ru c eF r a s e r F i rY e l l o w B ir c h

T o ta l

4 6 6 ± 7 03 0 1 ± 1 5 01 1 8 ± 3 8

9 8 0 ± 1 4 3

1 8 8 ± 2 5 a

6 5 3 ± 2 9 09 1 ± 2 5

1 0 2 9 ± 2 8 5

4 5 3 ± 1 7 34 1 7 ± 1 3 02 8 1 ± 1 0 3

1 3 2 8 ± 2 4 3

3 6 7 ± 1 1 53 3 1 ± 1 3 01 9 4 ± 6 8 b

1 0 6 7 ± 2 6 3

a . S ig n i f i c a n t ly d i f f e r e n t fr o m p r e v i o u s v a lu e a t p < 0 .0 5b . S ig n i f i c a n t ly d i f f e r e n t fr o m p r e v i o u s v a lu e a t p < 0 .1 0

37

FIGURE 1.17 A-F CHANGE IN FRASER FIR CROWN CLASS FOR EACH ELEVATION ZONE AND ASPECT.

Crown Class 2

Table 1.9 and Figures 1.16-1.18 show an overall rise of Class 2 density (stems/ha) for

all species at every elevation with the exception of yellow birch at 1525 and 1980 m. Red

spruce showed significantly large increases at 1675 m (p < 0.10) and 1830 m (p < 0.05)

where Class 2 density rose by 400 percent or more from 1986 to 2003. At 1980 m, Class 2

density for spruce and fir also increased greatly, but with high variance and therefore

statistically insignificant. The high density of Class 2 fir trees at 1980 m (Table 1.9) is

primarily due to regeneration on two plots at this elevation.

1525 meters N=4

0

20

40

60

80

100

1 2 3 4

Crown Class

Perc

ent

1986

2003

1675 meters N=7

0

20

40

60

80

100

1 2 3 4

Crown Class

Perc

ent

1986

2003

1980 meters N=4

0

20

40

60

80

100

1 2 3 4

Crown ClassP

erce

nt

1986

2003

1830 metersN=13

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

1986

2003

West Aspect N=9

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

1986

2003

East Aspect N=19

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

1986

2003

a

c

e

d

b

f

38

FIGURE 1.18 A-F CHANGE IN YELLOW BIRCH CROWN CLASS FOR EACH ELEVATION ZONE AND ASPECT. TABLE 1.9 CROWN CLASS 2 STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE,


When stratified by aspect (Table 1.10 and Figures 1.16-1.18), the upward trend in

Crown Class 2 density (stems/ha) is also very pronounced. Red spruce, Fraser fir, and the

1525 metersN=4

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

1986

2003

1675 meters N=7

0

20

40

60

80

100

1 2 3 4

Crown Class

Perc

ent

1986

2003

1830 meters N=13

0

20

40

60

80

100

1 2 3 4

Crown Class

Perc

ent

1986

2003

1980 meters N=4

0

20

40

60

80

100

1 2 3 4

Crown ClassPe

rcen

t

1986

2003

East Aspect N=19

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

1986

2003

West Aspect N=9

0

20

40

60

80

100

1 2 3 4

Crown Class

Per

cent

1986

2003

a

e f

dc

b



Total

138 ± 380 ± 06 ± 5

181 ± 40

256 ± 7513 ± 50 ± 0

300 ± 60a

43 ± 187 ± 529 ± 8

150 ± 35

246 ± 88b

79 ± 4857 ± 25

396 ± 103b

48 ± 15121 ± 4342 ± 18

325 ± 65

175 ± 60a

287 ± 10044 ± 14

581 ± 113b

6 ± 5306 ± 128

6 ± 5

356 ± 135

175 ± 1631181 ± 485

0 ± 0

1375 ± 620a. Significantly different from previous value at p < 0.05b. Significantly different from previous value at p < 0.10

39

overall total displayed significant (p < 0.05) increases from 70 to 187, 46 to 295, and 216 to

553 stems/ha respectively on east facing sites. Furthermore, Class 2 red spruce on west

facing sites increased significantly (p < 0.10) from 19 to 242 stems/ha. Likewise, Class 2 fir

density rose from 219 to 383 stems/ha on west facing plots. Combined, the total change in

Class 2 stem density on west facing sites was an almost 100 percent increase from the

previous survey. The difference between stands facing east and those facing west increased

from 153 stems/ha in 1986 to 172 stems/ha in 2003.

TABLE 1.10 CROWN CLASS 2 STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ASPECT, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

Crown Class 3

Overall the densities and percentages of Crown Class 3 trees remain relatively low as

this classification (51 to 99 percent crown damage) is a transition as trees move from the

hardier Class 1 and 2 trees to dead Class 4 trees. Table 1.11 shows a rising trend in Class 3

densities at all elevations when all species are taken into account with significant increases at

1525, 1675, and 1830m. Class 3 red spruce densities changed significantly (p < 0.10) at

1525 and 1675 m where increases were 57 stems/ha each. Increases in Class 3 fir densities

were only significant at 1830 m (p < 0.05) where the rise was 133 stems/ha from 1986 to

A S PE C T E a st W est (N = 19 p lo ts) (N = 9 p lo ts) S tem D en sity ( stem s/ha)Y ear Sam pled 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

R ed Spru ceFraser F irY ello w B irch

T ota l

7 0 ±1 34 6 ± 2 33 7 ± 1 3

2 1 6 ± 3 0

1 8 7 ± 4 3 a

2 9 5 ± 1 0 5 a

3 4 ± 5

5 5 3 ± 1 0 0 a

1 9 ± 1 32 1 9 ± 6 8

1 1 ± 5

3 6 9 ± 1 0 0

2 4 2 ± 9 3 b

3 8 3 ± 2 2 53 6 ± 2 0

7 2 5 ± 2 8 0

a. Sig nificantly diffe rent fro m previou s va lu e a t p < 0 .0 5b. Sig nificantly diffe rent fro m previou s va lu e a t p < 0 .1 0

40

2003 (Table 1.11). Increases in Class 3 yellow birch densities were only significant at 1675

m (p < 0.05) where the rise was 32 stems/ha (Table 1.11)

As a function of aspect (Table 1.12), Class 3 density almost tripled for both east and

west facing sites. Fraser fir, responsible for the majority of the total value, displayed the only

significant rise in Class 3 density from 21 to 117 (p < 0.10) and 33 to 136 (p < 0.50) stems/ha

on east and west aspect plots respectively. The difference in Class 3 density between east

and west facing sites remained relatively unchanged as both aspects rose by similar amounts.

TABLE 1.11 CROWN CLASS 3 STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ELEVATION, OF RED SPRUCE, FRASER FIR, YELLOW BIRCH, AND ALL OVERSTORY SPECIES FOR 28 PERMANENT PLOTS AT THE BLACK MOUNTAINS, NC.

TABLE 1.12 CROWN CLASS 3 STEM DENSITY WITH STANDARD ERROR, STRATIFIED BY ASPECT, OF RED SPRUCE,




Total

6 ± 50 ± 00 ± 0

6 ± 5

63 ± 30b

0 ± 00 ± 0

63 ± 30b

4 ± 30 ± 04 ± 3

46 ± 15

61 ± 25b

21 ± 1336 ± 13a

121 ± 38a

12 ± 527 ± 819 ± 8

92 ± 40

62 ± 23a

160 ± 53a

6 ± 5

242 ± 110a

0 ± 088 ± 636 ± 5

119 ± 85

13 ± 8306 ± 160

0 ± 0

319 ± 158a. Significantly different from previous value at p < 0.05b. Significantly different from previous value at p < 0.10

p p A S P E C T E a s t W e s t (N = 1 9 p l o t s ) ( N = 9 p lo t s ) S t e m D e n s i t y ( s t e m s /h a )Y e a r S a m p l e d 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

R e d S p r u c eF r a s e r F i rY e l l o w B i r c h

T o ta l

8 ± 32 1 ± 1 31 1 ± 5

7 0 ± 2 0

6 1 ± 1 81 1 7 ± 4 8 b

1 1 ± 5

1 9 3 ± 4 8 b

6 ± 53 3 ± 1 01 1 ± 8

7 8 ± 2 0

4 2 ± 1 51 3 6 ± 4 0 a

1 4 ± 8

2 0 6 ± 4 8 a

a . S ig n i f i c a n t ly d i f f e r e n t fr o m p r e v i o u s v a lu e a t p < 0 .0 5b . S ig n i f i c a n t ly d i f f e r e n t fr o m p r e v i o u s v a lu e a t p < 0 .1 0

41

1.3.7 Diameter Class Change per Species

For statistical significance of the mean parameter totals per species as stratified by elevation

refer back to previous sections. Although not analyzed statistically for differences between

surveys, the main purpose of this section was to observe the change in growth patterns and

recruitment of stems and basal area as a function of diameter size class.

Red Spruce

At 1525 m, red spruce appears to be lacking recruitment of new stems, resulting in a

reduction in live stem density and basal area (Tables 1.13 and 1.14) in the three lowest

diameter classes from 1986 to 2003. There was an especially sharp drop in live stem density

and basal area for stems 15 to 25 cm-dbh. At the same time at this elevation there were

increases in every diameter class for dead stem density and basal area (Tables 1.15 and 1.16).

Red spruce stands at this altitude appear to be aging and increasing the stock of dead stems.

Nicholas (1992) projected reductions in red spruce basal area for every diameter class at this

elevation by 2009 and our results show that this trend is occurring for most sites at this

elevation.

TABLE 1.13 RED SPRUCE LIVE STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 p lo ts ) (N = 1 3 p lo ts ) (N = 4 p lo ts )D ia m ete r C la s s(c m -d b h ) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

5 5 +

T o ta l

1 6 31 3 12 1 31 2 54 41 9

6 9 4

1 1 33 8

1 6 91 3 13 81 9

5 0 6

4 0 41 4 31 0 45 04 61 4

7 6 1

4 4 31 1 86 13 65 02 1

7 2 9

2 8 11 2 73 82 382

4 7 9

2 1 31 2 57 32 31 36

4 5 4

4 41 90066

7 5

2 3 81 96606

2 7 5

42

TABLE 1.14 RED SPRUCE LIVE BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

TABLE 1.15 RED SPRUCE DEAD STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY

DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. TABLE 1.16 RED SPRUCE DEAD BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY

DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

At 1675 m, red spruce is showing some signs of recruitment as live density and basal

area of stems in the 5 to 15 cm-dbh range were both increasing. The mid-range diameter

classes showed marked reductions in live basal area and live stem density. Dead stem

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo t s ) (N = 7 p lo ts ) (N = 1 3 p lo ts ) (N = 4 p lo ts )D ia m et er C la s s(c m -d b h ) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

5 5 +

T o ta l

1 .15 .1

1 5 .61 5 .28 .25 .0

5 0 .1

0 .91 .2

1 2 .01 6 .27 .35 .7

4 3 .3

2 .64 .77 .46 .38 .47 .5

3 7 .0

3 .03 .54 .24 .69 .76 .9

3 2 .0

2 .33 .82 .52 .91 .70 .5

1 3 .6

1 .64 .05 .32 .82 .41 .6

1 7 .7

0 .30 .40 .00 .01 .11 .6

3 .4

1 .10 .80 .40 .90 .01 .6

4 .8

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 p lo ts) (N = 13 p lo ts) (N = 4 p lo ts)D ia m eter C la ss(cm -db h) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

> 5 5

T ota l

4 43 11 3060

9 4

6 93 83 13 83 10

2 0 6

5 42 17440

8 9

3 64 63 24

1 10

1 2 9

3 51 34842

6 5

3 51 54204

6 0

06

6 3600

7 5

00

1 9060

2 5

E L E V A T IO N 1 5 25 m 16 75 m 1 8 30 m 1 98 0 m (N = 4 p lo ts) (N = 7 p lo ts) (N = 13 p lo ts) (N = 4 p lo ts)D iam eter C la ss(cm -db h) 1 98 6 20 0 3 1 9 86 2 0 03 19 86 20 03 19 86 2 00 3

5-151 5 -2 52 5 -3 53 5 -4 54 5 -5 5> 55

T otal

0 .40 .80 .80 .01 .10 .0

3 .1

0 .61 .22 .24 .45 .90 .0

14 .3

0 .40 .70 .40 .50 .70 .0

2 .6

0 .31 .62 .20 .41 .90 .0

6 .4

0 .20 .40 .31 .00 .70 .6

3 .2

0 .30 .40 .20 .30 .01 .1

2 .3

0 .00 .34 .30 .60 .00 .0

5 .2

0 .00 .01 .40 .01 .10 .0

2 .5

43

density and basal area in the 15-25 and 25-35 cm-dbh classes likewise displayed a doubling

of both parameters. Red spruce stands at this altitude appear to be in a state of flux but with

signs of balance as new growth is incorporated. Nicholas (1992) projected a reduction in

basal area for every diameter class at this elevation with the exception of those stems > 55

cm-dbh. Our findings support this hypothesis with the exception of the lowest and highest

diameter classes where basal area barely increased from 2.6 to 3.0 m2/ha and dropped from

7.5 to 6.9 m2/ha respectively.

At 1830 m, red spruce shows little change from the previous survey with only a slight

reduction in live density in the 5-15 cm-dbh class from 281 to 213 stems/ha. Overall, live

basal area at this elevation increased from 13.6 to 17.7 m2/ha, most of which occurred within

the 25-35 cm-dbh class. Dead parameters also show very little if any change on a diameter

class basis at this elevation. Nicholas (1992) projected a drop in overall live basal area with

reductions in most diameter classes except 25-35 cm-dbh and stems > 55 cm-dbh. Our

results somewhat support this trend as basal area did increase markedly in the

aforementioned classes; however, overall basal increased from 13.6 to 17.7 m2/ha.

At 1980 m, red spruce is reduced to a minor component of canopy codominance;

however, ingrowth of stems in the 5-15 cm-dbh class is very apparent. Live stem density of

this class increased from 44 to 238 stems/ha. Live stem density in the 15-25 cm-dbh class

did not change but basal area in this class doubled. Dead stem density in this same class

dropped from 63 to 19 stems/ha with a corresponding 60 percent drop in dead basal area.

Nicholas (1992) projected an extirpation of red spruce at this altitude by 2009 and our results

do not support this projection, as red spruce live basal area actually increased in most

diameter classes as well as an overall increase from 3.4 to 4.8 m2/ha.

44

Fraser Fir

At 1525 m there was virtually no change in an almost non-existent Fraser fir density

in any diameter class for both live and dead stems as shown by Tables 1.17 and 1.19. The

1986 and 2003 surveys reported 1 and 2 live stems of the 5-15 cm-dbh diameter class

respectively with no dead stems in either survey. This is somewhat below projected values

by Nicholas (1992); however, many plots at this elevation were not surveyed in 2003 so

much data is missing and trend analysis is difficult for Fraser fir.

At 1675 m Fraser fir begins to become more common with number of live stems

(Table 1.17) increasing largely in the 5-15 cm-dbh class from 57 to 175 stems/ha. Live basal

area for this class increased similarly as shown in Table 1.18. The only other notable change

for live Fraser fir at this altitude was in the 35 to 45 cm-dbh class where basal area dropped

from 0.4 to 0.0 m2/ha. This trend in live Fraser basal follows trends anticipated by Nicholas

(1992) for live growth. Dead stems at this elevation only changed in the 5-15 cm-dbh class

with a jump from 0 to 57 stems/ha and 0 to 0.5 m2/ha change in dead basal area (Table 1.20).

TABLE 1.17 FRASER FIR LIVE STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 p lo ts ) (N = 1 3 p lo ts ) (N = 4 p lo ts )D ia m eter C la s s(c m -d b h ) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

> 5 5

T o ta l

600000

6

1 300000

1 3

5 740400

6 4

1 7 540000

1 7 9

4 2 12 0 65 0400

6 8 1

5 5 81 4 65 01 020

6 6 5

6 6 41 8 85 03 800

9 1 9

3 8 4 42 5 04 41 360

4 1 5 6

45

TABLE 1.18 FRASER FIR LIVE BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

TABLE 1.19 FRASER FIR DEAD STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY

DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. TABLE 1.20 FRASER FIR DEAD BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY

DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

Both live and dead Fraser fir at 1830 m underwent some very notable changes in most

size classes. Live stems and basal area in the 5-15 cm-dbh class increased markedly from

421 to 558 stems/ha and from 2.9 to 3.9 m2/ha (Tables 1.17 and 1.18). The opposite trend

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 p lo ts ) (N = 13 p lo ts ) (N = 4 p lo ts )D ia m eter C la s s(c m -d b h ) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

5 5 +

T ota l

< 0 .10 .00 .00 .00 .00 .0

< 0 .1

< 0 .10 .00 .00 .00 .00 .0

< 0 .1

0 .20 .10 .00 .40 .00 .0

0 .7

1 .00 .20 .00 .00 .00 .0

1 .2

2 .96 .03 .10 .40 .00 .0

1 2 .5

3 .94 .43 .21 .00 .40 .0

1 2 .8

4 .05 .73 .64 .50 .00 .0

1 7 .9

2 1 .26 .23 .01 .51 .00 .0

3 3 .0

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 p lo ts ) (N = 1 3 p lo ts ) (N = 4 p lo ts )D ia m ete r C la s s(c m -d b h ) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

> 5 5

T o ta l

000000

0

000000

0

070000

7

5 740000

6 1

1 5 07 92 1040

2 5 4

2 1 31 5 83 5242

4 1 3

7 5 63 1 96 31 960

1 1 6 3

1 0 08 16 33 11 30

2 8 8

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 plo ts) (N = 1 3 plo ts ) (N = 4 plo ts )D ia m eter C la ss(c m -db h) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

> 5 5

T ota l

0 .00 .00 .00 .00 .00 .0

0 .0

0 .00 .00 .00 .00 .00 .0

0 .0

0 .00 .20 .00 .00 .00 .0

0 .2

0 .50 .10 .00 .00 .00 .0

0 .6

1 .32 .41 .40 .00 .70 .0

5 .8

1 .95 .02 .30 .20 .70 .7

1 0 .8

5 .58 .94 .22 .21 .10 .0

2 1 .9

0 .72 .84 .93 .92 .30 .0

1 4 .6

46

occurred in the 15-25 cm-dbh class as live density and basal area dropped from 206 to 146

stems/ha and 6.0 to 4.4 m2/ha. In larger diameter classes Fraser fir increased its live density

and basal area. Nicholas (1992) projected an increase in all but the lowest size class by 2009,

a trend that our data mostly supports; however, growth in the lowest size class (5-15 cm-dbh)

has yet to manifest itself in the larger size classes. However, with the increases in dead stem

density and basal area in most size classes this optimistic prediction may not be realized at

this altitude.

