Plants, herbivores and communities

More than half of the earth’s land surface is comprised of grazing ecosystems, aimed at sustaining populations of large herbivorous mammals, both wild and domestic. However, the goals of conserving wild species are often inconsistent with those of animal husbandry.

More than half of the earth’s land surface is comprised of grazing ecosystems, aimed at sustaining populations of large herbivorous mammals, both wild and domestic. However, the goals of conserving wild species are often inconsistent with those of animal husbandry. There are numerous examples where wild species have declined with the progressive intrusion of domestic ones.

The Trans-Himalayas represent a vast rangeland system where a large fraction of the original native species assemblages continues to survive alongside a diversity of livestock. However, the landscape is punctuated with instances of local extinctions. At a local scale, (e.g. at the scale of individual valleys or catchments), there are many instances where one or more wild species have gone extinct in the recent past. Our previous work has shed light on the mechanisms by which livestock can drive this process. However, a critical question remains to be answered – how does the ecosystem as a whole fare, with a reduced number of species?

For ecosystems that have evolved with a certain assemblage of herbivores and plants, any sudden extinction event can cause imbalances in the co-evolved pathways that the system would normally follow. An ecosystem’s performance is adjudged by the functions it carries out. For instance, among the most familiar attributes are the primary and secondary productivity i.e., the ability to provide food. Other functions include nutrient-cycling that keep soils fertile, hydro-dynamics that run the water cycle and so on. Loss of species can potentially have serious repercussions on ecosystem functions.

So we must ask, what are the consequences of losing native species and replacing them with livestock on ecosystem processes? This is the broad question we have set out to answer in this project.