Effect of Grazing on the Community Structure and Functional Diversity of Grazing Lawns in Sathyamangalam Tiger Reserve

Abstract

Understanding the effects of grazing (by both livestock and wild ungulates) on grasslands is paramount to come up with more robust managerial actions to conserve, and increase the ecosystem function of these valuable ecosystems. In the current study, we investigate the effects of grazing on a highly productive, mesic grassland ecosystem, viz. grazing lawn in Sathyamangalam Tiger Reserve, Tamil Nadu, India. We examined how species richness and composition of a grassland patch change across a grazing gradient by carrying out plot-based vegetation sampling in the grazing lawns of Sathyamangalam Tiger Reserve. We also looked at how trait composition and functional diversity changed across the grazing gradient, to better understand the plant functional response and resilience of the grazing lawn complex. We used a Linear Mixed Effect Model (LMM) to investigate the impact of grazing intensity on species richness, and a Non-metric Multidimensional Scaling (NMDS) to look at the differences in species composition between different grazing treatments. Functional composition and diversity were measured using Lavorel and Villeger’s index in the ‘FD’ package of R (4.0.2). We found that grazing lawns were minimally affected by grazing intensity in terms of species richness and trait composition, but showed a significant change in species composition and functional diversity across the grazing gradient.