Fraser fir at 1980 m underwent explosive growth in the 5-15 cm-dbh class. Live stem

density rose from 644 to 3844 stems/ha and basal area increased similarly from 4.0 to 21.2

m2/ha (Table 1.17 and 1.18). This was mainly due to high regeneration found on two plots at

this altitude. A slight increase in live stems was shown in the 15-25 and 45-55 cm-dbh

classes, with reductions or no change in the other classes. This trend is opposite of the

hypothesized change by Nicholas (1992) that predicted a slight drop in overall basal area

with the most pronounced drop in the 5-15 cm-dbh class. Fraser fir dead stem density (Table

1.19) at this elevation decreased dramatically from 756 to 100 and 319 to 81 stems/ha for the

5-15 and 15-25 cm-dbh classes respectively. Dead basal area (Table 1.20) followed the same

trend as it also dropped from 5.5 to 0.7 and 8.9 to 2.8 m2/ha for the 5-15 and 15-25 cm-dbh

classes respectively. The remaining diameter classes showed slight to moderate increases or

no change in dead basal area or stem density.

Yellow Birch

Yellow birch at 1525 m underwent very little change in all parameters as shown by

Tables 1.21-1.24. Only slight increases in live stem density and live basal area occurred in

the 5-15, 15-25, and 25-35 cm-dbh classes. Nicholas (1992) projected a general decrease in

47

basal area for all size classes at this elevation; however, our limited data do not support this

hypothesis. Dead yellow birch was not found at this altitude.

TABLE 1.21 YELLOW BIRCH LIVE STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

TABLE 1.22 YELLOW BIRCH LIVE BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY

DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC. TABLE 1.23 YELLOW BIRCH DEAD STEM DENSITY (STEMS/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED

BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 p lo ts ) (N = 1 3 p lots ) (N = 4 p lo ts )D ia m eter C la ss(c m -db h ) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 55 5 +

T ota l

61 33 8000

6 9

3 11 33 8000

8 1

3 5 01 0 7

7440

4 7 1

1 8 91 3 92 9004

3 6 1

9 07 16200

1 6 9

7 94 22 3220

1 4 8

2 500000

2 5

000000

0

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts) (N = 7 p lo ts) (N = 13 p lo ts) (N = 4 p lo ts)D ia m eter C la ss(c m -db h ) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

> 5 5

T o ta l

060000

6

000000

0

7 11 47000

9 3

5 41 84400

7 9

9 41 00002

1 0 6

1 91 00000

2 9

2 560000

3 1

1 300000

1 3

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 plo ts ) (N = 1 3 plo ts ) (N = 4 plo ts )D ia m eter C la s s(c m -db h) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5

5 5 +

T ota l

0 .10 .42 .60 .00 .00 .0

3 .1

0 .30 .53 .00 .00 .00 .0

3 .8

2 .72 .90 .40 .50 .80 .0

7 .4

1 .84 .21 .70 .00 .00 .9

8 .6

0 .62 .10 .30 .20 .00 .0

3 .2

0 .61 .31 .40 .20 .40 .0

3 .9

0 .20 .00 .00 .00 .00 .0

0 .2

0 .00 .00 .00 .00 .00 .0

0 .0

48

TABLE 1.24 YELLOW BIRCH DEAD BASAL AREA (M2/HA) AT PLOT ESTABLISHMENT AND IN 2003, STRATIFIED BY DIAMETER AND ELEVATION CLASS AT THE BLACK MOUNTAINS, NC.

At 1675 m, yellow birch reaches its peak in live density and live basal area. Live

density and basal area decreased most markedly in the 5-15 cm-dbh class as it dropped from

350 to 189 stems/ha and 2.7 to 1.8 m2/ha (Tables 1.21 and 1.22), however modest increases

were evident in the 15-25, 25-35, and > 55 cm-dbh classes. The trend at this elevation

closely follows the projected means by Nicholas (1992). Dead stem density and basal area

(Tables 1.23 and 1.24) underwent very little change in all diameter classes at this altitude.

By 1830 m yellow birch once again becomes a very minor component to the canopy.

Decreases in live stem density for the 5-15 and 15-25 cm-dbh classes were 90 to 79 and 71 to

42 stems/ha respectively (Table 1.21). An increase of 17 stems/ha was shown in the 25-35

cm-dbh class with very little if any change in the larger classes. Live basal area (Table 1.22)

underwent very small changes if any for all diameter classes. This trend somewhat follows

that hypothesized by Nicholas (1992) with the exception of an overall increase in live basal

area from 3.2 to 3.9 m2/ha. Dead stems at 1830 m dropped dramatically in the 5-15 cm-dbh

class from 94 to 19 stems/ha with a corresponding drop in dead basal area (Tables 1.23 and

1.24).

E L E V A T IO N 1 5 2 5 m 1 6 7 5 m 1 8 3 0 m 1 9 8 0 m (N = 4 p lo ts ) (N = 7 p lo ts ) (N = 13 p lo ts ) (N = 4 p lo ts )D ia m eter C la ss(c m -db h) 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3 1 9 8 6 2 0 0 3

5 -1 51 5 -2 52 5 -3 53 5 -4 54 5 -5 5> 5 5

T ota l

0 .00 .10 .00 .00 .00 .0

0 .1

0 .00 .00 .00 .00 .00 .0

0 .0

0 .60 .40 .40 .00 .00 .0

1 .3

0 .50 .50 .20 .50 .00 .0

1 .7

0 .80 .30 .00 .00 .00 .7

1 .7

0 .20 .30 .00 .00 .00 .0

0 .5

0 .20 .20 .00 .00 .00 .0

0 .4

0 .10 .00 .00 .00 .00 .0

0 .1

49

As projected by Nicholas (1992), live yellow birch disappeared from plots at 1980 m.

Both density and basal area for live trees dropped to zero between the 1986 and 2003

surveys. Very few dead stems remain at this altitude as well.

1.3.8 Disease and Insect Incidence

With the exception of cankers caused by Nectria spp. found on many yellow birches, very

few specific disease occurrences were noted. Approximately 20 percent of the birch trees we

surveyed had stem cankers. Additionally, we noted in many of the same areas there were

isolated birches possessing moderate amounts of necrotic and/or insect damaged leaves that

appeared otherwise in good condition. One plot (B-35) had a rare occurrence of many red

spruces with nodal galls on branches in their crowns. The cause of this phenomenon remains

unknown and was not found on any other plots. Other disease trends may be difficult to

determine, as the technicians on this project were not well experienced in tree pathology or

entomology. Most evaluations were reduced to recognizing crown damage from a distance,

lightning and ice damage, and general fungus and insect signs and symptom recognition

only.

The balsam woolly adelgid was not found at all during the summer of 2002, either on

surveyed Fraser firs and those we casually observed. This does not mean the adelgid was not

present but only that we failed to find it in areas where we spent a significant amount of time.

During the summer of 2003 we found a total of 7 infested fir trees on three isolated plots (B-

48, 51, and 53) and these trees ranged in size from 6.2 to 12.4 cm in diameter. Adelgid

infestations on tree boles ranged from one or two insects per cm2 upwards to approximately

10 insects per cm2. Mild cases of twig gouting, a symptom of past adelgid activity, were

50

found on several firs that had no live insects on the boles. During subsequent trips to the

southern Black Mountains in the summer of 2004, casual observation in several areas

revealed the presence of the adelgid in similar numbers.

51

1.4 DISCUSSION

1.4.1 Current Status

Overall, our results give us myriad synopsis for the recovery of spruce-fir forests in the Black

Mountains. High rates of mortality and decline are still evident, but there are also positive

indicators of regeneration in many locations, especially among Fraser fir at higher elevations.

While at the highest elevations it appears that recovery of Fraser fir is underway in the Black

Mountains, the amount of progression toward a climax high-elevation fir forest is highly

variable and very patchy.

Most of the forest is either still slowly collapsing, as evidenced by crown classes

shifting from healthier to poorer conditions (Figures 1.16-18), or is in a state of rapid

recovery under a now dead and largely removed upper canopy. The exogenous disturbances

of the balsam woolly adelgid and air pollution have greatly impacted the once uniform fir

forests at this altitude. Timing of adelgid infestation seems to have had the greatest impact

on stand structure, as earlier infested areas have already recovered somewhat while some

areas are just now making a comeback. The last wave of widespread adelgid induced

mortality was declared nearly complete back in the early 1990’s (Nicholas et al. 1992) and

our finding of few adelgid populations and minimal recent mortality seem to confirm this.

However, this may simply be a lull in adelgid numbers as the population of susceptible

Fraser firs has been drastically reduced since introduction in 1957. Young, vigorous fir trees

have few cauline feeding sites to allow feeding of the pheloderm and cannot support large

adelgid populations (Eagar 1984). Further research is needed to establish the current state of

BWA in the region.

52

The cycles of high elevation southern spruce-fir forests are not well understood and

17 years is a relatively short interval in a forest where the dominant species may have

average life spans of 150 to 300 years (Oosting and Billings 1951). However, Eagar (1984)

suggested that an approximately 35 to 60 year cycle of infestation may occur in the Great

Smoky Mountains. Given the hypothesized length of such a cycle, a long-lived species such

as Fraser fir has not had sufficient time for evolution of resistance to the adelgid. Whether or

not the remaining population of Fraser fir in the Black Mountains that has escaped infestation

is resistant to the adelgid remains to be confirmed, as is the potential for survivors to attain

reproductive maturity before succumbing to subsequent infestations (Busing et al. 1988).

The increase in fir sapling density suggests normal growth patterns resulting from a sufficient

seed bank, and at least a temporary recovery from adelgid infestation appears likely.

1.4.2 Comparison to “virgin” or undisturbed spruce-fir forest

A few key studies measured spruce-fir and fir forest parameters prior to the introduction of

the balsam woolly adelgid and the suspected impacts of atmospheric pollutants in the

Southern Appalachians. According to Whittaker (1956) undisturbed southern spruce-fir

forests in the Great Smoky Mountains tend to follow an elevation gradient with spruce forest

from 1370 to 1675 m, spruce-fir from 1675 to 1890 m, and almost pure fir forest above 1890

m. Current stand composition in the Black Mountains follows this pattern of a shift from red

spruce to Fraser fir as elevation increases. While our study area is far removed from what

would be considered “virgin” forest, there is a noticeable shift toward the stable, unmanaged,

uneven-aged forest that may have been found 50 years ago in the Black Mountains.

53

Cain (1935) reported a total basal area of 76 m2/ha, consisting of 89 percent red

spruce, near Mt. Mingus at 1550 m (5085 ft) in the Great Smoky Mountains. At this altitude

we found a somewhat lower total basal area of 70 m2/ha (80 percent red spruce), with an

upward trend since the last survey. However, the dead component of this total has increased

by 14 percent, mainly due to the loss of many large red spruces on one of the four plots

sampled at this elevation.

At 1675 m in the Great Smoky Mountains Oosting and Billings (1951) reported an

average basal area for combined spruce and fir to be 45.1 m2/ha, with a ratio of spruce to fir

of 63 to 37 percent respectively. The combined spruce and fir total from our findings at the

same elevation are again somewhat lower, with a mean total basal area of 39.8 m2/ha. The

main difference to be noted here is the overwhelmingly spruce dominated sites at this altitude

contributing 72 percent of the mean total basal area and 96 percent of the spruce-fir total.

At the next elevation class, 1830 m, Oosting and Billings (1951) reported the mean

basal area for spruce and fir in the Great Smoky Mountains to be 58.6 m2/ha. Our combined

live and dead basal areas for spruce and fir are only 44.0 m2/ha with a rise in the live

component mainly due to red spruce and very little difference in the dead component.

However, dead basal area still makes up 31 percent of the total input from spruce and fir.

Oosting and Billings additionally reported stems densities of red spruce and Fraser fir at this

altitude to be 236 and 896 stems/ha, respectively. Our results for total mean stem density,

while much greater in absolute numbers, gives only a slightly larger proportion of spruce to

fir with 30 and 70 percent, respectively. This shift toward red spruce is mainly due to the

lack of Fraser fir recruitment reported at this altitude.

54

Cain (1935) reported a total basal area of 66.0 m2/ha for fir and spruce on Mt.

LeConte at 1920 m (6300 ft) in the Great Smoky Mountains within a forest of 90 percent fir.

Oosting and Billings (1951) reported a live basal area of fir at the same elevation in the Great

Smoky Mountains to be 32.6 m2/ha with a density of 1300 stems/ha. The basal area of fir we

found at 1980 m mirrors Oosting and Billings’ values; however, our live fir density far

exceeded their findings. This discrepancy is mainly due to the high level of recruitment on

our sites and we expect the density to drop drastically in the coming decade due to

competition-induced mortality. We found a decreasing trend in dead stem basal area and

density, which we would have expected, as most of the larger overstory firs died over a

decade ago. Whittaker (1956), who also reported findings for Great Smoky Mountain high

elevation fir forests, found the bulk of canopy stems to be in the 18 to 23 cm-dbh range with

a canopy height of 9 to 12 m. Our findings show the bulk of fir stems in the 5-15 cm-dbh

range, and we expect the majority of survivors in this diameter class to shift to the 15-25 cm-

dbh range in next 20-30 years based on growth rates found by Oosting and Billings (1951).

At the same time we expect the canopy, which at this time is rather restricted on sites with

high recruitment, to slowly rise from our present estimations of 3-6 m.

1.4.3 Comparison with Trends of Recent Studies

DeSelm and Boner (1984) and Busing and Clebsch (1988) reported that Fraser fir is able to

recover in sufficiently large numbers following adelgid infestation. Their methods included

a count of subsaplings (< 2.5 cm-dbh) as well as stems over 2.5 cm-dbh at high elevation

plots in the Black and Great Smoky Mountains. Although they found fir density ranging

from 510 to 2400 stems/ha respectively, somewhat lower than our findings, high Fraser fir

55

density and recruitment of stems into sapling and overstory categories was becoming

apparent. As recently as 1988, Bruck et al. (1989) found rapid collapse of mature fir and

spruce at high altitude sites near Mt. Mitchell. Our results seem to be the reverse of this

trend, as our data suggest a rapid recovery in progress at high altitudes.

Results from a recent study in the Great Smoky Mountains (Smith and Nicholas

2000) are consistent with our findings in many ways. Mean basal area of Fraser fir in live

pure fir stands was 33.0 m2/ha, exactly what we found in the Black Mountain fir stands. Live

fir density was markedly higher than in the other stand types they analyzed, but was 50

percent lower than the mean value in fir we found at 1980 m. However, as we discovered on

our sites, this value can fluctuate greatly within a span of a few meters due to high spatial

variability of recruitment. Additionally, size class distribution in the live fir stands displayed

a similar response following overstory collapse. Red spruce, while not a major canopy

component in live fir stands at the highest altitudes, showed very similar live basal area and

density values to our study.

Few previous studies have quantified standing dead stem density and basal area in

Southern Appalachian fir forests, although standing dead trees are often used as a measure of

mortality. Smith and Nicholas (1998) state three processes that need to be analyzed in order

to understand the cycle of standing dead stems: fir death, the fall of dead fir stems, and

recruitment of understory fir into the overstory. For Fraser fir our overall results show a

marked decrease in standing dead stem proportion over time rather than an increase, along

with high recruitment of understory fir. Although annual mortality cannot be deduced from

our data, the trend over the past 17 years suggests a lower mortality rate for fir than

previously reported, as dead stems are occupying much less area. Our findings do coincide

56

with other studies for adelgid-impacted stands as Nicholas et al. (1992) and Bruck and

Robarge (1988) found 6 to 22 m2/ha and 10 to 20 m2/ha dead basal area in the Black

Mountains respectively. However, what certainly has changed is the once greater proportion

of standing dead fir basal area to live fir in high elevation stands, especially for those stands

that have had a longer recovery time.

