HR: 0800h
AN: H41D-0434    [Abstracts]
TI: Effects of Forest Thinning on Snow Accumulation in Lodgepole Pine Stands, Montana, U.S.A.
AU: * Woods, S
EM: swoods@forestry,umt.edu
AF: University of Montana, College of Forestry and Conservation 32 Campus Drive, Missoula, MT 59812 United States
AU: Ahl, R
EM: rob.ahl@montana.edu
AF: University of Montana, College of Forestry and Conservation 32 Campus Drive, Missoula, MT 59812 United States
AU: Sappington, J
EM: jmtsapp@yahoo.com
AF: University of Montana, College of Forestry and Conservation 32 Campus Drive, Missoula, MT 59812 United States
AU: McCaughey, W
EM: wmccaughey@fs.fed.us
AF: USDA Forest Service, Rocky Mountain Research Stn Forestry Sciences Laboratory, Missoula, MT 59812 United States
AB: Alternative silvicultural treatments such as thinning are being increasingly used to reduce wildfire hazards in forested watersheds, but the hydrologic effects of forest thinning are not well defined. We evaluated the effect of even thinning (SE) and group-retention thinning (SG) treatments, both with 60 % basal area removal, on snow accumulation in Lodgepole pine stands at the Tenderfoot Creek experimental forest, west-central Montana. The snow water equivalent (SWE) close to the seasonal peak was measured at >250 locations in the SE and SG treatments and a control in 2003, 2004 and 2005. Reduced interception in SE resulted in a significant (P < 0.0001), 20 to 35 % increase in SWE relative to the control in 2003 and 2004. In 2005, prolonged high intensity snowfall prior to sampling overwhelmed the canopy interception, so that the SWE in SE was just 9 % greater than the control, and the treatment effect was not significant. In the SG treatment, increased losses due to sublimation from south facing group edges and wind scour losses in the openings offset gains due to reduced interception. Consequently, SG always accumulated significantly less snow than SE (p < 0.0001), and the SG treatment and control means were not significantly different. Differences in snow accumulation between groups and openings meant that the SWE in SG was up to 3 times more variable than in either SE or the control. The contrasting responses in the SE and SG treatments demonstrate that thinning can have substantially different effects on snow accumulation depending on the spatial arrangement of tree removal.
DE: 1834 Human impacts
DE: 1863 Snow and ice (0736, 0738, 0776, 1827)
DE: 1876 Water budgets
DE: 1879 Watershed
SC: Hydrology [H]
MN: Fall Meeting 2005