ARCUS 14th Annual Meeting and Arctic Forum 2002May 16, 2002Arlington Hilton, Arlington, Virginia, USA Interactions between hydrological and biotic process in the Arctic landscapeJoshua Schimel1 Traditionally, terrestrial ecology had focused on individual study plots in distinct community types, in which the physical system was largely seen as a driver of biotic activity. This approach, however, has changed dramatically. The tundra is no longer a collection of community types, but an integrated landscape in which physical and biotic systems strongly feed back on each other. In this view, freshwater is a critical integrating force, moving carbon and nutrients across the landscape and into streams, lakes, and ultimately the ocean. One important aspect of this development is an appreciation of winter. We are coming to better understand how winter processes (snow timing and distribution) drive not only hydrology but also the biotic systems, which we used to assume "turn off" during the winter. Strong feedbacks develop through the winter, for example, shrubs trap blowing snow, producing a better insulating layer. Warmer, though still frozen, soils mineralize nitrogen that is available for plant uptake in the spring (or loss at snowmelt). Higher nutrient availability in turn encourages shrub growth, closing a positive feedback loop that has the potential to drastically change the tundra landscape. Such feedbacks may develop on a local scale, but apply broadly across the Arctic. Understanding the functioning of these feedback mechanisms has led to major rethinking in our understanding of the Arctic system. |
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