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Citation for publication number
506:
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Cole, David N., van Wagtendonk, Jan W., McClaran, Mitchel P., Moore, Peggy E., McDougald, Neil K. 2004. Response of mountain meadows to grazing by recreation pack stock. Journal of Range Management 57(2): 153-160.
Leopold
Publication Number 506
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Abstract:
Effects of recreational pack stock grazing mountain meadows in Yosemite National Park were assessed in a five-year study. Yosemite is a designated Wilderness, to be managed such that its natural conditions are preserved. Studies were conducted in single examples of three characteristic meadow types: shorthair sedge (Carex filifolia Nutt.), Brewer’s reed grass (Calamagrostis breweri Thurber), and tufted hairgrass [Deschampsia cespitosa (L.) Beauv.]. In each meadow, horses and mules grazed experimental plots, at various intensities, for four seasons. In all three meadows, grazing at typical intensities caused substantial changes in meadow characteristics--decreases in productivity, shifts in basal groundcover (usually a reduction in vegetation cover and increase in bare soil cover), and changes in species composition. In all three meadows, productivity decreased significantly as percent utilization increased. Relationships between grazing intensity and ground cover were less consistent, although in at least one meadow, vegetation cover decreased significantly and bare soil cover increased significantly as utilization increased. Changes in species composition were less predictably related to differences in grazing intensity. Passive management of grazing is insufficient in wilderness areas that are regularly used by groups with recreational stock. Wilderness managers need to monitor meadow conditions and the grazing intensities that occur. Our study suggests that biomass and ground cover are more sensitive indicators of grazing impact than species composition. Managers must make decisions about maximum acceptable levels of grazing impact and then develop guidelines for maximum use levels, based on data such as ours that relates grazing intensity to meadow response.
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