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

Tuesday, January 29, 2008
29

Dynamics of Perennial Shrub Density 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 trends in shrub density important for the assessment of range livestock resources. Density of perennial shrub species was determined 5 distinct range sites representative of over 90% of the rangeland resources currently utilized in this country. Density was determined by counting number of specimens by species in quadrats ranging in size from 100 to 250 square meters, according to sampling location. The larger size quadrats were used in the more sparsely vegetated arid sampling sites. For each year, season and site, 5 randomly placed quadrats were counted. Specimens were sorted into 5 different categories: 1-3: small to big; 4, recruitment, and 5, dead. All counts were performed by the same observers; values were averaged over observers within quadrat (replicate). Data were collected in spring, summer and fall from 2002 to 2005. The response variable analyzed was relative density (number of specimens per square meter). The experimental unit was the individual quadrat. Data were analyzed by categorical data analysis and linear mixed model analysis of variance. Precipitation was entered and retained as a covariate in the model, although not significant. Year did not significantly affect density of perennial shrubs. Location tended to be significant (p=0.058), whereas species and the species by location interaction effects were highly significant. A characteristic pattern of density by plant category emerged which appears to be related to degree of utilization. Changes in density by category over time were identified. The pattern of species richness is discussed in the context of an ordination analysis based on cover conducted on the same sites.

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