Climate change, prehistoric and current, affects different species differently, and, within species, different populations are affected differently. In the Great Lakes Region, where forest productivity is economically and ecologically important, predicting the response of major tree species to ongoing climate change can inform land managers and conservationists as they make decisions about planting and conservation strategies.
We took increment cores, which allow tree rings to be studied, from four to five species at each of three sites along a latitudinal gradient from central Indiana to central Lower Michigan. A total of six species were sampled between the three sites. We dated and measured ring widths (that is, radial growth) and modeled contemporary relationships between radial growth and climate. To compare contemporary growth-climate relationships within and among species, we used principal-components analysis (PCA) on the model coefficients. To project future growth, we plugged future climate change projections into the models.
Results/Conclusions
We have dated and measured tree rings of all populations but are still working on growth-climate modeling for five species. For one species, Quercus rubra (red oak), we have finished modeling and projecting growth. PCA showed no latitudinal pattern in the populations’ relationship with climate, with the most northern and southern populations being similar to each other and the middle population being different. This was driven by a positive relationship with summer maximum temperature in the central population and negative in the northern and southern populations. Regarding growth for the rest of this century, our projections suggest the central population will experience no significant growth change while the southern and northern populations will experience either no change or up to a 1.083-fold increase (±.012) depending on the climate model and the representative concentration pathway (that is, the climate change scenario).
Our results differ from those of most other studies of temperate tree species in that if anything climate change will improve red oak productivity in our study region. This highlights the importance of studying populations from throughout a species range to identify potentially climate-change resilient populations that could be a seed source for other locations.