Experimental defaunation of terrestrial mammalian herbivores alters tropical rainforest understorey diversity

Camargo–Sanabria, Angela A.; Mendoza, Eduardo; Guevara, Roger; Martı́nez-Ramos, Miguel; Dirzo, Rodolfo

doi:10.1098/rspb.2014.2580

Cited by 43 publications

(46 citation statements)

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“…Large vertebrates make important contributions to the composition, structure and dynamics of plant communities as seed dispersers (Corlett, ; Howe & Smallwood, ), granivores and herbivores (Beck, Snodgrass, & Thebpanya, ; Camargo‐Sanabria, Mendoza, Guevara, Martínez‐Ramos, & Dirzo, ; Kurten, ; Kurten, Wright, & Carson, ). Over two‐thirds of species of woody plants in tropical forests rely on animals for dispersal (Beaune et al., ; Muller‐Landau & Hardesty, ; Willson & Traveset, ), and large vertebrates are particularly effective dispersers because they consume large quantities of fruits and seeds and often pass the seeds intact after transporting them large distances (Blake, Deem, Mossimbo, Maisels, & Walsh, ; Fragoso, Silvius, & Correa, ; Holbrook & Loiselle, ; Stoner, Riba‐Hernández, Vulinec, & Lambert, ).…”

Section: Introductionmentioning

confidence: 99%

“…Over two‐thirds of species of woody plants in tropical forests rely on animals for dispersal (Beaune et al., ; Muller‐Landau & Hardesty, ; Willson & Traveset, ), and large vertebrates are particularly effective dispersers because they consume large quantities of fruits and seeds and often pass the seeds intact after transporting them large distances (Blake, Deem, Mossimbo, Maisels, & Walsh, ; Fragoso, Silvius, & Correa, ; Holbrook & Loiselle, ; Stoner, Riba‐Hernández, Vulinec, & Lambert, ). Vertebrates are also important mortality agents of seeds, seedlings and saplings in tropical forests (Beck et al., ; Camargo‐Sanabria et al., ; Kurten, ; Theimer, Gehring, Green, & Connell, ). Given the ubiquity of both mutualistic and antagonistic interactions between large vertebrates and plants, the dramatic declines of large‐vertebrate populations observed in tropical forests world‐wide will likely have major consequences for plant communities (Dirzo et al., ; Fa, Peres, & Meeuwig, ; Neuschulz, Mueller, Schleuning, & Böhning‐Gaese, ; Peres, Emilio, Schietti, Desmoulière, & Levi, ; Redford, ).…”

Section: Introductionmentioning

confidence: 99%

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Defaunation increases the spatial clustering of lowland Western Amazonian tree communities

et al. 2018

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Declines of large vertebrates in tropical forests may reduce dispersal of tree species that rely on them, and the resulting undispersed seedlings might suffer increased distance‐ and density‐dependent mortality. Consequently, extirpation of large vertebrates may alter the composition and spatial structure of plant communities and impair ecosystem functions like carbon storage. We analysed spatial patterns of tree recruitment within six forest plots along a defaunation gradient in western Amazonia. We divided recruits into two size cohorts (“saplings”: ≥1 m tall and <1 cm diameter at breast height [dbh], and juveniles, 1–2 cm dbh) and examined the spatial organisation of conspecific recruits within each cohort (within‐cohort) and around conspecific reproductive‐sized trees (between‐cohort). We used replicated spatial point pattern analysis to quantify relationships between recruit clustering and cohort, defaunation intensity, each tree species reliance on hunted dispersers and the interactions among these three covariates. Within‐cohort clustering of conspecific saplings increased with reliance of tree species on hunted dispersers, and this trend strengthened significantly as defaunation increased, probably because of reduced dispersal. Within‐cohort clustering of conspecifics declined from saplings to juveniles, suggesting density‐dependent mortality of saplings. However, the positive relationship between sapling clustering and defaunation did not lead to greater reductions in within‐cohort clustering during the sapling–juvenile transition, suggesting that higher conspecific densities did not translate into increased mortality. Instead, the increased spatial clustering associated with defaunation was retained for juvenile recruits. Between‐cohort clustering was unrelated to defaunation and did not change during the sapling–juvenile transition. Synthesis. Defaunation increased spatial aggregation of saplings of tree species reliant on hunted dispersers. The increase in sapling clustering did not increase density‐dependent thinning, and persisted into older recruit cohorts, suggesting that hunting may initiate long‐term spatial reorganisation of Amazonian tree communities. The lack of increased density‐dependent thinning indicates that reduced dispersal did not increase mortality of large‐vertebrate dispersed tree species that contribute disproportionately to forest biomass. We, therefore, caution against the fait accompli acceptance of the prediction by recent modelling studies that overhunting will precipitate a collapse in carbon sequestration by tropical forests.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Defaunation increases the spatial clustering of lowland Western Amazonian tree communities

