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School Research Conference, March 2009
Jennifer Wright
Supervisors: M.Williams, G. Starr, R.Mitchell, M.Mencuccini
Fire and Forest Ecosystems in the Southeastern USAPhoto by Richard
Bryant
Introduction
Yellowstone fire in 1988 (picture from University of Utah Meteorological Department)
Yellowstone in 1999, 11 years after fire (picture from Dr. Robert Ruhf)
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
Introduction
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
3 months after fire, biennial burning
regime
Longleaf pine forest, December 2008
Introduction
What?
To examine the influence of fire on carbon processes in a subtropical savanna -woodland over a soil moisture gradient.
“…a better understanding of the effects of natural disturbances on C cycling is critical, particularly in light of alterations to disturbance regimes that may occur with global climate change” (Litton et al., 2004)
Why?
How?
Development and testing of a modelling tool using 2 existing models (SPA2, GAPFIRE) and field data collection
Where?
Longleaf pine ecosystem of the South-eastern USA, fieldwork based at Joseph W. Jones Ecological Research Center, GA
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
Longleaf Pine Ecology 1
Regular burning
Understory (dominated by wiregrass (Aristida
stricta)
Overstory dominated by longleaf pine (Pinus
palustris)
Fire suppressed
Mid story of oaks developing in an area of fire
suppression
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
Longleaf Pine Ecology 2
Mesic (wet) site Xeric (dry) site
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
Longleaf Pine Ecology 3Pine early growth stage Low intensity fire
Post fire pine saplings Post fire pine saplings
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
“Grass” stage
Lasts up to 15 years
Most carbon to roots
Why model?
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
Carbon DynamicsAbiotic Factors
Pine/oak dynamics
Belowground processes
UnderstoryBiodiversity
Fuel Composition
Fuel Load
Fuel Distribution
Climate Management
Soil type
Soil moisture
Nutrient availability
Fire
External Forcing
Biotic Factors
The Model
Pines
Oaks
Understory
Soil
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
Savanna structure Closed canopy forest
Model
Canopy conductance
photosynthesis,
leaf respiration
Vegetation dynamics &
disturbance
Land -use and
land -cover change
Autotrophic andHeterotrophic
respiration
Phenology
Turnover
Solution of SEB;
canopy and ground
temperatures
and fluxes
Soil heat andmoisture
Surface water
balance
Atmosphere
FluxesEcosystem dynamics
Landscapedynamics
Canopy conductance,
photosynthesis
Vegetation dynamics & disturbance
Land use and land cover change
Allocation
Phenology
Litter production
Nutrient cycles
Surface temperatures
and heat fluxes
Soil heat and moisture
Surface water balance
Autotrophic & heterotrophic
respiration
Atmospheric forcing
Radiation, H2O, CO2 & heat fluxes
Rapid processes(hours)
Intermediate processes(days-weeks)
Slow processes(years+)
SPA DALEC GAPFIRE
Williams et al, 2009
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
SPA2
Key Questions
No Fire
Large Fire
Many small ground fires
Fire (size indicates magnitude)
Legend
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
?
Time
Liv
ing
Bio
ma
ss C
arb
on
Is this possible?
Carbon in living biomass in a fire-prone ecosystem
Other considerations:
- Soil carbon
- Coarse woody debris
- ecosystem GPP
Time
Key Questions
Time
Time
So
il C
arb
on
GP
P
Co
ars
e W
oo
dy
De
bris
Time
Liv
ing
Bio
ma
ss C
arb
on
Time
To
tal E
cosy
ste
m C
arb
on
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
The Plan…
Make sure the models work in the longleaf pine ecosystem
Make the models more specific
Put the models together and make sure that works
Use the model to explore the carbon dynamics in the longleaf pine ecosystem
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
3
2
1
4
Data needed to achieve The Plan
Introduction Longleaf Pine Ecosystem Model Overview Questions The Plan…
Already available Initiated Future
Long Term Ecological Monitoring Program
Ecosystem Productivity Study
Ford (2004) water use and productivity data
Addington (2001) rooting, water use, productivity and leaf-level ecophysiological data for P. palustris.
Jacqmain (1996) data on community composition and dynamics
Eddy covariance towers at 3 sites (xeric, mesic and intermediate)
Monthly hemispherical photographs and litterfall data
MODIS LAI time series
Further ecophysiological work, specifically on oak species and wiregrass
Further data on rooting depth and patterns, specifically on oaks
Biomass allometrics work
Canopy structure and characterization work
Eddy covariance tower at Red Dirt site Hemispherical photograph from January 09 (Baker Woods site)
Thank you!
Any Questions?
