Could climate change be to blame for declines in Dall sheep numbers?
Scientists funded by NASA's Arctic-Boreal Vulnerability Experiment (ABoVE) are studying the effects of global climate change on alpine vegetation and snowpack in an effort to understand how these changes impact iconic wildlife including Dall sheep. As a large ungulate requiring year-round access to forage, Dall sheep may be especially sensitive to changes in habitat and snow conditions, thus functioning as a bellwether for the unique alpine communities they inhabit. Recent declines in Dall sheep populations throughout their range have led to emergency harvest closures and made sheep harvest by far the most contentious wildlife management issue in Alaska.
The ABoVE Dall sheep project has four main objectives:
- Quantify changes in vegetation and snow extent in alpine ecosystems throughout the ABoVE domain from 1980-2018
- Assess the impact of changing snow and vegetation characteristics on Dall sheep habitat selection and population viability throughout their distribution
- Characterize snowpack properties at a spatial scale relevant to wildlife management
- Relate our improved understanding of alpine ecosystem dynamics to the societal implications of altered sheep harvest
The team conducted extensive fieldwork in March 2017 in Alaska’s Wrangell St-Elias National Park. They dug snow pits to examine layers in the snowpack and collected data such as snow depth, hardness, density, and grain size. Data from these snow pits were used, along with data from snow depth transects and snow depth stations, to calibrate and validate a physical snowpack evolution model. Additional surveys in March 2018 will provide information on how snow conditions are changing and affecting Dall sheep in northern alpine regions.
Data Products:
Mahoney, P., G. Liston, B. Mangipane, and L.R. Prugh. 2018. ABoVE: Responses of Dall Sheep to Snowpack Properties, AK, 2005-2008. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1602
Sivy, K.J., A.W. Nolin, C.L. Cosgrove, and L.R. Prugh. 2018. ABoVE: Dall Sheep Track Sinking Depths, Snow Depth, Hardness, and Density, 2017. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1583
Verbyla, D. 2017. ABoVE: Last Day of Spring Snow, Alaska, USA, and Yukon Territory, Canada, 2000-2016. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1528
Read more on NASA's Earth Observatory Blog: https://earthobservatory.nasa.gov/blogs/fromthefield/2018/03/30/wrangel…
ABoVE Dall Sheep Project site: https://dallsheep.weebly.com/
