The Holyoke Range hosts a combination of microclimates unusual in New England. Dry, hot upper ridges support oak savannas, often dominated by chestnut oak and a variety of understory grasses and ferns. Eastern red cedar, a dry-loving species, clings to the barren edges of cliffs. Backslope plant communities tend to be more similar to the adjacent Berkshire plateau containing species common to the northern hardwood and oak-hickory forest forest types. Eastern hemlock crowds narrow ravines, blocking sunlight and creating damp, cooler growing conditions with associated cooler climate plant species. Talus slopes are especially rich in nutrients and support a number of calcium-loving plants uncommon in Massachusetts. Because the traprock ridges generate such varied terrain, they are the home of several plant and animal species that are state-listed or globally rare, such as the timber rattlesnake.