et al. 2018

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“…The situation in plants has been less evaluated; thus it is difficult to compare them with animals, but there is little reason to believe that the extinction situation in plants is dramatically different (37). Furthermore, research shows that the loss of animal populations indirectly leads to changes in plant communities (20,37,39), frequently causing the reduction of local species richness and dominance of a few plant taxa that either experience "ecological release" in response to decreasing herbivore pressures (42,43), and/or experience population reductions due to the decline of animals responsible for pollination or dispersal (e.g., refs. [2][3]20).…”

Section: Discussionmentioning

confidence: 99%

Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines

Ceballos

Ehrlich

Dirzo

2017

Proc. Natl. Acad. Sci. U.S.A.

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1,247

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The population extinction pulse we describe here shows, from a quantitative viewpoint, that Earth's sixth mass extinction is more severe than perceived when looking exclusively at species extinctions. Therefore, humanity needs to address anthropogenic population extirpation and decimation immediately. That conclusion is based on analyses of the numbers and degrees of range contraction (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. We find that the rate of population loss in terrestrial vertebrates is extremely high-even in "species of low concern." In our sample, comprising nearly half of known vertebrate species, 32% (8,851/27,600) are decreasing; that is, they have decreased in population size and range. In the 177 mammals for which we have detailed data, all have lost 30% or more of their geographic ranges and more than 40% of the species have experienced severe population declines (>80% range shrinkage). Our data indicate that beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a "biological annihilation" to highlight the current magnitude of Earth's ongoing sixth major extinction event.sixth mass extinction | population declines | population extinctions | conservation | ecosystem service

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“…Nonetheless, unmanaged grazers have a negative impact on rainforests, by increased tree-and particularly seedling-death through wallowing and root compaction, consequently reducing plant recruitment and understorey diversity [52,53]. In the Australian monsoon tropics, feral pigs (Sus scrofa) and cattle (Bos Taurus/indicus) can damage rainforests through trampling vegetation, particularly affecting small rainforest patches [52,54].…”

Section: Introductionmentioning

confidence: 99%

Collaborative Research on the Ecology and Management of the ‘Wulo’ Monsoon Rainforest in Wunambal Gaambera Country, North Kimberley, Australia

Vigilante

Ondei

Goonack

et al. 2017

Land

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Indigenous groups are increasingly combining traditional ecological knowledge and Western scientific approaches to inform the management of their lands. We report the outcomes of a collaborative research project focused on key ecological questions associated with monsoon vine thickets in Wunambal Gaambera country (Kimberley region, Western Australia). The study mapped monsoon rainforests and analysed the environmental correlates of their current distribution, as well as the historical drivers of patch dynamics since 1949. Remote sensing was used to chart the effectiveness of an intervention designed to re-instate Aboriginal fire regimes according to customary principles. We identified the most vulnerable patches based on size, distance from neighbouring patches, and fire frequency. More than 6000 rainforest patches were mapped. Most were small (<1 ha), occurring predominantly on nutrient-rich substrates (e.g., basalt) and fire-sheltered topographic settings (e.g., slopes and valleys). Rainforests with low fire frequency and no cattle were more likely to expand into surrounding long-unburnt savannas. Frequent fires and cattle did not cause substantial contraction, although the latter affected rainforest understories through trampling. Fire management performed by Aboriginal rangers effectively shifted fire regimes from high-intensity late dry season fires to early dry season fires, particularly in areas with clusters of vulnerable rainforests. The remote sensing methods developed in this project are applicable to the long-term monitoring of rainforest patches on Aboriginal-managed land in North Kimberley, providing tools to evaluate the impacts of fire management, feral animal control, and climate change. The study confirmed the importance of the cattle-free and rarely burnt Bougainville Peninsula as one of the most important rainforest areas in Western Australia.

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Experimental defaunation of terrestrial mammalian herbivores alters tropical rainforest understorey diversity

Cited by 43 publications

References 40 publications

Defaunation increases the spatial clustering of lowland Western Amazonian tree communities

Defaunation increases the spatial clustering of lowland Western Amazonian tree communities

Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines

Collaborative Research on the Ecology and Management of the ‘Wulo’ Monsoon Rainforest in Wunambal Gaambera Country, North Kimberley, Australia

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