Decomposition of woody material: Nutrient dynamics, invertebrate/fungi relationships and management in northwest forests

Coarse woody debris (CWD) is being actively managed in many Pacific Northwe st forest ecosystems because of its ecological importance. This paper discu sses: (1) the source, amount and type of CWD present in ecosystems relative to their fire regime, (2) decomposition rates of CWD, (3) relationships am ong invertebrates, fungi and fire in the decomposition process, (4) nutrien t dynamics in CWD, and (5) management of CWD. Amounts of CWD have decreased as a result of forest management west of the Cascade crest, but increased in the drier areas east of the Cascade crest as a result of fire suppressio n, defoliator and bark beetle attacks and diseases. Logs decay slowly, but this depends on their species and size and the environmental conditions. Co arse woody debris provides a considerable amount of soil organic matter, bu t lower amounts of nutrients. However, it can be both a source and sink for nitrogen. Invertebrates and fungi are intimately related in the decomposit ion process and CWD is a source of ecosystem biodiversity. Understanding th e natural ecology of CWD in various ecosystems is important in determining how much CWD to leave and recruit. Long-term field experiments and simulati on modeling efforts are being conducted to determine the role of CWD in eco system sustainability and in maintaining long-term productivity.