1.4.4 Analysis of Projected Values

While we were only able to recover 28 of the 40 original plots installed by Nicholas (1992)

in 1986, some conclusions regarding the current live basal area and values projected for red

spruce, Fraser fir, and yellow birch can be made. Overall projections by Nicholas (1992) for

live basal area in 2009 were most accurate at the lower elevation classes and least accurate at

the highest elevation classes.

The response of red spruce at 1525 m shows a reduction of 14 percent in live basal

area. The reduction projected by Nicholas (1992) for spruce at this altitude by 2009 is 22

percent and even considering the large number of unrecovered plots at this elevation it is

conceivable that this trend is accurate. Response of red spruce live basal area at 1675 m is

also very similar to projected values, with our study showing a reduction of 8 percent

compared to the projected drop of 17 percent. Once again, only about half of the plots at this

altitude were recovered, but the trend in growth is similar to the projected value. At 1830

and 1980 m we were able to resample most of the plots established and our results for red

spruce live basal area contrast greatly with projected values. The projected trend in spruce

live basal area was a reduction of 23 percent at 1830 m while our results show an increase of

28 percent. At 1980 m we also showed an increase (41%) whereas the projected reduction in

57

spruce live basal area by 2009 was 100 percent. We did not find the elimination of red

spruce at this altitude and in fact saw increases in all but the largest size classes. Our mean

live basal area for spruce, while quite small in absolute terms, actually showed quite a large

amount of recruitment in the 5-15 cm-dbh class. Live density in this class grew from 75 to

275 stems/ha and with the remainder of the size classes growing or showing a shift towards

larger diameters. Zedaker et al. (1988) suggested that red spruce in fir dominated stands,

which is normal at 1980 m, may show increased mortality rates due to thinning shock caused

by the rapid removal of fir from the overstory, however our findings seem to refute this.

Fraser fir was projected to increase slightly at 1525 m and the large number of

unrecovered plots combined with low fir density at this altitude makes our results insufficient

in making any sort of trend analysis. Our results for fir live basal area at 1675 m are almost

identical to the projected values; however, the accuracy is in question as a large number of

plots were not sampled. At 1830 m most of the plots were recovered and our results were far

lower than the projected increase of over 120 percent in live fir basal area by 2009. Results

at 1980 m also contrast greatly as a large amount of fir recruitment caused an increase in live

basal area of 84 percent. Values at this elevation were actually projected to decrease slightly.

It appears the amount of recovery of fir at 1830 m was greatly overestimated and the

recovery at 1980 m was greatly underestimated.

Yellow birch showed gains in live basal area at all but the highest elevations, which is

in contrast to the prediction of Nicholas (1992) for 2009. However the low number of

recovered plots at 1525 and 1675 m makes this trend somewhat difficult to assess with

accuracy. As predicted by Nicholas (1992), live yellow birch practically disappeared from

the plots at 1980 m. No new live stems were reported and the number of dead stems also

58

dropped to essentially zero. These trends follow the projections made for the year 2009 and

appear unlikely to change by then, as the presence of this species was only noted at plot B-53

and then only as 2 dead stems.

Many weaknesses in modeling future stand projections are covered by Nicholas

(1992) and the results of this study may be able to help future modeling of growth or

mortality in this type of forest.

1.4.5 Conclusions

The objective of this study was to quantify the amount of change that has occurred in the

spruce-fir forest of the Black Mountains since the mid 1980’s. In addition to the amount of

change in various parameters for the three main tree species, we assessed the trend in forest

condition using a crown damage rating system. Furthermore, we gave a cursory assessment

of the presence of the balsam wooly adelgid in the Black Mountains. Additional studies will

of course be necessary in order to track annual rates of growth and mortality, as our study

was limited to determining current trends and making short range future projections. Other

variables such as soil chemistry, foliar tissue conditions, atmospheric pollutant loads, and

climate shifts will need to be further addressed as well. In light of the information we

derived from this study we can now make some potential scenarios of the future of spruce-fir

forests in the Black Mountains as well as the entire range of the ecosystem within the

Southern Appalachians.

The Southern Appalachian montane spruce-fir forest has undergone rapid change in

the last century with widespread impacts ranging from logging and fires in the early 20th

century to exotic insect-induced mortality and air pollution related stresses (Silver 2003).

59

Particularly in the Black Mountains there was considerable reduction in the size and density

of high elevation Fraser fir following those impacts. However, the wave of balsam woolly

adelgid infestation that spanned the 30 years following introduction to the region in 1957

appears to have ended. Fraser fir seems to have made significant gains in reestablishing itself

and maintaining dominance on the high peaks and ridges in the forests near Mt. Mitchell.

Even though we failed to find BWA in large numbers, the long range forecast for this forest

remains uncertain as adelgid populations are expected to rebound as the newly emergent fir

saplings reach susceptible size classes and enter the overstory. Because susceptible size

classes are much smaller than reproductive size classes for Fraser fir, we may expect to see

another wave of fir mortality with few trees reaching maturity in the near future.

Potential impacts due to climate change may become evident in the near future but

large detectable shifts in floristic composition are most likely still decades away. Forest

response to chronic long-term disturbances depends on many factors and the ability of other

species (namely spruce and birch) to colonize and prevent fir dominance in the high

elevations. We may even see a shift to a new type of climax ecosystem dominating the drier

ridges and peaks, one composed of more heath and bald type species. Some evidence, while

not strictly within our sampled areas, points to dominance of hardier shrubs as sites under

collapsed canopies are exposed to higher rates of drying. Rhododendron and mountain laurel

can surely survive in these conditions, especially when combined with elevated mean

temperatures at higher altitudes. We may expect to see a larger number and size of these

patches as they prevent the recolonization of spruce and fir. In effect, a mosaic of low

canopy shrubs and uneven age spruce-fir forest may be the result rather than the primarily

even aged old-growth stands that existed prior to the 20th century.

60

The area and location of spruce and fir forests has waxed and waned considerably

over the past several millennia and the present shift in forest composition may just be another

perturbation in this rather active cycle. Certainly climate change in the past has been a

driving force in the expansion and extirpation of spruce and fir species across most of the

eastern North American landscape. The fluctuation of montane spruce-fir forests may be an

indicator that mean temperatures and precipitation levels are indeed changing in the Southern

Appalachians. This portent, along with a series of others ranging from rising sea levels to

widespread drought, should not be taken lightly.

61

1.5 ACKNOWLEDGEMENTS

I wish to thank my summer technicians Kerby Smithson, Laura Vance, Matthew Cherry,

Margaret Worthington, and William Miller for their diligence in data and sample collection.

I sincerely extend my appreciation to the USDA Forest Service Southern Global Change

Program and the Stanback Foundation of North Carolina for financial support of this

research. Additionally I would like to thank the entire Mt. Mitchell State Park staff and

David Zietlow for allowing us access to park facilities and joining the spirit of scientific

pursuit.

62

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Battles, J. J., Fahey, T. J., Siccama, T. G., and A. H. Johnson. 2003. Community and

population dynamics of spruce-fir forests on Whiteface Mountain, New York: recent trends, 1985-2000. Can. J. of For. Res. 33: 54-63.

Bruck, R. I., and W. P. Robarge. 1988. Change in forest structure in the boreal montane

ecosystem of Mount Mitchell, North Carolina. Eur. J. Forest Pathol. 18: 357-366. Bruck, R. I., Robarge, W. P., and A. McDaniel. 1989. Forest decline in the boreal montane

ecosystems of the southern Appalachian Mountains. Water, Air, and Soil Pollution 48: 161-180.

Busing, R. T., and E. C. C. Clebsch. 1988. Fraser fir mortality and the dynamics of a Great

Smoky Mountains fir-spruce stand. Castanea 53: 177-182.

Busing, R. T., Clebsch, E. C. C., Eagar, C. C., and E. F. Pauley. 1988. Two decades of change in a Great Smoky Mountains spruce-fir forest. Bulletin of the Torrey Botanical Club 115(1): 25-31.

Busing, R. T., and E. F. Pauley. 1994. Mortality trends in a southern Appalachian red spruce

population. Forest Ecology and Management. 64: 41-45.

Cain, S. A. 1935. Ecological studies of the vegetation of the Great Smoky Mountains. II. The quadrat method applied to sampling spruce and fir forest types. American Midland Naturalist. 16: 566-584.

Cowling, E., Krahl-Urban, B., and C. Schimansky. 1988. Hypotheses to Explain Forest

Decline. Forest Decline: Cause-Effect Research in the United States of North America and Federal Republic of Germany. Assessment Group for Biology, Ecology, and Energy of the Julich Nuclear Research Center for the U.S. Environmental Protection Agency and German Ministry of Research and Technology.

DeSelm, H. R., and R. R. Boner. 1984. Understory changes in spruce-fir during the first 16-

20 years following the death of fir. In P. S. White (ed.), The Southern Appalachian spruce-fir ecosystem: Its biology and threats. U. S. Department of the Interior, National Park Service, Research/Resources Management Report SER-71. 268 p.

Eagar, C. 1984. Review of the biology and ecology of the balsam woolly aphid infestations

in Southern Appalachian spruce-fir forests. In P. S. White (ed.), The Southern Appalachian spruce-fir ecosystem: Its biology and threats. U. S. Department of the

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Interior, National Park Service, Research/Resources Management Report SER-71. 268 p. Edmonds, R. L., Agee, J. K., and R. I. Gara. 2000. Forest Health and Protection. McGraw-

Hill Co. Inc., Boston, Mass. Fernandez, I. J. 1992. Characterization of Eastern U.S. Spruce-Fir Soils, pp. 40-63. In C.

Eagar and M. B. Adams (eds.). Ecology and Decline of Red Spruce in the Eastern United States. Ecological Studies 96. Springer-Verlag, New York, NY.

Hornbeck, J. W., Smith, R. B., and C. A. Federer. 1986. Growth decline in red spruce and

balsam fir relative to natural processes. Water, Air, and Soil Pollution. 31: 425-430.

Houston, D. R. 1992. A host-stress-saprogen model for forest dieback-decline diseases, pp. 3-25. In P. D. Manion and D. Lachance (eds.). Forest Decline Concepts. American Pathological Society Press, St. Paul, Minn.

Johnson, A. H. 1992. The role of abiotic stresses in the decline of red spruce in high

elevation forests of the eastern United States. Annual Review of Phytopathology. 30: 349-367.

Johnson, A. H., Friedland, A. J., and J. G. Dushoff. 1986. Recent and historic red spruce

mortality: evidence of climatic influence. Water, Air, and Soil Pollution 30: 319-330. LeBlanc, D. C., Nicholas, N. S., and S. M. Zedaker. 1992. Prevalence of individual-tree

growth decline in red spruce populations of the southern Appalachian Mountains. Can. J. For. Res. 22: 905-914.

McLaughlin, S. B., Downing, D. J., Blasing, T. J., Cook, E. R., and H. S. Adams. 1987. An

analysis of climate and competition as contributors to decline of red spruce in high elevation Appalachian forests of the Eastern United States. Oecologia (Berlin). 72: 487-501.

McLeod, D.E. 1988. Vegetation patterns, floristics, and environmental relationships in the

Black and Craggy Mountains of North Carolina. Ph.D. Dissertation, UNC-Chapel Hill.

Mohnen, V. A. 1992. Atmospheric Deposition and Pollutant Exposure of Eastern U.S.

Forests, pp. 64-124. In C. Eagar and M. B. Adams (eds.). Ecology and Decline of Red Spruce in the Eastern United States. Ecological Studies 96. Springer-Verlag, New York, NY.

Nicholas, N. S. 1992. Stand structure, growth, and mortality in Southern Appalachian spruce-

fir. Ph.D. Dissertation, Virginia Polytechnic Institute and State University.

64

Nicholas, N. S., Zedaker, S. M., and C. Eagar. 1992. A comparison of overstory community structure in three southern Appalachian spruce-fir forests. Bulletin of the Torrey Botanical Club. 119(3): 316-332.

Nilsson, S., and P. Duinker. 1987. The extent of forest decline in Europe: a synthesis of

survey results. Environment. 29(9): 4-31. Oosting, H. J., and W. D. Billings. 1951. A comparison of virgin spruce-fir forest in the

northern and southern Appalachian system. Ecology. 32:84-103.

Pauley, E. F., and E. E. C. Clebsch. 1990. Patterns of Abies fraseri regeneration in a Great Smoky Mountains spruce-fir forest. Bulletin of the Torrey Botanical Club. 117(4): 375-381.

Peart, D. R., Nicholas, N. S., Zedaker, S. M., Miller-Weeks, M. M., and T. G. Siccama. 1992.

Condition and Recent Trends in High-Elevation Red Spruce Populations, pp. 125-191. In C. Eagar and M. B. Adams (eds.). Ecology and Decline of Red Spruce in the Eastern United States. Ecological Studies 96. Springer-Verlag, New York, NY.

Pitelka, L. F., and D. J. Raynal. 1989. Forest decline and acidic deposition. Ecology. 70(1):

2-10. Prinz, B. 1987. Causes of forest damage in Europe: Major hypotheses and factors.

Environment. 29(9): 11-37. Radford, A. E., Ahles, H. E., and C. R. Bell. 1968. Manual of the vascular flora of the

Carolinas. University of North Carolina Press. 1183 p. Schutt, P., and E. B. Cowling. 1985. Waldsterben, a general decline of forests in Central

Europe: Symptoms, development, and possible causes. Plant Disease. 69(7): 548-558. Schafale, M. P., and A. S. Weakley. 1990. Classification of the Natural Communities

of North Carolina, Third Approximation. North Carolina Natural Heritage Program and Department of Environment and Natural Resources. Raleigh, NC. 326 p.

Siccama, T. G., Bliss, M., and H. W. Vogelmann. 1982. Decline of red spruce in the Green

Mountains of Vermont. Bulletin of the Torrey Botanical Club. 109(2): 162-168. Silver, W. L., Siccama, T. G., Johnson, C., and A. H. Johnson. 1991. Changes in red spruce

populations in montane forests of the Appalachians. American Midland Naturalist. 125: 340-347.

Silver, T. 2003. Mount Mitchell and the Black Mountains; An Environmental History

of the Highest Peaks in Eastern North America. The University of Chapel Hill Press. Chapel Hill, NC. 322p.

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Skelly, J. M. 1992. A closer look at forest decline: a need for more accurate diagnostics, pp. 85-107. In P. D. Manion and D. Lachance (eds.). Forest Decline Concepts. American Pathological Society Press, St. Paul, Minn.

Smith, G. F., and N. S. Nicholas. 1998. Patterns of overstory composition in the fir and fir-

spruce forests of the Great Smoky Mountains after balsam woolly adelgid infestation. American Midland Naturalist. 139: 340-352.

Smith, G.F., and N. S. Nicholas. 2000. Size and age-class distributions of Fraser fir following

balsam woolly adelgid infestation. Can. J. For. Res. 30: 948-957. Speers, C. F. 1958. The balsam woolly aphid in the Southeast. J. For. 56: 515-516 Vogelmann, H. W., Perkins, T. D., Badger, G. J., and R. M. Klein. 1988. A 21-year record of

forest decline on Camels Hump, Vermont, USA. Eur. J. For. Path. 18: 240-249. White, P. S. 1984. The Southern Appalachian spruce-fir ecosystem: Its biology and threats.

U.S. Department of the Interior, National Park Service, Research/Resources Management Report SER-71. 268 p.

White, P. S, and C. V. Cogbill. 1992. Spruce-Fir Forests of Eastern North America, pp. 3-39. In C. Eagar and M. B. Adams (eds.). Ecology and Decline of Red Spruce in the Eastern United States. Ecological Studies 96. Springer-Verlag, New York, NY.

Whittaker, R. H. 1956. Vegetation of the Great Smoky Mountains. Ecol. Monogr. 26: 1-80. Zedaker, S. M., Nicholas, N. S., Eagar, C., White, P. S., and T. E. Burk. 1988. Stand

characteristics associated with potential decline of spruce-fir forests in the southern Appalachians. In Proceedings of the US/FRG Research Symposium: Effects of atmospheric pollutants on the spruce-fir forests of the eastern United States and the Federal Republic of Germany. October 19-23, 1987, Burlington, VT. USDA Forest Service, NE For. Exp. Stat. Gen. Tech. Rep. NE-120. pp. 123-131

66

2. Evidence of Montane Fraser Fir (Abies fraseri) and Red Spruce (Picea rubens) Recovery on the High Peaks and Ridges of the

Black Mountains, North Carolina.

