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Vermeulen LM, Verbist B, Van Meerbeek K, Slingsby J, Bernardino PN, Somers B. Wetness severity increases abrupt shifts in ecosystem functioning in arid savannas. Glob Chang Biol 2024; 30:e17235. [PMID: 38497525 DOI: 10.1111/gcb.17235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 02/08/2024] [Accepted: 02/22/2024] [Indexed: 03/19/2024]
Abstract
The accelerating pace of climate change has led to unprecedented shifts in surface temperature and precipitation patterns worldwide, with African savannas being among the most vulnerable regions. Understanding the impacts of these extreme changes on ecosystem health, functioning and stability is crucial. This paper focuses on the detection of breakpoints, indicative of shifts in ecosystem functioning, while also determining relevant ecosystem characteristics and climatic drivers that increase susceptibility to these shifts within the semi-arid to arid savanna biome. Utilising a remote sensing change detection approach and rain use efficiency (RaUE) as a proxy for ecosystem functioning, spatial and temporal patterns of breakpoints in the savanna biome were identified. We then employed a novel combination of survival analysis and remote sensing time series analysis to compare ecosystem characteristics and climatic drivers in areas experiencing breakpoints versus areas with stable ecosystem functioning. Key ecosystem factors increasing savanna breakpoint susceptibility were identified, namely higher soil sand content, flatter terrain and a cooler long-term mean temperature during the wet summer season. Moreover, the primary driver of changes in ecosystem functioning in arid savannas, as opposed to wetter tropical savannas, was found to be the increased frequency and severity of rainfall events, rather than drought pressures. This research highlights the importance of incorporating wetness severity metrics alongside drought metrics to comprehensively understand climate-ecosystem interactions leading to abrupt shifts in ecosystem functioning in arid biomes. The findings also emphasise the need to consider the underlying ecosystem characteristics, including soil, topography and vegetation composition, in assessing ecosystem responses to climate change. While this research primarily concentrated on the southern African savanna as a case study, the methodological robustness of this approach enables its application to diverse arid and semi-arid biomes for the assessment of climate-ecosystem interactions that contribute to abrupt shifts.
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Affiliation(s)
- L M Vermeulen
- Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
- African Climate and Development Initiative, University of Cape Town, Cape Town, South Africa
| | - B Verbist
- Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
| | - K Van Meerbeek
- Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
- KU Leuven Plant Institute, KU Leuven, Leuven, Belgium
| | - J Slingsby
- Department of Biological Sciences and Centre for Statistics in Ecology, Environment and Conservation, University of Cape Town, Cape Town, South Africa
- Fynbos Node, South African Environmental Observation Network, Centre for Biodiversity Conservation, Cape Town, South Africa
| | - P N Bernardino
- Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
- Department of Plant Biology, University of Campinas, Campinas, SP, Brazil
| | - B Somers
- Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
- KU Leuven Plant Institute, KU Leuven, Leuven, Belgium
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