HUMANS AND FIRE IN PREHISTORIC LANDSCAPES:

LEGACIES THAT INFLUENCE CONTEMPORARY

ECOLOGY AND MANAGEMENTRachel Loehman, USGS

Linn Gassaway, USFS

1909 1948

1968 1989

What is naturalness?

Competing hypothesis:

Predominance

Lightning or Human ignitions

“Lightning fires, including onsite ignitions and lightning fires spreading from

other areas, were well capable of maintaining most fire regimes in the West.”

(Barrett, et. al. 2005)

One authority on fire history, while conceding “significant Indian

influence” refers to nineteenth-century forests as “unmanaged” and

“natural” environments. (Robbins 1999)

Did Native Americans change vegetation to a “condition outside of the natural realm of historical variability”? (Parker 2002:237)

Was it the intent of Native Americans to change the vegetation?

How did they live, use and interact with fire?

Geographic and Ecological View Point

Anthropological View Point

Outside of “Natural Fire Regime”

• “Unnatural” Fire Return Interval

• Seasonality

• Asynchronous fire

• Fire in wet years

• No fire in dry years

Assumed

Anthropogenic Fire Signatures

Finding Human Ignitions in the Past:

At a national scale lightning strikes appear to be able to account for all

ignitions.

Is it a question of scale?

⁻ Complex ecological problems require complex approaches!

⁻ Detect human influences on landscapes, including persistent legacies that are not detectable by other disciplines

⁻ Augment other data sources - fading record in fire history

⁻ Extend spatial and temporal scales of inference in traditional ecology

⁻ Re-imagine baseline conditions and best practices in land management

Why study ancient human-environment interactions?

Limitations

• Inability to distinguish between human induced fire and

lightning fire in tree rings

• Failure to take into account the wide variety of uses

Native Americans had for fire

• Use of broad regional histories

• Failure to accurately take into account the ethnographic

and archaeological data in the study areas

Does the use of multiple comparable data sets at a similar scale

change the interpretation?

Known prehistoric

archaeological sites

MODIS

2000-2007

Two examples of pre-historic human impacts on landscapes and fire patterns

California –anthropogenic use of fire

Jemez Mountains, New Mexico –alteration of fuelscapes

Who lived there?

• Hunter-Gatherers

•Non-agriculturalist

• Seasonal rounds

•Few permanent villages

•Large numbers of seasonal camps

• “triblets” - 100-500 people

Southern Sierra Miwok

Ahwah’-nee

Proposed Cultural Chronology Moratto 1999

DATES

A.D. 1945-

A.D. 1891-1944

A.D. 1864-1890

A.D. 1848-1863

A.D. 1800-1847

A.D. 1350-1800

A.D. 650-1350

1200 B.C. - A.D. 650

3500-1200 B.C.

6000-3500 B.C.

7500-6000 B.C.

8500-7500 B.C.

9500-8500 B.C.

>9500 B.C.

PERIODS

Historic 4

Historic 3

Historic 2

Historic 1

Protohistoric

Late Prehistoric 3

Late Prehistoric 2

Late Prehistoric 1

Intermediate Prehistoric 2

Intermediate Prehistoric 1

Early Prehistoric 4

Early Prehistoric 3

Early Prehistoric 2

Early Prehistoric 1

COMPLEXES/PHASES

Rancheria

Tenaya

Yosemite

Mariposa

Tamarack (?)

Crane Flat

Merced, Wawona,

?

El Portal

?

?

?

The

Physical evidence

Archaeology

• Not all sites inhabited at same time

• Best correlation of occupation and fire use

FIRE

How often?

Where?

When?

Relationship of fire scarred trees

to

Habitation and Gathering

Fire Return Interval –

how often fire occurs in a selected location over a period of time

FRI = >70

Yosemite Dendrochronological Fire History

1552-2004

Study area Sample Area Sample

Size (hectares) 30 1.5-11 Tree

Samples 57 5-14

MFI

(Weibull Median)

1.92

(1.61)

4.69 - 17.83

(3.33 - 16.5)

17.7

Interval Range 1-11 1-43 2-56

Is it Human or Lightning?

