Use of BiomeBGC with the Ch EAS flux

Use of Biome-BGC with the Ch. EAS flux tower network to address scaling issues Faith Ann Heinsch NTSG, School of Forestry The University of Montana Ch. EAS Meeting July 1, 2003

The BIOME-BGC Terrestrial Ecosystem Process Model BIOME-BGC estimates fluxes and storage of energy, water, carbon, and nitrogen for vegetation and soil on a daily basis. Model algorithms represent physical and biological processes that control fluxes of energy and mass: • • • • New leaf growth and old leaf litterfall Sunlight interception by leaves, and penetration to the ground Precipitation routing to leaves and soil Snow (SWE) accumulation and melting Drainage and runoff of soil water Evaporation of water from soil and wet leaves Transpiration of soil water through leaf stomata Photosynthetic fixation of carbon from CO 2 in the air N uptake from the soil Distribution of C and N to growing plant parts Decomposition of fresh plant litter and old soil organic matter Plant mortality Plant phenology Fire/disturbance

BIOME-BGC Major Features: • Daily time step (day/night partitioning based on daily information) • Single, uniform soil layer hydrology (bucket model) • 1 uniform snow layer of SWE (no canopy snow interception/losses) • 1 canopy layer (sunlit/shaded leaf partitioning) • Dynamic phenology and C/N allocation (e. g. LAI, biomass, soil and litter) • Disturbance (fire) and mortality functions • Variable litter and soil C decomposition rates (3 litter and 4 soil C pools)

Meteorological Parameters Required by Biome-BGC • • Daily maximum temperature (°C) Daily minimum temperature (°C) Daylight average temperature (°C) Daily total precipitation (cm) • Daylight average partial pressure of water vapor (Pa) • Daylight average shortwave radiant flux density (W/m 2) • Daylength (s)

Site Data Latitude Elevation Slope/Aspect Soil Depth Soil Texture Meteorological Data Air Temperature Radiation Precipitation Humidity Atmospheric CO 2 Evaporation/ Transpiration Periodic Input Disturbance -fire -harvest -grazing -agriculture Temperature H 2 O Snow Photosynthesis Atmospheric CO 2 PSN GR MR HR Allocation to New growth Plant C H 2 O Annual Input N Deposition N Fixation LAI Soil H 2 O Outflow H 2 O Daily - Annual Photosynthesis Evapotranspiration Respiration Absorbed PAR Total Respiration C Soil and Litter Respiration C Daily - Annual Allocation Carbon, Nitrogen -leaf (LAI) -stem -coarse root -fine root N Uptak e Litter Soil Organic Matter Soil Mineral N Atmospheric N C Flux N Flux

BIOME-BGC Eco-physiological Parameters Biome-BGC uses a list of 43 parameters to differentiate biomes. • general eco-physiological characteristics • must be specified prior to each model simulation • can be measured in the field, obtained from the literature or derived from other measurements. Default Biome types with defined parameters • Deciduous Broadleaf Forest (temperate) • Deciduous Needleleaf forest (larch) • Evergreen Broadleaf Forest (subtropical/tropical) • Evergreen Needleleaf Forest • Evergreen Shrubland • C 3 Grassland • C 4 Grassland

Integration Surface weather database Di stu his rban da tor ce tab y ase Landcover database Simulation Hydrograph data Model Estimates of: Rh ET LAI Soil C NEE Flux tower data SNOTEL data Other inputs: soils, elevation, N-deposition Biome BGC Outflow Snow on i t a et eter g Ve am se r pa taba da NPP Biomass Ancillary measurements at flux sites Validation f. PAR Satellite data (MODIS, AVHRR) FIA, FHM, Ecodata (Inventory)

BIOME-BGC Simulated Daily Carbon and Water Exchange (1 Barrow Tussock / Wet Sedge Tundra Site, 2000) Daily 1 Meteorology 1 Daily C Budget meteorological data obtained from Barrow W Post Station, 71. 28 N 156. 76 W

BIOME-BGC Simulated Cumulative Net Carbon Exchange (1 Barrow Tussock / Wet Sedge Tundra Site) C sink (+) C source (-) 1 Daily meteorological data obtained from Barrow W Post Station, 71. 28 N 156. 76 W

Biome-BGC runs for 4 areas in Alaska Study Region C source (+) C sink (+) C source (+) Site Name Kenai AK Latitude 60. 18 N Bonanza Creek AK 64. 70 N Coldfoot AK 67. 15 N Atigun AK 68. 02 N C sink (+)

Biome-BGC Estimates of LAI Park Falls, WI

Biome-BGC Estimates of NEE and GPP

Suggested Improvements to Biome-BGC Simulations at Ch. EAS Flux Tower Sites

Wetland-BGC • Presently being tested in Barrow, AK and the Niyak floodplain near Glacier Park, MT • Dynamic groundwater component – Previously 1 soil layer, now 2 (saturated/unsaturated) • Designed to be require minimal additional data • Methane? ?

