Genesis Machek Winter Ecology, Spring 2010 Mountain Research Station - University of Colorado at Boulder

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)

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.

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

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/cm 3 ), t= thickness (cm), i = layer, and TI = insulative value

Insulative Value Data  The insulative value of the exposed sites were consistently higher than the sheltered sites

Density Profiles  The densities near the ground are all similar  The sheltered areas have higher densities, while the exposed areas have lower densities

Insulative Value Data  General increase in insulative value  Greater increase in insulative value at the sheltered site vs. the exposed site

Density Profiles  There is a large difference between the Sheltered site for week one and two  The exposed site is very similar between weeks one and two

Discussion  The snowpack seems to have a greater insulative value in exposed areas, this would suggest that animals would be in a more stable environment in exposed environments. Objections? Increase in convection due to wind exposure (Taylor and Buskirk, 1996) Temperature gradient values disagree with these findings  The density profiles show that the density is lower at the sites where the insulative value is higher Why? Exposure?

Discussion  Temperature Gradient values suggest that the sheltered sites were more insulative Might suggest that more animals would prefer more protected sites to create their tunnels (Sanecki et al., 2006)  This might also be a suggestion of the benefits of staying in protected areas to hide from predators or to be closer to trees and thus a food source.

Discussion  Reversal in the trend from week 1 to week 2, which suggests that disturbance could have a greater effect on sheltered environments less fresh snowfall in the sheltered area, causing this area to be more exposed to wind and temperature differences  More research might be done on the effects of disturbance due to snow-related recreation in different environments to see if sheltered areas are more sensitive than wind exposed areas

 The insulative value of the snowpack – sheltered vs. exposed and disturbed vs. un-disturbed  Insulative value: o higher in exposed areas before disturbance, higher in the sheltered area after disturbance o Effects of density Temperature Gradient Snow  Disturbance o effects of wind exposure o Recent snowfall in site with wind exposure higher density, more insulative snow  Future Research o Effects of snow-related recreation on sheltered vs. exposed sites Questions?? Main Points - Outline

References  Auerbach, N., & Halfpenny, J. (1991). Snowpack and the subnivean environment for different aspects of an open meadow in jackson hole, wyoming, USA. Arctic and Alpine Research, 23(1),  Marchand, PJ. (1982). An index for evaluating the temperature stability of a subnivean environment. The Journal of Wildlife Management, 46(2):  Sanecki, GM; Cowling, A; Green, K; Wood, H & Lindenmayer D. (2006). Winter distribution in relation to snow cover in the subalpine zone, Australia. Journal of Zoology 289,  Sanecki, GM; Green, K; Wood, H & Lindenmayer, D. (2006). The implications of snow-based recreation for small mammals in the subnivean space in south-east Australia. Biological Conservation 129,  Taylor, SL & Buskirk, SW. (1996). Dynamics of subnivean temperature and wind speed in subalpine forests of the rocky mountains. Journal of Thermodynamic Biology 21(2),  Whiteman, J. P. (2008). Impacts of snow compaction from human recreation on the biota of snowy regions

Week 1 Data  The trendlines show that the temperature gradients are very similar to each other.  In the exposed environment the ground is colder than the snow above (ground was frozen)  The sheltered environment was more insulative based on this data Exposed TI Temp Diff3.5 Sheltered TI Temp Diff4

Week 1 Data  The sheltered environment is still the better insulator based on this data as well Exposed TI Temp Diff4.5 Sheltered TI Temp Diff5.5

Week 2 Data  The exposed environment had a more consistent temperature gradient  At the sheltered site the temperature gradient was not consistent and the ground was frozen  According to this data, after disturbance, the exposed site was a better insulator than the sheltered site Exposed TI Temp Diff3.5 Sheltered TI Temp Diff3