Some mathematical programming approaches for optimizing timber age-class distributions to meet multispecies wildlife population objectives

Abstract

We investigated three approaches for finding optimum allocations of forest age-classes to meet multispecies conservation objectives for a community of terrestrial vertebrate species. We illustrate our approaches using data on relative abundances of 92 species of amphibians, reptiles, birds, and mammals sampled from five habitat types (age-classes) of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forests in northwestern California. Our three approaches involved maximizing (i) the expected number of viable species; (ii) the minimum probability of viability among all species; and (iii) the joint probability of viability across all species. Each approach was demonstrated using an assumption that viability is linearly related to abundance or that viability is logistically related to abundance. We discuss limitations of our approach focusing on assumptions of data quality, relative conservation priority among taxa, relationships between estimated abundance of a population and its probability of viability, interspecific interactions, and the need for evaluation of spatial distribution of habitats.