ASSESSING THE EFFECT OF HISTORIC LAND USE ON EASTERN HEMLOCK (TSUGA CANADENSIS) AND ON CLIMATE-DRIVEN SPECIES DISTRIBUTION MODEL PREDICTIONS IN THE UPPER MIDWESTERN U.S

Since the early 1800s, forests in Wisconsin, Minnesota, and Michigan (the upper Midwest) have experienced major changes in forest composition due to land use conversion for agriculture and logging and subsequent forest regeneration. Regional climate also changed in this time, becoming warmer and wetter. For many tree species, including eastern hemlock (Tsuga canadensis), the combination of land use change and climate change has led to a shift in the climate space that they occupy within the upper Midwest. Future shifts in climate space can be expected as the climate continues to change throughout this century, and as the climate becomes warmer, the range for hemlock is hypothesized to shift northward.

Future shifts in hemlock’s climate space and distribution can be predicted through species distribution modeling techniques that use the species-climate relationship. However, given past land use change, it may be important to take historical data into account when deriving the correlation between a species distribution and its occupied climate space because past distributions could better represent the realized niche. By using combinations of both modern and historic forest composition and climate datasets, the effects of historic land use on eastern hemlock’s species distribution model predictions is assessed.