Pattern of invasion by Adhatoda vasica in savannas of Sariska Tiger Reserve, Rajasthan, Western India

As part of global experiments on Savanna vegetation, we examined the ecological characteristics of an important semiarid savanna in the Indian sub-continent i.e Sariska Tiger Reserve, Rajasthan, Western India during April 2009 to May 2011. 149 plots across five line transects were sampled for phyto-sociological interpretation in the Sariska-Kalighati valley which is the largest savanna valley habitat in the study area. Plots were segregated on the presence/absence of native invasive species Adhatoda vasica and community analysis revealed a total of eleven communities (five from infested plots and six from non-infested plots) and communities having similar composition were compared. Tree density, seedling density, species richness of shrubs and herbs and diversity and evenness of herbs was higher in noninfested plots. Sapling density did not follow a trend. Evenness of shrubs was lower in non-infested plots. Furthermore, 2 mapping of Adhatoda vasica in the study area revealed that 5.22 km (26.1%) of the Sariska-Kalighati valley was under infestation and three sites were compared following removal of this species which resulted in increased sapling density, shrub density and grass cover and decreased seedling density and herb density.