Historically observed Lightning

1930-2002

2 villages

1 permanent year round

1 seasonal camp

2 gathering areas

2 “controls” - no known use

When -

0

1

2

3

4

5

6

7

8

1520-2004 1520-1800 1800-1847 1848-1863 1864-1890 1891-1944

All time periods Late Prehistoric 3 Protohistoric Historic 1 Historic 2 Historic 3

Mean

Fir

e R

etu

rn

In

terval

Changes in MFI by archaeological time period

Time Period Statistical Difference P

Prehistoric vs. Protohistoric

(A.D. 1520-1800) (1800-1847) Significant 0.0000

Protohistoric vs. Historic 1

(A.D. 1800-1847) (1848-1863) Not Significant 0.1929

Historic 1 vs. Historic 2

(A.D. 1848-1863) (1864-1890) Not Significant 0.9610

Historic 2 vs. Historic 3

(A.D. 1864-1890) (1891-1944) Significant 0.0001

2 Tail T-Test (P < 0.025)

1.922.4

1.091.5 1.47

5.0

Location Study

area

(ha)

# of trees

sampled

MFI

Study

Area

MFI

Range

Source

Blodgett 5 46 4.7 4-28 Stephens and

Collins 2004

Pilot Creek 15 15 5.7 3-18 Stephens and

Collins 2004

South fork

of

Tuolumne

2100 209 1.5 1-16 Scholl

Unpublished

Yosemite

Valley

30 57 1.92 1-11 Gassaway

2005

South fork

of Merced

1625 69 2.13 1-28 Scholl

Unpublished

Southern-

central

Sierra

Nevada

50 2-3 1-25 Swetnam et al

1998

SEKI –

Redwood

Creek

1030 37 2.1 1.73-

2.35

Kilgore and

Taylor 1979

Bearskin

Creek

770 183 1.7 1.55-

1.86

Kilgore and

Taylor 1979

SeasonalityLocation Fire Seas on Source

Blodgett 21% Dormant 79% Late wood

Stephens an d Colli ns 2004

Pilot Creek 21% Dormant 79% Late wood

Stephens an d Colli ns 2004

South fork of Tuolumne 51% Dormant 24% Late wood

Scholl Unpub lished

Yosemite Valle y 48% Dormant 31.5% Latewood 7.3% Early Earlywood 5.2% Middle Earlywood 7.3% Late Earlywood

Gassawa y 2005

South fork of Merced 38% Dormant 32% Late wood,

Scholl Unpub lished

Southern -central Sierra Nevada

23% Dormant 54% Late wood 18% Late Ear lywood 4% Middle Earlywood 1% Early Earlywood

Swetnam et al 1998

Mt. Home State Forest 20% Dormant 61% Late wood 16% Late Ear lywood 1% Middle Earlywood

Swetnam et al 1998

Fire Return Intervals and

Seasonality

can not be used alone

to determine

the source of ignition.

Testing competing hypothesis: Predominance: Lightning or Human ignitions

Minimum datasets needed

• Modern lightning fire return interval

• Location specific Human occupation

• Cultural chronology

• Fire History

Lightning ignited fires since 1878 and currently

recorded prehistoric sites

(Gray = no archaeological survey)

IMPLICATIONS

Major indicator is MFI change

corresponds to Culture Change

From an anthropological

standpoint the Southern Sierra

Miwok culture is not anomalous.

Archaeological data show no

major difference between the

material culture of the Ahwah’-nee

and other groups in the Sierra

Nevada

“Hunter-gatherers are necessarily responsive to

local environmental fluctuations and

perturbations, whether natural or man-made. Like

men everywhere, hunter-gatherers cannot long

ignore disruptions which adversely effect their

day-to-day subsistence. However, because their

subsistence strategies are more directly and

immediately linked to environmental imperatives,

they must soon make accommodations or else

become one more evolutionary failure” (Lewis

1993:56).

