Modeling changes in habitat conditions in northern hardwoods forests of the Adirondack Mountains of New York

Interest in enhancing the management of forest timber and wildlife resources has stimulated the development of modeling techniques to predict changes in timber and wildlife habitat characteristics. We assess the potential of combining models which predict forest structure with those which assess habitat quality to predict changes in forest habitat characteristics. We measured variables important to simulating forest growth and evaluating wildlife habitat in even-aged stands making up an 80 year chronosequence, and developed mathematical relationships between these sets of variables. The regression relationships were generally excellent (r² or R² > 0.63), and most habitat variables were strongly related to stand age. In earlier work, we incorporated these models into FORET, a model that successfully simulates succession in hardwoods forests of the eastern USA. In the present study, we adapted FORET to accommodate the growing season and species composition of northern hardwoods forests of the Adirondack Mountains of New York, creating a new model called FORDACK. We compared stand measurements with output generated by the model. FORDACK accurately simulated changes in structural characteristics of vegetation and predicted which species would be present in very low densities, but did not successfully predict the relative densities of the dominant species. Predictions were closest to actual conditions from 20 to 50 years after regeneration. The model performed well in predicting trends in habitat variables such as canopy height and closure. Departures of simulated conditions from the actual were greatest early (less than 20 years) and late in stand development (more than 50 years). Poor performance in predicting species composition may be related to excluding management history and site characteristics from the model. The approach exemplified by FORDACK shows good potential for predicting structural characteristics of wildlife habitat.