Shared pastures

The causes and mechanisms that determine herbivore species richness in grazing ecosystems are poorly understood. This study has been designed to determine the role of competition, habitat heterogeneity and biogeography in determining large herbivore species-richness patterns at a regional scale.

Large herbivores play a unique role in ecosystem functioning, and are economically important around the world. However wild herbivore diversity is declining and such rapid loss of diversity from grazing systems has stimulated research to evaluate how changing herbivore diversity influences functional properties of ecosystems. Nevertheless, the causes and mechanisms that determine herbivore species richness in grazing ecosystems are poorly understood. This project has been designed to determine the role of competition, habitat heterogeneity and biogeography in determining large herbivore species-richness patterns at a regional scale.

The Trans-Himalayan rangelands represent a dry-alpine-steppe ecosystem characterised by very low primary productivity and a short growth season in summer. Through aeons, a large-herbivore assemblage has evolved to exploit this otherwise hostile and marginal environment. However, human endeavours today threaten the integrity of this unique ecosystem.

The Indian Trans-Himalaya is located at the junction of three bio-geographic realms viz., Palaearctic, Ethiopian and Oriental, and contains biological elements of all these realms. Our work in the region over the last eight years has generated information on the ecology of wild and domestic herbivores. The proposed work is aimed at building upon that information, as well as addressing new ecological issues that challenge ecologists and conservationists.

Although large herbivore diversity on a continental or global scale may be ultimately determined by climatic factors, at local and regional scales, biotic interactions such as facilitation and competition become more important. Facilitation may enhance species richness in the high productive areas in the tropics, but it is perhaps less important in structuring herbivore assemblages in ecosystems with lower productivity, and competition is rather likely to play a more important role. This has been demonstrated by our recent work in the Indian Trans-Himalaya. Nevertheless, how competitive effect interacts with other potential determinants of herbivore species richness is less understood.

In this project, we are investigating the relative importance of competition, habitat heterogeneity, and biogeography in structuring the Trans-Himalayan large herbivore assemblages, and the spatial variation in species-richness at a regional scale. 

Our study is expected to make contributions to the current understanding of large herbivore community ecology, and will assist in better conservation management of the magnificent mountain ungulates of the Trans-Himalaya.