Sustained Timber Yield Claims, Considerations, and Tradeoffs for Selectively Logged Forests

Abstract

ABSTRACT What is meant by sustainability depends on what is sustained and at what level. Sustainable forest management, for example, requires maintenance of a variety of values not the least of which is sustained timber yields (STYs). For the 1 Bha of the world's forests subjected to selective or partial logging, failures to maintain yields can be hidden by regulatory requirements and questionable auditing practices such as increasing the number of commercial species with each harvest, reducing the minimum size at which trees can be harvested, and accepting logs of lower quality. For assertions of STY to be credible, clarity is needed about all these issues, as well as about the associated ecological and economic tradeoffs. Lack of clarity about sustainability heightens risks of unsubstantiated claims and unseen losses. STY is possible but often requires cutting cycles that are longer and logging intensities that are lower than prescribed by law, as well as effective use of low-impact logging practices and application of silvicultural treatments to promote timber stock recovery. These departures from business-as-usual practices will lower profit margins but generally benefit biodiversity and ecosystem services. Significance Statement Commitments to sustainable forest management (SFM) deserve praise but also scrutiny. Here we examine the sustained timber yield (STY) component of SFM for the 25% of Earth's forest subjected to selective logging. Legitimacy of STY claims depend on whether, over time, the number of species included in yield calculations increases, minimum cutting diameters decrease, or lower quality logs are accepted. STY is possible without such dubious accounting practices if harvest intensities and collateral damage decrease, harvest intervals increase, and treatments are applied to promote recovery. These changes will reduce profits relative to those of timber mining, but climate-change mitigation funds should be available to cover some of the costs given the carbon and other benefits of responsible forest management.