Increasing spruce budworm defoliation increases catchment discharge in conifer forests

Abstract

Forest insect outbreaks cause significant reductions in the forest canopy through defoliation and tree mortality that modify the storage and flow of water, altering catchment runoff and stream discharge patterns. Despite a growing understanding of the impacts of insect outbreaks on the hydrology of broadleaf forests, little is known about these impacts to catchment hydrology in northern conifer-dominated forests. We measured the effects of cumulative defoliation by spruce budworm (Choristoneura fumiferana) on stream discharge and runoff in 12 experimental catchments (6.33–9.85 km2) across the central Gaspé Peninsula in eastern Québec, Canada over a three-year period (2019–2021). Six catchments were aerially treated with BtK (Bacillus thuringiensis kurstaki) insecticide to suppress the outbreak and six catchments were left untreated, leading to a defoliation gradient across the study sites. Stage-discharge …

Publication
Science of The Total Environment
Erik J.S. Emilson
Erik J.S. Emilson
Research Scientist, Watershed Ecology Team Lead, Associate Editor CJFR

I am interested in how forests support freshwater ecosystem services. My research combines microbial and molecular approaches to undertand how forest productivity and disturbances affect ecosystem functions in headwater streams and lakes.

Lisa Venier
Lisa Venier
Research Scientist

I research biota (large and small) as indicators of sustaniable forest management

Brian Kielstra
Brian Kielstra
Cumulative Effects Research Scientist

I am a landscape/aquatic ecologist generally interested in the cumulative effects of landscape pattern and process on recipient waters