FILE NAME: TEM02-boreal.doc YEARS: NA PI: A. Dave McGuire OTHERS: JS Clein, AD McGuire, X Zhang, DW Kicklighter, JM Melillo, SC Wofsy, PG Jarvis, JM Massheder MANUSCRIPT TITLE: Historical and projected carbon balance of mature black spruce ecosystems across North America: The role of carbon-nitrogen interactions BRIEF DESCRIPTION: This data set includes model output of TEM for the gridcell containing the black spruce northern study area (-98.5, 55.5) compared to available tower flux data (field-based estimates of GPP, RESP, NEP) . It also contains the model output data of TEM simulations for the boreal region which is defined as vegetation type 4 in temveg (N= 1758) RESEARCH LOCATION: North American boreal forests. METHODS: We parameterized version 4.1 of TEM for a mature black spruce ecosystem at Bonanza Creek, Alaska. We developed a second parameterization in which the N cycle was uncoupled from the C cycle in the model. To verify the parameterizations, we simulated C dynamics for the old black spruce site in the northern study area (northern site, Manitoba, Canada, gridcell -98.5, 55.5) of BOREAS from 1975 to 1997 using local climate data. We compared simulated monthly C fluxes (GPP, RESP, and NEP) from 1994 to 1997 to available field-based estimates (Sutton et al., 1998; Wofsy, pers comm). As an independent test, we compared simulated monthly NEP to field-based estimates of NEP made at an old black spruce site in the southern study area (southern site, southern Saskatchewan, Canada) of BOREAS (Jarvis, pers comm). To evaluate the consequences of considering N feedbacks on simulated C dynamics of mature black spruce ecosystems in North America, we applied both parameterizations to simulate the response of C dynamics to historical and projected climate change from 1900 to 2100 across the range of black spruce in North America. We first analyzed the outputs for the spatial unit containing the northern site to evaluate mechanisms responsible for differences in the C dynamics simulated between the two parameterizations. Next, we evaluated spatial and temporal variability of black spruce C dynamics by comparing the spatial variation in C dynamics across North America for four different decades separated by 50-year intervals. TEM: The TEM is a process-based, global-scale ecosystem model that uses spatially referenced information on climate, elevation, soils, and vegetation to make monthly estimates of C and N fluxes and pool sizes of the terrestrial biosphere. In this study we used version 4.1 of the model (McGuire et al., 1997; Tian et al., 1999) as modified by McGuire et al. (2000), which was used to evaluate whether consideration of the effects of snowpack on winter decomposition would improve the ability of the model to simulate the seasonal cycle of atmospheric CO2 at high latitude monitoring stations. For each monthly time step, NEP is calculated as the difference between NPP and heterotrophic respiration (RH). NPP is calculated as the difference between GPP and plant autotrophic respiration. Algorithms describing calculations for RH and plant autotrophic respiration are described elsewhere (McGuire et al., 1997, Tian et al., 1999). Monthly GPP is initially calculated in TEM as a function of photosynthetically active radiation, air temperature, atmospheric carbon dioxide concentration, and moisture availability. Nitrogen availability also influences the ability of vegetation to incorporate elevated CO2 into production (McGuire et al., 1997; Pan et al., 1998; Tian et al., 1999). Elevated atmospheric CO2 decreases the N concentration of vegetation to influence the N requirements of production and decomposition (McGuire et al., 1997; Tian et al., 1999). If N supply, which is the sum of N uptake and labile N in the vegetation, cannot meet the stoichiometric C to N ratio of biomass production, then GPP is reduced to meet the constraint. In the case where N supply does not limit biomass production, N uptake is reduced so that N supply meets the constraints of biomass production. In this way, the C-N status of the vegetation causes the model to allocate more effort toward either C or N uptake (McGuire et al., 1992). CONDITIONS FOR USE: Acceptance and utilization of this data requires that: The Principal Investigator is sent a notice stating reasons for acquiring any data and a