Consequences of Rural Biomass Extraction for Bird Communities in an Indian Tropical Dry Forest and the Role of Vegetation Structure

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"There is limited information on the ecological effects of anthropogenic disturbance caused by extractive activities such as grazing and firewood collection. A study was carried out in Sariska Tiger Reserve in India, to investigate the effects of disturbance on forest bird communities. Vegetation structural parameters including canopy cover, tree basal area and average height of trees were significantly lower in disturbed sites in comparison to undisturbed sites. However, other attributes of tree structure and the features of the understorey and herbaceous layer were unaffected by the disturbance regime. There was no significant difference in the number of recorded species and bird abundance between disturbed (extracted) and undisturbed (nonextracted sites. However, bird species diversity was significantly lower in disturbed sites. Bird species composition also differed significantly between disturbed and undisturbed sites and was associated with disturbance indicators. Bird species composition was also significantly related to six different structural variables. Abundance of twelve of forty eight (25%) bird species (that were abundant enough to be analysed), showed significant associations with disturbance indicators as well as one or more of structural variables. Of these, four bird species showed selection for disturbed habitats while eight selected undisturbed habitats over disturbed. Most of the bird species choosing undisturbed over disturbed habitats were insectivores. Both the disturbance index and the vegetation structure had significant effects on bird composition even when the other was controlled for. Our study indicates that forest resource extraction can have significant effects on bird species composition of tropical dry forests through alteration of vegetation structure."
diversity, birds, biomass, forests, land degradation