Canopy Dynamics and Tree Well Size Does the canopy height and size of coniferous trees affect the size of the tree well at the snow surface? J. Kalin Puent Winter Ecology, Spring 2012 Mountain Research Station, University of Colorado, Boulder

Question in Ecological Context Numerical quantification of these processes awaits a field study not yet implemented Radiation influences are strongly affected by canopy existance Seasonal ground snow-cover evolution is strongly affected by the existence of a forest canopy Canopy interception and radiation greatly influences snow accumulation. A reduced amount of snow precipitation reaches the ground, which results in a lower maximum SWE. (LaMalfa,2008)

Question in Ecological Context Soil moisture is a fundamental property of mountain forests Patterns of soil moisture are linked to climate, soil properties, plant water use, stream flow, forest health, and other ecosystem features. Soil moisture and water flux through forest soils are linked to rain and snowmelt patterns, soil drainage properties, and withdrawal of water from the soil by plants and evaporation (Strasser,2011)

Question in Ecological Context The canopy’s ability to affect the radiation flux and snow cover flux in a particular region highlights its importance ecologically Snow cover flux yields SWE flux SWE is very important for ecological processes (subnivean and supernivean)

Methods Objective: to determine how the varying canopy sizes of lodge pole pine and subalpine fir affect the associated tree wells surrounding each tree Outline which variables with regards to my subject trees needed to be constant: slope angle and aspect, the plot from which the samples were taken. All plots were randomly chosen on different slopes. Match the tree by species and size in pairs.

Field Methods Measurements of slope angle and aspect, tree height and species, basal snow depth, canopy height, canopy length, and tree well depth and radius of the five pairs. Using these measurements, I calculated the volume of the tree well, tree height, and tree basal area for each subject tree.

Sub Alpine Fir with no canopy height

Results No correlation between primary factors (initial measurements) New parameter called “canopy area”- positive trend in both species of tree (the greater the area, the greater the well volume) New parameter called “canopy coverage”- positive correlation (the greater the coverage, the greater the well volume) The results of the Canopy Area and Canopy Coverage versus the Tree Well Volume show that there is a positive correlation between canopy size and tree well size For both relationships the lodge pole pine had a more radical correlation. Opposite of my assumption.

Data

Canopy Area vs. Tree Well Volume

Canopy Coverage vs. Tree Well Volume

Conclusion Main flaws:lack of data Only shows a preliminary correlation In order to conclude thesis, much more extensive research should be conducted. Several outliers in the data (may account for low R^2 values) Outliers were grossly out of place, were not within bounds of the series May be a result of site to site variations in snowpack, wind, and human error in the measurements, as well as many unfound sources of error. Calculations: most geometric shapes were calculated to be exact Due to these sources of error, this data and analysis may be successfully used as preliminary work for another, far more extensive field project. Further research can include the same primary question, but may specialize in a single species, or include more species.

References LaMalfa, Eric M., and Ron Ryle. "Differential Snowpack Accumulation and Water Dynamics in Aspen and Conifer Communities: Implications for Water Yield and Ecosystem Function." Ecosystems (2008): SpringerLink. Database. 3 Feb Strasser, Ulrich, Michael Warscher, and Glen Liston. "Modeling Snow–Canopy Processes on an Idealized Mountain." American Meteorological Society. (2011): Web. 20 Feb