Succession and livestock grazing in a northeastern Oregon riparian ecosystem
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Authors: D. M. Green, and J. B. Kauffman
Date: 1995
Journal: Journal of Range Management
Volume: 48
Number: 4
Pages: 307-313
Summary of Methods: Changes in vegetative species composition along Catherine creek in Northeastern Oregon were measured over a 10 year period examining grazed and ungrazed plots on eight plant communities (moist meadow, dry meadow, cheatgrass, ponderosa pine, black cottonwood, thinleaf alder, Douglas hawthorn, and gravel bar). Grazing began in late August for three to four weeks at a stocking density of 1.3 to 1.8 ha/AUM. Frequency was measured in late June to early July, and species diversity and evenness were calculated with Shannon's index and Pielou's J. Shrub height, density and composition were measured on gravel bar communities.
Article Summary / Main Points: Grazed sites, with a few exceptions, had higher species richness and evenness than ungrazed sites. Exotic species composition was reduce on sites where grazing was excluded. Dry Meadow communities were most highly utilized of all the community types ranging from 48-70% utilization, and experienced few compositional changes. Moist meadow communities had comparable utilization rates to dry meadows. Species eveness was higher on sites with no grazing, and frequency of Phleum pretense, and Ranunculus acris, both exotic species, decreased on these sites and stayed steady in grazed treatments. Utilization on the cheatgrass communities never exceeded 2%; there was little change in composition and they had the highest amount of exotic species. Ponderosa pine communities had utilization levels ranging from 10 to 27%; Elymus glaucus and Montia perfoliata increased and the exotic P. pratensis decreased on the non-grazed site. Utilization rates on the black cottonwood community and the thinleaf alder community were low and species richness was not different . Douglas hawthorn communities had variable utilization; as percent of hawthorn cover increased utilization decreased and exotic species declined in both treatments. Gravel bar communities experienced decreased shrub height and density in grazed treatments.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 43B Central Rocky Mountains 9 Palouse and Nez Perce Prairies
Agrovoc Control Words: Vegetation Rangelands Grazing
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: riparian, grazing, community succession, species diversity, disturbance
Annotation: Study does a good job of looking at specific community types over a moderately long study (10 yrs) in both grazed and ungrazed scenarios. This study provides range managers in the intermountain west good insight into effects of grazing and exclusion in late fall along a riparian system gradient.
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