Context
Habitat loss, fragmentation and degradation are widespread drivers of biodiversity decline. Understanding how habitat quality interacts with landscape context, and how they jointly affect ...species in human-modified landscapes, is of great importance for informing conservation and management.
Objectives
We used a whole-ecosystem manipulation experiment in the Brazilian Amazon to investigate the relative roles of local and landscape attributes in affecting bat assemblages at an interior-edge-matrix disturbance gradient.
Methods
We surveyed bats in 39 sites, comprising continuous forest (CF), fragments, forest edges and intervening secondary regrowth. For each site, we assessed vegetation structure (local-scale variable) and, for five focal scales, quantified habitat amount and four landscape configuration metrics.
Results
Smaller fragments, edges and regrowth sites had fewer species and higher levels of dominance than CF. Regardless of the landscape scale analysed, species richness and evenness were mostly related to the amount of forest cover. Vegetation structure and configurational metrics were important predictors of abundance, whereby the magnitude and direction of response to configurational metrics were scale-dependent. Responses were ensemble-specific with local-scale vegetation structure being more important for frugivorous than for gleaning animalivorous bats.
Conclusions
Our study indicates that scale-sensitive measures of landscape structure are needed for a more comprehensive understanding of the effects of fragmentation on tropical biota. Although forest fragments and regrowth habitats can be of conservation significance for tropical bats our results further emphasize that primary forest is of irreplaceable value, underlining that their conservation can only be achieved by the preservation of large expanses of pristine habitat.
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EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Tropical forest loss and fragmentation are due to increase in coming decades. Understanding how matrix dynamics, especially secondary forest regrowth, can lessen fragmentation impacts is key to ...understanding species persistence in modified landscapes. Here, we use a whole-ecosystem fragmentation experiment to investigate how bat assemblages are influenced by the regeneration of the secondary forest matrix. We surveyed bats in continuous forest, forest fragments and secondary forest matrix habitats, ~15 and ~30 years after forest clearance, to investigate temporal changes in the occupancy and abundance of old-growth specialist and habitat generalist species. The regeneration of the second growth matrix had overall positive effects on the occupancy and abundance of specialists across all sampled habitats. Conversely, effects on generalist species were negligible for forest fragments and negative for secondary forest. Our results show that the conservation potential of secondary forests for reverting faunal declines in fragmented tropical landscapes increases with secondary forest age and that old-growth specialists, which are often of most conservation concern, are the greatest beneficiaries of secondary forest maturation. Our findings emphasize that the transposition of patterns of biodiversity persistence in island ecosystems to fragmented terrestrial settings can be hampered by the dynamic nature of human-dominated landscapes.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Context
Although hydropower development is one of the primary drivers of habitat loss and insular fragmentation, its impacts on species identity and their functional and phylogenetic roles have often ...been overlooked.
Objectives
Here we use an integrative approach, considering taxonomic, functional and phylogenetic dimensions at multiple scales, to understand the processes underlying species (dis)assembly of two taxa exhibiting relatively low dispersal ability: small mammals and lizards.
Methods
We surveyed 26 islands within the Balbina Hydroelectric Reservoir, and adjacent continuous forest, in Central Amazonia. Each dimension of diversity was related to spatial and habitat variables. We also examined functional composition using community-weighted mean trait values, and community redundancy using functional uniqueness. β-diversity was partitioned into their richness (β
rich
) and replacement (β
repl
) components.
Results
Functional and phylogenetic α-diversities of both taxa mirrored the taxonomic dimension, all of which increased with forest area. Individual small mammal (body mass and matrix tolerance), and lizard traits (body length, heliothermic mode and habitat type) were also predicted by forest area. For both groups, functional uniqueness decreased with forest area, and all dimensions of β-diversity were predominantly partitioned in β
rich
.
Conclusions
The environmental filter created by forest area resulted in the low conservation value associated with small forest islands, only occupied by a small set of species comprised by generalist lizards and matrix-tolerant small mammals. On the other side, large forest sites ensured ecosystem resilience to disturbance. To maintain ecosystem integrity, creating myriad small islands over large expanses of floodwaters should be avoided in future hydropower development.