description of the publication intentions. The Principal Investigator of the data set be sent a copy of the report or manuscript prior to submission and be adequately cited in any resultant publications. A copy of any resultant publications should be sent to: A Dave McGuire 216 Irving I Building University of Alaska Fairbanks Fairbanks, AK 99775 VARIABLE DESCRIPTION: Variable name Variable description Units -------------------------------------------------------------------------------- --------------------------------------------------------------------- NPP Net Primary Production g C m-2 yr-1 RH Heterotrophic Respiration g C m-2 yr-1 NEP Net Ecosystem Production g C m-2 yr-1 FOR MORE INFORMATION, CONTACT: A Dave McGuire 216 Irving I Building, University of Alaska Fairbanks Fairbanks, AK 99775 Email: ffadm@uaf.edu FILES: File Name: cflux-gridcell.xls File Type: Excel File Name: TEMcoupled-NEP.dat File Type: Comma-delimited ASCII File Name: TEMuncoupled-NEP.dat File Type: Comma-delimited ASCII FILE FORMAT: Excel file: this notebook has 4 sheets, each one represents figures 1, 2,3, and 4 of the manuscript. They all have year and month (if needed) in the first one or two columns. Column labels are in the first tow rows in each sheet. Fig 2: year, month, tower GPP, coupled GPP output, uncoupled GPP output, tower RESP, coupled RESP output, uncoupled RESP output (all from the northern site) Fig 3: year, month, tower NEP, coupled NEP output, uncoupled NEP output (all from northern site)' tower NEP, coupled NEP output, uncoupled NEP output (all from southern site) Fig 4: year, NPP coupled output, NPP uncoupled output, RH coupled output, RH uncoupled output, NEP coupled output, NEP uncoupled output Fig 5: year, changes in veg C coupled output, changes in veg C uncoupled output, changes in soil C coupled output, changes in soil C uncoupled output, changes in ecosystem C coupled output, changes in ecosystem C uncoupled output TEM: longitude, latitude, variable, veg type, NA*, NA*, NA*, cell area, NA*, sum, max, mean, min, jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec, continent/country NA* = not used All monthly values: 1 decimal place, excluding the mean, which has 2 decimal places NUMBER OF RECORDS: 62,483. (per ASCII file) REFERENCE CITATIONS: McGuire AD, Melillo JM, Kicklighter DW & Joyce LA (1995) Equilibrium responses of soil carbon to climate change: Empirical and process-based estimates. Journal of Biogeography 22:785-796. McGuire AD, Melillo JM, Kicklighter, DW, Pan Y, Xiao X, Helfrich J, Moore B III, Vorosmarty CJ, Schloss AL (1997) Equilibrium responses of global net primary production and carbon storage to doubled atmospheric carbon dioxide: Sensitivity to changes in vegetation nitrogen concentration. Global Biogeochemical Cycles 6: 101-124. McGuire AD, Melillo JM, Randerson JT, W. J. Parton, M. Heimann, R. A. Meier, J. S. Clein-Curley, D. W. Kicklighter, W. Sauf (2000) Modeling the effects of snowpack on heterotrophic respiration across northern temperate and high latitude regions: Comparison with measurements of atmospheric carbon dioxide in high latitudes. Biogeochemistry 48: 91-114. Raich JW, Rastetter EB, Melillo JM, Kicklighter DW, Steudler PA, Peterson BJ, Grace AL, Moore B III & Vörösmarty CJ (1991) Potential net primary productivity in South America: Application of a global model. Ecological Applications 1:399-429. Sutton D, Goulden M and Wofsy S 1998 BOREAS TF-03 NSA-OBS Tower Flux, Meteorological, and Soil Temperature Data. Available online at [http://www-eosdis.ornl.gov/] from the ORNL Distributed Active Archive Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A. Tian, H, Melillo JM, Kicklighter DW, McGuire AD (1999) The sensitivity of terrestrial carbon storage to historical atmospheric CO2 and climate variability in the United States. Tellus 51B: 414-452. ACKNOWLEDGEMENTS: This research was supported by the Arctic System Science (ARCSS) Program of the National Science Foundation as a Synthesis, Integration, and Modeling Study (SIMS: OPP-9614253) and as an Arctic Transitions in the Land Atmosphere System (ATLAS) Study, by the Earth Observing System of the National Aeronautics and Space Administration, by the Vegetation/Ecosystem Modeling and Analysis Project, and by the Bonanza Creek Long Term Ecological Research Program of the National Science Foundation.