Effect of ecological factors on the grass dynamics at Point Calimere Wildlife Sanctuary, India

Abstract

Grass dynamics play a major role in the density and diversity of grazing mammals. To understand the drivers of grass quality and quantity, we assessed the height, cover, soft-texture, green leaves, and reproductive phase of grass species in relation to 13 ecological covariates belonging to climate, vegetation, human disturbance, and wild herbivores at Point Calimere Wildlife Sanctuary, southern India during November 2018─September 2020. From the 1,024 quadrates, we recorded 22 grass species and 10 sedges. The grass parameters varied significantly among habitats and between seasons. The grass height and grass cover were more in open scrub, while the soft-textured green grasses were more in grasslands. All the grass parameters except reproductive stage were highest during the wet season. The general linear model (GLM) based analysis on the covariate effect on grass quantity and quality demonstrated that among the 13 covariates compared, Prosopis, an alien invasive species, is the major driver, with negative influence on both grass quantity; the cover, and grass quality; soft-texture and greenness of grass. The feral horse, an alien invasive, negatively influenced grass height. Earlier studies have also shown the devastating effects of these exotics on native flora and fauna at Point Calimere, and measures suggested by these studies are recommended to safeguard natural communities in the area.