Changing Shrublines

Treeline is a familiar ecological term to many that means the elevation limit beyond which trees do not occur. Shrubline has the same meaning relative to upright shrubs, which show a similar limitation on the landscape, although shrubline is usually at a higher elevation than treeline. Just as treelines are rising higher in elevation, so are shrublines. In some areas, open alpine vegetation now has to compete with taller growing shrubs. As trees and shrubs march up in elevation together, what do you think will follow? These tall and sturdy plants have a large influence on local microclimates by slowing wind, accumulating snow and moisture at their bases, and cooling ground temperatures by casting shade.

As you browse these photo pairs, imagine the landscape as if you were a bird or small mammal. Have you gained or lost habitat?