Long-term exclosure of large terrestrial vertebrates: Implications of defaunation for seedling demographics in the Amazon rainforest

Beck, Harald; Snodgrass, Joel W.; Thebpanya, Paporn

doi:10.1016/j.biocon.2013.03.012

Cited by 64 publications

(64 citation statements)

References 43 publications

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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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“…We therefore have a poor understanding of direct effects of diversity within higher trophic levels or the indirect, cascading effects of biodiversity loss across tropic levels (but see [14]). There is mounting evidence that changes in forest vertebrate communities can lead to direct top-down consequences for plant demography, community composition and diversity [15][16][17][18][19][20][21][22], with knock-on effects for forest services and resilience [23,24]. However, because the indirect, multitrophic consequences of changing mammal communities are rarely experimentally tested, we have limited understanding of the ecosystem-wide consequences of anthropogenic impacts on tropical forests.…”

Section: Introductionmentioning

confidence: 99%

The value of trophic interactions for ecosystem function: dung beetle communities influence seed burial and seedling recruitment in tropical forests

et al. 2016

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Anthropogenic activities are causing species extinctions, raising concerns about the consequences of changing biological communities for ecosystem functioning. To address this, we investigated how dung beetle communities influence seed burial and seedling recruitment in the Brazilian Amazon. First, we conducted a burial and retrieval experiment using seed mimics. We found that dung beetle biomass had a stronger positive effect on the burial of large than small beads, suggesting that anthropogenic reductions in large-bodied beetles will have the greatest effect on the secondary dispersal of large-seeded plant species. Second, we established mesocosm experiments in which dung beetle communities buried Myrciaria dubia seeds to examine plant emergence and survival. Contrary to expectations, we found that beetle diversity and biomass negatively influenced seedling emergence, but positively affected the survival of seedlings that emerged. Finally, we conducted germination trials to establish the optimum burial depth of experimental seeds, revealing a negative relationship between burial depth and seedling emergence success. Our results provide novel evidence that seed burial by dung beetles may be detrimental for the emergence of some seed species. However, we also detected positive impacts of beetle activity on seedling recruitment, which are probably because of their influence on soil properties. Overall, this study provides new evidence that anthropogenic impacts on dung beetle communities could influence the structure of tropical forests; in particular, their capacity to regenerate and continue to provide valuable functions and services.

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“…These animals affects plant population dynamics through herbivory and physical damage (e.g. Dirzo & Miranda 1990, Keuroghlian & Eaton 2009, Beck et al 2013, and also through their role as seed dispersers and predators (e.g. Asquith et al 1997, Asquith et al 1999, Galetti et al 2006, Donatti et al 2009, Kuprewicz 2013 contributing to plant local diversity.…”

Section: Introductionmentioning

confidence: 99%

Medium and large-sized mammals of the Reserva Ecológica de Guapiaçú, Cachoeiras de Macacu, RJ

2014

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Medium and large-sized terrestrial mammals develop important functions in ecosystems maintenance. However, this group is the most vulnerable to local extinctions, through habitat loss or hunting. This study inventoried the community of medium and large mammals in the Reserva Ecológica de Guapiaçú (REGUA), Cachoeiras de Macacu, RJ, providing data on species composition, richness and abundance. Species were registered through the use of camera traps, sign survey and visual encounters on pre-existing trails and roads. The study was conducted from January to October 2012, with each month considered as a sample unit. An effort of 1568 cameras-day and 120 km traveled, resulted on 302 records of 22 species of medium and large-sized mammals, belonging to eight orders. This value corresponds to more than three-quarters of the richness described from this group in the Atlantic Forest of Rio de Janeiro state. Five species are under some level of regional, national or global threat. Three game species, Pecari tajacu, Cuniculus paca and Dasyprocta leporina were abundant in the area. The observed richness was comparable to that found in other studies conducted in rain forests. Thus, for its high number of species, including those under some degree of threat, we conclude that REGUA is an important area to mammal conservation, especially in the Atlantic Forest of Rio de Janeiro state.

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Long-term exclosure of large terrestrial vertebrates: Implications of defaunation for seedling demographics in the Amazon rainforest

Cited by 64 publications

References 43 publications

Defaunation increases the spatial clustering of lowland Western Amazonian tree communities

Defaunation increases the spatial clustering of lowland Western Amazonian tree communities

The value of trophic interactions for ecosystem function: dung beetle communities influence seed burial and seedling recruitment in tropical forests

Medium and large-sized mammals of the Reserva Ecológica de Guapiaçú, Cachoeiras de Macacu, RJ

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