As climate warms, species shift

Yellowstone is changing, as warmer weather encourages Canada Thistle to move in. Pocket gophers feed on the roots, and grizzlies feed on both the roots and the pocket gophers.

As climate change alters ecosystems, Dr. Crabtree said, “the winners are going to be the adaptive foragers, like grizzlies that eat everything from ants to moose, and the losers are going to be specialized species that can’t adapt.”

He said one specialized declining species was the long-tailed weasel. It feeds primarily on voles, which are also declining. The changes in the Lamar Valley might point to a new approach for invasive species, which are overwhelming many natural systems. “Invasives are the single biggest threat to biodiversity,” Dr. Crabtree said.

In another example of species shift, ecosystems are moving higher and higher up the mountains of Vermont as the climate warms:

We resurveyed forest plots established in 1964 along elevation transects in the Green Mountains (Vermont) to examine whether a shift had occurred in the location of the northern hardwood–boreal forest ecotone (NBE) from 1964 to 2004. We found a 19% increase in dominance of northern hardwoods from 70% in 1964 to 89% in 2004 in the lower half of the NBE... Our results indicate that high-elevation forests may be jeopardized by climate change sooner than anticipated.