Download - by Emily Bernhardt
The effects of fire severity and site moisture on functional properties of black spruce forests in interior
Alaska
by Emily Bernhardt
• Functional diversity– Relative abundance of functionally different
kinds of organisms Walker, B. 1992.
• Plant functional types (PFT)– Assemblage of species with certain similar
plant functional attributes (traits) Skarpe, C. 1996
• Defined by ecological properties in question Naemm and Li 1997
• Functional redundancy– Taxonomically distinct species that perform the same
functional role in the ecosystem Walker, B. 1992; Micheli and Halpurn 2003
What factors make a black spruce forest stay a black spruce forest
• If black spruce as a forest type has definable characteristics:
• Self replacing low severity fire• Cold / wet / acidic soils• Permafrost • Does an alteration of one (fire regime) affect
the communities ability to maintain the others? – By altering the community composition, thereby
altering the communities ability to maintain BS forest type characteristics, resulting in a change of forest type
Hypothesis
Post-fire change in species composition will alter functional properties of re-growth
and residual vegetation in relation to burn severity/site moisture
Burn severity
Site moistureL HH H
H L L L
• Sampled – 5 individuals per
species
• Measured– Hard / soft traits– Rooting depth
• CPCRW sites
• Conducted– Reléve
Examining changes in functional diversity
• Analyzed changes in 3 ways
– 1) Created list of plant traits for boreal species
– 2) Hypothesized trait relationships with burn severity and site moisture
– 3) Reported observed trait relationships• How plant traits are distributed across study
sites
Trait type
Trait Soft Hard ConstantMeasure
dLife
historyStructura
l
Growth form x x x
Species longevity x x x
Leaf life span x x x
Rooting type x x x
Dispersal type x x x
Pollination x x x
Seed bank x x x
Response to fire x x x
Nitrogen fixation x x x
Plant height x x x
Shoot length x x x
Leaf length x x x
SLA x x x
Rooting depth x x x
Rooting substrate x x x
Plant traits for each species
Ability to Establish/Flourish After Disturbance
Ability To Withstand Disturbance
Dispersal - how does it get there? Avoidance
Dispersal type Life history Height Morphological
Chemical defenses Life history
Establishment - how well does it germinate? Regeneration strategy
SLAMorphological Rooting depth
Seed bank potential Life history Growth form Life history
Leaf life span
Seed bank Life history
Root type
Persistence - how well does it grow and reproduce? Tolerance
HeightMorphological Longevity Life history
Life cycle Life history Leaf life span
Seed persistence Life history Root type
SLAMorphological Growth form
Root type
Nutrient status of plant
Hypothesized trait relationships
Response to Effect on
Fire
severitySite
moistureFlammabilit
ySite
moisturePermafros
t
low high low high
Growth form + + + + +
Resprout ability + +
SLA + -
Rooting depth + + + +
Rooting substrate + + + +
Root type + + + + +
Seed bank + - + -
Life span + - + - +
Seed mass + - - +
Height + - + +
Leaf longevity - - + +
Fire resistance - + - +
Seed persistence - + + -
Shoot length - + - + +
Leaf length +
Life cycle +
Dispersal
Hypothesized trait relationships
site
trait averagewithin site
trait average of all species within a site for each trait
within BS/SM type
all sites
trait averageacross all sites
species Species trait value independent of site
Site trait value independent of species
2 tables were created from these data
Species trait value for each sampled year
Species Shoot Leaf Height Leaf Weight Leaf Area
2005 2006 2005 2006 2005 2006 2005 2006 2005 2006
Arc lat 1.57 2.80 1.92 3.31 1.57 2.82 2.98 2.84 3.65 3.48
Arc rub 1.35 2.26 1.01 1.22 1.05 1.95 0.34 0.72 0.31 0.63
Bet gla 0.91 0.54 0.89 0.89 0.67 0.79 1.08 0.90 0.90 0.90
Bet nan 5.25 5.72 6.33 6.68 5.89 6.32 2.05 2.56 4.16 4.66
Bet neo 7.69 7.42 7.70 7.07 7.02 6.57 5.14 2.97 4.67 3.07
Cal can 15.97 18.0021.8
0 23.0516.0
9 18.2615.9
817.4
413.1
713.9
5
Cal lap 1.00 1.00 1.00 1.00 1.00 1.00 0.00 0.00 0.00 0.00
Car big 3.30 4.67 3.77 5.16 3.41 4.72 3.82 3.91 4.72 5.18
Cor can 1.30 1.84 0.77 1.29 2.42 2.89 1.95 2.36 1.73 2.31
Cor sem 1.43 2.07 1.18 2.08 1.43 2.07 1.67 1.67 1.80 1.80
Emp nig 0.83 0.08 1.00 0.10 1.00 0.10 0.00 0.00 0.00 0.00
Epi ang 25.30 24.8127.0
3 26.0025.6
1 24.86 2.55 2.5311.5
311.3
7
Epi gla 1.00 0.10 1.00 0.10 1.00 0.10 0.00 0.00 0.00 0.00
Epi pal 1.05 1.27 1.06 1.31 1.05 1.27 1.76 1.38 1.36 1.18
Equ arv 4.18 3.41 3.57 2.57 4.36 3.28 1.00 0.50 1.00 0.50
