Corridors restore animal-mediated pollination in fragmented tropical forest landscapes

Kormann, Urs G.; Scherber, Christoph; Tscharntke, Teja; Klein, Nadja; Larbig, Manuel; Valente, Jonathon J.; Hadley, Adam S.; Betts, Matthew G.

doi:10.1098/rspb.2015.2347

Cited by 81 publications

(92 citation statements)

References 49 publications

(100 reference statements)

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“…tortuosa (a species for which green hermits are a primary pollinator; [19]), isolated patches [21] despite adequate pollen delivery suggesting that lower quality pollen is being delivered. Strong avoidance of open areas at the path scale should result in greater rates of pollen flow in connected versus unconnected patches [45] with implications for heterozygosity in the short term, and ultimately the capacity for plants to respond to environmental change [11]. Conservation policies that promote forest connectivity are likely to be vital for the maintenance of healthy ecosystems by promoting increased gene exchange among flowering plants [13].…”

Section: Discussionmentioning

confidence: 99%

Tropical Forest Fragmentation Limits Movements, but Not Occurrence of a Generalist Pollinator Species

et al. 2016

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Habitat loss and fragmentation influence species distributions and therefore ecological processes that depend upon them. Pollination may be particularly susceptible to fragmentation, as it depends on frequent pollinator movement. Unfortunately, most pollinators are too small to track efficiently which has precluded testing the hypothesis that habitat fragmentation reduces or eliminates pollen flow by disrupting pollinator movement. We used radio-telemetry to examine space use of the green hermit hummingbird (Phaethornis guy), an important ‘hub’ pollinator of understory flowering plants across substantial portions of the neotropics and the primary pollinator of a keystone plant which shows reduced pollination success in fragmented landscapes. We found that green hermits strongly avoided crossing large stretches of non-forested matrix and preferred to move along stream corridors. Forest gaps as small as 50 m diminished the odds of movement by 50%. Green hermits occurred almost exclusively inside the forest, with the odds of occurrence being 8 times higher at points with >95% canopy cover compared with points having <5% canopy cover. Nevertheless, surprisingly. the species occurred in fragmented landscapes with low amounts of forest (~30% within a 2 km radius). Our results indicate that although green hermits are present even in landscapes with low amounts of tropical forest, movement within these landscapes ends up strongly constrained by forest gaps. Restricted movement of pollinators may be an underappreciated mechanism for widespread declines in pollination and plant fitness in fragmented landscapes, even when in the presence of appropriate pollinators.

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Section: Discussionmentioning

confidence: 99%

Tropical Forest Fragmentation Limits Movements, but Not Occurrence of a Generalist Pollinator Species

et al. 2016

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“…We chose the fragmented Coto Brus region, where the degree of habitat destruction (70% forest loss of the original forest cover (Zahawi, Duran, & Kormann, ) is representative for HMTLs of many Latin American regions with moderately intensive land‐use (Lindquist et al., ). Birds are crucial providers of key ecosystem functions, and their disappearance in tropical systems has been linked to pervasive reductions of ecosystem functions such as pollination, seed dispersal and herbivore control, and rapid evolutionary changes in mutualistic partners (Galetti et al., ; Hadley, Frey, Robinson, John Kress, & Betts, ; Karp et al., ; Kormann et al., ). Further, birds are highly sensitive to disturbance of native forest (Barlow et al., ; Gibson et al., ), with forest specialists and particularly forest‐dependent insectivores being among the most vulnerable organisms to forest modification (Barlow et al., ; Carrara et al., ; Gibson et al., ; Morante‐Filho et al., ; Powell, Cordeiro, & Stratford, ; Powell, Wolfe, et al., ).…”

Section: Introductionmentioning

confidence: 99%

Primary rainforest amount at the landscape scale mitigates bird biodiversity loss and biotic homogenization

