S

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

http://nice-cool-pics.com/img-winter-birch-and-aspen-forest,-alaska-4508.htm

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 = 13.728% 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. 2014. <onlinelibrary.wiley.com/doi/10.1029/97DJ01335/full>.

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. 2014. <http://books.google.com/books?hl=en&lr=&id=FtMt4DuwCncC&oi=fnd&pg=PA5&dq=Snow+accumulation+and+forest+density&ots=HGE3ibbCFO&sig=s_7ftNqHQFZp9_EeDPGJUa3rfnU#v=onepage&q=Snow %20accumulation%20and%20for>.

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. 2014. <onlinelibrary.wiley.com/doi/10.1029/1998JD200121/full>.

Pomeroy, J W., D M. Gray, N R. Hedstrom, and J R. Janowicz. "Prediction of seasonal snow accumulation in cold climate forests." Hydrological Processes 16.18 (2002). Web. 4 Mar. 2014. <onlinelibrary.wiley.com/doi/10.1002/hyp.1228/full>.

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. 2014. <http://onlinelibrary.wiley.com/store/10.1002/eco.45/asset/45_ftp.pdf?v=1&t=hs7v0twl&s=c4ae69166fb55fb2f152cfd5b885fdd522c7c1ab>.

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