|Simonds, Greg -|
|Sant, E -|
Submitted to: Ecological Indicators
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 29, 2011
Publication Date: July 1, 2012
Citation: Booth, D.T., Cox, S.E., Simonds, G., Sant, E. 2012. Willow cover as a recovery indicator under a conservation grazing plan. Journal of Ecological Indicators. 18:512-519. Interpretive Summary: The wetland areas associated with rangeland streams are so preferred by grazing animals that lack of specific control of this animal preference results in overgrazing of willows and associated vegetation. We used intermittent, high-resolution (0.8-inch GSD; GSD is a measure of digital-photo resolution) aerial photography obtained in 2003, 2004, and 2006 to test for a change in willow cover through four summers of reduced hot-season grazing along 11 streams in northeastern Nevada. The aerial photography documented increases in willow cover (and in other indicators of riparian improvement), demonstrating the ecological benefits of reduced hot-season grazing on a degraded riparian system, and also demonstrating the utility of the aerial-photographic method for documenting watershed-wide conservation benefits from a federal cost-share-eligible conservation practice. This appears to be the first successful use of willow measurements from an aerial survey as a particular indicator of riparian condition and trend.
Technical Abstract: The Squaw Valley Ranch (SVR) of Elko County, Nevada, in cooperation with the Bureau of Land Management and Barrick Goldstrike Mines, Inc., is attempting to improve riparian conditions in the portions of the Rock Creek watershed affected by SVR operations. The watershed includes both historical and occupied habitat for the threatened Lahonton cutthroat trout (Oncorhynchus clarki henshawi (Richardson)). From 2003 and continuing through 2006, hot-season livestock grazing on SVR private and permitted public-land riparian areas was greatly reduced. To assess the result of this conservation effort, we conducted low-altitude, high-resolution aerial surveys in 2003, 2004 and 2006. Willow (Salix spp.) cover was chosen as the primary indictor of grazing effects and was used with other indicators of riparian condition. Change-over-time analysis of aerial images revealed increases in willow cover along the channel, and a 55% increase in willow canopy diameters as measured from the chance 2006 recapture of twenty 2004 scenes. Riparian-area width, and total riparian vegetation cover and width, all increased between 2004 and 2006. The increases in willow cover, width, and canopy diameter demonstrate the ecological benefits of reduced hot-season grazing on a degraded riparian system. The aerial images documented measurable changes, demonstrating the utility of the aerial method for assessing watershed-wide conservation benefits from a federal cost-share-eligible conservation practice. This appears to be the first successful use of willow measurements from an aerial survey as a particular indicator of riparian condition and trend.