Snow Compaction Variation Across a Subalpine Transect William

Snow Compaction Variation Across a Subalpine Transect William Weaver EBIO 4100 April 15, 2017 CU Mountain Research Station

Introduction • Winter sports common in Colorado • Ski and snowshoe traffic compacts snow • Lots of animals live under snow • Difference between disturbed and undisturbed areas?

Introduction • Subnivean space Area above ground, beneath snowpack Provides critical habitat(Corn & Raphael, 1992) • Snowpack Insulates against large temperature changes(Yan, 2010) Determines habitability of subnivean space Martens, insects, squirrels, snowshoe hares, etc. Question: • Do winter trails increase snow compaction in the subnivean space relative to undisturbed areas?

Hypothesis • HO: Winter trails have no effect on snow compaction relative to other forest locations. • HA 1: Winter trails increase snow compaction relative to other forest locations. • HA 2: Winter trails decrease snow compaction relative to other forest locations.

Forest Site z = 53, 55 cm. Trail Site z = 37 cm. Methods Clearing Site z = 48, 55 cm.

Methods • Raw Data Net mass of snow Layer thickness Snowpack depth Crystal structure Layer hardness • • Calculations • Density • Insulative Capacity Limitations Only one transect, one trail site Lower elevation Warm day, snow melted quickly

Results • Snow Insulative Capacity Sum of layer densities times thickness (Marchand, 2013) • Most Insulative = Forest • Least Insulative = Trail • Top and bottom layers provide most insulation

Faceting Profile 4 Results Count 3 2 1 0 Clearing Top Forest Top Rounding Trail Top Clearing Bottom Rounding and Faceting Forest Bottom Trail Bottom Faceting • Top two layers vs. bottom two layers • Trail - only rounding and faceting

Hardness 4 Results Count 3 2 1 0 Clearing Top Clearing Bottom Forest Top P 1 F Forest Bottom 4 F F • Trail had most consistent hardness • Bottom forest layers, rounding Trail Top Trail Bottom

Results • Green = Forest • Red = Clearing • Blue = Trail • Forest density increased linearly with depth • Others had highest densities halfway down

Results • Tukey test (using ANOVA) • P-value = bar position • If bars cross middle line, correlation is significant • No significant difference between top layers

Results • Tukey test (using ANOVA) • P-value = bar position • If bars cross middle line, correlation is significant • No significant difference between bottom layers, but the trial and forest are nearly there (p-value = 0. 12)

Discussion • No significant difference between forest, clearing, or trail • Data show importance of temperature gradient Trail and clearing exposed to heat loss at night • Bottom forest layer had highest densities • Insulative capacity highest in forest: depth, density • Chosen trail Moderate traffic Likely no early season compaction • Future Research Earlier in the season More heavily used trail Three transects

Conclusion • No significant difference between upper or lower layer densities • Fail to reject the null hypothesis • No significant difference between lower layer densities • Likely a result of the chosen trail Lack of consistent compaction

Citations Corn, J. G. , & Raphael, M. G. (1992). Habitat characteristics at marten subnivean access sites, 56(3), 442– 448. https: //doi. org/10. 2307/3808856 Ge, Y. , & Gong, G. (2010). Land surface insulation response to snow depth variability. Journal of Geophysical Research: Atmospheres, 115(D 8), D 08107. https: //doi. org/10. 1029/2009 JD 012798 Marchand, P. J. (2013). Life in the cold an introduction to winter ecology /. Rixen, C. , Haeberli, W. , & Stoeckli, V. (2004). Ground Temperatures under Ski Pistes with Artificial and Natural Snow. Arctic, Antarctic, and Alpine Research, 36(4), 419– 427. https: //doi. org/10. 1657/1523 -0430(2004)036[0419: GTUSPW]2. 0. CO; 2