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 res ources has stimulated the development of modeling techniques to predic t changes in timber and wildlife habitat characteristics. We assess th e potential of combining models which predict forest structure with th ose 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 a n 80 year chronosequence, and developed mathematical relationships bet ween these sets of variables. The regression relationships were genera lly excellent (r(2) or R(2) > 0.63), and most habitat variables were s trongly related to stand age. In earlier work, we incorporated these m odels into FORET, a model that successfully simulates succession in ha rdwoods forests of the eastern USA. In the present study, we adapted F ORET to accommodate the growing season and species composition of nort hern hardwoods forests of the Adirondack Mountains of New York, creati ng a new model called FORDACK. We compared stand measurements with out put generated by the model. FORDACK accurately simulated changes in st ructural characteristics of vegetation and predicted which species wou ld be present in very low densities, but did not successfully predict the relative densities of the dominant species. Predictions were close st to actual conditions from 20 to 50 years after regeneration. The mo del performed well in predicting trends in habitat variables such as c anopy height and closure. Departures of simulated conditions from the actual were greatest early (less than 20 years) and late in stand deve lopment (more than 50 years). Poor performance in predicting species c omposition may be related to excluding management history and site cha racteristics from the model. The approach exemplified by FORDACK shows good potential for predicting structural characteristics of wildlife habitat.