The Impact of Climate Change on the Flora of Thoreau’s Concord

摘要

Climate change is driving major shifts in ecosystems all over the world, including here in the United States. Tree swallows and many other bird species are breeding earlier, forest edges are extending up the sides of mountains, and the distri- butions of pest insect species such as the hemlock woolly adelgid are shift- ing northward. Notably, most of the evidence for biological responses to climate change, including these exam- ples, is based on studies of one or a few species. The number of examples is large, but it is diffcult to know how representative they are. How is cli- mate change affecting entire natural communities of plants and animals? Are all of the species within a commu- nity changing, or are just a few? Are most species in a location changing in the same way, or are there substantial differences among species? Are there ways to predict how species within communities might change and what the consequences of these changes will be? Despite the obvious impor- tance of these questions, we do not really know the answers. We know many changes are happening, some of them major, but thus far our knowl- edge is limited to a relatively few spe- cies in a few places.