Temporal Connectivity of Mature Forest Patches In Spatially-Explicit Harvest Scheduling Models

We present a forest harvest scheduling model that can ensure the temporal con1 nectivity of mature forest habitat over time in a landscape managed for timber production. 2 Past models addressed the spatial aspects of habitat connectivity by requiring that a certain 3 amount of mature forest habitat is retained throughout a planning horizon in contiguous 4 patches of minimum size and age. These models failed to recognize, however, that the dy5 namic patches of a managed forest ecosystem might not provide escape routes for certain 6 wildlife unless there is temporal overlap among the patches. According to biologists, the 7 lifespan of the patches is often more important than their size and contiguity for species sur8 vival. We propose a mixed integer programming formulation that guarantees escape routes 9 among patches of mature forest habitat that arise and diappear over time as the forest ages 10 and gets harvested. Using four real forests as examples, we illustrate the mechanics of the 11 approach and show that the new model is not only tractable computationally, but it can also 12 make harvest scheduling models with minimum patch size constraints easier to solve. 13