We think of vegetation as stationary and remaining pretty constant. Usually that is true, but  when you look closer, especially over long periods, you see how vegetation changes. This article summarizes some of the major changes  we are seeing in Alaska's vegetation communities. 
"A survey of the recent #ecological literature reveals that #Alaska’s vegetation is already responding in myriad ways to our changing #climate  with profound consequences for resident biota. There is copious evidence for both process-related and structural changes being manifested with important and lasting implications for both humans and Alaska’s #ecosystems."  https://www.nps.gov/articles/000/aps-22-1-3.htm