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As part of global experiments on Savanna vegetation, we examined the ecological characteristics of an importantsemiarid savanna in the Indian sub-continent i.e Sariska Tiger Reserve, Rajasthan, Western India during April 2009 toMay 2011. 149 plots across five line transects were sampled for phyto-sociological interpretation in the Sariska-Kalighativalley which is the largest savanna valley habitat in the study area. Plots were segregated on the presence/absence ofnative invasive species Adhatoda vasica and community analysis revealed a total of eleven communities (five frominfested plots and six from non-infested plots) and communities having similar composition were compared. Treedensity, seedling density, species richness of shrubs and herbs and diversity and evenness of herbs was higher in noninfestedplots. 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 underinfestation 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.

1. Plant organ biomass partitioning has been hypothesized to be driven by resources, such that species from drier environments allocate more biomass to roots than species from wetter environments to access water at greater soil depths. In savanna systems, fire may select for greater allocation to root biomass, especially in humid environments where fire is more frequent. Therefore, species from drier environments may have been under selection pressure to reach deeper soil water more effectively than species from humid environments, through faster root extension, more efficient depth penetration, and faster plant growth rates to respond rapidly to variable rainfall events. 2. We compared biomass partitioning, root morphology traits [root extension rate, RER; specific taproot length (STRL)] and relative growth rate (RGR) of seedlings of 51 savanna tree species, sampled from three continents (Africa, Australia and South America) in a greenhouse experiment. We used phylogenetically corrected and uncorrected analyses to compare the traits of the groups. We conducted a permanova on the combined traits to establish whether species could be distinguished on the basis of their combined traits. 3. On average, species from humid environments allocated more biomass to roots and less to stems than species from semi-arid environments, consistent with the expectation that fire pressure selects for greater allocation to roots in humid environments. However, some species from humid environments had fast growth rates instead of high allocation to roots. Both RER and STRL were greater among species of semi-arid environments than among species of humid environments, and also differed between continents. Differences between strategies under each climate type appear to be associated with leaf habit. 4. Synthesis. Plant biomass partitioning has been selected by defoliation pressure and the effects of this selection pressure can supersede any selection in response to local water constraints. Root morphological adaptations, but not plant growth rate, of tree seedlings, have been selected in response to water deficits