Dr. Williams is an associate professor of geography and a research fellow at the Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80309–0450, where Mr. Losleben is a professional research associate. Dr. Hamann is a visiting scholar in the Hulbert Center for Southwest Studies, Colorado College, Colorado Springs, Colorado 80903.
ALPINE AREAS IN THE COLORADO FRONT RANGE AS MONITORS OF CLIMATE CHANGE AND ECOSYSTEM RESPONSE*
Article first published online: 21 APR 2010
2002 American Geographical Society
Volume 92, Issue 2, pages 180–191, April 2002
How to Cite
WILLIAMS, M. W., LOSLEBEN, M. V. and HAMANN, H. B. (2002), ALPINE AREAS IN THE COLORADO FRONT RANGE AS MONITORS OF CLIMATE CHANGE AND ECOSYSTEM RESPONSE. Geographical Review, 92: 180–191. doi: 10.1111/j.1931-0846.2002.tb00003.x
Tim Bardsley and Chris Seibold provided field and laboratory assistance. Funding assistance was provided by National Science Foundation grants deb 9211776 and deb 9810218 to the Niwot Ridge Long-Term Ecological Research site, by the Division of Environmental Geochemistry and Biogeochemistry of the National Science Foundation, by the Air Resources Division of the National Park Service, and by National Aeronautics and Space Administration, Earth Observing System grant nagw-2602.
- Issue published online: 21 APR 2010
- Article first published online: 21 APR 2010
- bighorn sheep;
- biogeochemistry shift;
- climate change;
- water acidification
ABSTRACT. The presence of a seasonal snowpack in alpine environments can amplify climate signals. A conceptual model is developed for the response of alpine ecosystems in temperate, midlatitude areas to changes in energy, chemicals, and water, based on a case study from Green Lakes Valley–Niwot Ridge, a headwater catchment in the Colorado Front Range. A linear regression shows the increase in annual precipitation of about 300 millimeters from 1951 to 1996 to be significant. Most of the precipitation increase has occurred since 1967. The annual deposition of inorganic nitrogen in wetfall at the Niwot Ridge National Atmospheric Deposition Program site roughly doubled between 1985–1988 and 1989–1992. Storage and release of strong acid anions, such as those from the seasonal snowpack in an ionic pulse, have resulted in episodic acidification of surface waters. These biochemical changes alter the quantity and quality of organic matter in high-elevation catchments of the Rocky Mountains. Affecting the bottom of the food chain, the increase in nitrogen deposition may be partly responsible for the current decline of bighorn sheep in the Rocky Mountains.