Ecosystems at the Arctic LTER site at Toolik Lake, Alaska, respond to variations in climate at a number of temporal scales. At the scale of a single season, changes in PAR directly affect NEP, whereas rainfall events change stream flow and associ ated lake stratification and ecosystems. At the scale of year-to-year variation, warming lake temperatures may reduce the habitat suitable for lake trout, and the growth of grayling is positively correlated with wet and cold summers. For land plants, soil warming caused by early snow melt or by warm summers causes the synchronous flowering across northern Alaska of arctic cotton grass and an increase in leaf area. Finally, at the scale of multiyear variation in air temperatures, the alkalinity in lakes and steams near the Toolik Lake Field Station has doubled in the last decade. The exact reasons for this change are unknown, but they are likely related to long-term trends in climate.


Brown, J., G. W. Kling, K. M. Hinkel, L. D. Hinzman, F. E. Nelson, V. E. Romanovsky, and N. I. Shiklomonov. 2000. Arctic Alaska and Seward Peninsula. Pages 182-187 in J. Brown, K. M. Hinkel, and F. E. Nelson, editors. The circumpolar active layer monitoring (CALM) program: Research designs and initial results. Polar Geography 24 (3): 165-258.

Chapman, W. L., and J. E. Walsh. 1993. Recent variations of sea ice and air temperatures in high latitudes. Bulletin of the American Meteorological Society 74(1): 33-47.

Deegan, L. A., H. E. Golden, C. J. Harery, and B. J. Peterson. 1999. Influence of environmental variability on the growth of age-0 and adult Arctic grayling. Transactions of the American Fisheries Society 128: 1163-1175.

Eugster, W., J. P. McFadden, and F. S. Chapin III. 1997. A comparative approach to regional variation in surface fluxes using mobile eddy correlation towers. Boundary-Layer Meteorology 85: 293-307.

Haugan, R. K. 1982. Climate of remote areas in north-central Alaska 1975-1979. Summary. Cold Regions Research and Engineering Laboratory Report 82-35. Hanover, New Hampshire.

Haugan, R. K., and J. Brown. 1980. Coastal-inland distributions of summer air temperature and precipitation in Northern Alaska. Arctic and Alpine Research 12(4): 403-412.

Hobbie, J. E., B. J. Peterson, N. Bettez, L. A. Deegan, W. J. O'Brien, G. W. Kling, and G. W. Kipphut. 1999. Impact of global change on biogeochemistry and ecosystems of an arctic freshwater system. Polar Research 18: 207-214.

Kane, D. L., L. D. Hinzman, J. P. McNamara, Z. Zhang, and C. S. Benson. 2000. An Overview of a nested watershed study in Arctic Alaska. Nordic Hydrology 31: 245266.

McGraw J. B., A. L. Chester, and L. Stuart. 1983. A note on July senescence in tundra plants at Eagle Creek, Alaska, U.S.A. Arctic and Alpine Research 15: 267-269.

O'Brien, J., editor. 1992. Toolik Lake: Ecology of an aquatic ecosystem in arctic Alaska. Developments in Hydrobiolgia 78: 1-269.

Oberbauer, S. F., W. Cheng, B. Ostendorf, A. Sala, R. Gebauer, C. T. Gillespie, R. A. Virginia, and J. D. Tenhunen. 1996. Landscape patterns of carbon gas exchange in tundra ecosystems. Pages 223-257 in J. F. Reynolds and J. D. Tenhunen, editors. Landscape Function and Disturbance in the Arctic. New York: Springer Verlag.

Oberbauer, S. F., G. Starr, and E.W. Pop. 1998. Effects of extended growing season and soil warming on carbon dioxide and methane exchange of tussock tundra in Alaska. Journal of Geophysical Research 103: 29075-29082.

Peterson, B. J., L. A. Deegan, J. Helfrich, J. E. Hobbie, M. Hullar, B. Moller, T. E. Ford,

A. E. Hershey, A. Hiltner, G. Kipphut, M. A. Lock, D. M. Fiebig, V. McKinley, M. C. Miller, R. Westal, R. Ventullo, and G. Volk. 1993. Biological responses of a tundra river to fertilization. Ecology 74: 653-672.

Pop, E. W., S. F. Oberbauer, and G. Starr. 2000. Predicting vegetative bud break in two arctic deciduous shrub species, Salix pulchra and Betula nana. Oecologia 124: 176-184.

Shaver, G. R., F. S. Chapin III, and B. L. Gartner. 1986a. Factors limiting seasonal growth and peak biomass accumulation in Eriophorum vaginatum. Journal of Ecology 74: 257-278.

Shaver, G. R., N. Fetcher, and F. S. Chapin III. 1986b. Growth and flowering in Eriophorum vaginatum: Annual and latitudinal variation. Ecology 67: 1524-1525.

Starr, G., S. F. Oberbauer, and E. W. Pop. 2000. Effects of extended growing season and soil warming on phenology and physiology of Polygonum bistorta. Global Change Biology 6: 357-369.

Stieglitz, M., J. Hobbie, A. Giblin, and G. Kling, 1999. Hydrologic modeling of an arctic watershed: Towards Pan-Arctic predictions, Journal of Geophysical Research-Atmospheres 104(D22): 27507-27518.

Williams, M., W. Eugster, E. B. Rastetter, J. P. McFadden, and F. S. Chapin III. 2000. The controls on net ecosystem productivity along an Arctic transect: A model comparison with flux measurements. Global Change Biology 6(1): 116-126.

Williams, M., E. B. Rastetter, G. R. Shaver, J. E. Hobbie, E. Carpino, and B. L. Kwiatkowski. 2001. Primary production of an Arctic watershed: An uncertainty analysis. Ecological Applications 11: 1800-1816.

Zhang, T., T. E. Osterkamp, and K. Stamnes. 1996. Some characteristics of the climate in northern Alaska. Arctic and Alpine Research 28: 509-518.

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