Periodic Reporting for period 1 - SpatialSAVE (Spatial patterns in savannas may increase ecosystem resilience and reverse biome transitions)
Reporting period: 2021-08-01 to 2023-07-31
Savannas ecosystems cover almost one-eighth of the earth’s surface and is inhabited by millions of people whose livelihood depend on it. Hence, it is important to understand how the savannas will respond to the ongoing climate change. Spatial vegetation patterns is often deemed important to understand how changing environment will impact ecosystems. However, spatial patterns in the savannas had been largely overlooked. The project addresses this problem by studying the different mechanisms of pattern formation in the savannas and investigates their role in ecosystem resilience. In the humid region, the savanna-forest boundary is widely believed to be prone to tipping which refers to an abrupt transition of an ecosystem state to another alternative stable state. The project studies how spatial patterns observed in this region may challenge this notion. It also aims to understand the vegetation patterns across the whole rainfall gradient in the savannas and the resilience of the those patterned states. The results from the project helps to advance fundamental understanding of how the savannas may respond to ongoing climate change. They provide fresh impetus to examine more carefully the conditions under which the ecosystem might undergo tipping.
In this project, the different mechanisms of pattern formation in the savannas were studied. Results showed that while the well-studied Turing patterns can be seen in the water-limited region, these cannot be observed at the humid savanna-forest boundary. At the humid savannas, environmental spatial heterogeneity plays an important role in pattern formation. Disturbances like grazing and deforestation can form stable savanna-forest patterns in the presence of such heterogeneity. In that case, changing climatic conditions may not lead to tipping of one ecosystem state to another. Instead, a part of the system may collapse to produce stable savanna-forest patterns which we refer to as coexistence states. These coexistence states can adapt gradually to changing climatic conditions and can exist much beyond the tipping point thus making the ecosystems more resilient. This forces us to rethink ecosystem response to climate change and indicates the important role played by spatial processes in ecosystems. In the mesic savannas, where rainfall is in the intermediate ranges, results showed that fire is key to formation of Turing patterns which may also increase resilience of the ecosystem. These results from the project have been disseminated through scientific manuscript and presentations in scientific conferences. The findings have also been communicated to the general public using a project website and a news article from the university which has been shared on various social media platforms.
The project has advanced our understanding beyond the state of the art in savanna ecosystems. It has thrown light into the possible mechanism of spatial patterns in the savannas along the rainfall gradient. It also went one step further to assess how such pattern formation affect the response of savannas to climate change. Although the results do not directly inform policy, they contribute significantly to our understanding of ecosystem response in the present era of ongoing climate change. This paves the way for better conservation strategies and have significant societal impact as millions of people inhabit the savannas and depend on it for their livelihood.