当前世界环境

Changes in the dispersion pattern of native tree species were studied inSalforests of Chhotanagpur plateau by selecting 1 hectare (ha) plot at four sites, located 2 to 10 km apart from each other. Each plot was divided into 100 quadrats each of 10 m x 10 m in size. For each 10 m x 10 m quadrat, the number of species and density of adult trees (>30 cm circumference at breast height: 1.37 m) were measured and identified. The range of uniform dispersion (77-89%) was greater than clumped dispersion (6-19%) and random dispersion (4-8%) in all four sites. About 78% of the plant species were characterised by uniform dispersion indicating dominant ecological reaction (i.e. dispersion behaviour) in response to alterations in the habitat conditions. A greater part of quadrats had 1-3 species and 1-4, 5-8 and 9-12 individuals indicating a patchy habitat with poor species richness and density at each site, a characteristic of the highly disturbed Sal forests.