The Effects of Wind Exposure and Disturbance on the Insulative Value of the Subnivean Space

1. The Effects of Wind Exposure and Disturbance on the Insulative Value of the Subnivean Space Genesis Machek Winter Ecology, Spring 2010 Mountain Research Station - University of Colorado at Boulder

2. Background Information The subnivean environment – the space under the snow Affects of small boulders and other obstructions under the snow – creating a larger subnivean space (Sanecki et al., 2006) Wind exposure Less interaction with environment above the snow (Taylor and Buskirk, 1996) Implications for ability to get food Disturbance with snow-related recreation Causes compaction, increases density, decreases height of subnivean space (Sanecki et al., 2006; Whiteman, 2008) “Small mammal detections were…positively correlated with the complexity of structures and microtopography” (Sanecki et al., 2006). This means that the number of mammals in the subnivean space increases with a greater amount of ‘microtopography’ or small boulders and plants under the snow. Although this wasn’t measured, it gives some indication of the location of mammals living in the subnivean environment.“Small mammal detections were…positively correlated with the complexity of structures and microtopography” (Sanecki et al., 2006). This means that the number of mammals in the subnivean space increases with a greater amount of ‘microtopography’ or small boulders and plants under the snow. Although this wasn’t measured, it gives some indication of the location of mammals living in the subnivean environment.

3. Introduction Question: How does wind exposure affect the insulative value of the snowpack and perhaps the viability of animals living in the subnivean environment? Question: How does disturbance effect how insulative the snow pack is in exposed and not exposed environments? Hypotheses: The snow pack will be more insulative in less exposed environments; however, disturbance of the snowpack will have a greater, negative effect on the insulative ability of the snow pack in less exposed environments. The viability of the animals living in the subnivean space is not directly tested, but discussed (based on the results) in the Discussion.The viability of the animals living in the subnivean space is not directly tested, but discussed (based on the results) in the Discussion.

4. Methods and Materials 4 sites were chosen 2 sites sheltered from wind exposure 1 at 55 cm, 1 at 65 cm 2 sites with wind exposure 1 at 55 cm, 1 at 65 cm 65 cm sites were visited twice over one week to see the effects of recent disturbance of the snowpack Density and Temperature were taken at each site Exposed environments were about 10 yards from surrounding trees and were in the sun constantly. Sheltered environments were directly under the trees and were protected from both wind and sun. I returned to the 65 cm sites to test the density and temperature gradient again to see if there was a notable difference; a difference would be expected since I had disturbed the snowpack a week previously, probably causing some change in compaction and exposure in both sites. However, there was recent snowfall at the site as well and this probably effected my data.Exposed environments were about 10 yards from surrounding trees and were in the sun constantly. Sheltered environments were directly under the trees and were protected from both wind and sun. I returned to the 65 cm sites to test the density and temperature gradient again to see if there was a notable difference; a difference would be expected since I had disturbed the snowpack a week previously, probably causing some change in compaction and exposure in both sites. However, there was recent snowfall at the site as well and this probably effected my data.

5. Methods and Materials The temperature gradient was measured – qualitatively assessing the significance of the calculated insulative value Insulative Value was measured Marchand’s equation to test the insulative value: Where d = density (g/cm3), t= thickness (cm), i = layer, and TI = insulative value