The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council.

Tuesday, January 29, 2008
25

Shrub and Herbaceous Cover Dynamics in the Arid Zone of Uzbekistan

Wolfgang Pittroff, Livestock Systems Research, Wingertstr. 3, Idar-Oberstein, Germany, José Ramón Arévalo, Departamento de Ecología, Universidad de La Laguna, La Laguna, Spain, Bakhtiyor Mardonov, Uzbek Academy of Sciences, Samarkand, Uzbekistan, and Gustave Gintzburger, INRA, Montpellier, France.

Rangeland-based livestock production is the major agricultural use in most of Uzbekistan. After independence, range management practices changed radically and the objective of this study was to analyze temporal trends in cover on representative sites to provide an assessment of changes in range condition. Cover of shrub and herbaceous species were analyzed for rangeland inventory data collected on 5 range sites representative for over 90% of the rangeland resources used for livestock production in Uzbekistan. Data were collected in spring, summer and fall from 2001 to 2006. Perennial cover was estimated as aerial intercept along linear replicated transects varying in length from 50 to 200 m. Cover was expressed as proportion aerial intercept of total transect length. Month, year, location, species, species by location interaction and the covariate precipitation were all highly significant factors determining perennial shrub cover. Trend analysis separating annual and precipitation trends was conducted using regression analysis. Results appear to confirm earlier reports of increasing utilization pressure on Uzbek rangeland resources within reach of current management systems that significantly decreased use of range sites more distant to settlements. Cover of herbaceous species was determined using a 1 square meter quadrat divided into 400 grid elements of 5 by 5 cm. Each sampling location was sampled in spring from 2002 to 2005. Quadrats were located at random, repeated 5 times, on each sampling occasion. Data were analyzed as number of grid elements per frame in 6 evenly spaced categories ranging from 0% to 100% cover (within grid element). The data analysis is preliminary as important theoretical statistical considerations are awaiting further elucidation. The effects of year, location, cover category and all interactions were highly significant. Results seem to confirm similar data obtained for perennial shrub cover.

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