Photo: Craig Allen, USGS

Photo: NPS

Modeling the prehistoric human-ecological landscape

⁻ Ancient Jemez WUI, AD 1200-1900

⁻ Varied population levels, wood use amounts, number of ignitions, agricultural footprints

⁻ Detected thresholds, scales of impacts

Jemezreservation

Bandelier NM

Valles Caldera NPHuman

“footprint”

Annual area burned (ha)

Fire size (ha)

Scenarios:LP/HP: Low or High population

LF/HF: Low (1 cord/person/yr) or High (2 cords/person/yr) fuelwood use

EI: Elevated ignitions (+50%)

SF: Live tree harvest @ 1 tree/person/yr

MIA: elevated ignitions @ 0.15% per person/yr + 1 acre/person/yr ag land

HIA: elevated ignitions @ 0.30%/ per person/yr + 4 acre/person/yr ag land

AD 1200-1325 1326-1450 1451-1525 1526-1625 1626-1700 1701-1900

Humans and local fire regimes: altered area burned, fire size

15

0

40

00 5

00

0

50

00

50

0

50

0

70

00 8

00

0

80

00

30

00

Vallecitos Paliza Early Jemez Late Jemez Guadalupe

Low popn High popn

No people

Fewer peopleMore people

More ignitions

More ignitions, ag land, live tree harvest

Profound human impacts on fuelscapes

Scenarios:LP/HP: Low/High pop’n.LF/HF: Low/High fuelwood SF: Structural wood harvestMIA: Mod. ignitions & agric.HIA: High ignitions & agric.

Mean fire return interval, AD 1526-1625: Local and landscape-scale human impacts

Fuelwood collection fragments fuels, fewer

spreading fires

Added ignitions spread fires across landscape

HP,SF, MIA

8.5x

25x

25 times more fire

than “null” no-human scenarios

LP,SF, HIA

13x16x

----

Ecosystems respond to human activity

Ponderosa pine

Juniper spp.

Piñon pine

Grasses

Gambel oak

Scenarios:LP/HP: Low or High population

LF/HF: Low (1 cord/person/yr) or High (2 cords/person/yr) fuelwood use

EI: Elevated ignitions (+50%)

SF: Live tree harvest @ 1 tree/person/yr

MIA: elevated ignitions @ 0.15% per person/yr + 1 acre/person/yr ag land

HIA: elevated ignitions @ 0.30%/ per person/yr + 4 acre/person/yr ag land

AD 1526-1625:5000 people, 1 cord fuelwood/person/yr., 8.5x background ignitions, 1 acre ag land/person/yr., 1 live tree/person/yr.

AD 1526-1625:8000 people, 2 cords fuelwood/person/yr., 13x background ignitions, 1 acre ag land/person/yr., 1 live tree/person/yr.

AD 1200-1325 1326-1450 1451-1525 1526-1625 1626-1700 1701-1900

Po

nd

ero

sa p

ine

Gra

sse

s

No people

Fewer peopleMore people

More ignitions

More ignitions, ag land, live tree harvest

(p.181) …it is possible that prehistoric Native Americans used fire widely in the southwest, but little evidence has survived to our current day due to the ”fading record" problem. The role of people in southwestern fire regimes relates to a larger question: Were the pre-European landscapes of the Southwest in the 1500s pristine wildernesses or humanized culturescapes? …despite a variety of early human land uses, most mountains in the Southwest retained a dominantly wilderness character until the advent of Anglo-American exploitation in the late nineteenth century, as evidenced by the persistence of natural fire regimes until this time.

(p.180) Multiple lines of evidence from this region overwhelmingly suggest that in A.D. 1850, as in A.D. 1580, most mountain landscapes were "natural" and "wild'" with regard to fire regimes and associated vegetation patterns. Evidence of landscape-scale fire use by aboriginal people in the southwest is scanty to nonexistent, and most assertions of aboriginal burning are based upon anecdotal accounts or sources subject to substantial historical bias.

– Humans as fire surrogates

– Recent land use and management have destabilized forests

– Restoration can’t be achieved by natural processes alone

– Fire management includes fuel manipulation…then and now

– Archaeology highlights the complexity of land management and land use

– Biasness of older fire histories

Significance for contemporary ecology, archaeology, & management

Time

(Population density,

Period of culture conflict or cultural movement,

Changes in material culture)

Location

(topography,

fuels, weather)

Culture

(Hunter-Gatherer,

Agricultural)

“The only constant is change. Ecology is a science of place. Native influence varied by place.” James Agee