Southern Sierra vegetation forecasts

The Nature Conservancy (TNC) has derived climate suitability forecasts for most species of trees and shrubs considered to be ecological dominants of terrestrial Californian habitat types. Our plant projections are compiled as decision support tools to help Conservancy project staff, as well as our external partners, develop the necessary plans, priorities and strategies to successfully adapt to uncertain changes in future climate. In the recently completed Southern Sierra Partnership’s 2010 Climate-Adapted Conservation Plan for the Southern Sierra Nevada and Tehachapi Mountains, species and habitat forecasts shown here informed the development of a regional conservation design that explicitly incorporates long-term conservation values based upon potential climate adaptation threats and opportunities.

Maps of our species forecasts rely on colors to distinguish those areas where climates appear to be suitable both today and in the future (i.e. blue = ’climate refugia’), in contrast to those areas where suitable climates are projected to be lost (i.e. red = ’climate stress’), or gained in the future (i.e. purple = ‘expansion zones’). For ensemble forecasts, we treat all futures as equally likely, and use color saturation to denote relative levels of uncertainty between future projections, where dark colors imply > 80% model consensus (i.e. ‘low uncertainty’), and light colors imply > 60% model consensus (i.e. ‘moderate uncertainty’). For scenario forecasts (i.e. ‘hot & wet’, ‘warm & dry, ‘hot & dry’), projections are based upon individual climate models, and can be used collectively to bracket the potential extremes of future climate changes.We caution that species distributions are often limited by many factors other than climate, and ultimately, the climate vulnerability of each species will depend upon its exposure and sensitivity to climate impacts, as well as factors that influence adaptation potential, such as species attributes (e.g. dispersal ability, physiology, behavior, genetic diversity), landscape attributes (e.g. topography, hydrology) and management context (e.g. conservation status, habitat loss, fragmentation).