Net Carbon Exchange Across the Arctic Tundra-Boreal Forest Transition in Alaska 1981–2000
- 140 Downloads
Shifts in the carbon balance of high-latitude ecosystems could result from differential responses of vegetation and soil processes to changing moisture and temperature regimes and to a lengthening of the growing season. Although shrub expansion and northward movement of treeline should increase carbon inputs, the effects of these vegetation changes on net carbon exchange have not been evaluated. We selected low shrub, tall shrub, and forest tundra sites near treeline in northwestern Alaska, representing the major structural transitions expected in response to warming. In these sites, we measured aboveground net primary production (ANPP) and vegetation and soil carbon and nitrogen pools, and used these data to parameterize the Terrestrial Ecosystem Model. We simulated the response of carbon balance components to air temperature and precipitation trends during 1981–2000. In areas experiencing warmer and dryer conditions, Net Primary Production (NPP) decreased and heterotrophic respiration (R H ) increased, leading to a decrease in Net Ecosystem Production (NEP). In warmer and wetter conditions NPP increased, but the response was exceeded by an increase in R H ; therefore, NEP also decreased. Lastly, in colder and wetter regions, the increase in NPP exceeded a small decline in R H , leading to an increase in NEP. The net effect for the region was a slight gain in ecosystem carbon storage over the 20 year period. This research highlights the potential importance of spatial variability in ecosystem responses to climate change in assessing the response of carbon storage in northern Alaska over the last two decades.
Keywordsnet carbon exchange net primary productivity Alaskan Arctic tundra
Unable to display preview. Download preview PDF.
- Clein, J.S., Kwiatkowski, B.L., McGuire, A.D., Hobbie, J.E., Rastetter, E.B., Melillo, J.M. and Kicklighter, D.W.: 2000, ‘Modelling carbon responses of tundra ecosystems to historical and projected climate: A comparison of a plot- and a global-scale ecosystem model to identify process-based uncertainties’, Global Change Biology 6, 127–140.CrossRefGoogle Scholar
- Hobbie, S.E. and Chapin, III., F.S.: 1998, ‘The response of tundra plant biomass, aboveground production, nitrogen and CO2 flux to experimental warming’, Ecology 79, 1526–1544.Google Scholar
- Le Dizes, S., Kwiatkowski, B.L., Rastetter, E.B., Hope, A., Hobbie, J.E., Stow, D. and Daeschner, S.: 2003, ‘Modeling biogeochemical responses of tundra ecosystems to temporal and spatial variations in climate in the Kuparuk River Basin (Alaska)’, Journal of Geophysical Research DOI 10.1029/2001JD000960.Google Scholar
- McGuire, A.D., Melillo, J.M., Joyce, L.A., Kicklighter, D.W., Grace, A.L., Moore, III. B. and Vorosmarty, C.J.: 1992. ‘Interactions between carbon and nitrogen dynamics in estimating net primary productivity for potential vegetation in North America’, Global Biogeochemical Cycles 6, 101–124.CrossRefGoogle Scholar
- Melillo, J.M., Kicklighter, D.W., McGuire, A.D., Peterjohn, W.T. and Newkirk, K.M.: 1995, ‘Global change and its effects on soil organic carbon stocks’, in R. G. Zepp and C. Sonntag (eds.), Role of Nonliving Organic Matter in the Earth’s Carbon Cycle., John Wiley & Sons Ltd., pp. 175–189.Google Scholar
- Michaelson, G.J. and Ping, C.L.: 2003. Soil organic carbon and CO2 respiration at subzero temperature in soils of Arctic Alaska, Journal of Geophysical Research DOI 10.1029/2001JD000920.Google Scholar
- Shaver, G.R. and Chapin, III, F.S.: 1986. Effect of fertilizer on production and biomass of tussock tundra, Alaska, U.S.A. Arctic and Alpine Research 18, 261–268.Google Scholar
- Stow, D.A., Hope, A., McGuire, D., Verbyla, D., Gamon, J., Huemmerich, F., Souston, S., Racine, C., Sturm, M., Tape, K., Hinzman, L., Yoshikawa, K., Tweedie, G., Noyle, B., Silapaswan, C., Douglas, D., Griffeth, B., Jia, G., Epstein, H., Walker, D., Daeschner, S., Petersen, A., Zhou, L. and Myneni, R.: 2003, ‘Remote sensing of vegetation and land-cover change in Arctic Tundra Ecosystems’, Remote Sensing of Environment 89, 281–308.CrossRefGoogle Scholar
- Wielgolaski, F.E., Bliss, L.C., Svoboda, J. and Doyle, G.: 1981, ‘Primary production of tundra’, in L. C. Bliss, J. B. Cragg, D. W. Heal and J. J. Moore (eds.), Tundra Ecosystems: A Comparative Analysis. Cambridge University Press.Google Scholar
- Zhuang, Q., McGuire, A.D., Melillo, J.M., Clein, J.S., Dargaville, R.J., Kicklighter, D.W., Myneni, R.B., Romanovsky, V.E., Harden, J. and Hobbie, J.E.: 2003, ‘Carbon cycling in extratropical terrestrial ecosystems of the Northern Hemisphere during the 20th century: A modeling analysis of the influences of soil thermal dynamics’, Tellus 55B, 751–776.CrossRefGoogle Scholar