Kormann

Hadley

Tscharntke

et al. 2018

Journal of Applied Ecology

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Tropical conservation strategies traditionally focus on large tracts of pristine forests but, given rapid primary forest decline, understanding the role of secondary forest remnants for biodiversity maintenance is critical. Until now, the interactive effects of changes in forest amount, configuration and disturbance history (secondary vs. primary forest) on the conservation value of tropical landscapes have remained unknown, hampering the incorporation of these global change drivers into local and global conservation planning. We disentangled effects of landscape‐wide forest amount, fragment size and forest age (old growth vs. secondary forest) on abundance, α‐diversity, β‐diversity (biotic homogenization) and community shifts of bird communities in human‐dominated landscapes of southern Costa Rica. Utilizing two complementary methods, yielding 6,900 individual detections and 223 species, we characterized bird communities in 49 forest fragments representing independent gradients in fragment size (<5 ha vs. >30 ha) and forest amount (5%–80%) in the surrounding landscape (within 1000 m). Abundance and α‐diversity of forest specialists and insectivores declined by half in small fragments, but only in landscapes with little old‐growth forest. Conversely, secondary forest at the landscape scale showed no such compensation effect. Similarly, a null‐model approach indicated significant biotic homogenization in small vs. large fragments, but only in landscapes with little old‐growth forest, suggesting forest amount and configuration interactively affect β‐diversity in tropical human‐dominated landscapes. Finally, dramatic abundance‐based community shifts relative to intact forests are largely a result of landscape‐scale loss of old growth rather than changes in overall forest cover. Policy implications. Our study provides strong evidence that retaining old growth within tropical human‐modified landscapes can simultaneously curb erosion of avian forest specialist α‐diversity, mitigate collapse of β‐diversity (biotic homogenization) and dampen detrimental avian community shifts. However, secondary forests play, at best, a subordinate role to mitigate these processes. To maintain tropical forest biodiversity, retaining old‐growth forest within landscapes should be first priority, highlighting a land‐sparing approach.

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“…For these reasons, the maintenance of biological corridors is a valuable conservation strategy to protect biological diversity (Saunders and Hobbs 1991). Knowledge of connections between environments and the biota exchange is essential for planning the accurate management of natural areas and avoiding habitat fragmentation processes (Evans et al 2013, Kormann et al 2016, MacClintock et al 1977). Studies on connections and interactions between the biota are considered as a crossroad where biogeographical provinces converge (Morrone 2017), creating a mosaic of environments in a relatively small territory (Grela 2004, Simó et al 2014, Simó et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The spider fauna from Uruguay River islands: understanding its role in a biological corridor

Laborda¹,

de²,

Pérez‐Miles³

et al. 2018

BDJ

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Biological corridors are connections which link habitats in a regional scale, allowing the gene flow between populations. The Uruguay River comprises riverside and insular riparian forests along subtropical to temperate zones passing through different biogeographic provinces. The aim of this study was to characterise the spider fauna from the Uruguay River islands highlighting their connection role for the spider community of riparian forest. Spiders were studied from surveys in a fluvial island of the southern course of the river with nine campaigns being carried out from September 2007 to September 2009. Three complementary collecting methods were used: G-Vac, night hand collecting and pitfall traps. A total of 58 samples were taken in each campaign. A total of 33 families, 145 species/morphospecies and 8 guilds were registered. Theridiidae and space web weavers showed the highest abundance and species richness. Web weavers were predominant in the spider community evidencing the importance of the forest vegetation heterogeneity in spider diversity. Fifteen species have been recorded for the first time for Uruguay. Additional data of previous surveys in the northern islands of the river were analysed and compared. Several species confirm the role of the Uruguay River as a biological corridor from the upper to lower course of the river. The riparian forests from the islands constitute a southernmost intromission of Paranaense biota between Chaco and Pampa regions along the river. The results obtained are an important input for the conservation of these areas. Knowing the biodiversity, as well as its dynamics and the flow of biota that exists in these environments, would allow planning the management from a regional point of view.

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Corridors restore animal-mediated pollination in fragmented tropical forest landscapes

Cited by 81 publications

References 49 publications

Tropical Forest Fragmentation Limits Movements, but Not Occurrence of a Generalist Pollinator Species

Tropical Forest Fragmentation Limits Movements, but Not Occurrence of a Generalist Pollinator Species

Primary rainforest amount at the landscape scale mitigates bird biodiversity loss and biotic homogenization

The spider fauna from Uruguay River islands: understanding its role in a biological corridor

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