Long-term riparian forest loss around streams, lakes, and wetlands in ecologically diverse managed and unmanaged landscapes

Abstract

Riparian forests are at risk from the cumulative effects of human and natural disturbance. We assessed the magnitude and rate of forest loss adjacent to freshwater features in the province of British Columbia, Canada, from 2000 to 2021. We used Global Forest Change data to quantify percent tree cover lost annually across six ecologically and topographically diverse ecosections containing 361,370 streams, lakes, and wetlands. We stratified the aquatic features into large and small size classes within and outside parks. We hypothesized that cumulative forest loss would be greater outside of parks as a consequence of human-caused and natural disturbance. Also, we hypothesized greater rates of forest loss around small aquatic features that generally receive less protection outside of parks. Loss of riparian forest was consistently greater outside of parks (median losses of 3.20% versus 1.29%), and adjacent to small streams (median = 3.31%) and wetlands regardless of size (median = 3.10%). Rates of cumulative riparian forest loss were nonlinear, increasing substantially in 2013. Though the annual riparian forest losses were small, the cumulative losses from 2000 to 2021 were substantial. We anticipate the continued loss of riparian forest as climate changes and natural disturbances intensify. We recommend further investigation of the implications of these observed trends for ecosystem values that are found within or adjacent to riparian forest across managed and unmanaged landscapes.