Unique Site Disturbance History • Natural Disturbances – Timing – Intensity – Examples • Fire • Blowdown • Managed Disturbances – Timing – Intensity – Examples • • Fertilization Harvest Slash burn Plant

Ensembling of Simulations • Temporal – Necessary for historic disturbances • 1 simulation for each year of the meteorological record • Obscures effects of meteorology to allow recovery to be seen • Spatial – Non-interactive • Age class – Old growth forests – Selective harvest and replant • Vegetation Type – ENF vs. DBF • Hydrology – Upland vs. wetland

Disturbance History Credit: P. Thornton, NCAR

Seasonal Cycle of GEP Credit: P. Thornton, NCAR

Annual LAI in Final Simulation Year Credit: P. Thornton, NCAR

Annual NEE in Final Simulation Year Credit: P. Thornton, NCAR

Annual ET in Final Simulation Year Credit: P. Thornton, NCAR

Suggested Improvements • Difficult to attribute discrepancies to either the model or measurements • Probably a combination of: – Site-specific parameterization • Low maximum stomatal conductance • Incorrect treatment of respiration at low Tair – Site-specific measurement biases • Undermeasurement of warm season respiration – Need to find a way to decompose NEE

Biome-BGC Default Ecophysiological Parameters: Evergreen Needleleaf Forest

BIOME-BGC Example Initialization File MET_INPUT (keyword) start of meteorology file control block metdata/TDE. mtc 41 meteorology input filename 4 (int) header lines in met file RESTART (keyword) 1 (flag) restart file 0 (flag) restart/TDE_n. endpoint restart/TDE. endpoint TIME_DEFINE 8 8 1993 0 simulation 6000 simulation) CLIM_CHANGE 0. 0 1. 0 start of restart control block 1 = read restart file 0 = don't read 1 = write restart file 0 = don't write 1 = use restart metyear input restart filename output restart filename 0 = reset metyear (keyword - do not remove) (int) number of meteorological data years (int) number of simulation years (int) first simulation year (flag) 1 = spinup simulation 0 = normal (int) maximum number of spinup years (if spinup (keyword - do not remove) (deg C) offset for Tmax (deg C) offset for Tmin (DIM) multiplier for Prcp (DIM) multiplier for VPD (DIM) multiplier for shortwave radiation CO 2_CONTROL (keyword - do not remove) 1 (flag) 0=constant 1=vary with file 2=constant, file for Ndep 356. 0 (ppm) constant atmospheric CO 2 concentration TDE_co 2. txt (file) annual variable CO 2 filename SITE 0. 765 fraction) 28. 0 64. 0 8. 0 290. 0 35. 95 0. 2 0. 0005 (keyword) start of site physical constants block (m) effective soil depth (corrected for rock (%) sand percentage by volume in rock-free soil (%) silt percentage by volume in rock-free soil (%) clay percentage by volume in rock-free soil (m) site elevation (degrees) site latitude (- for S. Hem. ) (DIM) site shortwave albedo (kg. N/m 2/yr) wet+dry atmospheric deposition of N 0. 0004 (kg. N/m 2/yr) symbiotic+asymbiotic fixation of N

BIOME-BGC Example Initialization File (cont. ) RAMP_NDEP 0 2099 0. 0001 EPC_FILE dbf. epc (keyword - do not remove) (flag) do a ramped -deposition N run? 0=no, 1=yes (int) reference year for industrial N deposition (kg. N/m 2/yr) industrial N deposition value (keyword- do not remove) (file) TDE DBF ecophysiological constants W_STATE 0. 0 0. 5 (keyword) start of water state variable initialization block (kg/m 2) water stored in snowpack (DIM) initial soil water as a proportion ofturation sa C_STATE 0. 001 0. 0 0. 0 (keyword) start of carbon state variable initialization block (kg. C/m 2) first -year maximum leaf carbon (kg. C/m 2) first -year maximum stem carbon (kg. C/m 2) coarse woody debris carbon (kg. C/m 2) litter carbon, labile pool (kg. C/m 2) litter carbon, unshielded cellulose pool (kg. C/m 2) litter carbon, lignin pool (kg. C/m 2) soil carbon, fast microbial recycling pool (kg. C/m 2) soil carbon, medium microbial recycling pool (kg. C/m 2) soil carbon, slow microbial recycling pool (kg. C/m 2) soil carbon, recalcitrant SOM (slowest) N_STATE 0. 0 (keyword) start of nitrogen state variable initialization block (kg. N/m 2) litter nitrogen, labile pool (kg. N/m 2) soil nitrogen, mineral pool OUTPUT_CONTROL outputs/TDE_out 1 (flag) 1 = 0 (flag) 1 = 1 (flag) for (keyword- do not remove) (text) pr efix for output files write daily output 0 = no daily output monthly avg of daily variables 0 = no monthly avg annual avg of daily variables 0 = no annual avg write annual output 0 = no annual output on -screen progress indicator DAILY_OUTPUT (keyword) 3 (int) number of daily variables to output 516 0 epv. vwc (%) 43 1 wf. soilw_trans (kg m^ -2) 38 2 wf. canopyw_evap (kg m^ -2) ANNUAL_OUTPUT (keyword) 2 (int) number of annual output variables 545 0 annual maximum projected LAI 636 1 vegetation C END_INIT (keyword) indicates the end of the initialization file

What if Some Met Data is Missing? • Use a nearby weather station • Use MT-CLIM to estimate radiation and humidity measurements from Tmax, Tmin – designed to handle complex terrain – uses a base station to calculate “site” data • Use DAYMET (conterminous U. S. only) – uses several met stations surrounding site – data available from 1980 -1997 – takes into account complex terrain

(MPa) BIOME-BGC 1 Soil Water – Soil Water Potential Curves (%) Soil Class β-value VWC_sat PSI_sat Silt loam -4. 625 0. 48 -0. 0073 Silt -3. 84 0. 48 -0. 0078 Loam -5. 275 0. 41 -0. 0013 1 after Cosby et al. , 1984

BIOME-BGC Environmental Controls on Canopy Conductance (Walker Branch Site) M_total, sun, shade = (MPPFD, sun, shade * MTmin * MVPD * MPSI) where multipliers range from 0 (full Gs reduction) to 1 (no effect) Gs, sun, shade = Gs, max * M_total, sun, shade