Fire in an Indian deciduous tropical forest: Effects on tree seedling and juvenile communities

A two-year study was conducted to examine the effects of anthropogenic fire on tree seedling and juvenile growth and diversity in a tropical deciduous forest of central India. Experimental burns in the study area were supplemented by another experiment in which seedling functional traits of 14 common trees (height growth rate, root to shoot biomass ratio, survival after clipping, and stem die-back among unclipped seedlings) were recorded and regressed against juvenile abundance in the forest to determine which might be associated with factors affecting species abundance in the forest. Fires reduced the diversity of tree seedlings. Juveniles experienced zero mortality, but increase in stem density of clonal species occurred in burned plots, which led to declines in juvenile and seedling diversities. Seedlings died in response to fire, but the seedlings of non-clonal species showed greater mortality than those of the clonal species. Of the four seedling traits, survival after clipping was the only one to explain significant variance in juvenile abundance in the study area: greater survival after clipping led to greater abundance of the species. Plant-water relations played an important role and interacted with fire to affect the seedling and juvenile abundance and diversity. The interaction of plant water relations with fire was examined by studying the vegetative phenology of tree juveniles in burned and fire-excluded plots. Fires impacted the vegetative phenology of three species, of which Diospyros melanoxylon showed the strongest response by completing leaf expansion and flushing earlier in burned plots. Fires had effects over and above those of water stress experienced by plants.