Freshwater ecosystems make numerous contributions to people’s wellbeing and are home to a wide diversity of species. However, the integrity of freshwaters, as well as the services and biodiversity they support are threatened by a growing suite of anthropogenic stressors. Timber harvesting is among these stressors, as it is known to result in shifts in water quality and aquatic biodiversity. However, there is a great deal of variation in the approaches used to assess the effects of timber harvesting on water quality and biodiversity, as well as findings concerning effects, and no recent publications synthesizing research in this field. In this presentation, we address that gap by showcasing results from our review that compiles information from existing literature assessing the effects of timber harvesting in boreal and temperate forests on water quality and biodiversity in running waters. We identify relevant publications using Scopus, Web of Science and Google Scholar, and turn to these to better understand methodological, spatial, and temporal aspects of existing research in this field. Building from findings, we identify relevant research gaps, and point toward key future research directions that can help improve understanding of the effects of timber harvesting on freshwaters and inform related policy.
We identified 9394 potentially relevant publications, 494 of which contained qualitative or quantitative information regarding the effects of timber harvesting in boreal and temperate forests on water quality or biodiversity. Almost half (47%) of retrieved studies were based out of the United-States, with none in Russia and China. The majority of studies (72%) collected information about water quality, whereas less than half (35%) focused on biodiversity, and only 13% looked at both. Most studies (53%) assessed impacts of clearcutting, but a range of types of timber harvesting practices were considered (e.g. thinning, restoration logging). Studies collected information from anywhere between 1 and 191 sites (mean = 13, sd = 27), and generally used “control impact” (34%) and “before-after control-impact” (33%) designs. The time between harvest events and water quality or biodiversity data collection ranged between 0 and 87 years, but the majority of studies (53%) collected information no more than 10 years after harvest events. Together, our findings highlight several key future research directions for this field, including: 1) the assessment of understudied regions of the boreal and temperate forests (e.g. Northern Canada, Russia and China), and 2) robust evaluations of the long-term effects of harvesting on freshwaters.
****Note that results are based on a subset of 144 of the 494 articles that will be assessed in this review given the current state of project data collection. Complete and updated results will be presented in August 2022.