ABSTRACT

Spruce-fir forests of the Southern Appalachians are ice age relics currently existing as




1980’s. In 2002-3, we resurveyed 4 permanent spruce-fir forest plots installed in 1985 at

1980 m in the Black Mountains of North Carolina. Following previous protocols, we

measured live and dead basal area, stem density, tree crown damage and noted insect and

disease occurrences when found. Individual plot assessment revealed a wide range of

response over the 17-year interim. A large significant (p < 0.10) increase in live Fraser fir

stem density of 3237 stems/ha was very evident at 1980 m. Results also show large increases

in live basal area and live stem density for both fir and spruce populations with a

corresponding decrease in dead fir stems. Additionally crown condition improvements for fir

were observed on most sites. Data suggests a rapid regeneration of dense and healthy fir is

currently underway at this altitude, especially in areas of former severe mortality and

overstory collapse. The amount of progression towards a climax high-elevation fir forest is

highly variable and very patchy. Balsam woolly adelgid (Adelges piceae Ratz.) was not

frequently encountered suggesting that adelgid populations are currently low. Long term

recovery for fir is uncertain as stems reach adelgid-susceptible age and size classes.

67

2.1 INTRODUCTION

2.1.1 Background

The spruce-fir forest ecosystem of the Southern Appalachian Mountains, consisting primarily

of dominant tree species red spruce (Picea rubens Sargent)2 and Fraser fir (Abies fraseri

[Pursh] Poiret), once covered much of southeastern North America and is considered a

remnant of the last ice age (White and Cogbill 1992; Whittaker 1956). As the climate

ameliorated since the last ice age, the lowland spruce, fir, and northern hardwood species

gave way to deciduous forests. The montane spruce and fir moved northward along the

mountains and upward in the southern ranges, which had sufficient altitude to provide the

damp and relatively cold climate necessary for their survival (Oosting and Billings 1951).

The current range of red spruce extends northeast to Canada, while Fraser fir is endemic to

the Southern Appalachians (Busing et al. 1988). Contained almost exclusively in the higher

elevations of North Carolina and Tennessee, the spruce-fir forest type exists in a region

where harsh winter conditions coincide with hot and humid summers. In the Black

Mountains the montane spruce-fir forest type now covers approximately 26,600 hectares

(65,730 acres) above 1500 m (4920 ft) (DeSelm and Boner 1984; Adams and Eagar 1992;

and Fernandez 1992).

Montane spruce-fir forest species are highly dependent on elevation and moisture

conditions in the Southern Appalachians, with an abrupt ecotone between dominance of

spruce-fir and hardwood species (White 1984). However, a few deciduous species continue

to thrive with increasing elevation. Above the hardwood zone dominated by oaks and

maples, red spruce and Fraser fir share dominance of the canopy and understory with a few

less common and smaller trees and shrubs, namely yellow birch (Betula lutea Michaux f.),

68

rhododendron (Rhododendron catawbiense Michaux and R. maximum L.), fire or pin cherry

(Prunus pennsylvanica L. f.), striped and mountain maple (Acer pensylvanicum L. and A.

spicatum Lam.), and, at the highest elevations, mountain ash (Sorbus americana Marshall)

and hobblebush (Viburnum alnifolium Marshall) (Whittaker 1956; McLoed 1988). Red

spruce, as a dominant or codominant tree, usually makes its appearance at about 1375 m

(4500 ft) elevation, depending on topography, and may share the canopy with common

hardwood species such as American beech (Fagus grandifolia Erhart), sugar maple (A.

saccharum Marshall), eastern hemlock (Tsuga canadensis L. [Carr.]), northern red oak (Q.

rubra var. borealis [Michaux f.] Farwell), black birch (B. lenta L.), and black cherry (P.

serotina Ehrhart). At about 1500 m (4900 ft) Fraser fir makes its appearance but is limited to

occupying the low understory. With increasing altitude, Fraser fir gains importance in the

forest, until it becomes a codominant with spruce around 1700 m (5600 ft) and by 1830 m

(6000 ft) it may constitute 80 percent or more of the stand (Cain 1935; Whittaker 1956).

Above this altitude in the Black Mountains, Fraser fir dominates the ridges and high peaks up

to 2037 m (6684 ft) on Mt. Mitchell, the highest peak in eastern North America.

Interest in forest health of Southern Appalachian spruce-fir heightened following

studies in the early to mid 1980s that documented widespread forest deterioration in Europe

(Schutt and Cowling 1985; Nilsson and Duinker 1987; and Prinz 1987) and decline of red

spruce in the northeastern United States (Siccama et al. 1982; Hornbeck et al. 1986; Johnson

et al. 1986; and Vogelmann et al. 1988). The European studies were prompted by increased

levels of decline phenomena, which included simultaneous and rapid decreases of health and

vigor of many tree species with corresponding growth-decreasing symptoms and prevalence

of new diseases (Schutt and Cowling 1985). Regional air pollution and acid precipitation


69

was believed to be contributing to declining crown health in red spruce in Vermont (Siccama

et al. 1982), while climate change was theorized as a potential cause behind poor growth

patterns in New England and upstate New York (Hornbeck et al. 1986). Decline in the

southern spruce-fir forests, underway since the introduction of an exotic insect, the balsam

woolly adelgid (Adelges piceae Ratz.) in 1957 (Speers 1958; White 1984; and Smith and

Nicholas 1998), was hypothesized to be a result of a combination of factors. The montane

southern spruce-fir ecotype is one that has always been considered to be a fragile ecosystem

as several factors that contribute to decline such as thin acidic soils, harsh climate, acid

deposition, and high ozone levels are constantly interacting to cause stress on the trees.

Many regional studies, organized under the Forest Response Program of the National

Atmospheric Deposition Assessment Program (NAPAP), began in the mid 1980s to

document the myriad decline symptoms that were becoming evident in the montane forests

of the Great Smoky and Black Mountains (Busing et al. 1988; Bruck et al. 1989; Pitelka and

Raynal 1989; LeBlanc et al. 1992; and Nicholas 1992). By 1987, a rapid deterioration in the

physical appearance of Southern Appalachian spruce-fir ecosystems was evident across the

region (Bruck et al. 1989). Along with these trends, the predominant cause behind the wave

of decline in spruce-fir forests, and pinpointing a common factor, remained elusive and

controversial. Theories behind the decline syndrome ranged from competition (LeBlanc et

al. 1992), acid precipitation and air pollution (Bruck et al. 1989), soil acidification (Cowling

et al. 1988), severe winter weather conditions (Nicholas 1992), to blackberry (Rubus spp.)

encroachment (Busing et al. 1988; Pauley and Clebsch 1990). Even the term “forest decline”

is a considered a misnomer, with perhaps a more correct term being “forest species decline”

70

(Skelly 1992) since the terms “dieback”, “decline”, and “blight” neither identify, nor even

suggest, causal relationships (Houston 1992).

Estimations of mortality or dieback have also proved to be problematic when applied

to forest or species decline, and efforts to find a single, reliable index of tree health or vigor

have remained unproductive. Percent standing dead is often used erroneously to illustrate the

decline of certain species. According to Peart et al. (1992), percent standing dead is not an

estimate of mortality rate nor can it easily be converted to such, as it represents a cumulative

result. Changes in mortality rates over time, for example, would not normally be detected

against background variation without large samples of trees monitored continuously for at

least several years, unless the changes were abrupt and dramatic. A tree population is

considered to be relatively steady over time if the total number in the population and its age

and size structure remain reasonably constant (Peart et al. 1992). But few studies have been

established to monitor changes in entire ecosystems over time. Problems in measuring vigor

(crown condition) exist mainly due to the variety of methods available and observer

inaccuracy and bias (Peart et al. 1992), which introduce error even when experienced

personnel perform the evaluations.

The spruce-fir ecosystem of the Southern Appalachian Mountains exists where few

species of plants, especially trees, can survive. Winters at higher elevations in these

mountains can be quite harsh, with frequent occurrence of punishing winds and ice. Due to

these conditions, red spruce and Fraser fir can thrive because few trees can compete with

them in this environment. The environmental conditions are highly variable to the point

where even the hardier plant species experience some stress, which may eventually lead to

decline symptoms. The degree to which trees are altered by stress is controlled in part by

71

their genetics and in part by the conditions of their immediate surroundings (Houston 1992).

Stresses, such as extreme cold and drought, can combine with many other factors such as

slope, aspect, and elevation to impact trees tremendously.

Climatic stresses may have also had an impact on the southern spruce-fir forests. In

contrast to Northern Appalachian forests, there is very little evidence of winter injury to

foliage in southern forests. Ice, snow, wind damage, and droughts are not uncommon, but

few studies have considered their role (Peart et al. 1992; Mohnen 1992). According to one

study in the Black Mountains of North Carolina (Bruck et al. 1989), between 1985 and 1989

annual mortality rates for red spruce ranged from 1.1 to 8.4 percent, although these values are

thought to be well within natural limits (Adams and Eagar 1992). Bruck et al. (1989)

speculated whether the increase in the number of dead trees per plot observed in 1985-6

would have continued in 1987 without the intervention of drought in 1986 and rime ice

damage during December 1986 and February 1987.

Elevation, a critical factor for competing species at higher altitudes, plays a role in

amplifying the effects of other stresses. Those trees at higher elevations are generally

exposed to greater amounts of wind, ice, acidic deposition, ozone and other air pollutants.

Elevation has been linked with decline but not necessarily as a causal factor. According to

LeBlanc et al. (1992) and Busing and Pauley (1994) the only factor found to be associated

with red spruce decline is elevation, but only as an inciting factor due to exposure to high

winds and ice (thinning shock) following fir mortality. The impact of fir mortality on red

spruce growth due to thinning shock may be greatest at 1980 m (6500 ft). The proportion of

trees that exhibited decreasing or slowed growth rates after 1967 was substantially greater

among trees growing at 1980 m than at lower elevations. Additionally, mortality of Fraser fir

72

was 55 percent of standing basal area in the 1980 m stands studied throughout the Southern

Appalachians (LeBlanc et al. 1992).

Bruck et al. (1989) and Nicholas et al. (1992) carried out detailed multi-annual forest

surveys throughout the Southern Appalachians, including the Black Mountains of North

Carolina, in order to quantify the deterioration of the spruce-fir forests during the 1980’s.

While these surveys varied drastically in their approach, both studies concluded that a rapid

collapse of forest structure was in progress, but failed to determine the primary underlying

causes of the collapse. Several hypotheses were offered, including direct acidic deposition,

leaching of nutrients from and toxic levels of aluminum in the soil, adelgid infestation, and

severe weather events during the winter of 1986-7 (Cowling et al. 1988; Bruck et al. 1989;

and Nicholas 1992). Regardless of the causes and effect mechanisms, the physical condition

and structure of the montane ecosystems on and around Mt. Mitchell had greatly deteriorated

by 1987.

In the spring of 2001, an alarming observation by several scientists was made near

Mt. Mitchell State Park in North Carolina. Low altitude red spruce forests at 1500 m had

undergone a noticeable decline during the winter of 2000-2001. Initial meteorological data

analysis failed to indicate any unusual events over this period of time. More detailed

meteorological analysis at nearby Grandfather Mt. in North Carolina indicated a slow but

significant rise in mean temperatures from 1954 to 2000. Additionally, soil temperature and

moisture data taken from the summer of 2001 indicated a warming and drying of montane

soils relative to observations made in the 1980’s (Bruck, personal communication).

Historically, serious decline of red spruce had only been observed at the much higher

elevations of the montane spruce-fir forests of the Southern Appalachians above 1500 m

73

(Adams and Eagar 1992). Detailed observations of spruce and fir forests in the Black

Mountains had not been performed in over a decade, and in conjunction with the theorized

red spruce decline, recent trends in Fraser fir were also in question.

In order to gain an understanding of the recent change in Fraser fir and red spruce

health, we began a resurvey of the Black Mountain montane forests within and adjacent to

Mt. Mitchell State Park in May 2002, returning to plots used by Nicholas (1992) in the

1980s. To the best of our knowledge no recent surveys had been performed within the high

elevation spruce-fir ecosystem of the Black Mountains in approximately 14 years. In order

to characterize long term changes in forest structure and community dynamics another in-

depth survey was needed to ensure continuity of monitoring. We wished to quantify any

further deterioration or changes in spruce-fir forest composition and compare the new data to

existing historical data and forecasted trends. We hypothesized several trends would be

evident including the continued collapse of mature Fraser fir, an increase in density of young

Fraser fir, especially in smaller size classes, a decrease in mature red spruce density due to

thinning shock, and an increase of yellow birch at this altitude. This study was accomplished

through the cooperation of the North Carolina State University (NCSU) Departments of Plant

Pathology and Soil Science, and the USDA Forest Service Southern Global Change Program.

This paper reports the findings made during the resurvey of the high elevation plots at 1980

m during the summers of 2002-3.


The Black Mountains are situated in western North Carolina, 40 kilometers northeast of the

city of Asheville NC, at approximately 35°35’ N, 82°15’ W (Figure 2.1). Mount Mitchell, at

74

2037 m, is the highest peak in eastern North America and is only one of several high peaks

within the Black Mountain range. The bulk of the range, and thus our study area, is oriented

roughly north-south, extending from Celo Knob in the north to Black Mountain Gap in the

south (Figure 2.2). The Black Mountains are part of the Southern Appalachian and Blue

Ridge Mountain ecophysiographic zone, which extends northeast from northern Georgia to

northern Virginia. Approximately 15 percent of the high elevation spruce-fir forests of the

Southern Appalachians occur in the Black Mountains, with the majority of the remainder

occurring in the Great Smoky Mountains and the Balsam Mountains, which lie to the south

and west in Tennessee and North Carolina.

75

FIGURE 2.1 LOCATION OF MT. MITCHELL AND THE BLACK MOUNTAINS IN WESTERN NORTH CAROLINA.

76


2.2.1 Original Plot Establishment

In 1985 and 1986, a stratified, randomly located, system of 40 permanent plots was

established in the Black Mountains by Nicholas (1992) of the Virginia Polytechnic Institute

(VPI). Stratification factors included elevation (four classes: 1525, 1675, 1830, 1980 m, +/-

30 m [5000, 5500, 6000, 6500 ft +/- 100 ft]), exposure to prevailing winds, and topographic

type (ridge/slope/draw) with three replicates per stratal combination wherever possible.

Permanent plot size was a 20 x 20 m projected quadrangle (0.04 ha [0.10 ac]), corrected for

slope angle, and staked with PVC pipe in each corner to denote plot boundaries.

The a priori definition of the southern spruce-fir forest type used by Nicholas (1992)

required that plots have at least 25 percent spruce and/or fir present (live) or former (dead

standing stems) canopy coverage. Overstory strata were defined as woody stems with

diameter at breast height (dbh) ≥ 5.0 cm-dbh. Measurements by species included dbh (to

nearest mm), crown condition evaluation (Class 1: 100-90% needles or leaves intact; Class 2:

90-50% intact; Class 3: 49-1% intact; and Class 4: dead), and disturbance symptomology

(signs and symptoms of disease or damage to stems) for every tree on each plot. Site data

recorded at each plot included elevation, slope percent, aspect, and topographic features.

2.2.2 Field Sampling

We relocated and resurveyed 4 of the original 5 VPI plots at the 1980 m stratification level

during the summers of 2002 and 2003. Plots B-44, 52, 53, and 54 have a mean elevation

above sea level of 1973 m (6473 ft) and their location along the Black Mountain ridgeline is

shown below in Figure 2.2. Plots were found using written directions, topographic maps, and

77

hand drawn maps when available. The 2002-3 survey attempted, as much as possible, to re-

evaluate each plot according to the original methods.

FIGURE 2.2 HIGH ELEVATION SPRUCE-FIR PLOT LOCATIONS ALONG THE MAIN RIDGELINE OF THE BLACK

MOUNTAINS.

78

Data recorded for each plot included coordinates and elevation determined by global

positioning system (GPS), slope percent, aspect of plot face, live and dead basal area

estimation using a forester’s prism (factor 10), a list of woody and herbaceous species within

the plot, an estimation of dead woody debris present, a brief description of the topography

and groundcover, and canopy closure percentage estimation. Plots that were damaged or

vandalized were repaired (i.e. corner stakes replaced) when necessary, making sure to correct

for slope angles. A new set of written directions as well as new hand drawn maps were made

to augment GPS coordinates and allow for ease in relocating for future surveys. Weather

conditions during sampling were noted and included temperature, precipitation (if in

progress), cloud cover, and wind.

Resurveyed trees were identified by their tag number, measured dbh to the nearest

mm, and evaluated for crown damage. Ingrowth trees (those that met the original size

criteria [≥ 5.0 cm-dbh]) were assigned a number, tagged at the base, measured for dbh to the

nearest mm, and evaluated for crown damage. Each qualified tree within the plot was

evaluated on the 4-point rating equivalent to the one discussed above (Class 1: 0-10% crown

damage, Class 2: 11-50% crown damage, class 3: 51-99% crown damage, and Class 4:

standing dead) to estimate individual decline or damage percentage of the crown (Figure

2.3). Every tree crown was assigned a position within the forest canopy (dominant,

codominant, intermediate, or suppressed) as determined by estimation of the mean canopy

height. Each tree bole and crown was visually examined for abnormalities such as decay,

insect infestation, fungi, excessive foliar chlorosis and/or necrosis, and crown and stem

damage. All qualitative observations were made by at least 2 technicians for each tree, with

79

occasionally a third technician consulted to confirm judgment in case of disagreement. All

data were subsequently entered into a spreadsheet for statistical analysis.

FIGURE 2.3 EXAMPLES OF CROWN CLASS 1-4 RATINGS ON SPRUCE AND FIR TREES.

