5: Non-equilibrium environments, rangeland management and climate change

Pastoral systems must make use of highly variable environments, subject to frequent droughts, floods or heavy snowfall events. In such settings standard rangeland management approaches, premised on ‘Clementsian’ succession models, do not work. Theories of non-equilibrium rangeland ecology emerged from an understanding that climatic events drive the dynamics of such systems.

When a drought strikes regularly, livestock populations are rarely at ‘equilibrium’ level, meaning that notions of ‘carrying capacity’ and ‘stocking rate’ control become irrelevant. High levels of spatial and temporal variation in fodder production means that mobility is an essential response, and fencing and land fragmentation can undermine production. Arguments about land degradation and desertification are further challenged by understandings of how such environments recover rapidly, and how ‘deserts’ may indeed be prevented by pastoral use.

*Pastoralists in Kenya. Photo: Ian Scoones*

However (inevitably), in many settings the story is not so clear-cut. For example, in some areas, different parts of a landscape may be more or less at equilibrium, and this may change over time. Access to ‘key resource’ patches – those areas where the last food and water is available – may be crucial in determining potential livestock population sizes, and their removal or reduced productivity may have major impacts. Equally, where fodder or water is trucked into an area, the dynamics change again.

Climate change is likely to affect the dynamics of rangelands in profound ways, shifting the frequency of extreme events, as well as increasing the extent of dryland areas in some regions. As well as covering the scientific debates, the lecture also examines some of the science-policy relationships in discussions around rangelands and desertification.

Watch the lecture

Questions

What characteristics of a ‘non-equilibrium’ environment exist in pastoral areas you know?
How are these features being changed by for example climate change, infrastructure development, competing land uses, fencing, fodder imports and so on?
What are some of the problems with the policy/operational approaches to ‘climate adaptation’ and ‘resilience’ in light of our understanding of non-equilibrium systems and climate change variability?
How do scientific and policy discourses on rangelands and pastoralism shift (or not) in your area, and why?