from Part III - Equilibrium and Nonequilibrium on Geographical Scales
Published online by Cambridge University Press: 05 March 2013
Introduction
The Arctic lies at a global extreme of human impact as well as climatic gradients. Human population density is low. Climate precludes agriculture in all areas but the southernmost ones, and hunting and reindeer husbandry have been the traditional ways of life. More recently coal, oil and gas exploitation and associated infrastructure have affected the vegetation locally and led to species introductions (Walker & Everett, 1987; Forbes et al., 2001). Long-range pollution from industrial regions has reached the Arctic and is accumulating in some animals. Even so, except for Antarctica, the arctic tundra remains the least disturbed major world biome (CAFF, 2001). Short growing seasons, low temperature means and extremes, and high inter-annual variability act as strong environmental filters that allow only the hardiest species to survive. The region has experienced extreme climate changes in the past and is expected to do so in the future. Our focus of this chapter, therefore, is also on past plant responses to rapid climate change, since this history provides a basic framework to help understand the future.
The Arctic comprises relatively low-diversity ecosystems with a dramatic and relatively well-documented history of past responses to repeated climatic oscillations. New paleoecological evidence, recent advances in molecular studies, and predictive modeling of arctic species ranges have greatly increased our understanding of how arctic plants may respond to future environmental change, from individual species to communities. On a short timescale (< 100 years), the species composition of arctic plant communities is often remarkably stable. This partly reflects perennial strategies and clonal growth, enabling survival of fluctuating inter-annual climatic conditions (de Witte & Stöcklin, 2010; Jónsdóttir, 2011). In the longer term, however, plant communities and species ranges have been highly dynamic. During the Late Pleistocene, some regions experienced a change from complete ice cover to boreal forest within a few thousand years, with accompanying transformation of vegetation and species range shifts (Miller et al., 2010a).
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