 Vegetation Density and Snow Accumulation Evan Esfahani Winter Ecology 2014 Mountain Research Station

Introduction  The relationship between vegetation density and canopy cover influences snowpack and how it accumulates/depreciates.  Accumulation of snow under forest canopies will decline with increased canopy cover because of sublimation and interception in canopy (Pomeroy, 2002).  Will forest density alone determine snow depth?  In Colorado and Wyoming, the lowest density forest plots accumulated the greatest amount of snow (Gary, 1982).  Areas with high forest density and increased canopy cover will display larger snow depths than those areas where solar radiation is increased and forest density in decreased (Veatch, 2009).

Introduction  Question: How will the vegetation density of three specific species impact snow depth and how will density relate to affect of solar radiation?  Hypothesis 1: Change in vegetation density will change snow depth.  Null Hypothesis: Differences between vegetation density and snow depth will not be observed.

Methods  Nine experimental 10x10m plots varying by species (3x Lodgepole pine, 3x Aspen, 3x Willow) selected randomly.  Elevation (m) and aspect remained constant.  Determine density by number of trees/vegetation in each plot.  Average snow depth (cm)  Canopy cover determined by canopy mirror calculation.  Estimation of solar radiation based on canopy mirror value.  ANOVA to determine differences in snow depth per species.  How does canopy cover, solar radiation effect the difference?

Willow

Lodgepole

Aspen

Results  Sample size: 121 Aspen, 102 Lodgepole pines, 131 Willow.  Lodgepole-Aspen p value = 0.11  Willow-Aspen p value = 0.77  Willow-Lodgepole p value = 0.28

Results  Measurement of canopy cover to determine solar input.  Lodgepole = 76.78% cover  Willow = 0.52% cover  Aspen = % cover

Discussion  No difference between snow depth and forest density. Retain null hypothesis.  Why?  Solar radiation. More important than forest density in snow accumulation (Link, 2012).  Average snow depth in Willow and Aspen forest was similar. Observed: little to no canopy cover.  Solar fluxes dominate the net transfer of energy (Davis, 2012).  Indirect role: Canopy cover is influenced by forest density, species specific.  Maximum Snow accumulation in forests with density between 25-40% (Veatch, 2009).

Work Cited Davis, R E., J P. Hardy, C Woodcock, J C. McKenzie, and Jordan X. Li. "Variation of snow cover ablation in boreal forest: A sensitivity study on the effects of conifer canopy." Geophysical Research: Atmospheres 102.D24 (2012). Web. 4 Mar Gary, Howard L., and Charles A. Troendle. "Snow Accumulation and Melt Under Various Stand Densities in Lodgepole Pine in Wyoming and Colorado." USDA Forest Service: Rocky Mountain Forest and Range Experiment Station(1982). Web. 4 Mar Link, Timothy E., and Danny Marks. "Point Simulation of seasonal snow cover dynamics beneath boreal forest canopies." Geophysical Research: Atmospheres 104.D22 (2012). Web. 4 Mar Pomeroy, J W., D M. Gray, N R. Hedstrom, and J R. Janowicz. "Prediction of seasonal snow accumulation in cold climate forests." Hydrological Processes (2002). Web. 4 Mar Veatch, W, P D. Brooks, J R. Gustafson, and N P. Molotch. "‘Quantifying the effects of forest canopy cover on net snow accumulation at a continental, mid-latitude site’." Ecohydrology 2.2 (2009). Web. 28 Feb

Acknowledgements  Dr. Tim Kittel  Derek Sweeney  Kelly Matheson  Scott Clingen (forced his way onto this page)  Collin Pettinati  University of Colorado Mountain Research Station  University of Colorado Boulder Department of Ecology and Evolutionary Biology