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EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Hydroelectric dams are among the main cause of anthropogenic impacts in tropical environments. Damming interrupts the continuity of the river and produces the flooding of adjacent terrestrial ...ecosystems. Despite the negative effects on terrestrial and aquatic biodiversity, studies of the impacts of hydroelectric dams on species and community functional responses to flooding are scarce. Here, we evaluated the effects of river damming on taxonomic and functional diversity of phyllostomid bats sampled before (flooded sites) and after (unflooded sites) the construction of a mega hydroelectric dam in the southwestern of the Brazilian Amazon. The flooding of the lowlands significantly increased the taxonomic and functional α-diversity, as well as the species- and the community-level functional uniqueness of the bat assemblages, reflecting a reduction in the abundance of functional redundant species. Based on functional trait composition, we detected an increase in the frequency of animalivorous bats, and a reduction in phytophagous bats. Pre- and post-dam temporal differences show that functional β-diversity shifts were more determined by replacement of traits weighted by species abundance than by the loss or gain of traits. Functional traits linked to trophic level, body mass, and diet proved to be powerful indicators of the bat community’s responses to temporal changes caused by run-of-the-river dams, which degrade riparian and
várzea
forests. Plans to expand the electric power matrix in Brazil include the construction of several dams, potentially flooding large areas of
várzea
forests. We demonstrate the importance of the
várzea
and the riparian forests to phytophagous bats to guarantee the ecological functions they perform.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The high levels of biodiversity in the Amazon are maintained mostly due to its composition as a natural mosaic of different habitats, including both unflooded and flooded forests, campinaranas, and ...savannahs. Here, we compared multiple dimensions of α- and β- bat biodiversity between four natural Amazonian habitats (savannah, campinarana, forest patches, and continuous forest). In addition, we explored the extent to which bat communities in the different habitats are nested within one another, and compared the community-level functional uniqueness and community-weighted mean traits between habitats. Our results show that taxonomic, functional and phylogenetic α-diversity of bats is higher in continuous forest than in any of the other habitat types. The continuous forest also harbours more unique species, and indeed, the bat community assemblages in the less-complex habitats, including forest patches, campinarana and savannahs, are taxonomic, functional and phylogenetic sub-sets of the assemblage found in the continuous forest. By examining β-diversity partitions and species composition, we are able to shed light on the mechanisms behind the variation in diversity between the four habitat types, which reflect a process of environmental sorting along a habitat gradient going from a more complex to a less complex habitat. We conclude that nesting patterns along the mosaic of habitats are determined by differences in complexity between habitats and that taxonomic and functional uniqueness contribute to overall regional bat diversity and functionality. Ongoing human-induced disturbances of these habitats could provoke an unprecedented loss of bat diversity and functionality with negative consequences for biodiversity and ecosystem services.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Which functional traits allow a bat species to survive habitat disturbance? Empirical evidence regarding this question remains limited for many tropical regions despite their importance for ...conservation. Here, we used body mass, wing morphology, trophic level, and diet to identify which traits make phyllostomid bat species more vulnerable to human impacts in the Colombian Orinoco Llanos. Bats were sampled using mist nets in riparian forests, unflooded forests, flooded savannahs, and conventional rice crops on traditional farmlands with high-intensity agriculture and in private reserves with greater ecosystem protection. We tested the associations between species traits and landscape-structure variables (habitat cover and type, number of habitat patches, shortest distance to water) using RLQ and fourth-corner analyses, accounting for both spatial and phylogenetic autocorrelation. Trophic level and diet were the most important traits linked to disturbance sensitivity. Our results indicated that rice crop cover, savannah patches, and altered unflooded forest act as a filter, benefiting disturbance-adapted frugivorous genera in farmlands (e.g.,
Artibeus
spp.,
Carollia
spp.,
Platyrrhinus
spp.,
Uroderma
spp.). Conversely, animalivorous species were strongly associated with savannah cover and riparian forests within reserves (e.g.,
Lampronycteris brachyotis
,
Lophostoma brasiliense
,
Micronycteris minuta
,
Trachops cirrhosus
