Developing landscape connectivity in commercial boreal forests using minimum spanning tree and spatial optimization

Abstract

Currently, habitat connectivity is poorly integrated in forest-planning calculations related to decision-making in commercial boreal forests. This study developed a method that utilizes graph theory and minimum spanning tree (MST) to improve the connectivity of broadleaf-rich habitats in such forests. The location of created habitat corridors could change over time, and the method did not require adjacency between the stands that constituted the MST. Losses in net present value (NPV) due to improved connectivity were also examined. The planning area was located in southern Finland and included 1040 forest stands. Treatment schedules for the stands were created using simulation software, and heuristic optimization methods were used to find optimal treatments for the stands to meet the specified objectives. Incorporating even-flow harvest removals and NPV in an objective function provided real-world conditions in the optimization framework. The developed method clearly improved the connectivity of broadleaf-rich patches. The monetary losses of improved connectivity were moderate compared with the ecological-based connectivity benefits gained with the method. The developed MST method can be applied to any desired forest feature and modified to work in various situations related to connectivity problems.