Why are species located where they are? This is a primary question ecologists have long been asking, and the classic answer is that vegetation depends on climate, parent material, organisms, disturbance, topography, and time (1). Prehistoric records show that the climate has changed through time, as have the roles of organisms (including humans) and disturbances such as fire. In present times, however, the climate is changing rapidly. Human-caused greenhouse gas emissions have raised peak levels of atmospheric carbon dioxide above 400 ppm for the first time in at least 3 million years. The changing climate is affecting species distributions via changes in growth, reproduction, and mortality, with increasing likelihood of more marked changes in the coming decades. Climate changes can act to directly influence species distributions (e.g., drought, floods, wind) as well as indirectly (e.g., temperature and weather related changes in patterns of wildfire, insects, and disease outbreaks).
Management under climate change increases complexity, but the basic toolbox is the same as for current management. As discussed elsewhere, forest management under climate change can be categorized as mitigation, adaptation, or both. Some specific actions when considering how species may shift in response to climate include 1. Encourage increased connectivity for species modeled to increase with climate change; 2. Evaluate potential for assisted migration; 3. Encourage retention of refugia which may allow persistence of species modeled to decline under climate change; 4. Prepare for additional costs likely required to maintain forest health due to increased stress and disturbances (e.g., insect pests, diseases, fire, ice, drought); and 5. Identify species likely to be especially vulnerable.
Iverson, L.; McKenzie, D. (February, 2014). Species Distribution and Climate Change. U.S. Department of Agriculture, Forest Service, Climate Change Resource Center. www.fs.usda.gov/ccrc/topics/species-distribution
