A carregar...
Projeto de investigação
Assessment of the effects of forest fragmentation on aerial insectivorous bats in the Amazonian rainforest
Financiador
Autores
Publicações
Edge effects and vertical stratification of aerial insectivorous bats across the interface of primary-secondary Amazonian rainforest
Publication . Yoh, Natalie; Clarke, James A.; López-Baucells, Adriá; Mas, Maria; Bobrowiec, Paulo E.D.; Rocha, Ricardo; Meyer, Christoph F.J.
Edge effects, abiotic and biotic changes associated with habitat boundaries, are key drivers
of community change in fragmented landscapes. Their influence is heavily modulated by
matrix composition. With over half of the world’s tropical forests predicted to become forest
edge by the end of the century, it is paramount that conservationists gain a better understanding
of how tropical biota is impacted by edge gradients. Bats comprise a large fraction
of tropical mammalian fauna and are demonstrably sensitive to habitat modification. Yet,
knowledge about how bat assemblages are affected by edge effects remains scarce. Capitalizing
on a whole-ecosystem manipulation in the Central Amazon, the aims of this study
were to i) assess the consequences of edge effects for twelve aerial insectivorous bat species
across the interface of primary and secondary forest, and ii) investigate if the activity
levels of these species differed between the understory and canopy and if they were modulated
by distance from the edge. Acoustic surveys were conducted along four 2-km transects,
each traversing equal parts of primary and ca. 30-year-old secondary forest. Five
models were used to assess the changes in the relative activity of forest specialists (three
species), flexible forest foragers (three species), and edge foragers (six species). Modelling
results revealed limited evidence of edge effects, except for forest specialists in the understory.
No significant differences in activity were found between the secondary or primary forest
but almost all species exhibited pronounced vertical stratification. Previously defined bat
guilds appear to hold here as our study highlights that forest bats are more edge-sensitive
than edge foraging bats. The absence of pronounced edge effects and the comparable
activity levels between primary and old secondary forests indicates that old secondary forest can help ameliorate the consequences of fragmentation on tropical aerial insectivorous
bats
Assessment of the effects of forest fragmentation on aerial insectivorous bats in the Amazonian rainforest
Publication . López-Baucells, Adrià; Meyer, Christoph Friedrich Johannes; Palmeirim, Jorge Manuel Mestre Marques
Land use change and habitat fragmentation are among the most severe threats to biodiversity, especially in the tropics. In the Amazon, the abandonment of formerly deforested areas allowed the expansion of secondary regrowth, a type of habitat where bats are known to provide important ecosystem services. Amongst them, aerial insectivorous bats have been neglected in most Neotropical studies and remain poorly studied. However, the current upsurge in acoustic technology makes them easy targets to be monitored using ultrasound detectors. The aim of this thesis was to reveal the diversity of aerial insectivorous bats and quantify the effects of forest fragmentation on this ensemble within the Biological Dynamics Forest Fragments Project, a whole ecosystem experiment in the Amazon, currently composed of a mosaic of unflooded rainforest with continuous forest, and forest fragments embedded in a matrix of secondary regrowth.
As part of this thesis, the first “Field Guide to the Bats of the Amazon” was published. A custom-built classifier was developed which was able to identify a large proportion of files to sonotype level (with > 90% accuracy), leaving the rest (<25%) to be manually classified. I also tested 20 different recording schemes and provided guidelines to optimize protocols for acoustic studies. In forest fragments and their adjoining secondary forests, taxonomic, phylogenetic and functional α diversity became gradually poorer with decreasing fragment size. In terms of β diversity, bat assemblage composition in secondary forests after ~30 years of recovery was still significantly different from that in continuous forest. However, forest edges harboured highly diverse bat assemblages due to the opening of cluttered areas, and the increase of less-sensitive species. Responses towards fragmentation were species-specific and strongly related to their functional traits. The results of this thesis highlight the irreplaceable value of tropical primary forests due to the long time required to recover fragmented ecosystems.
Unidades organizacionais
Descrição
Palavras-chave
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
FARH
Número da atribuição
PD/BD/52597/2014