title: Projections of suitable habitat for rare species under global warming scenarios.
abstract: OBJECTIVE
  Modeling the contemporary and future climate niche for rare plants is a major hurdle in conservation, yet such projections are necessary to prevent extinctions that may result from climate change. •
  
  
  METHODS
  We used recently developed spline climatic models and modified Random Forests statistical procedures to predict suitable habitats of three rare, endangered spruces of Mexico and a spruce of the southwestern USA. We used three general circulation models and two sets of carbon emission scenarios (optimistic and pessimistic) for future climates. •
  
  
  RESULTS
  Our procedures predicted present occurrence perfectly. For the decades 2030, 2060, and 2090, the ranges of all taxa progressively decreased, to the point of transient disappearance for one species in the decade 2060 but reappearance in 2090. Contrary to intuition, habitat did not develop to the north for any of the Mexican taxa; rather, climate niches for two taxa re-materialized several hundred kilometers southward in the Trans-Mexican Volcanic Belt. The climate niche for a third Mexican taxon shrank drastically, and its two mitotypes responded differently, one of the first demonstrations of the importance of intraspecific genetic variation in climate niches. The climate niche of the U.S. species shrank northward and upward in elevation. •
  
  
  CONCLUSIONS
  The results are important for conservation of these species and are of general significance for conservation by assisted colonization. We conclude that our procedures for producing models and projecting the climate niches of Mexican spruces provide a way for handling other rare plants, which constitute the great bulk of the world's endangered and most vulnerable flora.
authors.affiliation: Institute of Forest Genetics, Pacific Southwest Research Station, USDA Forest Service, 2480 Carson Road, Placerville, California 95667 USA and Department of Plant Sciences, University of California, Davis, California 95616 USA.
authors.forename: F Thomas
authors.initials: FT
authors.lastname: Ledig
authors.forename: Gerald E
authors.initials: GE
authors.lastname: Rehfeldt
authors.forename: Cuauhtémoc
authors.initials: C
authors.lastname: Sáenz-Romero
authors.forename: Celestino
authors.initials: C
authors.lastname: Flores-López