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Hydropower dams induce widespread species extinctions across Amazonian forest islands

Amazon river
Credit: Pixabay/CC0 Public Domain

Hydropower developments should avoid flooding forests to reduce biodiversity loss and disruptions to ecosystems in Amazonian forest islands, new research from the University of East Anglia (UEA) finds.

Deforestation, and fragmentation are linked and so are driving the ongoing biodiversity crisis, with hydropower to be blamed for a lot of this degradation. In lowland tropical forests, river damming typically floods vast low-elevation areas, while previous ridgetops often become insular forest patches.

In a fresh study, scientists from UEA, Portugal and Brazil used to comprehend how insular habitat fragmentation affects tropical forest biodiversity. This process perceives habitat patches and species as connected units at the whole-landscape scale, encompassing a species-habitat network.

The analysis, “Emergent properties of species-habitat networks within an insular forest landscape,” is published today in the journal Science Advances.

The authors studied 22 habitat patches, comprising forest islands and three continuous forest sites, that have been developed by the Balbina Hydroelectric Reservoir, among the largest in SOUTH USA. The 608 species surveyed represented eight biological groups: mid-sized to ; small non-flying mammals; understorey birds; lizards; frogs; dung beetles; orchid bees and trees.

The analysis revealed widespread species extinction, especially of large-bodied species, but this varied across different sets of plants, vertebrates and invertebrates. Island size determined the persistence of species diversity, with just a couple of islands holding probably the most diversity.

Large tracts of tropical forests become rarer because they are subdivided and isolated into small habitat patches. Removing larger forest sites will exert the best impact, likely inducing secondary extinctions of species that occur only at an individual site or people with larger spatial requirements.

Conversely, small patches proportionally harbor more species than one or perhaps a few larger patches of equal total area, therefore the lack of smaller sites can be likely to cause secondary extinctions.

Prof Carlos Peres, co-author of the analysis, is Professor of Environmental Studies at UEA. He said: “Tropical developing countries remain hellbent on creating vast hydropower reservoirs beneath the banner of ‘green’ energy.

“It is a double-jeopardy because we lose both unique lowland biodiversity and the carbon stocks of the now inundated old-growth forests.

“Such actions also generate a robust methane pump, never mind the huge financial costs of mega-dams in comparison to diffuse in-situ electrification predicated on low-impact renewables.

“We are in need of a far greater strategic dialogue between sustainable energy security and biodiversity conservation, particularly in the world’s most biodiverse emergent economies.”

Dr. Ana Filipa Palmeirim, a researcher from CIBIO-University of Porto, led the analysis, which investigated a complex landscape as an individual unit. She said: “This process allowed us to unveil previously unknown patterns, like the simplification of the network structure and changes in important network parameters because of the lack of species suffering from the dam.”

Dr. Carine Emer, a co-author of the analysis from the Rio de Janeiro Botanical Garden, said: “The wonder of the study lays in the mix of sophisticated network and statistical analyses, with the natural history of high-quality inventories from an astonishing tropical living lab.

“A lot more than 3,000 islands were created 35 years back because of the Uatum River damming, and by observing these we could actually understand the functioning of this type of complex and rich human-modified landscape.”

The analysis was a collaboration between UEA in the united kingdom; the study Center in Biodiversity and Genetic Resources (CIBIO) and the University of Porto, in Portugal; the study Institute of the Rio de Janeiro Botanical Garden; hawaii University of Santa Cruz; hawaii University of Mato Grosso; and the Farroupilha Federal Institute of Education, Science and Technology, in Brazil.



More info: Ana Filipa Palmeirim, Emergent properties of species-habitat networks within an insular forest landscape, Science Advances (2022). DOI: 10.1126/sciadv.abm0397. www.science.org/doi/10.1126/sciadv.abm0397

Citation: Hydropower dams induce widespread species extinctions across Amazonian forest islands (2022, August 26) retrieved 27 August 2022 from https://phys.org/news/2022-08-hydropower-widespread-species-extinctions-amazonian.html

This document is at the mercy of copyright. Aside from any fair dealing for the intended purpose of private study or research, no part could be reproduced minus the written permission. This content is provided for information purposes only.

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