Simulating forest and habitat change in south‐east Alaska with the landscape model PAYSAGE

Abstract

We used the landscape model PAYSAGE to demonstrate the use of GIS and simulation models for ecosystem management over a portion of Mitkof Island in the Tongass National Forest. The objectives of the study were to: 1) depict the natural heterogeneity in environment and resource distributions across the study area; 2) quantify changes in vegetation and vertebrate habitats (brown creeper, orange‐crowned warbler, marten) during the period of commercial timber harvest (1954 to the present); and 3) simulate likely long‐term changes in vegetation and vertebrate habitat under three management scenarios – the Tongass Forest Plan, the wildlife habitat conservation strategy, and the Pacific Fisheries Task Force strategy. The results indicated that productive forest lands and vertebrate habitats are naturally patchy in the study area due to topography and climate. This natural fragmentation was exacerbated by past logging, which targeted high‐productivity old growth stands. This stand type was reduced in area by 76 per cent from 1954 to 1994. Patch density and mean patch size decreased during this time while mean nearest neighbour distance increased. Simulations of the three management scenarios for a 200‐year period projected relatively minor differences in landscape patterns among the scenarios. This is because the forest plan scenario is relatively restrictive in timber harvest and because most of the area protected in the other two scenarios does nor currently support old growth. We discuss the role of decision‐support tools such as PAYSAGE in adaptive ecosystem management and evaluate limitations of the model.