Assessing the impact of management unit design and adjacency constraints on forestwide spatial conditions and timber revenues

Spatial considerations in ecosystem management are addressed within the framework of the forest management scheduling adjacency problem. Emphasis is on both the effectiveness of adjacency regulations and the consequences of strategies for management unit design. Four strategies are presented that subdivide stands into maximum-sized harvest units. A dynamic-programming heuristic is used to plan harvest schedules that comply with adjacency constraints over temporal horizons extending up to eight 10-year periods. The impact of stand design and adjacency constraints upon the output of the forest management problem is assessed. Specifically, timber revenues and spatial conditions generated by combining adjacency constraints with alternative strategies are analyzed. Results from test computer runs are discussed for applications in nine scenarios. Results suggest that timber adjacency costs are not overly sensitive to alternative strategies for management unit design that emphasize the generation of specific spatial conditions (e.g., amount of edge and interior space). They further indicate that emphasis on timber production when designing the management units' boundaries substantially reduces adjacency costs. They show that adjacency constraints contribute to maintain spatial heterogeneity and yet may be inadequate for addressing other spatial concerns.