Nonlinear Growth and Physiological Responses of White Spruce at North American Arctic Treeline

Abstract

The boreal forest biome covers a quarter of the Earth's terrestrial surface and plays a critical role in the global carbon and water cycles. Approximately one third of the globe's terrestrial carbon stock is stored in boreal forests (Bradshaw & Warkentin, 2015;Pan et al., 2011), where the growth of trees is responsible for most of the carbon sink activity in the Arctic (McGuire et al., 2009). These high-latitude forests are ecologically sensitive regions and can show amplified response to the strong warming observed in the Arctic (Chapin et al., 2005;Seddon et al., 2016). In the last few decades, global warming and related changes in surface hydrology and energy budgets (Chapin et al., 2010(Chapin et al., , 2005 have led to substantial changes in forest productivity and structure (Beck et al., 2011). These changes have been quite pronounced at the Arctic latitudinal treeline where unprecedented changes in vegetation composition and growth have occurred (Pearson et al., 2013).