Patrick Ewing, M.S.
From the Tree to the Forest: the Influence of a Sparse Canopy on Stand Scale Snow Water Equivalent
M.S. (Watershed Science) 2007 Colorado State University, Fort Collins, CO, USA 80523-1472
B.S. (Natural Resources Management) 2004 Colorado State University, Fort Collins, CO 80523-1472
Ewing, P.J., 2007. From the Tree to the Forest: the Influence of a Sparse Canopy on Stand Scale Snow Water Equivalent.
Unpublished M.S. project, Watershed Science, Colorado State University, Fort Collins, Colorado, USA, 35pp.
The canopy of an individual tree has a negative effect on the accumulation of snow
around tree boles, resulting in a decrease in snow depth inward from the edge of the
canopy to the tree trunk. This influence of trees on snow distribution affects the total
volume of water stored in the snowpack, especially for a sparse forest stand. However,
snow measurements, in particular depth, are typically made between trees, and this
neglects the decreased accumulation around trees. As well, little is known about changes
in snowpack density under the canopy compared to between trees. Sparse individual
trees have their own microclimate (energy balance, wind profiles, etc.) that could
produce directional variations in snowpack properties. To establish how the decreased
snow depth and possibly change in snowpack density under the canopy can affect
estimates of stand scale SWE, depth and density measurements were taken in the four
cardinal directions around three Picea engelmanii and two Abies lasiocarpa during the
winters of 2005 and 2007 near Cameron Pass, northern Colorado. These near tree
measurements were assessed against existing snow depth models and superimposed on a
50-m transect of depth measurements taken at 0.5-m intervals. Three scenarios of a
sparse forest were considered: one tree with a 1-m canopy radius, one tree with a 2-m
canopy radius, and three trees each with a 2-m canopy radius. Directionality was
observed in the snow depth increasing away from each tree. An increasing trend in
snowpack density was observed outward from each tree. The estimated average snow
water equivalent for the transect decreased by 14.4% with the addition of three trees with
2-m canopy radii.
Last update: SRF, 2016-06-15
Advisor: Steven Fassnacht
William Sanford (Geosciences)
Greg Butters (Soil and Crop Sciences)