Fire, Grazing and the Dynamics of Tall-Grass Savannas in the Kalakad-Mundanthurai Tiger Reserve, South India

Abstract

Prescribed burning is often used to enhance forage availability for herbivores in rangelands worldwide. This study evaluated the utility of such prescribed burning as a management tool to improve herbivore habitat quality in the Mundanthurai plateau region of the Kalakad-Mundanthurai Tiger Reserve (KMTR), south India. Currently, large tracts of the plateau are dominated by the unpalatable tall-grass species Cymbopogon flexuosus, and populations of mammalian herbivores and predators in the region are low. Responses of C. flexuosus communities to experimentally-imposed fire and grazing regimes were studied, and the effectiveness of fire in suppressing this tall-grass species assessed. Two years following burning, C. flexuosus cover in burnt plots was indistinguishable from unburned sites, suggesting that C. flexuosus individuals are fairly stable against perturbations by fire. On the other hand, clipping experiments which simulated a scenario of high intensity grazing indicate that C. flexuosus fares poorly under sustained grazing, suggesting the potential for grazer-control of this species. However, C. flexuosus is typically avoided by grazers except for short periods following burning. Although grazing in these communities was higher post-burn responses of plots experiencing 'natural' levels of grazing indicate that grazer densities at KMTR are presently too low to prevent C. flexuosus from quickly re-attaining competitive dominance following burning. Under the current conditions of low herbivore densities, prescribed burning, by itself, is therefore unlikely to significantly improve herbivore habitat in KMTR. For burning to be effective, it must be coupled with other parallel management strategies aimed at augmenting grazer densities in the reserve.