Understanding Northeastern US Alpine Mountains: Context, Causal Agents of Treeline, and Meteorology to Approximate their Response to Climate Change

Understanding climate change and air pollution impacts on the northeastern region's restricted alpine ecosystems is complex. Reduced in size and spatial distribution post deglaciation, these alpine ecosystems survived the Hypsithermal warming period with less change than lower-elevation ecosystems. They are low for their latitude and below physiologically limited treeline. More-recent data support and expand on earlier researchers' hypotheses that wind and moisture, not temperature, explains the continued existence of alpine ecosystems in the Northeast. Shifts in species composition and abundance may occur, but frequency of free troposphere exposure, wind, clouds, and rime-icing events, and related topographic, aspect, and microhabitat may maintain resistance to major alpinetreeline ecotone boundary shifts in this century. Under scenarios assuming high levels of emission of greenhouse gases, future predictions become less clear.