Modelling Tundra Vegetation Response to Recent Arctic Warming
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The Arctic land area has warmed by >1 °C in the last 30 years and there is evidence that this has led to increased productivity and stature of tundra vegetation and reduced albedo, effecting a positive (amplifying) feedback to climate warming. We applied an individual-based dynamic vegetation model over the Arctic forced by observed climate and atmospheric CO2 for 1980–2006. Averaged over the study area, the model simulated increases in primary production and leaf area index, and an increasing representation of shrubs and trees in vegetation. The main underlying mechanism was a warming-driven increase in growing season length, enhancing the production of shrubs and trees to the detriment of shaded ground-level vegetation. The simulated vegetation changes were estimated to correspond to a 1.75 % decline in snow-season albedo. Implications for modelling future climate impacts on Arctic ecosystems and for the incorporation of biogeophysical feedback mechanisms in Arctic system models are discussed.
KeywordsArctic tundra vegetation Climate change Shrub expansion Ecosystem modelling LPJ-GUESS Biogeophysical feedbacks
The authors would like to acknowledge the valuable contributions of both Rita Wania and Annett Wolf to the development of process descriptions in LPJ-GUESS. They would also like to thank Dan Hayes (Oak Ridge National Laboratory, USA) for producing the wetland map for the study domain shown in Fig. 1b. The authors acknowledge financial support from the Swedish Research Council FORMAS. This study is a contribution to the Strategic Research Area Modelling the Regional and Global Earth System (MERGE) and to the Nordic Top-Research Initiative DEFROST.
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