Grasslands: not wastelands but creations of ancient creatures
In a world of assumptions, for hundreds of years the people of Madagascar have been widely blamed for destroying their own magnificent environment: by making grassland from forest. Now, new research from the Royal Botanic Garden Edinburgh and Royal Botanic Gardens, Kew, discovers evidence of how ancient and now extinct four-legged creatures shaped these maligned open spaces.
Against a common narrative, that Madagascar was only covered by forest prior to human settlement, botanists from the two research institutes have set back a great conservation myth. In a new research paper* they reveal that the vast grasslands of the Central Highlands are not degraded forests. Rather, they were shaped both by animals and fire over millions of years and they urgently require further research.
Senior author of the research paper, Dr Caroline Lehmann, a Tropical Biologist at the Royal Botanic Garden Edinburgh and at the University of Edinburgh, explained: “Grasslands are important in their own right, with their own irreplaceable benefits to people and other biodiversity.
“There are some deep and important issues needing to be addressed beyond the fact that we have evidence of animals shaping grasslands in Madagascar over the last millions of years. It is a real call for cross-disciplinary work. While our research is conclusive about the role of megafauna shaping some grasslands in Madagascar, it is also part of a building narrative of grasslands as a widespread ancient part of Madagascar’s landscapes. Scientifically, this is interesting because the palaeo-record and biodiversity data do not see eye-to-eye.”
In a modern sense, the findings are important for the people of Madagascar who, for hundreds of years, have been told by outsiders that their arrival destroyed the biodiversity of the world’s most magnificent island: where grasslands were only a product of human degradation.
Lead author Cédrique Solofondranohatra, a PhD student at the University of Antananarivo based with the RBG Kew Madagascar Conservation Centre said: “In Madagascar, from primary school, children learn how grasslands are a product of the degradation of forests caused by their ancestors. Yet, we now know that while human arrival led to the extinction of the megafauna, as it did the world over, whether when people first arrived to Australia or Latin America, human arrival is likely to have re-shaped already existing grasslands in the Central Highlands.”
Dr Lehmann pointed out the profound irony that the only reason it is possible to link the extinct megafauna to modern grasslands is because people introduced domestic livestock: “Cattle are almost a megafauna substitute in the grasslands, without which the capacity to detect links would have been lost like the megafauna itself,” she added. “The grass species observed in the research are dependent on grazing to proliferate. Such grasses would have rapidly become extinct without the presence of a grazer to keep that niche open.”
The research was a collaboration with the Royal Botanic Gardens, Kew’s Research Leader in Grasses, Dr Maria Vorontsova, and Cédrique Solofondranohatra, who said that the discovery was possible via drawing on the legacy of research in African grasslands to see Madagascar through a new lens: “Co-evolution between plants and animals spanning millions of years now supports the livelihoods of millions of people… in a set of ecosystems that Malagasy people have been told they destroyed.
“Today, Madagascar is in the midst of a shocking biodiversity catastrophe - as is the world - but the rate of modern forest clearance is quite apart from what would have happened with the first arrival of people. Drivers of 20th and 21st century forest clearing and land use change are primarily caused by a struggle for survival and economic development in the one of the world’s poorest countries.”
Stressing the necessity for urgent new research Caroline Lehmann concluded: “There is a clear need for all areas of science to engage with landscapes hitherto dismissed as being of no value. Cross-disciplinary efforts are now urgently required to unlock mysteries about how these ecosystems are assembled and how resilient they are to climate change in a region with fragile food security.
“Grasslands provide essential food, cultural and financial resources to millions of Malagasy people. Effective land use policies are necessary to preserve these ecosystems. Grasslands can be productively managed to create a mosaic of habitats for both people’s livelihoods and biodiversity. That must be an ultimate ambition in the midst of our biodiversity and climate crises.”
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*Fire and grazing determined grasslands of central Madagascar represent ancient assemblages is published in the Proceedings of the Royal Society B on Wednesday, May 13, 2020 Manuscript: RSPB20200598: https://royalsocietypublishing.org/doi/10.1098/rspb.2020.0598
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