Forum Article: Why a Network of Old-Growth and Mature Forests Across the Douglas-Fir Region is Good for the Timber Industry

The Douglas-fir region of the Pacific Northwest is one of the most productive forestry regions in the world, combining sustainable timber production with native species management, particularly Douglas-fir. This landscape also supports a network of old-growth and mature forests that sustain the biodiversity of these regional forests, including beneficial biota such as fungi and other microbes, insects and other invertebrates, vertebrates, and lichens and other plants. I believe it is in the interests of the timber industry to protect these remaining old-growth and older mature forests because they contain a reservoir of beneficial biota that aids in protection and health of managed plantations. Beneficial invertebrates include parasitoid wasps, predaceous insects and spiders, pollinators, and decomposers, while beneficial microbes include mycorrhizal fungi, decomposers, and biocontrol agents. Beneficial vertebrates, especially the insect gleaning birds and bats are also important, as well as many plants and lichens. These organisms enhance forest resilience by protecting younger trees from pests and pathogens and contributing to nutrient cycling and soil health. Although forest plantations necessarily simplify forest structure and composition, potentially excluding this biodiversity, older forests help maintain this critical beneficial biota. Contrary to a common belief that old-growth forests are a source of pests and pathogens, their above- and below-ground complexity often provides habitat for organisms that moderates the influence of pests and pathogens. Therefore, on balance, I believe that protecting old-growth and mature forests across the region is essential for maintaining forest health and supporting the long-term productivity of Douglas-fir plantations.