Department of Biosciences, Saurashtra University, Rajkot 364 002, INDIA.
Biodiversity assessment and impact of disturbance on distribution of species in space constitute one of the fundamental themes in ecological research. It is being increasingly recognized that studies on ecological status and factors determining species diversity are essential to understand the mechanism of maintenance of biological diversity. Tropical scrubland savanna of Saurashtra called “Vidis” were overexploited and neglected, where no efforts are being made to assess their role in conservation of native wildlife. This study highlight the ecological importance of degraded and exploited “vidis” in conservation of wildlife considering avifauna as an indicator group.
At the outset, it becomes important to know the status of the biological community of the “vidis” in an ecological perspective, to evolve a conservation strategy for the region. The avifauna profile and effects of human activities on avifaunal assemblages remain largely unknown for the region. A few past studies were conducted which either provided avifaunal checklists (Ali, 1954-55, Dharamkumar Singhji, 1956) or were specific to the region (Naik, et al,1990., Singh and Tatu, 1992).
Thus, the present study evaluates the ecological status of grassland biome and structure of the avian fauna assemblages in the grasslands having varied anthropogenic pressures and management practices. It was intended to fulfill gaps in knowledge about biodiversity of semi arid grasslands and impact of use.
A total of 7,775 individuals of 79 species were encountered with a frequency of 4,126 on nine transects at the three study sites. None of the study area could be considered as very rich area in terms of bird species richness in the grassland biome of the peninsula. Exploitation of resources and long exposure to ill planned management strategies resulted into impoverishment of avifauna.
The study suggests that insectivores are the indicators of disturbance on a grassland ecosystem. Thus composition of insectivores indicates stressors in the system whereas fluctuations in omnivores indicate its intensity. The outcome can be used as an important tool in rapid assessment for determining the health of the grassland area. Granivorous guilds remain more or less constant at all sites. It suggests is a robust group with adaptability to utilize resources at different strata. As the group consisted of grassland specialist species of Alaudidae and Phasianidae, it was important to investigate their role in the system to understand the complete dynamics of the semi arid grasslands.
No final conclusion could be drawn on the nature of the relationship between alpha and taxonomic diversity in the absence of strong evidence. But if the value at which taxonomic distinctness peaks is considered as an empirical measure of phylogenetic stock/reservoir of ecological communities [i.e., the minimum number of species required to maintain the taxonomic integrity of local assemblages], it can be used as a potential optimality indicator in biodiversity assessment and monitoring surveys.
My result showed that there were 32 constitutively rare species (for all sites combined). This category did not include migratory species. However, such species need to be viewed in light of factors such as their habitat specificity, body size, guilds and endemism for conservation purposes.
The first null hypothesis proposed was found true and hence accepted. The second null hypothesis was false and rejected. Thus it can be concluded that vidis are important for wildlife conservation, considering avifauna as indicator group and all the vidis have different cover and composition with different pressures.