This interdisciplinary study examined six priority ecosystems in three National Forest Systems Regions. The vulnerability assessment emphasized key resource areas - water, fisheries, vegetation and disturbance, wildlife, recreation, infrastructure, cultural heritage, and ecosystem services - regarded as the most important for ecosystems and human communities. The six priority ecosystems identified in the USDA Forest Service, Rocky Mountain Region include: alpine turf and dwarf-shrubland; aquatic, riparian, and wetland ecosystems in glaciated valleys; subalpine spruce-fir; low-gradient mountain stream reaches; ponderosa pine; and Great Plains streams and riparian areas.
Researchers found during the 20th century, the mean annual temperature in all five Rocky Mountain Region states rose between 1 and 2 degrees Fahrenheit; all five states are expected to experience historically unprecedented warming during the 21st century. Ponderosa pine woodlands and savannahs were rated as moderately vulnerable to climate change. While ponderosa pine ecosystems are widespread, ponderosa seed and seedling production is highly dependent on temperature and precipitation conditions. Subalpine spruce-fir forests were rated as moderately vulnerable, based on factors such as expected late-season moisture and insect outbreaks and fire that can be made worse by warmer, dryer conditions. Alpine turf and dwarf-shrublands were rated as highly vulnerable, based on factors such as limited shift capacity and extent, potentially early snowpack decline, and sensitivity to variations in spring/fall freeze timing. Great Plains streams and riparian areas were rated as very highly vulnerable, based on factors such as limited shift capacity and external, potential reduced water flows and increasing levels of human use. Aquatic, riparian and wetland ecosystems in glaciated valleys were rated as very highly vulnerable, because of limited shift capacity and extent, glacial retreat, and potential reduced stream flows. Low-gradient mountain stream reaches were rated as very highly vulnerable, with expectations of debris flow increases from more frequent fires and flooding, along with often extensive human use and development.