Biodiversity implications of changes in the quantity of dead organic matter in managed forests

Abstract

Dead organic matter is an important structural and functional element in natural forests, but its quantity, quality, and spatial distribution are greatly modified by intensive harvesting and management through forestry. From the perspective of conflicts with biodiversity, the most important changes are associated with reductions in the abundance of snags, cavity trees, and coarse-woody debris, all of which are well known as critical habitat elements for a wide range of indigenous species. Changes in the depth and quality of the forest floor of managed stands are also important for some species and guilds of wildlife. Resolution of this conflict between forestry and biodiversity will require the design and implementation of management systems that accommodate the critical habitat qualities associated with dead organic matter, particularly with large-dimension deadwood and cavities. This goal may be most effectively achieved by an integrated strategy that involves (i) basing forest-management planning on shifting-mosaic habitat models of stand harvesting and replacement, designed to ensure a continuous availability of sufficient areas of stands old enough to sustain habitat features associated with dead organic matter, along with (ii) the provision of protected areas of mature and older growth forest, associated with riparian buffers, deer yards, and nonharvested ecological reserves and other kinds of protected areas. The protected areas are necessary to accommodate those elements of biodiversity that cannot tolerate the conditions of managed stands.Key words: biodiversity, managed forests, plantations, old-growth forests, coarse-woody debris, cavity trees, snags.