Graduate Thesis Or Dissertation
 

Twenty-five years of grazing research at Meadow Creek in the Starkey Experimental Forest and Range

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  • Three studies were conducted to evaluate different grazing systems on mixed conifer rangelands in eastern Oregon, and photo points and aerial photography was used to determine effects of 25 years of cattle grazing on stream channel changes and vegetation responses. The first study was designed to determine if grazing treatment and pasture aspect had an affect on forage quality, ADG and cattle distribution. Yearling heifers were assigned randomly to two treatments: 1) free choice season-long access to both a grassland (south-slope aspect) pasture and a forest (north-slope aspect) pasture, riparian zone excluded; and 2) a predefined grazing system between grassland and forest pastures, with the riparian zone excluded. The second study was designed to determine if season long grazing produced higher gains with yearling heifers than a rest-rotation grazing system within riparian pastures. The third study was designed to evaluate the difference in animal performance between a traditional 2-pasture 1-herd deferred rotation grazing system and a predefined plant community grazing system. For study 1, in three of five years, total weight gain of managed heifers was greater (P<.10) than the weight gain of free choice heifers. As the grazing season progressed, forage CP and IVDMD decreased (P<.05). Forage quality was influenced by aspect (P<.10). Specifically, Idaho fescue (Festuca idahoensis) CP and IVDMD were greater (P<.10) for north- vs. south-facing aspects. Bluebunch wheatgrass (Pseudoroegneria spicata) CP was higher (P<.10) for north aspects, but IVDMD only tended to be greater (P.≤17) for north aspects. Distribution patterns in the first year favored (P<.10) south aspects later in the grazing season. In the second year, distribution patterns favored (P<.10) south aspects for the entire grazing season. In the second study, only one year showed differences (P<.10) in total gain, with rest rotation grazing system having the greater gains. In the third study, there was no statistical difference (P>.10) between mature cow performance in any of the weigh periods or for total gain. Total gain by the calves on the plant community grazing system was higher across all years but only different (P.≤10) in the final year. Aerial photos were taken in 1976, 1984 and 2001, and photos were geocorrected using 33 permanent blocks. In 1976 stream channel length was 1109 m, and by 2001 was 1148 m long. Channel widths are difficult to analyze due to changes in flow between 1976 and the following years. In 1984 the width was 4.79 m and by 2001 increased by 0.11 m. Islands present in 1976 and 2001 are different from each other. Photo points began in 1976 and continued every year. The photo points revealed an increase in shrub cover and abundance regardless of presence or absence of cattle. All photos indicate that since 1976 the riparian is recovering and that grazing is having no negative effects on the riparian area.
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