Design matters : an evaluation of the impact of small man-made forest clearings on tropical bats using a before-after-control-impact design

Rocha, R, Ovaskainen, O, Lopez-Baucells, A, Farneda, FZ, Ferreira, DF, Bobrowiec, PED, Cabeza, M, Palmeirim, JM and Meyer, CFJ ORCID: 2017, 'Design matters : an evaluation of the impact of small man-made forest clearings on tropical bats using a before-after-control-impact design' , Forest Ecology and Management, 401 , pp. 8-16.

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In recent years, large clearings (>1000 ha) accounted for gradually smaller amounts of total annual deforestation in the Brazilian Amazon, whereas the proportion of small clearings (<50 ha) nowadays represents more than 80% of annual deforestation. Despite the ubiquity of small clearings in fragmented Amazonian landscapes, most fragmentation research has focused on the effects of large-scale deforestation, leading to a poor understanding of the impacts of smaller barriers on Amazonian vertebrates. We capitalized on the periodical re-isolation of experimental forest fragments at the Biological Dynamics of Forest Fragments Project in the Central Amazon as a before-after-control-impact experiment to investigate the short-term effects of small clearings on bat assemblages. Over the course of three years we sampled six control sites in continuous forest, the interiors and edges of eight forest fragments as well as eight sites in the surrounding matrix. Sampling took place both before and after the experimental manipulation (clearing of a 100 m wide strip of regrowth around each fragment), resulting in ~4000 bat captures. Species were classified as old-growth specialists and habitat generalists according to their habitat affinities and a joint species distribution modeling framework was used to investigate the effect of fragment re-isolation on species occupancy. Following fragment re-isolation, species richness declined in all habitats other than fragment edges and, although responses were idiosyncratic, this decline was more pronounced for forest specialist than for generalist species. Additionally, fragment re-isolation led to a reduction in the similarity between assemblages in modified habitats (fragment interiors, edges and matrix) and continuous forest. Sampling of controls in continuous forest both prior to and after reisolation revealed that much of the variation in bat species occupancy between sampling periods did not arise from fragment re-isolation but rather reflected natural spatiotemporal variability. This emphasizes the need to sample experimental controls both before and after experimental manipulation and suggests caution in the interpretation of results from studies in which the effects of habitat transformations are assessed based solely on data collected using space-for-time substitution approaches.

Item Type: Article
Schools: Schools > School of Environment and Life Sciences > Ecosystems and Environment Research Centre
Journal or Publication Title: Forest Ecology and Management
Publisher: Elsevier
ISSN: 0378-1127
Related URLs:
Funders: Fundação para a Ciência e a Tecnologia, CAPES, Bat Conservation International, Academy of Finland, Research Council of Norway
Depositing User: Dr Christoph Meyer
Date Deposited: 10 Jul 2017 12:50
Last Modified: 15 Feb 2022 22:12

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