2.2.3 Analysis

Tree species considered for statistical analysis include Fraser fir (Abies fraseri), red spruce

(Picea rubens), and yellow birch (Betula lutea). Mountain-ash (Sorbus americana) and

rhododendron (Rhododendron maximum and R. catawbiense) although common, were

excluded due to the amount of prolific basal sprouting, low basal area contribution to the

total, and failure of each species to reach true canopy codominance in most cases. Plot level

calculations of live and dead basal area (m2/ha), live and dead stem density (stems/ha), and

Class 1

Class 3 Class 4

Class 2

80

crown class for each species were made for comparison to the previous survey. Data from

the 1986 survey were obtained from the previous investigators at VPI and compiled to

summarize the parameters listed above for each species at the plot level. Plots were paired

for statistical analysis using paired t-testing (Battles et al. 2003) in order to determine the

statistical significance of the difference of each parameter mean as stratified by elevation or

aspect. Increment classes above 5 cm-dbh, in 10 cm-dbh increments, were made for

comparison and assessment of size distribution of each species.

81

2.3 RESULTS

2.3.1 Individual Plot Assessments

Plot B-44 Cattail Peak

This plot is located on a very gently sloping northwest facing site adjacent to Cattail

Peak, with some rock outcrops of moderate size. The canopy is dominated by Fraser fir, with

red spruce and a couple of large mountain ashes. The canopy is not very vigorous, and it is

open in half the plot with many large and dead standing firs occupying the site. There is a

moderate understory of fir and spruce saplings with some mountain ash. Many trees have

lost their apical leaders possibly due to lightning and ice damage. Ingrowth since the last

survey was found to be minimal. Balsam woolly adelgids were not found. Groundcover is

thick with ferns and white hellebore (Veratrum viride Aiton).

Plot B-52 Potato Knob

The plot is located on very gently sloping site astride a saddle between two peaks

north of Potato Knob. The former overstory canopy of fir appears to have completely

collapsed and is 98 percent open; most tagged trees from the previous survey are long dead

with none left standing. The new emerging canopy is composed of a very dense growth of fir

saplings 3-5 m high, and includes some mountain ash and rhododendron. The groundcover is

composed of many ferns and moss. Balsam woolly adelgids were not found. There is a high

amount of recruitment of Fraser fir on this site.

Plot B-53 Balsam Cone

The topography at this site on the southeastern flank of Balsam Cone is moderately

steep with some rock outcrops. The plot appears to have collapsed from the former high

canopy of Fraser fir. Most previously tagged trees are dead and decaying with a few still

82

standing. The site has a very thick stand of young fir, creating a canopy of codominant trees

about 5 to 6 m high. Dead woody debris is common throughout with some large deadfall in

abundance. Many trees are growing on rock outcrops. There are a few spruce seedlings

among the overwhelming number of fir. Balsam woolly adelgids were found here on three

fir trees. Many of the taller new firs are losing their apical leaders possibly due to wind, ice,

or lightning, with approximately 20 percent damaged in this fashion.

Plot B-54 Mt. Mitchell

This plot is on a gently sloping south facing site near the summit of Mt. Mitchell.

The high canopy of this site is highly damaged, approximately 50 to 60 percent open, with

few large dead Fraser firs remaining. The remaining live canopy is composed of some rather

large spruce and mountain ash trees. The subcanopy of fir saplings is very thick in some

areas and rather patchy under the open canopy. Balsam woolly adelgids were not found.

Blackberry is abundant throughout the plot in places where fir recruitment is not thick. Fern

and white hellebore comprise the remainder of groundcover.

Plots with trends indicating rapid recovery with large amounts of regeneration under a

dead or dying overstory include B-52, 53, and 54. These plots had live stem densities

exceeding 3000 stems/ha giving evidence as vigorous recovery. Extreme examples of this

trend are plots B-52 and 53, where live fir densities rose from 1,275 to 5,700 and 800 to

6,200 stems/ha respectively over 17 years. Other mean parameter trends include a reduction

in dead stem density and basal area, and an increase in live basal area. These plots were in

areas of recent severe mortality, resulting in an almost completely open canopy. Fraser fir

tends to be the primary contributor to sapling density on these sites with a minor amount of

regenerating spruce. Each parameter trend is discussed in detail below.

83

2.3.2 Stem Density

An increase in total live stem density was apparent for most plots at 1980 m (Table 2.1).

There was a significant (p < 0.10) increase of 385 percent in mean total live stem density

from the previous survey. The bulk of this change can be attributed to Fraser fir, which

showed more than a four-fold significant increase in mean live stem density, rising from 919

stems/ha in 1986 to 4156 stems/ha in 2003. Over the same period, red spruce increased

noticeably, but not significantly, at the same locations. This high-density increase was due to

growth on plots B-52 and 53, which had very high amounts of fir recruitment with densities

approaching and exceeding 6000 stems/ha. On the four plots at this elevation live yellow

birch was not found in the latest survey.

Although no statistically significant changes occurred for each species and the overall

total, there were some notable trends in mean dead stem density (Table 2.1). The drop in

mean total dead stem density from 1986 to 2003 was 1068 stems/ha. The most dramatic

change was a reduction in Fraser fir standing dead stems from 1163 to 288 stems/ha.

Additionally, red spruce and yellow birch mean dead stem densities dropped by roughly two-

thirds in these locations. The plots appeared to have lost most of their previously dead stems,

as they have dropped out of the canopy creating large amounts of dead woody debris.

TABLE 2.1 LIVE AND DEAD STEM DENSITY WITH STANDARD ERROR FOR FRASER FIR, RED SPRUCE, YELLOW BIRCH, AND THE TOTAL FOR ALL OVERSTORY SPECIES AT 1980 M (N=4).

Live Dead Stem Density (stems/ha)Species 1986 2003 1986 2003

Fraser FirRed SpruceYellow Birch

Total

919 ± 24075 ± 1025 ± 25

1181 ± 288

4156 ± 1105a

275 ± 1880 ± 0

4556 ± 1088a

1163 ± 63175 ± 7431 ± 31

1406 ± 649

288 ± 9725 ± 2513 ± 12

338 ± 114

a. Significant change from previous value at p < 0.10

84

2.3.3 Basal Area

Overall there is no statistically significant difference in live basal area for any of the species

or the total at 1980 m (Table 2.2), however several trends were noted. At 1980 m Fraser fir

showed a substantial increase in basal area from 17.9 to 33.0 m2/ha, mainly due to the

quadrupling of live stems ≥ 5 cm-dbh at this elevation. Vigorous regeneration of fir saplings

on two of the four plots at this altitude is responsible for this trend. Additionally, live yellow

birch disappeared from the 1980 m plots since the previous survey in 1986.

There were no statistically significant differences between the 1986 and 2003 surveys

for dead basal area at 1980 m as shown by Table 2.2. However, the trend for all species is

downward causing a drop in the mean dead basal area from 29.4 to 16.6 m2/ha. This

decrease was mainly influenced by the 37 percent drop in the mean fir dead basal area at this

altitude, which resulted from a single stand’s (plot B-52) loss of all its dead stems and a drop

in dead basal area from 32.0 to 0 m2/ha.

TABLE 2.2 LIVE AND DEAD BASAL AREA WITH STANDARD ERROR FOR FRASER FIR, RED SPRUCE, YELLOW BIRCH,

AND TOTAL FOR ALL OVERSTORY SPECIES AT 1980 M (N=4).

Live Dead Basal Area (m2/ha)Species 1986 2003 1986 2003


Total

17.9 ± 5.53.4 ± 1.5 0.2 ± 0.1

23.7 ± 6.1

33.0 ±5.74.8 ± 2.50.0 ± 0.0

41.3 ± 3.6

22.0 ± 5.05.2 ± 5.10.4 ± 0.3

29.4 ± 4.7

13.9 ± 5.02.5 ± 2.40.1 ± 0.1

16.6 ± 5.6

85

2.3.4 Crown Class Condition

Crown class was evaluated for each tree with ≥ 5 cm-dbh. Classes 1-3 consist of live trees

and cumulatively are the components of live stem density while Class 4 trees are dead.

Although no statistically significant findings were obtained, the breakdown of live stem

density into separate classes allowed us to see the trends occurring within this parameter

much more precision.

The mean density of Crown Class 1 trees (stems/ha) greatly increased with an overall

rise of 400 percent in the total (Table 2.3). Fraser fir Class 1 density was responsible for the

bulk of this rise, with a large increase of 2144 stems/ha from 1986 to 2003. This rise in

density was attributed to dense fir regeneration on three of the four plots at this altitude.

Figure 2.4 illustrates the shift in crown class categories for fir on a plot by plot basis. The

proportion of Class 1 firs rose greatly on B-52 (Figure 2.4b) and showed various different

shifts on the remaining plots. When combined on plots B-53 and B-54 (Figures. 2.4c and

2.4d), Class 1 and 2 trees account for a much higher proportion of trees than in 1986.

Mean Class 2 density for fir and spruce also increased greatly, causing the mean total

to rise from 356 to 1375 stems/ha (Table 2.3). The high density of Class 2 trees at 1980 m is

primarily due to fir ingrowth on plots B-53 and B-54 (Figures 2.4a and 2.4d). Overall, the

densities and percentages of Class 3 trees remains relatively low as this classification is a

transition as trees move from healthier Class 1 and 2 trees to dead Class 4 trees. Table 2.3

shows a rising trend of 200 stems/ha in mean Class 3 density mainly due to the rise in Class 3

proportions on plots B-44 and B-53 (Figures 2.4a and 2.4c).

As with dead stem density, mean Class 4 density dropped sharply from 1406 to 338

stems/ha (Table 2.3). Many of the older dead firs have dropped out of the canopy with little

86

to no dead stem recruitment. The proportion of Class 4 firs on most plots showed the inverse

of the rise or fall in Class 1 and 2 trees. Plot B-44 (Figure 2.4a) underwent the smallest shifts

overall and actually had a small increase in Class 4 firs. However this site did not experience

a large amount fir mortality in the last 20 years and appears to be in a state of slow decline.

TABLE 2.3 CROWN CLASS 1-4 STEM DENSITY WITH STANDARD ERROR FOR FRASER FIR, RED SPRUCE, YELLOW BIRCH, AND TOTAL FOR ALL OVERSTORY SPECIES AT 1980 M (N=4).

FIGURE 2.4A-D PERCENTAGE OF CHANGE IN FRASER FIR CROWN CLASS FROM 1986 TO 2003 FOR EACH PLOT AT

1980 M.

Class 1 Class 2 Class 3 Class 4 (0-10 % damage) (11-50 % damage) (51-99 % damage) (standing dead) Stem Density (stems/ha)Species 1986 2003 1986 2003 1986 2003 1986 2003


Total

525 ± 14369 ± 1513 ± 13

706 ± 150

2669 ± 109388 ± 250 ± 0

2863 ± 1115

306 ± 1286 ± 56 ± 5

356 ± 135

1181 ± 485175 ± 163

0 ± 0

1375 ± 620

88 ± 630 ± 06 ± 5

119 ± 85

306 ± 16013 ± 80 ± 0

319 ± 158

1163 ± 63175 ± 7431 ± 31

1406 ± 649

288 ± 9725 ± 2513 ± 12

338 ±114

Figure 4 1 Figure 4 2

Figure Figure 4 4

Fraser Fir Crown Class Change 1986 to 2003Plot B-54

0

10

2030

40

50

60

7080

90

100

1 2 3 4

Crow n Class

Perc

enta

ge o

f Tre

es

1986

2003

Fraser Fir Crown Class Change 1986 to 2003Plot B-53

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4

Crown Class

Perc

enta

ge o

f Tre

es

1986

2003

Fraser Fir Crown Class Change 1986 to 2003 Plot B-52

0102030405060708090

100

1 2 3 4

Crown Class

Perc

enta

ge o

f Tre

es

1986

2003

Fraser Fir Crown Class Change 1986 to 2003 Plot B-44

0102030405060708090

100

1 2 3 4

Crown Class

Perc

enta

ge o

f Tre

es

1986

2003

a

c

b

d

87

2.3.5 Diameter Class Change

Although not analyzed statistically for differences between surveys, the main purpose of this

section was to observe the change in growth patterns and recruitment of live stems and live

basal area as a function of diameter size class. The author deemed it cumbersome to perform

in-depth statistical comparisons and realizes this oversight in data analysis.

Fraser Fir

Fraser fir underwent explosive growth in the 5-15 cm-dbh class. Live stem density

rose from 644 to 3844 stems/ha and basal area increased similarly from 4.0 to 21.2 m2/ha

from 1986 to 2003 (Figure 2.5). This was mainly due to the high regeneration found on the

two plots B-52 and B-53. A slight increase in live stems was shown in the 15-25 and 45-55

cm-dbh classes with reductions or no change in the other classes. This trend is opposite of

the hypothesized change by Nicholas (1992) that projected a slight drop in overall basal area

with the most pronounced drop in the 5-15 cm-dbh class.

FIGURE 2.5 FRASER FIR LIVE BASAL AREA AND STEM DENSITY 1986 TO 2003 AT 1980 M FOR EACH 10-CM DIAMETER CLASS (N=4).

0

5

10

15

20

25

5-15. 15-25 25-35 35-45 45-55 >55

Diameter Class (cm-dbh)

Basa

l Are

a (m

2/ha

)

0

500

1000

1500

2000

2500

3000

3500

4000

4500D

ensi

ty (s

tem

s/ha

)

1986 basal area2003 basal area1986 live stems2003 live stems

88

Dead stem density for fir at this elevation decreased dramatically from 756 to 100 and

319 to 81 stems/ha for the 5-15 and 15-25 cm-dbh classes respectively. Dead basal area

followed the same trend as it also dropped from 5.5 to 0.7 and 8.9 to 2.8 m2/ha for the 5-15

and 15-25 cm-dbh classes respectively. The remaining diameter classes showed slight to

moderate increases or no change in dead basal area or stem density for fir.

Red Spruce

At 1980 m, red spruce is reduced to a minor component of canopy codominance;

however, recruitment of stems in the 5-15 cm-dbh class is very apparent (Figure 2.6). Live

stem density of this class dramatically increased from 44 to 238 stems/ha. Live stem density

in the 15-25 cm-dbh class did not change, but basal area in this category doubled. Density

and basal area of the >55 cm-dbh class remained constant as the few large canopy trees at

this altitude remained alive.

FIGURE 2.6 RED SPRUCE LIVE BASAL AREA AND STEM DENSITY 1986 TO 2003 AT 1980 M FOR EACH 10-CM DIAMETER CLASS (N=4).

0

1

2

3

4

5

5-15. 15-25 25-35 35-45 45-55 >55

Diameter Class (cm-dbh)

Basa

l Are

a (m

2/ha

)

0

50

100

150

200

250

Dens

ity (s

tem

s/ha

)

1986 basal area2003 basal area1986 live stems2003 live stems

89

Dead stem density in this same class dropped from 63 to 19 stems/ha with a

corresponding 60 percent drop in dead basal area. Nicholas (1992) projected an extirpation

of red spruce at this altitude by 2009 and our results do not support this projection, because

red spruce live basal area actually increased in most diameter classes as well as an overall

increase from 3.4 to 4.8 m2/ha (Table 2.2).

Yellow Birch

Live yellow birch was absent from plots at 1980 m. Both density and basal area for

live trees dropped to zero from 1986 and 2003. Very few dead stems remain at this altitude

as well.

2.3.6 Disease and Insect Incidence

With the exception of cankers caused by Nectria spp. incidentally found on yellow birch,

very few specific disease occurrences were noted. Additionally we noted in many of the

same areas there were isolated birches possessing necrotic and/or insect damaged leaves that

appeared otherwise in good condition. Other disease trends may be difficult to determine, as

the technicians on this project were not well experienced in tree pathology or entomology.

Most evaluations were reduced to recognizing crown damage from a distance, lightning and

ice damage, and general fungal and insect sign and symptom recognition only.

The balsam woolly adelgid was not found at all during the summer of 2002, either on

surveyed Fraser firs or those we casually observed. This does not mean the adelgid was

absent, but only that we failed to find it in areas where we spent a significant amount of time.

During the summer of 2003 we found 3 infested firs at plot B-53 on trees 6.2 to 12.4 cm in

diameter. Adelgid infestations on tree boles were light with approximately one or two

90

insects per cm2. Mild cases of twig gouting, a symptom of past adelgid activity, were found

on several trees that had no live insects on the boles. During subsequent trips to the southern

Black Mountains in the summer of 2004, casual observation in several areas near the Mt.

Mitchell summit revealed the presence of the adelgid in numbers similar to those recorded in

2003.

91

2.4 DISCUSSION

While it appears that recovery of Fraser fir is underway in the Black Mountains, the amount

of progression towards a climax high-elevation fir forest is highly variable and very patchy.

