Chronic anthropogenic disturbance as a secondary driver of ant community structure: interactions with soil type in Brazilian Caatinga

Oliveira, Fernanda M. P.; Ribeiro‐Neto, José Domingos; Andersen, Alan N.; Leal, Inara R.

doi:10.1017/s0376892916000291

Cited by 29 publications

(20 citation statements)

References 44 publications

(76 reference statements)

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“…Such results are contrary to those of Leal, Andersen, & Leal, (), who found at another Caatinga location that CAD had negative effects on the abundance of high‐quality dispersers and consequently on seed dispersal services by ants. However, our study was conducted on sandy soils while the previous study included clay soils, and Caatinga ant communities on sandy soils have been previously shown to be particularly resilient to CAD (Oliveira, Ribeiro‐Neto, Andersen, & Leal, ). In addition, mean annual rainfall in the previous study was only 550 mm, at the arid extreme of our study, and this might also be a factor explaining the higher sensitivity of seed‐disperser ants to disturbance.…”

Section: Discussionmentioning

confidence: 99%

Effects of increasing aridity and chronic anthropogenic disturbance on seed dispersal by ants in Brazilian Caatinga

Oliveira

Andersen

Arnán

et al. 2019

Journal of Animal Ecology

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Anthropogenic disturbance and climate change are the main drivers of biodiversity loss and ecological services around the globe. There is concern that climate change will exacerbate the impacts of disturbance and thereby promote biotic homogenization, but its consequences for ecological services are unknown. We investigated the individual and interactive effects of increasing chronic anthropogenic disturbance (CAD) and aridity on seed dispersal services provided by ants in Caatinga vegetation of north‐eastern Brazil. The study was conducted in Catimbau National Park, Pernambuco, Brazil. Within an area of 214 km2, we established nineteen 50 × 20 m plots that encompassed gradients of both CAD and aridity. We offered diaspores of six plant species, three myrmecochorous diaspores and three fleshy fruits that are secondarily dispersed by ants. We then quantified the number of interactions, seed removal rate and dispersal distances, and noted the identities of interacting ant species. Finally, we used pitfall trap data to quantify the abundances of ant disperser species in each plot. Our results show that overall composition of ant disperser species varied along the gradients of CAD and aridity, but the composition of high‐quality dispersers varied only with aridity. The total number of interactions, rates of removal and mean distance of removal all declined with increasing aridity, but they were not related to CAD. These same patterns were found when considering only high‐quality disperser species, driven by the responses of the dominant disperser Dinoponera quadriceps. We found little evidence of interactive effects of CAD and aridity on seed dispersal services by ants. Our study indicates that CAD and aridity act independently on ant‐mediated seed dispersal services in Caatinga, such that the impacts of anthropogenic disturbance are unlikely to change under the forecast climate of increased aridity. However, our findings highlight the vulnerability of seed dispersal services provided by ants in Caatinga under an increasingly arid climate due to low functional redundancy in high‐quality disperser species. Given the large number of plant species dependent on ants for seed dispersal, this has important implications for future plant recruitment and, consequently, for the composition of Caatinga plant communities.

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Section: Discussionmentioning

confidence: 99%

Effects of increasing aridity and chronic anthropogenic disturbance on seed dispersal by ants in Brazilian Caatinga

Oliveira

Andersen

Arnán

et al. 2019

Journal of Animal Ecology

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“…Some studies have found that CADs and rainfall influence plant (Ribeiro et al., ; Ribeiro et al. ; Rito et al., ) and ant (Oliveira et al., ; Ribeiro‐Neto et al., ) community structure and composition in the Caatinga. We also observed that CADs and rainfall levels were associated with changes in the compositions of EFN‐bearing plant communities and attendant ant communities, supporting part of our third hypothesis.…”

Section: Discussionmentioning

confidence: 99%

“…Although such networks occur in many different ecosystems (Rico‐Gray & Oliveira, ), the protection provided by ants to EFN‐bearing plants appears to be particularly effective in arid environments (Leal & Peixoto, ). However, arid environments usually experience significant anthropogenic disturbance (Miles et al., ), which can lead to declines in the abundance of specialist EFN‐bearing plants (Leal et al., ), the abundance of specialist arboreal ants (Oliveira et al., ) and ant visitation rates (Leal et al., ).…”

Section: Introductionmentioning

confidence: 99%

“…The consequence is the emergence of heterogeneous landscapes of resource use (Martorell & Peters, 2005;Ribeiro, Arroyo-Rodríguez, Santos, Tabarelli, & Leal, 2015). Although the effects of CADs have only recently started to be evaluated, some studies have already revealed they are significant for plants (Hernández-Oria, Chavez, & Sánchez, 2006;Ribeiro et al, 2015;Rito, Arroyo-Rodríguez, Queiroz, Leal, & Tabarelli, 2017), animals (Oliveira, Ribeiro-Neto, Andersen, & Leal, 2017;Ribeiro-Neto, Arnan, Tabarelli, & Leal, 2016) and plant-animal interactions (Leal, Andersen, & Leal, 2014. Moreover, in the dry tropics, it has been predicted that climate change will increase temperatures and decrease precipitation by 2100 (Magrin et al, 2014), which will threaten natural biota (Feng, Porporato, & Rodriguez-Iturbe, 2013;Miles et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…However, arid environments usually experience significant anthropogenic disturbance (Miles et al, 2006), which can lead to declines in the abundance of specialist EFN-bearing plants , the abundance of specialist arboreal ants (Oliveira et al, 2017) and ant visitation rates .…”

