Predicting the spatial distribution of aspen growth potential in the upper Great Lakes region

Abstract

One way to increase aspen yields is to produce aspen on sites where aspen growth potential is highest. Aspen growth rates are typically predicted using site index, but this is impractical for landscape-level assessments. We tested the hypothesis that aspen growth can be predicted from site and climate variables and generated a model to map the spatial variability of aspen growth potential across the upper Great Lakes region. The model predicting aspen growth from climate and site characteristics performed nearly as well as the site index model. Sites currently growing aspen have a somewhat lower growth potential than do nonaspen upland sites. The mean growth potential of national forest sites is lower than on other ownerships, except in Michigan. Upland sites with the highest aspen growth potential had higher growth potential than sites currently growing aspen, suggesting that productivity could be increased by shifting the location of aspen production. Only 6.7% of the highest growth sites are located on national forests across the region. The spatially explicit nature of these results may facilitate cooperative planning to better optimize where aspen will be managed across a subregion to enhance regional productivity and to focus management where the potential for production is the greatest.