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Accueil du site → Master → Etats Unis → 1977 → Interpretation of long-term vegetation data from permanent quadrats on semiarid shrublands of western Wyoming

University of Wyoming (1977)

Interpretation of long-term vegetation data from permanent quadrats on semiarid shrublands of western Wyoming

Gdara, Abdalla O

Titre : Interpretation of long-term vegetation data from permanent quadrats on semiarid shrublands of western Wyoming

Auteur : Gdara, Abdalla O

Université de soutenance : University of Wyoming

Grade : Master of Science (MS) 1977

Résumé
The long term studies of vegetation cover dynamics on grazed and protected sites in western Wyoming were initiated in 1960 with a cooperative agreement between the Bureau of Land Management and the University of Wyoming, Range Management Department. Data were obtained from 29 livestock exclosures distributed throughout western Wyoming on semiarid northern desert shrub rangelands, and at an 8-pasture research grazing study area on a Gardner’s saltbrush vegetation type. Vegetation cover data were obtained from permanently located quadrats inside and outside of exclosure areas. Within the 2’ x 20’ quadrats, crown cover of shrubs, halfshrubs, plains pricklypear, and mat form species such as Phlox hoodii , was determined by position mapping procedures : within 4’ x 4’ quadrats, herbaceous cover was determined utilizing a 10-point frame with pins spaced at 2" intervals. The point frame was positioned at 10 locations within each quadrat. First hits of all species as well as ground surface character were recorded. Data were obtained at 4-year intervals during the years 1960, 1964, 1958, 1972, and 1976. Changes of vegetation cover on the study areas were due to a combination of several factors. Grazing influence in almost all the study areas, and depending on the vegetation type difference apparently played an important part in dynamics of the vegetation cover. Shrub and forb species generally increased, but grass species decreased in average cover on the grazed areas as compared to the protected areas.

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