The forests at this altitude appear to be a mosaic of disturbances and recovery with very few

large stable stands of mature fir remaining. Most of the forest is either still slowly

collapsing, as evidenced by crown classes for older trees shifting from healthier to poorer

conditions, or is in a state of rapid recovery under a now dead and largely absent upper

canopy. The exogenous disturbances of the balsam woolly adelgid and air pollution have

greatly impacted the once uniform fir forests at this altitude. Timing of adelgid infestation

seems to have had the greatest impact on stand structure as earlier infested areas have already

recovered somewhat, while some later-infested areas are just now making a comeback. The

last wave of widespread adelgid induced mortality was declared nearly complete back in the

early 1990’s (Nicholas et al. 1992), and our lack of finding widespread adelgid populations

and large amounts of recent mortality seem to confirm this. However, this may simply be a

lull in adelgid numbers as the population of susceptible Fraser firs has been drastically

reduced since introduction in 1957. Young, vigorous firs have few cauline feeding sites to

allow feeding of the pheloderm and cannot support large adelgid populations (Eagar 1984).

Further research is needed to establish the current state of BWA in the region.

The cycles of high elevation southern fir forests are not well understood and 17 years

is a relatively short interval in a forest where the dominant species may have an average life

span of 150 years (Oosting and Billings 1951). However, Eagar (1984) suggested that an

approximately 35 to 60 year cycle of infestation may occur in the Great Smoky Mountains.

Given the hypothesized length of such a cycle, a long-lived species such as Fraser fir has not

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had sufficient time for evolution of resistance to the adelgid. Whether or not the remaining

population of fir in the Black Mountains that has escaped infestation is resistant to the

adelgid remains to be confirmed, as is the potential for fir to attain reproductive maturity

before succumbing to subsequent infestations (Busing et al. 1988). The increase in fir

sapling density suggests normal growth patterns resulting from a sufficient seed bank, and at

least a temporary recovery from adelgid infestation appears likely.

Along with the positive growth trends in Fraser fir we can speculate that the soil and

climate are still sufficiently unchanged to support emerging fir forests at this altitude.

Recovered data from the soil and foliar samples we extracted from these sites can perhaps

answer these speculations with better accuracy.

2.4.1 Comparison to “virgin” or undisturbed fir forest

A few key studies measured spruce-fir and fir forest parameters prior to the introduction of

the balsam woolly adelgid and the suspected impacts of atmospheric pollutants in the

Southern Appalachians. While our study area is far removed from what would be considered

“virgin” forest, there is a noticeable shift towards the stable unmanaged uneven-aged forest

that may have been found 50 years ago in the Black Mountains. Cain (1935) reported a total

basal area of 66 m2/ha for fir and spruce on Mt. LeConte at 1920 m (6300 ft) in the Great

Smoky Mountains within a forest of 90 percent fir. Oosting and Billings (1951) reported the

live basal area of fir at the same elevation in the Great Smoky Mountains to be 32.6 m2/ha

with a density of 1300 stems/ha. The basal area of fir we found mirrors these values;

however, our live fir density far exceeded their findings. This discrepancy is mainly due to

the high level of recruitment on our sites, and we expect the density to drop drastically in the

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coming decade due to competition induced mortality. On plot B-44, where the trend in

growth is most stable, the density of fir matches findings by Oosting and Billings (1951).

The amount of dead stems was not quantified but they reported that dead standing and down

trees are common in fir stands and characteristic of virgin climax forest. We found a

decreasing trend in dead stem basal area and density, which we would have expected, given

that most of the larger overstory firs died over a decade ago.

Whittaker (1956), who also reported findings for Great Smoky Mountain high

elevation fir forests, found the bulk of canopy stems to be in the 18 to 23 cm-dbh range with

a canopy height of 9 to 12 m. Our findings show the bulk of fir stems in the 5-15 cm-dbh

range and we expect the majority of survivors in this diameter class to shift to the 15-25 cm-

dbh range in next 20-30 years based on growth rates found by Oosting and Billings (1951).

At the same time we expect the canopy, which at this time is rather restricted on sites of high

recruitment, to slowly rise from our present estimations of 3-6 m.

2.4.2 Comparison with Recent Studies

DeSelm and Boner (1984) and Busing and Clebsch (1988) reported that Fraser fir is able to

recover in sufficiently large numbers following adelgid infestation. Their methods included

a count of subsaplings (< 2.5 cm-dbh), as well as stems over 2.5 cm-dbh at high elevation

plots in the Black and Great Smoky Mountains. Although they found fir density ranging

from 510 to 2400 stems/ha respectively, somewhat lower than our findings, high Fraser fir

density and recruitment of stems into sapling and overstory categories was becoming

apparent. As recently as 1988, Bruck et al. (1989) found rapid collapse of mature fir and

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spruce at high altitude sites near Mt. Mitchell. Our results seem to be the reverse of this

trend, as our data suggest a rapid recovery in progress.

Results from a recent study in the Great Smoky Mountains (Smith and Nicholas

2000) are consistent with our findings in many ways. Mean basal area of Fraser fir in live

pure fir stands was 33.0 m2/ha, exactly what we found in the Black Mountain fir stands. Live

fir density was markedly higher than in the other stand types they analyzed, but was much

lower than the mean value we found. However, as we discovered on our sites, this value can

fluctuate greatly within a span of a few meters due to high spatial variability of recruitment.

Additionally, size class distribution in the live fir stands displayed a similar response

following overstory collapse. Red spruce, while not a major canopy component in live fir

stands, showed very similar live basal area and density values to our study.

Few previous studies have quantified standing dead stem density and basal area in

Southern Appalachian fir forests, although standing dead trees are often used as a measure of

mortality. Smith and Nicholas (1998) state three processes that need to be analyzed in order

to understand the cycle of standing dead stems: fir death, the fall of dead fir stems, and

recruitment of understory fir into the overstory. For Fraser fir our overall results show a

marked decrease in standing dead stem proportion over time rather than an increase, along

with high recruitment of understory fir. Although annual mortality cannot be deduced from

our data, the trend over the past 17 years suggests a lower mortality rate for fir than

previously reported, as dead stems are occupying much less area. Our findings do coincide

with other studies for adelgid-impacted stands as Nicholas et al. (1992) and Bruck and

Robarge (1988) found 6 to 22 m2/ha and 10 to 20 m2/ha dead basal area in the Black

Mountains respectively. However, what certainly has changed is the once greater proportion

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of standing dead fir basal area to live fir in high elevation stands, especially for those stands

that have had a longer recovery time.

2.4.3 Analysis of Projected Values

Our results contrast greatly with projections of fir composition and size distribution at 1980

m made by Nicholas (1992) for the year 2009. The amount of potential recruitment of Fraser

fir at this altitude seems to have been overlooked because the basal area for the 5-15 cm-dbh

class was only projected to be 0.5 m2/ha by 2009, and the total live basal area projected for

2009 was 12.5 m2/ha (Nicholas 1992). It appears that this prediction will be grossly

inaccurate as we found a mean basal area of 33.0 m2/ha for fir. The majority of this was due

to massive ingrowth in the 5-15 cm-dbh class. However, the amount of recruitment we

found especially for plots B-52 and B-53 should keep the mean live basal area much higher

than 12.5 m2/ha for quite some time even if half of the new stems die in the next 6 years. It is

possible that the remaining plot at this altitude we did not survey could have diminished our

mean basal area but even if the plot were void of live Fraser fir (highly unlikely) than our

mean would only have been reduced by 20 percent.

The response of red spruce at this altitude was also opposite of the trend projected by

Nicholas (1992). Her study showed the elimination of red spruce by 2009 at 1980 m. This

was assuming the death of remaining larger spruce on these sites and a lack of ingrowth

recruitment of new stems. Our mean live basal area for spruce, while quite small in absolute

terms, actually showed quite a large amount of recruitment in the 5-15 cm-dbh class. Live

density in this class grew from 75 to 275 stems/ha and with the remainder of the size classes

growing or showing a shift towards larger diameters. Zedaker et al. (1988) suggested that

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red spruce in fir dominated stands, which is normal at 1980 m, may show increased mortality

rates due to thinning shock caused by the rapid removal of fir from the overstory, however

our findings seem to refute this.

As projected by Nicholas (1992), live yellow birch practically disappeared from the

plots at this elevation. No new live stems were reported and the number of dead stems also

dropped to almost nothing. These trends follow the projections made for the year 2009 and

appear unlikely to change by then as the presence of this species was only noted at plot B-53

and then only as 2 dead stems.

Many weaknesses in modeling future stand projections are covered by Nicholas

(1992) and the results of this study may be able to help future modeling of growth or

mortality in this type of forest.

2.4.4 Conclusions

The Southern Appalachian montane spruce-fir forest has undergone considerable change in

the last century, with widespread impacts ranging from logging and fires in the early 20th

century to exotic insect induced mortality and air pollution related stresses (Silver 2003).

Particularly in the Black Mountains there was considerable reduction in the size and density

of high elevation Fraser fir following those impacts. However, the wave of adelgid

infestation that spanned the 30 years following introduction to the region does appear to have

ended. Fraser fir seems to have made significant gains in reestablishing itself and

maintaining dominance on the high peaks and ridges in the forests near Mt. Mitchell.

Live fir density and basal area has greatly improved since the previous survey in

1986; however, some of the large dominant trees are still showing signs of poor crown vigor.

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It is expected that fir will stabilize at much lower densities in the coming decades as

competition for canopy status naturally thins the stand while it continues to grow. Even

though we did not find the balsam woolly adelgid in large numbers, the long range forecast

for this forest remains uncertain, because adelgid populations are expected to rebound as the

newly emergent fir saplings reach susceptible age and size classes and enter the overstory.

Because susceptible size classes are much smaller than reproductive size classes for Fraser

fir, we can expect to see another wave of fir mortality with few trees reaching maturity. The

survival of Fraser fir in the Southern Appalachians will depend on its growth and

reproduction cycle and the ability to withstand subsequent infestations. Potential impacts

due to climate change, air pollution, and precipitation chemistry may become evident in the

near future but are most likely still decades away. Forest response to chronic long-term

disturbances depends on many factors and the ability of other species (namely spruce and

birch) to colonize and prevent fir dominance in the high elevations.

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research. Additionally I would like to thank the entire Mt. Mitchell State Park staff for

allowing us access to park facilities and joining the spirit of scientific pursuit.

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3. Species composition and crown condition of northern hardwood forests of the Black Mountains, North Carolina.

ABSTRACT

Northern hardwood forests of North Carolina, found up to approximately 1525 m where they

give way to spruce-fir forests, exhibit a unique assemblage of many species endemic to the

Southern Appalachians. Common northern hardwood type canopy trees of the Black

Mountains include northern red oak (Quercus rubra var. borealis Michaux f.), chestnut oak

(Q. prinus L.), red maple (Acer rubrum L.), sugar maple (A. saccharum Marshall), American

beech (Fagus grandifolia Ehrh.), and eastern hemlock (Tsuga canadensis (L.) Carr.). In the

summers of 2002-3 we undertook an investigative survey of northern hardwood forests to

characterize the forest structure, crown conditions, and emerging diseases of typical

dominant species by installing 40 400 m2 permanent plots in 9 areas throughout the Black

Mountains between 1220 and 1525 m. Special attention was given to the presence of

hemlock woolly adelgid (Adelges tsugae Annand) on hemlock, beech scale insect

(Cryptococcus fagisuga Lindinger) and cankers caused by Nectria coccinea var. faginata

(Lohman, Watson and Ayers) on beech, and low crown vigor or defoliation in oaks. With

the exception of red spruce (Picea rubens Sarg.) and eastern hemlock, the survey found most

tree species in an excellent condition. Many feared emerging pathogens and insects were not

evident, however it is expected that they may have profound impacts on forests throughout

the region. The main value of this study is in the long-term monitoring of these sites and

detection of disease onset and incipient mortality before epidemic levels are achieved.

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3.1 INTRODUCTION

3.1.1 Background

The composition and condition of the northern hardwood and cove forests surrounding the

Black Mountains of North Carolina has only been sparsely studied since the days of

widespread logging in the region and the loss of the American chestnut (Castanea dentata

(Marsh.) Borkh)3 throughout the Southern Appalachians in the early 20th Century (McLeod

1988; Silver 2003). The introduction of the chestnut blight fungus (Cryphonectria

[Endothia] parasitica [Murr.] Barr.) radically changed the composition and structure of the

eastern deciduous forest (Myers et al. 2004) by the removal of a key dominant species.

Chestnut blight had only minor direct effects on oaks (Quercus spp.); however, the indirect

effects were profound. As chestnut died, newly available growing space was quickly

occupied by other species already positioned in the mid- and understory by earlier

disturbances. Chestnut replacement was variable, but typically oak species (Q. prinus L., Q.

rubra L., and Q. velutina Lam.) increased (Oak 2002). Recovery from the chestnut blight in

the form of gap colonization appears to be complete in areas of former chestnut dominance in

the Black Mountains. Since the 1940’s there has been relatively little disturbance in the form

of direct human activity throughout the northern hardwood and cove forests at the higher

elevations of the Black Mountains, although the land continues to be used for some private

game management, scientific research, and various forms of public recreation (Silver 2003).

The name "northern hardwood forest", traditionally given to these communities,

implies a similarity to hardwood forests of the northern Appalachians. Many tree, shrub, and

herb species are shared; however, the northern hardwood forests of North Carolina have

evolved under different climatic regimes, with a different phytogeographic history, and

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exhibit many plant and animal species endemic to the Southern Appalachians. They are

clearly not the same natural community types as the forests of the northern United States

(Schafale and Weakley 1990) and are unique in their own right. In the Black Mountains

most topographic features such as slopes, ridges, sheltered valleys, and coves support forests

dominated by mixed deciduous hardwood trees with mesic shrub types and numerous herbs

in the understory. This general forest type is found up to approximately 1525 m (5000 ft)

where it gives way to forests dominated by red spruce (Picea rubens Sarg.), yellow birch

(Betula lutea Michaux f.), and Fraser fir (Abies fraseri [Pursh] Poiret) (McLeod 1988).

Whittaker (1956) and Stupka (1964) described similar forest types occurring under similar

elevational and moisture ranges throughout the Great Smoky Mountains National Park in

Tennessee and North Carolina.

Southern Appalachian northern hardwood trees common at higher altitudes below the

spruce-fir zone of the high ridges and peaks of the Black Mountains include northern red oak

(Quercus rubra var. borealis Michaux f.), chestnut oak (Q. prinus L. or Q. montana Willd.),

red maple (Acer rubrum L.), striped maple (A. pensylvanicum L.), mountain maple (A.

spicatum Lam.), sugar maple (A. saccharum Marshall), American beech (Fagus grandifolia

Ehrh.), eastern hemlock (Tsuga canadensis (L.) Carr.), yellow birch, black birch (Betula

lenta L.), fire or pin cherry (Prunus pensylvanica L. f.), black cherry (P. serotina Ehrhart),

red spruce, chinquapin (Castanea pumila [L.] Miller), tulip poplar (Liriodendron tulipifera

L.), black locust (Robinia pseudo-acacia L.), witchhazel (Hamamelis virginiana L.),

basswood (Tilia heterophylla Vent.), sourwood (Oxydendrum arboreum [L.] DC.), hickory

(Carya spp.), alternate-leaved dogwood (Cornus alternifolia L. f.), yellow buckeye (Aesculus


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octandra Marshall), cucumbertree (Magnolia acuminata L.), and Fraser magnolia (M. fraseri

Walt.) (Whittaker 1956; Stupka 1964; McLeod 1988; and Schafale and Weakley 1990).

Several current and emerging threats to forest communities within the high elevation

northern hardwood and oak forests of the Black Mountains exist, with various levels of

severity to selected dominant tree species. These threats include, but are not limited to,

diseases and insects such as hemlock woolly adelgid (HWA) infestations of hemlock, the

beech bark disease (BBD) complex of American beech, gypsy moth defoliation of oaks,

ramorum leaf blight of oaks and many other tree and shrub species, and oak wilt; many of

which are caused by the introduction of non-native species to the Southern Appalachians

(USDA 2001). The introduction of these exotic species and their spread within the region are

expected to modify forest succession patterns and alter native forest character as the

abundance and diversity of trees in North America are matched by the number of diseases

and insects that affect them (Manion 1991; Jenkins et al. 1999; Dey 2002; Oak 2002; USDA

2003).

A current threat to the eastern hemlock and Carolina hemlock (Tsuga caroliniana

Engelm.) in the Black Mountains is the hemlock woolly adelgid, Adelges tsugae Annand

(Homoptera: Adelgidae). Believed to be a native of the hemlock regions in Asia where it

does little damage, the adelgid was first detected in the eastern United States in Richmond,

Virginia in the 1950’s (McClure 2001; Salom et al. 2001). Following introduction, the HWA

spread rapidly west into the Blue Ridge Mountains and north into New England. By the late

1980s, isolated infestations were discovered in forests in Virginia, eastern Pennsylvania,

Connecticut, and New Jersey, where the abundance of host trees and lack of effective natural

enemies contributed to its rapid buildup and spread. Today, HWA infestations have spread

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to portions of 16 states from Georgia to Maine and westward to Tennessee. Decline and

mortality have been significant in close to 30 percent of the geographic range of eastern

hemlock, and the adelgid is continuing to expand its range throughout eastern North America

(Salom et al. 2001; Onken et al. 2002; and Onken 2004).