). Encouraging the creation of more wildlife-friendly landscapes through payments for ecosystem services across the Colombian Llanos will ensure the long-term persistence of disturbance-sensitive species and sustain a complete set of ecological functions and ecosystem services that these bats provide.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Understanding how interspecific variation in functional traits influences species’ capacity to persist in fragments and use patches in fragmented landscapes is fundamental for the creation of ...effective conservation plans. This study uses phylogenetic comparative methods to investigate which functional traits of bat species are correlated with their vulnerability to fragmentation in a tropical landscape with low fragment–matrix contrast. Bats were captured over two years in eight forest fragments, nine control sites in continuous forest, and in the secondary forest matrix at the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. We tested the hypothesis that there is a significant relationship between species functional traits, environmental gradients (continuous forest and fragment interiors, edges and matrix) and patterns of species distribution using phylogenetic generalized least squares (PGLS) models, as well as a combination of RLQ and fourth‐corner analyses. Mobility, body mass, wing morphology, and trophic level were the most important traits linked to fragmentation sensitivity based on the PGLS analysis, while body mass and trophic level emerged as the best predictors in the fourth‐corner analysis. These last two traits were correlated with the loss of continuous forest characteristics, such as high‐stature trees and forest cover. Many animalivorous bat species rarely persist in small fragments (<100 ha) and in the secondary forest matrix, reflecting strong effects of trait‐mediated environmental filters that selectively benefit the smaller and phytophagous species. Synthesis and applications. Functional traits of species and environmental variables jointly predict local variation in patterns of bat occupancy and abundance in fragmented tropical landscapes. To minimize local extinctions, we recommend increasing habitat availability and enhancing structural and functional connectivity at the landscape scale through the creation, restoration and maintenance of corridors and stepping stones. These measures should be coupled with improving matrix quality by promoting secondary forest regeneration and persistence to effectively reduce fragment–matrix contrast.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
We investigate how variation in patch area and forest cover quantified for three different spatial scales (buffer size of 500, 1500 and 3000 m radius) affects species richness and functional ...diversity of bat assemblages in two ecosystems differing in fragment–matrix contrast: a landbridge island system in Panama and a countryside ecosystem in the Brazilian Amazon. Bats were sampled on 11 islands and the adjacent mainland in Panama, and in eight forest fragments and nearby continuous forest in Brazil. Species–area relationships (SAR) were assessed based on Chao1 species richness estimates, and functional diversity–area relationships (FAR) were quantified using Chao1 functional diversity estimates measured as the total branch length of a trait dendrogram. FARs were calculated using three trait sets: considering five species functional traits (FARALL), and trait subsets reflecting ‘diet breadth’ (FARDIET) and ‘dispersal ability’ (FARDISPERSAL). We found that in both study systems, FARALL was less sensitive to habitat loss than SAR, in the sense that an equal reduction in habitat loss led to a disproportionately smaller loss of functional diversity compared to species richness. However, the inhospitable and static aquatic matrix in the island ecosystem resulted in more pronounced species loss with increasing loss of habitat compared to the countryside ecosystem. Moreover, while we found a significant FARDISPERSAL for the island ecosystem in relation to forest cover within 500 m landscape buffers, FARDIET and FARDISPERSAL were not significant for the countryside ecosystem. Our findings highlight that species richness and functional diversity in island and countryside ecosystems scale fundamentally differently with habitat loss, and suggest that key bat ecological functions, such as pollination, seed dispersal and arthropod suppression, may be maintained in fragments despite a reduction in species richness. Our study reinforces the importance of increasing habitat availability for decreasing the chances of losing species richness in smaller fragments.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Context
Human-modified landscapes are globally ubiquitous. It is critical to understand how habitat loss and fragmentation impact biodiversity from both a local habitat context and landscape-scale ...perspective to inform land management and conservation strategies.
Objectives
We used an experimentally fragmented landscape in the Brazilian Amazon to investigate variation in aerial insectivorous bat diversity in response to local habitat and wider landscape characteristics, applying a multiscale approach.
Methods
We conducted bat acoustic surveys at 33 sites, comprising old secondary forests and fragments of primary forest. Taxonomic, functional and phylogenetic diversity facets were calculated within a Hill numbers framework. We analysed responses to fragment size, interior-edge-matrix gradients, as well as local vegetation structure, continuous forest cover, edge density and patch density across five spatial scales (0.5−3 km) surrounding detector locations.
Results
Compared with continuous forest, secondary forest matrix around the smallest fragments harboured lower diversity. The overall negative effect of the matrix became less pronounced with increasing fragment size. In contrast, forest edges generally contained higher taxonomic, functional and phylogenetic diversity. We found subtle scale-sensitive associations for functional diversity, responding positively to forest cover (at the 1 km scale) and negatively to edge (1 km scale) and patch density (2.5 km scale).
Conclusions
Despite a low-contrast matrix of tall secondary forest surrounding fragments after ~ 30 years of forest recovery, aerial insectivorous bat diversity is not comparable to continuous primary forest. Assemblage functional diversity responds to compositional and configurational landscape characteristics at scales deserving further evaluation at guild and species level.
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EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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