Catastrophic shifts in drylands: How can we prevent ecosystem degradation?

degradation forest fire
The hill in the foreground has been affected by fire. Its vegetation is recovering poorly, especially along the southwest-facing slopes. Photo: Hanspeter Liniger
It is often difficult to fully understand – much less predict – major changes or shifts in ecosystems. Nevertheless, signs of vegetation loss or soil erosion, for example, may indicate that a particular ecological threshold has almost been reached. When that threshold is crossed – producing a rapid or irreversible transition from one ecosystem state to another, with serious socio-ecological consequences – we speak of a "catastrophic shift". Studying these thresholds and shifts in dryland ecosystems is at the heart of the CASCADE Project. At present, our understanding of the causes and characteristics of sudden shifts in Mediterranean drylands is limited. It remains difficult to predict if or when a particular shift will occur. Nevertheless, when a shift appears imminent and is considered undesirable by land users, it is critical to know whether anything can be done to prevent it from happening.
degradation overgrazing
Overgrazing is damaging the vegetation cover, causing soils to dry out and erode. Together with their partners, CDE researchers are analysing the causes of land degradation and helping to identify appropriate land use practices. Photo: Matteo Jucker, CDE

The CASCADE Project seeks to collect experimental data, implement them in ecological models, and interpret the results to help answer the following questions:

  • Why and when do catastrophic shifts occur in ecosystems or landscapes? 
  • Why are some ecosystems or landscapes more resilient (i.e. less likely to change) than others? 
  • What can be done to prevent catastrophic shifts? 
  • Can degraded ecosystems or landscapes be restored to previous states? 
  • Is it economically feasible to restore degraded ecosystems or landscapes? Or is it too costly? 
degradation of landscapes
The degradation of landscapes often takes the form of abrupt, irreversible changes that are difficult to predict. Photo: Matteo Jucker, CDE

Analysing the resilience of natural resource management practices

CDE researchers are studying land use and management practices, and the role of these practices in preventing catastrophic shifts. Our research approach follows three steps. Firstly, we inventory, document, and evaluate any natural resource management practices that are already applied locally. Before coming up with new practices, it only makes sense (e.g. economically) to identify and scale up existing practices that are capable of preventing, or even reversing, harmful ecosystem shifts. Secondly, we develop and apply an effective, simple method to assess the resilience of natural resource management practices.

Researchers examine a shrub with thorns that protect it from grazing animals. More vulnerable plants may grow between and below it. Photo: G. Neeson
Further, we investigate how practices could or should be altered to adapt to such changes. Sometimes the necessary adaptations are small, such as replacing a particular hedgerow plant with a species that is more drought-resistant; or reducing grazing pressure on grasslands by introducing a rotational grazing regime. In general, increasing the sustainability of resource management practices usually means increasing the resilience of the affected ecosystem – indeed, resilience is inherent to the concept of sustainability and sustainable land management.Thirdly and lastly, we are preparing best-practice guidelines for natural resource managers. These guidelines include technical aspects as well as broader approaches to implementation. We also seek to elaborate region-specific and ecosystem-specific recommendations and principles that make it possible to scale up effective practices.

The project is funded by the EU’s FP7 programme. Visit its site at: www.cascade-project.eu​

Project duration: 2012 to 2017

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The CASCADE Project is funded by the EU’s FP7 programme. It is slated to run from 2012 to 2017. Visit its site at: www.cascade-project.eu​