We are studying treeline, the ecotone between taiga (boreal forest) and tundra. What is the impact of climate change on treeline?

We want to answer three general questions: Has warming in the last 100 years caused treeline to expand northward or uphill? How has the growth rate and the shape of trees at treeline changed? How do climate and disturbance interact together to affect treeline?
Listen to Dr. Andrea Lloyd describe the major question. Click here for text.	Treeline from above: continuous forest changes to tundra. (Wrangell View site on the Denali Highway, 1998.)