Projections of suitable habitat under climate change scenarios: Implications for trans-boundary assisted colonization

Climate change may threaten endemic species with extinction, particularly relicts of the Arcto-Tertiary Forest, by elimination of their contemporary habitat. Projections of future habitat are necessary to plan for conservation of these species.

We used spline climatic models and modified Random Forests statistical procedures to predict suitable habitats for Brewer spruce (Picea breweriana), which is endemic to the Klamath Region of California and Oregon. We used three general circulation models and two sets of carbon emission scenarios (optimistic and pessimistic) for future climates.

Our procedures predicted present occurrence of Brewer spruce perfectly. For the decades 2030, 2060, and 2090, its projected range within the Klamath Region progressively declined, to the point of disappearance in the decade 2090. The climate niche was projected to move north to British Columbia, the Yukon Territory, and southeastern Alaska.

The results emphasize the necessity of assisted colonization and trans-boundary movement to prevent extinction of Brewer spruce. The projections provide a framework for formulating conservation plans, but planners must also consider regulations regarding international plant transfers.