Section: Introductionmentioning

confidence: 99%

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Effects of chronic anthropogenic disturbance and rainfall on the specialization of ant–plant mutualistic networks in the Caatinga, a Brazilian dry forest

Câmara

Leal

Blüthgen

et al. 2018

Journal of Animal Ecology

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Anthropogenic disturbance and climate change might negatively affect the ecosystem services provided by mutualistic networks. However, the effects of such forces remain poorly characterized. They may be especially important in dry forests, which (1) experience chronic anthropogenic disturbances (CADs) as human populations exploit forest resources, and (2) are predicted to face a 22% decline in rainfall under climate change. In this study, we investigated the separate and combined effects of CADs and rainfall levels on the specialization of mutualistic networks in the Caatinga, a seasonally dry tropical forest typical of north-eastern Brazil. More specifically, we examined interactions between plants bearing extrafloral nectaries (EFNs) and ants. We analysed whether differences in network specialization could arise from environmentally mediated variation in the species composition, namely via the replacement of specialist by generalist species. We characterized these ant-plant networks in 15 plots (20 × 20 m) that varied in CAD intensity and mean annual rainfall. We quantified CAD intensity by calculating three indices related to the main sources of disturbance in the Caatinga: livestock grazing (LG), wood extraction (WE) and miscellaneous resource use (MU). We determined the degree of ant-plant network specialization using four metrics: generality, vulnerability, interaction evenness and H '. Our results indicate that CADs differentially influenced network specialization: we observed positive, negative, and neutral responses along LG, MU and WE gradients, respectively. The pattern was most pronounced with LG. Rainfall also shaped network specialization, markedly increasing it. While LG and rainfall were associated with changes in network species composition, this trend was not related to the degree of species specialization. This result suggests that shifts in network specialization might be related to changes in species behaviour, not species composition. Our study highlights the vulnerability of such dry forest ant-plant networks to climate change. Moreover, dry forests experience highly heterogeneous anthropogenic disturbances, creating a geographic mosaic of selective forces that may shape the co-evolution of interactions between ants and EFN-bearing plants.

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Habitat‐contingent responses to disturbance: impacts of cattle grazing on ant communities vary with habitat complexity

Arcoverde

Andersen

Leal

et al. 2018

Ecological Applications

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Predicting community responses to disturbance is a major challenge for both ecology and ecosystem management. A particularly challenging issue is that the same type and intensity of disturbance can have different impacts in different habitats. We investigate how habitat contingency influences ant community responses to disturbance in arid Australia, testing the hypothesis that disturbance has a greater impact in more complex habitats. We also assess the effectiveness of a highly simplified ant assessment protocol that considers larger species only. We sampled ants at 46 sites from two habitats (Chandler, low chenopod shrubland; and mulga, low woodland) with contrasting complexity, using distance from water as a surrogate for variation in grazing intensity. We assessed variation in habitat structural variables (basal area of perennial grass, and cover of herbs, litter, and bare ground) and ant communities in relation to habitat and distance from water, first using data from the entire ant community and then for larger ants (>4 mm body length) only. Site species richness was almost twice as high in mulga, the more structurally complex habitat, than in Chandler, and ant communities in mulga showed far more variation in relation to distance from water. Litter cover was the key environmental variable associated with the interaction between grazing and habitat: it increased with increasing distance from water in mulga and was virtually absent from Chandler. Analysis of only larger species revealed the same patterns of variation in ant abundance, species richness and composition in relation to habitat and grazing as shown by entire ant communities. Our findings support the hypothesis that disturbance impacts on faunal communities increase with increasing habitat complexity. An appreciation of such habitat contingency is important for a predictive understanding and therefore effective management of disturbances such as rangeland grazing. Our findings also show that simplified assessment can provide robust information on the responses of highly diverse ant communities to disturbance, which enhances their feasibility for use as bio-indicators in land management.

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Chronic anthropogenic disturbance as a secondary driver of ant community structure: interactions with soil type in Brazilian Caatinga

Cited by 29 publications

References 44 publications

Effects of increasing aridity and chronic anthropogenic disturbance on seed dispersal by ants in Brazilian Caatinga

Effects of increasing aridity and chronic anthropogenic disturbance on seed dispersal by ants in Brazilian Caatinga

Effects of chronic anthropogenic disturbance and rainfall on the specialization of ant–plant mutualistic networks in the Caatinga, a Brazilian dry forest

Habitat‐contingent responses to disturbance: impacts of cattle grazing on ant communities vary with habitat complexity

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