EXPANDING THE SCALE OF FOREST MANAGEMENT - ALLOCATING TIMBER HARVESTSIN TIME AND SPACE

This study examined the effect of clustering timber harvest zones and of changing the land use categories of zones (dynamic zoning) over var ying temporal and spatial scales. Focusing on the Hoosier National For est (HNF) in Indiana, USA as a study area, I used a timber harvest all ocation model to simulate four management alternatives. In the static zoning alternative, harvests were dispersed throughout the timber harv est land base (65% of HNF) for 15 decades. The three dynamic zoning al ternatives varied in the degree to which harvests were clustered in ti me and space. Two levels of harvest intensity were simulated, and at e ach level of harvest intensity, the area harvested was held constant a mong all four zoning alternatives. The dynamic zoning strategies resul ted in substantial increases in the amount of forest interior and redu ctions in the amount of forest edge across the landscape, as well as a n increase in the average age of stands when harvested. The greatest r eduction in fragmentation was produced by the alternative that most ti ghtly clustered harvests in time and space (i.e. intensive harvesting of small blocks in a relatively short time). When harvest intensity wa s high, this alternative produced amounts of forest interior and edge comparable to those of the dispersed alternative with half the rate of harvest. The results suggest that the injection of dynamics in specif ying disturbance regimes, and the clustering of disturbance in time an d space, can be used to sustain larger blocks of mature forest than ca n static zoning. Dynamic zoning encourages explicit specification of t he disturbance regimes that will be imposed across the land base over long periods of time.