Determinants of population persistence and abundance of terrestrial and arboreal vertebrates stranded in tropical forest land-bridge islands

Benchimol, Maíra and Peres, Carlos A (2020) Determinants of population persistence and abundance of terrestrial and arboreal vertebrates stranded in tropical forest land-bridge islands. Conservation Biology. ISSN 0888-8892

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Abstract

Mega-dams are among the key modern drivers of habitat and biodiversity loss in emerging economies. The Balbina Hydroelectric Dam of Central Brazilian Amazonia inundated 312,900 ha of primary forests and created ∼3500 variable-sized islands that still harbor vertebrate populations after nearly three decades of post-isolation history. Here, we estimated the species richness, abundance, biomass, composition, and group size of medium to large-bodied forest vertebrates in response to patch, landscape and habitat quality metrics across 37 islands and three continuous forest sites throughout the Balbina archipelago. We recorded 34 species based on 1,168 km of diurnal censuses and 12,420 camera-trapping-days, and found that patch area was the most significant predictor explaining patterns of vertebrate populations. Additionally, the maximum group size of several group-living species was consistently larger on large islands and continuous sites. Our results show that most vertebrate populations were either locally extirpated or are now committed to future extinction events in most post-inundation islands, clearly disrupting their ecological functions. If all vertebrate species were once widely distributed across the pre-flooding reservoir area, we estimate that ∼75% of all individual vertebrates were lost from all 3,546 islands, and 7.4% of the animals in all persisting insular populations are currently committed to local extinctions. Our study demonstrates that including population abundance estimates into predictions of "small island" community disassembly results in even worse biodiversity outcomes. Given the rapidly escalating hydropower infrastructure projects in developing counties, we suggest that faunal abundance and biomass estimates should be considered in environmental impact assessments and large strictly-protected reserves should be set aside to minimize the detrimental effects of future dams on biodiversity. Finally, setting-aside large tracts of continuous forests represents the most critical conservation measure to ensure that animal populations can persist at natural densities in Amazonian forests. Article impact statement: Tropical forest islands created by major hydroelectric dams can only retain very small, if any, vertebrate populations. This article is protected by copyright. All rights reserved.

Item Type: Article
Additional Information: This article is protected by copyright. All rights reserved.
Faculty \ School: Faculty of Science > School of Environmental Sciences
Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: LivePure Connector
Date Deposited: 02 Sep 2020 23:54
Last Modified: 10 Sep 2020 23:57
URI: https://ueaeprints.uea.ac.uk/id/eprint/76740
DOI: 10.1111/cobi.13619

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