Adelgid feeding impacts shoot development and subsequently growth of new needles

in hemlock. The HWA kills hemlock within 4-7 years of infestation, yet the trees often live

longer (Salom et al. 2001). HWA is steadily spreading into the oldest and largest hemlock

forests of the Southern Appalachians, with people having the greatest influence on its spread

(Snider 2004). There are no known parasites of Adelgidae and existing natural enemies are

not effective in controlling HWA in eastern North America (Onken 2004). Some progress

has been made in controlling the adelgid in selected areas where laboratory raised predatory

beetles have been released. Two tiny nonnative beetles, Laricobuius nigrinus Fender

(Coleoptera: Derodontidae) and Pseudoscymnus tsugae Sasaji and McClure (Coleoptera:

Coccinellidae), show the most promise as both actively hunt the adelgid as prey (McClure

and Cheah 2003; Zilahi-Balogh et al. 2003; and Lamb et al. 2005). The recent establishment

of HWA in the Great Smoky Mountain region, including the Pisgah and Nantahala National

Forests of Western North Carolina, threatens some of the oldest and largest specimens of

eastern hemlock in North America.

Another cause for considerable concern in the Southern Appalachians is beech bark

disease, which constitutes a serious problem for northern hardwood forests in eastern North

America. BBD is caused by a complex that occurs on American beech, its southern variety

(F. grandifolia var. carolinana [Loudon]), and European beech (F. sylvatica), characterized

by a sequential attack of the beech scale insect (Cryptococcus fagisuga Lindinger) and fungi

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in the genus Nectria (Manion 1991; Tainter and Baker 1996; and LeGuerrer et al. 2003).

Since initial Cryptococcus damage is a prelude to the severe Nectria infection associated

with BBD, the spread of BBD is largely governed by the wind- and animal-borne dispersal of

Cryptococcus. After 3–5 years of scale insect population buildup, known as the “killing

front”, enough damage occurs for Nectria to become established (Tainter and Baker 1996;

Griffin et al. 2003).

Damage from the feeding activity of the beech scale insect predisposes the bark of

beech trees to infection by the fungus Nectria coccinea var. faginata (Lohman, Watson and

Ayers), one of several species of Pyrenomycete (Ascomycota) fungi that affect hardwood

trees in North America and Europe (Mahoney et al. 1999; Latty et al. 2003). Since being

introduced in the United States around 1920 (Ehrlich 1934), beech bark disease and the

associated damage has spread throughout New England, west to Michigan, and south through

West Virginia and Virginia, and into the Southern Appalachian mountains (Mielke et al.

1985; Manion 1991; Houston 1994; Tainter and Baker 1996; and O’Brien et al. 2001).

Special attention has been given to this disease complex, as it is now known to occur in the

Pisgah National Forest that surrounds the Black Mountains.

One of the most recent examples of an emerging forest disease and a potential threat

to eastern oak trees is a disease known as “sudden oak death”, or ramorum leaf blight. The

symptoms that define it were first recognized during 1994–95, and over the next few years it

reached epidemic proportions in oak forests and yards along approximately 300 km of the

central California coast (Garbelotto et al. 2001). The most visibly affected hosts included

tanoak (Lithocarpus densiflora [Hook and Arn] Rehd.), coast live oak (Quercus agrifolia

Nee), and California black oak (Q. kellogii Newb.) (Rizzo et al. 2002; Rizzo and Garbelotto

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2003). Eventually it was shown that the pathogen Phytophthora ramorum, recently

described from rhododendron (Rhododendron spp.) and viburnum (Viburnum spp.) in Europe

(Werres et al. 2001; Rizzo et al. 2002), was causing the disease. To date, over 40 species in

12 plant families are known to be naturally infected by P. ramorum. Species in the Ericaceae

and Fagaceae families appear to be especially prone to infection (Davidson et al. 2003).

Because of the limited knowledge of the ecology of P. ramorum, the impact of this newly

described pathogen in regions outside of the western United States and Europe is difficult to

predict. Specifically, species of high susceptibility in the Black Mountains may include but

are not limited to northern red oak, scarlet oak (Q. coccinea Muenchh), chestnut oak,

mountain laurel (Kalmia latifolia L.), and rhododendron (Werres et al. 2001; Rizzo and

Garbelotto 2003).

Along with chestnut blight, the European gypsy moth (Lymantria dispar L.) is

another example of an exotic organism that has and continues to profoundly effect oak forest

ecosystems in North America (USDA 2001; Oak 2002). Since its introduction in 1868 near

Boston, the insect has spread south with a leading edge in North Carolina (Elkinton et al.

2002). The gypsy moth is a major defoliator of oak forests throughout forests in the eastern

United States and in most regions it remains at a low density in most years but it occasionally

erupts into an outbreak phase. Defoliation by the gypsy moth can result in growth loss,

crown dieback, and tree mortality. Trees that have been defoliated begin the next year with

much lowered food reserves and are far more vulnerable to other insect and disease pests

(USDA 2003). The insect does especially well on chestnut oaks and sugar maple and other

common hosts in the Black Mountains include northern red oak, beech, eastern hemlock, and

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red spruce. During severe outbreaks, all forest trees species except tulip poplar, black locust,

and ash may be partially or entirely defoliated (Lechowicz 1983, USDA 2003).

Oak wilt, another common problem in the Southern Appalachians, a systemic

vascular wilt disease caused by the fungus Ceratocystis fagacearum Bretz, is now regarded

as one of the most internationally dangerous tree diseases (Nair 1996). The range of oak wilt

in the Appalachian Mountains extends from Pennsylvania south to South Carolina. Oaks

(Quercus spp.) become infected when the fungus is vectored by contaminated adults of one

of several species of sap feeding or oak bark beetles (Nitidulidae and Scolytidae,

respectively). Symptoms include incipient wilt of leaves for a day or two, followed by the

dull discoloration with slight curling of the tops of these leaves, usually in the upper crown.

These leaves later become progressively brown from the margins and tips toward the base

(Manion 1991; Nair 1996; and Tainter and Baker 1996). Symptoms spread rapidly and

defoliation of the entire tree is usually complete within three to six weeks after infection.

Species in the red oak group are more susceptible to this disease and may die within weeks of

first symptom expression, especially in cool, moist environments (Nair 1996; Tainter and

Baker 1996; and Oak 2002), which are prevalent in the sheltered coves and north facing

slopes of the Black Mountains.

In tandem with a resurvey of the high elevation spruce-fir forests of the Black

Mountains, we conducted another survey in the adjacent northern hardwood forests at lower

elevations in the same region. The purpose of this investigative survey was to establish a

permanent plot system and collect baseline data for future monitoring of pathogens and

insects, and to characterize the crown conditions of typical dominant northern hardwood tree

species in the Black Mountains. Special attention was given to the presence of hemlock

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woolly adelgid on hemlocks, beech scale and the associated bark disease on beeches, and low

crown vigor or defoliation in oaks. This paper reports the findings of the survey of northern

hardwood and cove forests made in the summers of 2002-03. The information we collected

can be used to characterize commonly encountered forest species in the region; however, one

is reminded that our data were not collected as part of a completely randomized sample and

should not be treated as such. Lack of randomization prevents us from inferring gradient

trends, and this type of analysis was deemed beyond the scope of our project.


The Black Mountains are part of the Southern Appalachian and Blue Ridge Mountain

ecophysiographic zone, which extends northeast from northern Georgia to northern Virginia.

They are situated in western North Carolina, 40 kilometers northeast of the city of Asheville

NC (Figure 3.1), at approximately 35°35’ N, 82°15’ W. Mount Mitchell, at 2037 m (6684

ft), is the highest peak in eastern North America and is only one of several high peaks within

the Black Mountain range. The bulk of the range, thus our study area, is oriented roughly

north-south extending from Celo Knob in the north to Black Mountain Gap in the south.

112

FIGURE 3.1 LOCATION OF MT. MITCHELL AND THE BLACK MOUNTAINS IN WESTERN NORTH CAROLINA.

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3.2.1 Site Selection and Plot Establishment

Criteria for site selection followed a simple rubric. We wished to capture representative

examples of northern hardwood forest species in an equal array of elevations and aspects

surrounding the Black Mountains. We surveyed stands between 1220 and 1525 m (4000 and

5000 ft) above mean sea level as determined by a global positioning system locator and

topographic map. This was not intended to be a random sample of forest types but rather an

establishment of baseline data for future surveys; thus sites were selected for ease of access.

The goal of this survey was to gain a better understanding and establish baseline data of the

dominant tree species in the Southern Appalachian northern hardwood and montane oak

forests surrounding the Black Mountains in Yancey County, North Carolina. All plots are at

least 20 m (65.6 ft) from any established footpath or road. Our sampling protocol covered

the entire elevation range and a full range of aspects while avoiding spruce-birch and spruce-

fir forests at the higher altitudes.

Potential areas to survey with accessible trials were delineated with a projected

average of five plots designated per area. Plots were grouped and designated with a number,

with consecutive numbers in the same general location. Locations were named as follows

and shown on Figure 3.2: Bald Knob Ridge (plots 1-5), Buncombe Horse Range Ridge (plots

6-9), Blue Ridge Parkway (plots 10-15), Mt. Mitchell Trail (plots 16-20), Locust Creek (plots

21-25), Woody Ridge (plots 26 and 27), Celo Ridge (plots 31-33), Bowlens Creek (plots 36-

40), and North Fork (plots 41-45).

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FIGURE 3.2 NORTHERN HARDWOOD PLOT LOCATIONS IN THE VICINITY OF THE BLACK MOUNTAINS IN YANCEY

COUNTY, NORTH CAROLINA.

Blue Ridge Parkway Bald Knob Ridge

Buncombe Horse Range Ridge

Mt. Mitchell Trail

Locust Creek

North Fork

Woody Ridge

Celo Ridge Bowlens Creek

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Plots were specifically established by the following methodology. Suitable locations

were determined using USGS topographic maps and local trail descriptions. When at a

desired elevation and aspect, we established a starting point adjacent to the trail or road using

a live tree or permanent object. Starting point trees were marked with aluminum tags at the

base and labeled with the plot number (eg. HW-18). From the starting point we proceeded

perpendicularly upslope or downslope for 20 m and established the plot “origin” in which we

performed a point-quarter sample of the four closest live trees ≥ 10 cm-dbh (diameter at

breast height). The origin remained unmarked, but the sampled trees can be used to

triangulate the position of the origin. From the origin we continued upslope or downslope at

the same azimuth for a randomly determined distance between 0 and 30 m. At this point we

randomly proceeded ± 90 degrees perpendicular to the previous azimuth for a randomly

determined distance between 0 to 10 m. At this point one of the four corner posts of the plot

was established with an orange PVC stake marked with 1 to 4 notches to denote which corner

of the plot it represented. From this stake we built a 20 x 20-m rectangular (400 m2) plot.

Upper and lower plot boundaries are perpendicular to the slope. Side boundaries are parallel

to the slope with lengths corrected for the measured declination angle.

3.2.2 Field Sampling

Once plot boundaries were established, we identified, numbered, tagged, and measured the

diameter to the nearest mm of each overstory tree within the plot. Overstory strata were

defined as woody stems with a ≥ 10 cm-dbh. Each tree was subsequently rated by two

technicians for crown class condition using the following criteria: Class 1: 0-10% crown

damage, Class 2: 11-50% crown damage, Class 3: 51-99% crown damage, and Class 4:

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standing dead. Each tree was then inspected for specific damage including signs and

symptoms of disease and insects or damage to stems and crowns. Plot level data recorded

included canopy closure estimation, elevation, slope percent, aspect, and topographic

features. Additionally, live and dead basal area estimations of each plot were made using a

forester’s prism (factor 10). Live or dead trees that could not be identified were listed as

unknown. Trees with a < 10 cm-dbh and > 2 m in height were identified and counted as

saplings.

Plots surveyed in the summer of 2002 (plots 1-15) did not have individual dead trees

measured and this oversight was corrected the following summer for plots 16-45. Data were

compiled into spreadsheets for statistical analysis of plot and species level parameters

including live and dead stem density, live and dead basal area, crown class ratings, and

sapling counts.

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3.3 RESULTS

A total of 40 400 m2 plots were constructed, with 15 plots (Bald Knob Ridge, Buncombe

Horse Range Ridge, and Blue Ridge Parkway) surveyed in the summer of 2002, and 25 plots

(Mt. Mitchell Trail, Locust Creek, Woody Ridge, Celo Ridge, Bowlens Creek, and North

Fork) surveyed in the summer of 2003. Evaluation and mensuration data are presented in

subsample groups, as plots within each group tended to be in relatively close proximity, with

similar characteristics and species composition.

3.3.1 Mensuration Data and Evaluation of Each Plot Group

Bald Knob Ridge

The 5 plots sampled at Bald Knob Ridge are on the southeast flank of the Black

Mountains at the headwaters of the South Toe River. Plot elevations range from 1270 to

1420 m (4167 to 4659 ft). Dominant tree species include eastern hemlock (Tsuga

canadensis), northern red oak (Quercus rubra), sugar maple (Acer saccharum), red maple (A.

rubrum), and red spruce (Picea rubens). Table 3.1 shows the various parameters for the top

5 encountered species according to live stem density (stems/ha).

TABLE 3.1 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE BALD KNOB RIDGE PLOTS (N=5).

Species

Stem Density (stems/ha)

Live Dead

Basal Area (m2/ha)

Live Dead Tsuga canadensis Quercus rubra Acer saccharum Acer rubrum Picea rubens

180 ± 78 110 ± 17 105 ± 25 65 ± 28 40 ± 23

N/a N/a N/a N/a N/a

9.4 ± 3.9 16.1 ± 5.0

8.5 ± 4.3 3.3 ± 1.5 1.1 ± 1.0

N/a N/a N/a N/a N/a

Total 715 ± 101 25 ± 11 46.8 ± 4.1 2.1 ± 0.9

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Hemlock dominates, with the highest live stem density, but was only found on 4 of

the 5 sites. In terms of basal area, northern red oak dominates and was found on all 5 plots.

Sugar maple was also found on all 5 plots. Individual dead tree parameters were not

measured on these sites and the total dead basal area at each site was estimated using a

forester’s prism. Two sites had no standing dead trees. Some chlorosis was noted on a

single sugar maple on one site as well as one large dying American elm (Ulmus americana

L.). White fungal tendrils were noted emanating from fissures in black birch (Betula lenta)

bark. No other diseases or decline symptoms were noted in this area.

Buncombe Horse Range Ridge

The 4 plots sampled on the Buncombe Horse Range Ridge are on the southeast flank

of the Black Mountains at the headwaters of the South Toe River. Plot elevations range from

1235 to 1340 m (4050 to 4400 ft). Dominant species include red maple, eastern hemlock,

black birch, northern red oak, and chestnut oak (Q. prinus). Table 3.2 shows the various

parameters for the top 5 encountered species according to live stem density (stems/ha).

TABLE 3.2 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE BUNCOMBE HORSE RANGE RIDGE PLOTS (N=4).

Species


Live Dead

Basal Area (m2/ha)

Live Dead Acer rubrum Tsuga canadensis Betula lenta Quercus rubra Quercus prinus

231 ± 64 156 ± 46 56 ± 47 50 ± 33 25 ± 17

N/a N/a N/a N/a N/a

14.2 ± 5.6 8.1 ± 3.3 3.9 ± 3.2 5.0 ± 3.3 1.8 ± 1.5

N/a N/a N/a N/a N/a

Total 700 ± 87 25 ± 10 34.3 ± 6.1 2.3 ± 0.9

Red maple dominates in both live stem density and basal area and was found on all 4

sites. Northern red oak was found on 3 of the 4 plots, and it accounts for the slightly higher

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mean basal area than black birch. Individual tree dead parameters were not measured on

these sites and the total dead basal area at each site was estimated using a forester’s prism.

One site had no dead standing trees. Crown thinning was noted on many oaks in this area

with no underlying cause determined.

Blue Ridge Parkway

The 6 plots sampled near the Blue Ridge Parkway are between mile markers 348 and

352. Plots are on the ridge opposite the southeast flank of the Black Mountains at the

headwaters of the South Toe River and generally face due west. Plot elevations range from

1230 to 1415 m (4035 to 4642 ft). Dominant tree species include red maple, chestnut oak,

northern red oak, eastern hemlock, and beech. Table 3.3 shows the various parameters for

the top 5 encountered species, ranked according to live stem density (stems/ha).

TABLE 3.3 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE BLUE RIDGE PARKWAY PLOTS (N=6).

Species


Live Dead

Basal Area (m2/ha)

Live Dead Acer rubrum Quercus prinus Quercus rubra Tsuga canadensis Fagus grandifolia

383 ± 54 192 ± 38 75 ± 23 67 ± 41 54 ± 40

N/a N/a N/a N/a N/a

10.7 ± 2.0 12.7 ± 2.3 7.3 ± 2.9 2.0 ± 1.4 1.4 ± 1.1

N/a N/a N/a N/a N/a

Total 900 ± 58 38 ± 13 34.5 ± 2.9 3.3 ± 1.2

Red maple clearly dominates with the highest live stem density; however, chestnut

oak dominates with the highest live basal area. Mean stem density was the highest in this

area when compared to all other areas sampled. Both species were found at all 6 sites.

