Forest disturbance effects on snow and water yield in interior British Columbia

Long-term studies at Mayson Lake (ML) and Upper Penticton Creek (UPC) in British Columbia's southern interior quantify snow-dominated hydrologic response to natural disturbances and logging. Following natural disturbance at ML, changes in snow accumulation related directly to mountain pine beetle attack were measurable by the fifth year following attack, when canopy transmittance had increased 24% due to needlefall. In year 1, April 1 snow water equivalent (SWE) was 48% higher in the clearcut than in the pine forest. This difference was reduced to 23% by year 8. A 3-year lag in snow response was also observed in a nearby burned stand where SWE was on average 27 and 59% higher in the clearcut than in the burn and forest, respectively. At UPC, April 1 SWE averaged 12% more and 12% less in a low and high elevation clearcut than forest, respectively, and snow disappeared similar to 10 days earlier in both clearcuts. Partially as a result of snowmelt synchronization from higher with lower elevations after 50% of the treatment watersheds had been clearcut, April water yield increased and June to July yield decreased. Research results improve evaluation of hydrologic response to forest disturbance, including retention of beetle-killed stands versus salvage logging.