Climate drivers of rapid ecological change at the landscape scale over the last 21,000 years in the Middle and Southern Rockies, U.S.A.

These model objects are the outputs of three Boosted Regression Tree models (for three different time periods) to explore the role of climate change and variability in driving ecological change and transformation. Response variables were the proportion of sites in each ecoregion with peak rates of change at 100-year time steps. Predictor variables included temperature anomaly, temperature trend, temperature variability, precipitation anomaly, precipitation trend, precipitation variability and ecoregion, also at 100-yr time steps. Models focused on the most distant time periods (0-21000 BP and 7500 - 21000 BP) show that rapid vegetation change was initiated across these landscapes once a 2 ℃ temperature increase (positive temperature anomaly, relative to 21,000 yr BP) was realized. The model focused on the more recent time periods, 0-7500 BP, shows that rapid vegetation change was initiated across these landscapes again recently with reduced rainfall.