Dry tropical forest communities are among the world's most threatened systems and urgent measures are required to protect and restore them in degraded landscapes. For planning conservation strategies, there is a need to determine the few essential measurable properties, such as number of species and basal area, that best describe the dry forest vegetation and its environment, and to document quantitative relationships among them. This paper examines the relationships between forest basal area and diversity components (number of species and evenness) for a disturbed dry tropical forest of northern India. Data were collected from five sites located in the Vindhyan dry tropical forest of India, selected on the basis of satellite images and field observations to represent the entire range of conditions in terms of canopy cover and disturbance regimes. These sites represented different communities in terms of species composition. The forest was poorer in species richness, and lower in stem density and basal area than wet forests of the tropics. Across sites (communities), the diversity components and tree density were positively related with total tree basal area. Considering basal area as a surrogate of biomass and net production, diversity is found to be positively associated with productivity. A positive relationship between basal area, tree density and species diversity may be an important characteristic of the dry forest, where recurring disturbance does not permit concentration of biomass or stems in only a few strong competitors. However, the relationships of basal area with density, alpha diversity and evenness remain statistically significant only when data from all sites, including the extremely disturbed one, are used in the analysis. In some sites there was a greater coefficient of variation (CV) of basal area than in others, attributed to patchy distribution of stems and resultant blanks. Therefore, to enhance the tree diversity of these forests, the variability in tree basal area must be reduced by regulating local disturbances. Conservation activities, particularly fuelwood plantations near human settlements, deferred grazing and canopy enrichment through multi-species plantations of nursery-raised or wild-collected seedlings of desirable species within the forest patches of low basal area, will be needed to attain restoration goals, but reforestation programmes will have to be made attractive to the forest-dwelling communities.
The dry tropical ecosystems are among the world's most threatened, and the dry deciduous forest of northern India is being progressively converted to scrub, savannah and grasslands through industrialization, agriculture, fuelwood collection, lopping of trees for fodder and severe grazing/browsing. This habitat destruction threatens the survival of many species. This study examined the demographic instability of tree species in 3-ha permanent plots: at five sites differing in the degree of disturbance. Based on the proportion of seedlings of a species in its total population (seedling + sapling + adults), about 52% of the total 65 species exhibited local demographic instability, and at one or more sites a single individual represented 10 species. The increase in the proportion of declining species with increase in disturbance intensity indicated that local anthropogenic pressure is responsible for the depletion. Apart from stronger protection measures, it is necessary to encourage fuelwood plantations, develop village pastures and reduce livestock numbers.