Vegetation patterns - the missing link in our understanding of ecosystem resilience and tipping points

Mathematical models predict that climate change will cause large catastrophic collapse of our ecosystems. We speak to Swarnendu Banerjee about how vegetation patterns may be the missing link in our understanding of ecosystem tipping points and resilience and can help us fine-tune conservation interventions and take steps toward ecosystem recovery.

Banerjee studies savannas and how they respond to climate change. At this moment he is finishing up his Marie Skłodowska-Curie Individual Fellowship at the Copernicus Institute of Sustainable Development. “My training is in mathematics, but I was always interested in its relevance in the real world,” he says. During his doctoral studies in India, he was introduced to the tipping point theory and the idea that ecosystems could abruptly collapse in response to environmental change. “I wanted study the theory in more detail, as well its role in making ecosystems more resilient”. This ultimately led to the development of the Marie Curie post-doctoral proposal with Prof. Max Rietkerk. 

Getting to the bottom of how ecosystems respond to climate change

It has been argued that a changing climate could result in us crossing irreversible “tipping points”, leading to the transition of large swathes of land from forest to savanna or from savanna to barren land. This would cause significant damage to both the millions of people inhabiting the region and the Earth’s climatic system.

“The goal of my Marie Curie fellowship was to understand better how vegetation patterns in ecosystems like savannas might make them more resilient to climate change than earlier believed,” he explains. “The research set out to study how spatial patterns form in different rainfall regimes and how they respond to climate change”. The idea was to pave the way for more informed conservation interventions.

The Copernicus Institute was the perfect place to do this, he says. With an interdisciplinary sustainability focus with many cross-interactions between thematic areas, it’s been a dynamic environment for research. He also points to the strong expertise and network of Professor Max Rietkerk in the area of global change ecology and spatial vegetation modelling as one of the key motivations for joining the organisation.

Surprising results

The results have been surprising to many, suggesting that savanna ecosystems may be more resilient than previously thought. “We show that the mathematical models which are used to predict tipping points in savannas are too simplistic,” he explains. “They do not take into account spatial processes like plant dispersal which might hold the key to our understanding of ecosystem response to changing climate ”.

The goal of my Marie Curie fellowship was to understand better how vegetation patterns in ecosystems like savannas might make them more resilient to climate change than earlier believed

For instance, in humid savannas, spatial dynamics may lead to pattern formation which are stable when local environmental conditions like rainfall vary across the landscape.  “We see that these patterns are better able to adapt to changing climate, leading to a more gradual degradation instead of a catastrophic collapse and can also exist much beyond the tipping point. These results force us to rethink more carefully where and under what conditions there could be abrupt transitions and how we can prevent it”.

Looking to the future

Now that the project is wrapping up, Banerjee is joining the Dutch Institute of Emergent Phenomena (DIEP) and the Institute of Biodiversity and Ecosystem Dynamics (IBED) at the University of Amsterdam. The plan is to develop new research lines and at the same time, build on the Marie Curie project.  He reflects on his time at the institute: “The two years I spent in the department left me with many happy memories. Hanging out colleagues after work, taking lunch breaks in the beautiful botanical garden next to the office and building a snowman with colleagues on the rare occasion when it snowed last winter are all memories I will always cherish”.