Inter-Temporal Aggregation for Spatially Explicit Optimal Harvest Scheduling under Area Restrictions

We propose a new approach to solve inter-temporal unit aggregation issues under maximum opening size requirements using two models. The first model is based on Model I formulation with static harvest treatments for harvest activities. This model identifies periodic harvest activities using a set of constraints for inter-temporal aggregation. The second model is based on Model II formulation, which uses dynamic harvest treatments and incorporates periodic harvest activities directly into the model formulation. The proposed approach contributes to the literature on spatially constrained harvest scheduling problems as it allows a pattern of unit aggregation to change across multiple harvests over time, as inter-temporal aggregation under a maximum opening size requirement over period-specific duration. The main idea of the proposed approach for inter-temporal aggregation is to use a multiple layer scheme for a set of spatial constraints, which is adapted from a maximum flow specification in a spatial forest unit network and a sequential triangle connection to create fully connected feasible clusters. By dividing the planning horizon into period-specific durations for different spatial aggregation patterns, the models can complete inter-temporal spatial aggregation over the planning horizon under a maximum opening size requirement per duration. Study Implications Inter-temporal unit aggregation is important because it provides flexible aggregation patterns for maximum opening size problems with multiple harvests over time. We have proposed a new modeling approach capable of solving spatially constrained harvest scheduling problems by allowing a pattern of unit aggregation to change across multiple harvest periods over time, as inter-temporal aggregation under flexible maximum opening size requirements. Forest managers can benefit from this approach for their future requirements based on the public interests as well as their own.

Logging Damage Using an Individual-Tree Selection Practice in Appalachian Hardwood Stands

Four West Virginia hardwood stands, managed using individual-tree selection for the past 30 years, were examined after the third and, in one instance, the fourth periodic harvest to determine the severity of logging damage. On existing skid roads, trees were removed with a rubber-tired skidder or a crawler tractor with a rubber-tired arch. Logging damage reduced residual stand basal area by 6%, a total of 6.1 ft² per acre. Damage was concentrated in the saplings—85% of the stems lost to logging damage were less than 5.0 in dbh. An adequate number of undamaged stems in all diameter classes remained after logging to achieve individual-tree selection stand structure goals. North. J. Appl. For. 2:117-120, Dec. 1985.