Individual tree dead parameters were not measured on these sites and the total dead basal

area at each location was estimated using a forester’s prism. No dead standing trees were

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found on two of the sites. Some canopy thinning of oaks and maples was noted, with

symptoms including chlorosis and insect herbivory. Mountain laurel damage was widely

noted with symptoms including chlorosis, and brown spots.

Mt. Mitchell Trail

The 5 plots sampled are near the trail leading from Black Mountain campground to

Commissary Hill (Mt. Mitchell Trail 190) on the eastern flank of Mt. Mitchell. These plots

are generally east facing with elevations ranging from 1260 to 1465 m (4134 to 4806 ft).

Dominant tree species include red maple, red spruce, and northern red oak. Table 3.4 shows

the various parameters for the top 5 encountered species ranked according to live stem

density (stems/ha).

TABLE 3.4 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE MT. MITCHELL TRAIL PLOTS (N=5).

Species


Live Dead

Basal Area (m2/ha)

Live Dead Acer rubrum Picea rubens Quercus rubra Betula lutea Tsuga canadensis

250 ± 68 135 ± 85 130 ± 57 40 ± 39 30 ± 29

20 ± 19 50 ± 49 5 ± 5

10 ± 10 0 ± 0

14.8 ± 7.5 3.5 ± 2.8

27.1 ± 10.8 1.5 ± 1.4 1.1 ± 1.1

0.8 ± 0.8 1.4 ± 1.4 0.2 ± 0.2 0.2 ± 0.2 0.0 ± 0.0

Total 640 ± 143 120 ± 57 51.9 ± 11.2 3.8 ± 1.9

Red maple dominates with the highest live stem density and was found on all 5 sites.

In terms of live basal area, northern red oak dominates but was only found on 4 of 5 plots.

Mean live basal area was the highest in this area of all areas sampled with the highest

individual plot value of 92.1 m2/ha. Red spruce leads in dead stem density and basal area

and this is mainly attributed to a single plot where all canopy size spruces were found dead

for unknown reasons. No other disease or insect anomalies were reported for this area.

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Locust Creek

The 5 plots sampled in this area are at the headwaters of Locust Creek on the northern

flank of Colbert Ridge east of Winter Star Mountain. Plot elevations range from 1300 to

1415 m (4265 to 4642 ft). Dominant canopy tree species include hemlock, yellow birch

(Betula lutea), beech, red spruce, and sugar maple. Tree crowns here appeared very vigorous

overall with few large openings. Table 3.5 shows the various parameters for the top 5

encountered species ranked according to live stem density (stems/ha). Hemlock, found on all

five sites, dominates with the highest live stem density and basal area. Yellow birch and

beech were also found on every plot, and have a combined density and basal area

approximately equal that of hemlock. Yellow birch has the highest density and basal area of

dead stems in this location. Beech scale and hemlock woolly adelgid were not found on any

of these sites; however, an anthracnose-like fungus was found on the leaves of many of the

larger beeches. Red spruce twig tip abscission was noted on 3 of the plots.

TABLE 3.5 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE LOCUST CREEK PLOTS (N=5).

Species


Live Dead

Basal Area (m2/ha)

Live Dead Tsuga canadensis Betula lutea Fagus grandifolia Picea rubens Acer saccharum

260 ± 43 105 ± 29 100 ± 35 40 ± 23 30 ± 14

15 ± 10 20 ± 9 0 ± 0

10 ± 10 0 ± 0

21.2 ± 3.4 17.8 ± 6.4 4.2 ± 1.9 2.3 ± 1.9 1.9 ± 1.1

0.9 ± 0.7 2.8 ± 1.4 0.0 ± 0.0 0.4 ± 0.4 0.0 ± 0.0

Total 600 ± 61 60 ± 30 47.9 ± 6.4 4.7 ± 1.8

Woody Ridge

The 2 plots sampled at Woody Ridge are on the eastern flank of the Black Mountains

at the headwaters of Roaring Spout Creek. Plot elevations are 1250 and 1280 m (4100 and

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4200 ft). Dominant tree species include red maple, northern red oak, black birch, black

cherry (Prunus serotina), and sugar maple; all found on both sites. The canopy on these sites

appeared well closed with full and robust crowns. Table 3.6 shows the various parameters

for the top 5 encountered species ranked according to live stem density (stems/ha). Red

maple has the highest live stem density but in terms of basal area northern red oak dominates.

Black birch was the only species positively identified as dead, with remainder of dead

density and basal area attributed to unknown species. No disease signs or symptoms were

noted.

TABLE 3.6 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE WOODY RIDGE PLOTS (N=2).

Species


Live Dead

Basal Area (m2/ha)

Live Dead Acer rubrum Quercus rubra Betula lenta Prunus serotina Acer saccharum

138 ± 87 113 ± 62 88 ± 12 75 ± 25 50 ± 0

0 ± 0 0 ± 0

13 ± 12 0 ± 0 0 ± 0

7.7 ± 5.9 13.8 ± 3.1 3.2 ± 0.4 1.9 ± 1.2 3.3 ± 2.0

0.0 ± 0.0 0.0 ± 0.0 0.5 ± 0.4 0.0 ± 0.0 0.0 ± 0.0

Total 600 ± 25 63 ± 12 28.0 ± 7.3 1.1 ± 0.6

Celo Ridge

The 3 plots sampled at Celo Ridge are on the northeast flank of the Black Mountains,

adjacent to the ridge extending from Celo Knob to Little Celo Mountain. Plot elevations

range from 1270 to 1355 m (4167 to 4446 ft). Dominant tree species, ranked according to

live stem density (stems/ha), include hemlock, northern red oak, sugar maple, red maple, and

yellow birch (Table 3.7). Northern red oak overwhelmingly dominates in all live and dead

parameters, contributing to over half of the basal area. Yellow birch and sugar maple were

only found on two sites each and are the only other canopy dominant species. Many other

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common species such as beech, red spruce, chestnut oak, hemlock, and striped maple were

found in the understory. Crowns on these sites were in generally good condition, but some

thinning of dominant oaks was noted. No widespread disease symptoms or signs were found

in this area.

TABLE 3.7 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE CELO RIDGE PLOTS (N=3).

Species


Live Dead

Basal Area (m2/ha)

Live Dead Quercus rubra Betula lutea Acer saccharum Acer rubrum Tsuga canadensis

150 ± 43 117 ± 59 92 ± 50 25 ± 25 8 ± 8

17 ± 16 8 ± 8 17 ± 8 0 ± 0 0 ± 0

23.3 ± 6.5 6.8 ± 3.5 5.8 ± 3.4 0.7 ± 0.7 0.3± 0.3

0.5 ± 0.5 0.1 ± 0.1 0.4 ± 0.2 0.0 ± 0.0 0.0 ± 0.0

Total 408 ± 92 42 ± 22 36.9 ± 4.1 1.0 ± 0.5 Bowlens Creek

The 5 plots sampled are at the headwaters of Bowlens Creek, adjacent to the Black

Mountain Crest Trail on the northwest flank of the Black Mountains. Plot elevations range

from 1250 to 1495 m (4100 to 1495 ft). Dominant tree species, ranked according to live

stem density (stems/ha) include northern red and chestnut oak, sugar and red maple, red

spruce, beech, and birches (Table 3.8).

TABLE 3.8 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE BOWLENS CREEK PLOTS (N=5).

Species


Live Dead

Basal Area (m2/ha)

Live Dead Quercus rubra Acer saccharum Quercus prinus Acer rubrum Betula lutea

175 ± 112 95 ± 54 80 ± 40 80 ± 50 50 ± 34

0 ± 0 0 ± 0 0 ± 0 0 ± 0 0 ± 0

12.2 ± 6.6 11.8 ± 7.1 5.6 ± 2.5 5.0 ± 3.3 1.8 ± 1.5

0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0

Total 630 ± 131 70 ± 22 34.3 ± 6.1 3.3 ± 1.3

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Northern red oak dominates with the highest live stem density and basal area but was

only found on 4 of the 5 sites, as was sugar maple which contributed almost the same basal

area as northern red oak. Individual tree dead basal area and density were measured on these

sites; however, the total reflects contributions by unknown species. No beech scale, hemlock

woolly adelgid, or widespread disease symptoms were found on these sites.

North Fork

The 5 plots sampled at the North Fork headwaters of Cattail Creek are on the western

flank of the Black Mountains. Plot elevations range from 1310 to 1520 m (4300 to 4990 ft)

and all the plots have a generally west facing aspect. Dominant tree species include beech,

sugar maple, yellow birch, Carolina silverbell (Halesia carolina), tulip poplar (Liriodendron

tulipifera), black cherry, and black locust (Robinia pseudo-acacia). Table 3.9 shows the

various parameters for the top 5 encountered species ranked according to live stem density

(stems/ha).

TABLE 3.9 PARAMETER MEANS AND STANDARD ERRORS OF THE 5 MOST COMMON TREE SPECIES ENCOUNTERED IN THE NORTH FORK PLOTS (N=5).

Species


Live Dead

Basal Area (m2/ha)

Live Dead Fagus grandifolia Acer saccharum Betula lutea Halesia carolina Liriodendron tulipifera

285 ± 12 80 ± 36 60 ± 37 45 ± 32 30 ± 19

5 ± 5 5 ± 5

10 ± 10 0 ± 0 5 ± 5

9.7 ± 1.1 8.8 ± 4.2 2.9 ± 1.7 3.3 ± 2.5 5.4 ± 3.3

0.0 ± 0.0 0.5 ± 0.3 0.0 ± 0.0 0.0 ± 0.0 0.2 ± 0.2

Total 635 ± 51 90 ± 17 34.3 ± 6.1 2.6 ± 0.6

The forest here was quite different than those found in other locations at similar

elevations, because beech clearly dominates, with the highest live stem density on all sites;

oaks were virtually absent. Sugar maple contributes greatly to mean basal area but was only

found on 4 of the 5 plots. Carolina silverbell and tulip poplars were particularly dense on one

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site, with the mean density just overshadowing the more commonly found black locust. No

beech scale insects or beech bark disease signs were found on these sites, however a minor

amount of anthracnose-like symptoms was encountered on two plots. No other widespread

disease symptoms or signs were noted.

3.3.2 Crown Class Condition of the Most Common Species

Crown class condition ratings for the 10 most common species found during our survey

based on live stem density are shown in Figure 3.3. Each species shown comprises greater

than 2 percent of the total stem density for all 40 plots.

FIGURE 3.3 CROWN CLASS RATINGS OF 10 MOST COMMON TREE SPECIES FOUND IN BLACK MOUNTAIN NORTHERN

HARDWOOD AND MONTANE OAK FORESTS.

Some species appear to be extremely robust, with American beech, sugar maple, black

birch, and chestnut oak exhibiting over 80 percent of their crowns in the class 1 rating. Red

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4

Crown Class

Per

cent

of T

rees

Red Maple n=230Sugar Maple n=81Black Birch n=32Yellow Birch n=78American Beech n=104Red Spruce n=59Black Cherry n=17Northern Red Oak n=142Chestnut Oak n=72Eastern Hemlock n=143

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maple, yellow birch, black cherry, and northern red oak appear to be in good health with

most of their crowns in the class 1 category. These species also have slightly higher

proportions of Class 2 crowns than the previously mentioned trees. Hemlock stands out with

the highest proportion of Class 2 crowns (32%) and only 63 percent of crowns in the Class 1

category. Red spruce, which was found in the lower end of its normal elevation range,

exhibited the poorest condition overall with the lowest proportion of Class 1 crowns (44%)

and the highest proportion of Class 3 and 4 trees with 10 and 20 percent respectively.

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3.4 DISCUSSION

3.4.1 Current Status

Our data suggest that, by the end of the summer of 2003, most of the dominant trees

encompassing the mid altitude forests of the Black Mountains are in excellent condition. No

dominant species of tree displayed a high incidence of mortality on a landscape level. Only

red spruce showed anything that resembled an abnormal amount of decline, which was

hypothesized in the summer of 2001. Most of this mortality was based on, and somewhat

limited to, the findings of one plot near the Mt. Mitchell Trail. In another area (Locust creek)

an unusual amount of red spruce twig abscission was noted. The reason behind the amount

of dead spruce and twig abscission found in those areas remains unknown, and a cause for

further investigation. The density of dead red spruce was not shown at similar levels in any

other areas; however, red spruce was not as dominant in other locations at similar elevations.

Symptoms of emerging diseases and insect problems were not evident. We found no

signs or symptoms of beech bark disease, including the beech scale insect, cankers on beech

boles, or erumpent perithecia from the bark of beeches. The absence of beech cankers leads

us to conclude that the “killing front”, composed mainly of the first wave of insects to infest

the trees, has not passed through the region. The insect may be present in small numbers

with only very localized outbreaks but the breadth of area sampled and the number of beech

trees tagged lends support that beech bark disease has yet to enter these woods in significant

strength.

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3.4.2 Possible Outcomes and Potential Trends

While we found very little to suggest that widespread mortality or specific diseases are

present in the northern hardwood forests of the Black Mountains, we are reluctant to be too

optimistic at this time. Absence of evidence does not necessarily mean we can say with

absolute certainty that these diseases are not present, whereas it is more likely that, especially

in the case of beech bark disease and hemlock woolly adelgid, these problems are impacting

the forest on some level. This level of occurrence must therefore be below a threshold that

our survey could detect. It is not likely that these insects and pathogens will stay at their

current levels, especially with such a wide distribution and high density of hosts in the

region. Both oak and hemlock are widespread in the forests at this altitude and as such we

can expect infestations and disease occurrences to rise as they spread into the relatively non-

impacted landscape.

Beech bark disease has moved into the region from forests in the north and is

expected to make a significant impact on the density of beech in the canopy. Loss of beech

in these forests presents a rather large niche to fill, as this is the fourth most common tree and

almost 10 percent of the live stem density encountered. While a phase out of living beech

would create some canopy gaps, it is not likely that this disease will maximize its mortality

rate in the region without the combined impacts from other disease and insect infestations.

The most likely large-scale impact to these forests in the immediate future is from the

loss of hemlock due to the hemlock woolly adelgid. Mortality rates for previously infested

areas range such as Virginia, New Jersey and Connecticut have been severe, with mortality

from 42 to 90 percent among stands (Proceedings 2002) and particularly devastating to

hemlock in the Shenandoah National Park over the past decade. Similar impacts throughout

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the region are expected to occur in areas where both eastern and Carolina hemlock are

common, because the adelgid is starting to encompass the entire range of these trees in the

Southern Appalachians. Research continues with predatory beetle mediation in controlling

adelgid populations but so far the results have been marginally effective and very expensive

to deploy (Lamb et al. 2005). Loss of hemlock in the Black Mountains will remove the

second most common tree in the areas we sampled and create widespread canopy gaps,

especially in the southeast part of the Blacks where Tsuga is more common.

The two species of oak we found (Quercus rubra and Q. prinus) together constitute

almost 20 percent of the live stems we encountered and rival the density of red maple in the

area we sampled. While the discovery of Phytophthora ramorum and the disease “sudden

oak death” are relatively new and little is known about this pathogen, there is much cause for

concern for forests in the Southern Appalachians. Particularly of great concern is the

potential for the spread of P. ramorum to forests outside California and Oregon. Laboratory

inoculations have found two eastern North American oaks, northern red oak and pin oak (Q.

palustris) to be susceptible to P. ramorum infection (Rizzo and Garbelotto 2003).

The release of this pathogen into the forests of the eastern United States may initiate

an epidemic of widespread and devastating mortality in the red oak species (section Lobatae)

throughout the Southern Appalachians as well as in the Black Mountains. Evidence is

mounting as new susceptible species are found, that hosts for P. ramorum include canopy

trees and understory shrubs and the long-term consequences regarding mortality for non-oak

hosts are unknown at this time. However, branch dieback on these non-oak hosts may affect

seed production, negatively impact growth and regeneration, and prematurely predispose the

plant to attacks by other pathogens and insects. Sublethal infections of non-oak hosts may

130

also allow P. ramorum to persist indefinitely in infested forests and affect the success of

future regeneration and restoration efforts (Rizzo and Garbelotto 2003). While it is unclear

what the long-term consequences will be, worst case scenarios for P. ramorum include the

loss of several red oak species creating canopy gaps not seen since the chestnut blight

devastated American chestnut in eastern forests.

3.4.3 Conclusion

While our survey found most tree species in an excellent state of health, we expect that

introduced pathogens and exotic insects will continue to have profound impacts on the

structure of forests throughout the region. How each pest will change the composition of

species of trees in the Black Mountains, both individually and in tandem with myriad other

factors including climate change, air and soil pollution, and emerging diseases, remains to be

seen. While our sampling was not designed randomly on a landscape level, bias was kept to

a minimum by choosing sites that well represented and exemplified the surrounding woods

and by setting exact plot placement (within certain bounds) randomly. Our findings are

limited in scope and definitive; however, we remain speculative about the condition of these

forests in the near future. We believe the main value of this study is in the long-term

monitoring of these sites. The fact that disease incidence displayed a low baseline value can

allow us to detect disease onset and incipient mortality before they achieve epidemic levels.

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research. Additionally I would like to thank the entire Mt. Mitchell State Park staff and

David Zietlow for allowing us access to park facilities and joining the spirit of scientific

pursuit.

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