Equ sci 3.38 3.06 5.12 5.20 2.08 1.82 0.00 0.00 0.00 0.00
Equ syl 18.76 18.5018.3
4 18.3313.6
1 13.33 4.91 2.41 3.52 1.02
Eri vag 4.43 6.43 6.51 9.47 6.87 9.82 6.54 9.68 6.09 9.24
Gal bor 1.86 1.09 1.90 1.09 1.79 1.08 1.00 1.00 1.00 1.00
Hie sca 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00
Led gro 10.79 10.52 3.96 3.9012.6
1 12.08 5.52 5.6410.3
510.4
9
Site trait value for each sampled year
TraitTC010
5TC010
6TC040
5TC040
6TC080
5TC080
6TC190
5TC190
6DC460
5DC460
6
Shoot 3.97 7.44 4.95 7.56 6.49 5.47 2.57 2.15 3.93 3.92
Leaf 4.70 7.79 4.15 5.31 6.46 5.81 3.53 2.91 5.29 5.42
Height 3.86 5.61 4.20 5.52 5.59 5.09 2.69 2.35 3.10 3.80
Leaf Weight 5.27 3.51 4.16 4.47 5.37 3.99 2.25 1.78 4.24 3.48
Leaf Area 4.51 3.34 5.01 5.75 5.75 4.27 2.60 2.04 4.15 4.19
H H L H L H L L H L
Determining how traits relate in ecosystem
• A ordination represents a species (or site) of interest in ordination space, where the species location along the axis represents its similarity to other species located along the axis – Using data collected from reléve
3
Preliminary results
• Certain traits appear to respond similarly to burn severity and site moisture and can potentially become a PFT group
• Site / species table:– Species with similar trait values often have different
growth forms– Low moisture sites have lowest trait values
• From ordination:– Growth form is not a good functional type grouping
variable– Burn severity and site moisture were accurately
determined– Low burn severity sites have similar trait values
Final product – species trait matrix
Constant
Species
Growth form
life cycle
life span shoot leaf height
leaf weight
leaf area
rootabgr ht
root abgr wt
Aln cri dec shr p
Bet gla dec shr p
Bet nan dec shr p
Ros aci dec shr p
Rub ide dec shr p
Sal ale dec shr p
Sal gla dec shr p
Sal myr dec shr p
Sal pul dec shr p
Sal sco dec shr p
Spi bea dec shr p
Vac uli dec shr p
Measured
Response to Effect on
Fire
severitySite
moistureFlammabilit
ySite
moisturePermafros
t
low high low high
Growth form + + + + +
Resprout ability + +
SLA + -
Rooting depth + + + +
Rooting substrate + + + +
Root type + + + + +
Seed bank + - + -
Life span + - + - +
Seed mass + - - +
Height + - + +
Leaf longevity - - + +
Fire resistance - + - +
Seed persistence - + + -
Shoot length - + - + +
Leaf length +
Life cycle +
Dispersal
Hypothesized trait relationships
Acknowledgments
• JFSP• UAF – Biology department• Teresa Hollingsworth• Terry Chapin• Field crew and technical advisement
– Christa Mulder, Emily Tissier, Jamie Hollingsworth, Mark Winterstien, Gretchen Garcia, Kate McGlone, Brian Charlton, Katie Villano and Dana Nossov
References• Naeem, S. and S. Li. 1997. Biodiversity enhances ecosystem reliability. Letters to nature 390:507-509.• Micheli F., and B.,S. Halpurn. 2005. Low functional redundancy in costal marine assemblages.
Ecology letter 8:391-400. • Skarpe, C. 1996. Plant functional types and climate in a southern African savanna. Journal of
vegetation science 7:397-404.• Walker, B. 1992. Biodiversity and ecological redundancy. Conservation Biology 6:18-23.
• Plant functional type example– Growth form popular– But may not be appropriate or validly explain
community response– Used a a sort of base line to compare
functional type groupings against
• Constant trait– general traits with little to no variation
(growth form)
• Variable trait– plastic morphological traits (plant height)
Rooting depth measurements in C P C R W sites (burned and unburned)
Measured rooting depth of each individual • 8 burned sites
– 2 of each site moisture/burn severity• 4 unburned sites
• Sampling design – 30m belt transect – 5 individuals of each species
Response and effect groups
• In relation to ecosystem characteristics of interest
– Flammability– Permafrost– Acidity– N-fixation– Site moisture
Examining changes in functional diversity
• Assign species into functional groups based on their growth form (evergreen vs. deciduous)
• Create a list of constant and variable traits
• Separated into– Response of plants to fire regime
(tolerance, disturbance response)– Effect of plants on fire regime
(flammability, formation of permafrost, nitrogen fixation)
Trait Value Categorization
• All measured trait values standardized
• Trait values categorized by site for each species – abundance value multiplied by trait value
• Trait values calculated between sites by species– Trait values totaled to give a species trait
value
• Trait values calculated for site – Species trait values totaled to give a site trait
value 3