Ecosystem impacts of disturbance in a dry tropical forest in southern India

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Abstract

Indian forests provide a multitude of services to vast populations. Common human activities including livestock grazing, fuelwood extraction and burning have the potential to impact forest ecosystem structure and function. The effects of these activities on vegetation, ecology and soil properties were investigated in Bandipur National Park (BNP) in southern India. Data were collected from 200 sites in four watersheds within the park. Sample sites spanned a degradation gradient measured by a field disturbance index (FDI). This paper focusses on the impacts on vegetation structure, diversity and composition, and integrates impacts on soil. Shrub and tree species were inventoried and evaluated in plots 10-m in diameter. The tree layer was dominated by Anogeissus–Emblica–Tectona species. The understory was dominated by invasives Chromolaena odorata and Lantana camara, and native Gymnosporia emarginata. Vegetation plot heights, canopy cover and tree diameters were negatively correlated with field disturbance resulting in stunted forest stature in degraded sites. Vegetation composition in degraded watersheds was dominated by small woody tree species and a greater diversity of shrub species. Ordination analysis was used to integrate soil data with vegetation and disturbance, revealing that deciduous forest in the park is degrading to scrub forest along with negative impacts on soil characteristics. Consequences of services currently enjoyed by local populations are discussed. Copyright © 2008 John Wiley & Sons, Ltd.

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