Related plant species respond similarly to chronic anthropogenic disturbance: Implications for conservation decision‐making

Martínez‐Blancas, Alejandra; Paz, Horacio; Salazar, Gerardo A.; Martorell, Carlos

doi:10.1111/1365-2664.13151

Cited by 15 publications

(11 citation statements)

References 56 publications

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“…As consequence, chronic disturbances and water availability show similar impact on both taxonomic and phylogenetic β-diversity. Other studies have also found similar responses to chronic disturbances and water deficit in phylogenetically related species (Martínez-Blancas et al 2018;Aguirre-Gutiérrez et al 2020). The importance of water availability for plant assemblages is known to be positively related to plant species richness (Francis and Currie 2003;Hawkins et al 2003).…”

Section: Discussionsupporting

confidence: 57%

Unraveling the drivers of plant taxonomic and phylogenetic β-diversity in a human-modified tropical dry forest

et al. 2021

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Biodiversity maintenance in human-modified landscapes largely depends on spatial variations in species composition (β-diversity), but the impact of human disturbance on β-diversity remains poorly understood. We examined how taxonomic and phylogenetic β-diversity of woody plant communities in the Brazilian Caatinga dry forest respond to two emerging threats-chronic anthropogenic disturbance and water scarcity. We separately assessed diversity metrics that give a disproportionate weight to rare species, and metrics weighted by dominant species. We recorded a total of 5118 individuals from 104 species across 19 0.1-ha plots into a 21,430-ha human-modified landscape exposed to chronic disturbances and a high variation in climatic water deficit. At the landscape scale, β-diversity was higher when considering rare species than when focusing on dominant species, especially for the phylogenetic dimension of β-diversity. Water deficit was the primary driver of plant taxonomic and phylogenetic β-diversity, followed by the number of cattle and inter-site isolation; however, rare species seem to depend more strongly on these factors than the dominant ones. Therefore, preserving as much forest as possible, including areas exposed to different disturbance level and climate variables, is critical to prevent the loss of rare species and maintain the compositional differentiation of biotic assemblages. Such forest cover should be maintained in a large number of forest patches scattered through the landscape to preserve biologically and functionally distinct components of this ecosystem, avoid landscape-scale biotic homogenization, and thus favor its ecological resilience.

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Section: Discussionsupporting

confidence: 57%

Unraveling the drivers of plant taxonomic and phylogenetic β-diversity in a human-modified tropical dry forest

et al. 2021

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“…However, there should be a point where human induced changes may decrease local diversity beyond natural levels by combined local extinctions and less likely colonizations through a disturbed matrix (e.g. [ 3 , 75 ]). Thus, in landscapes where most species are sensitive to ongoing disturbances, species losses are likely to overcome arrivals of tolerant species.…”

Section: Discussionmentioning

confidence: 99%

Dynamic and diverse amphibian assemblages: Can we differentiate natural processes from human induced changes?

Lima¹,

Oliveira²,

Souza³

2019

PLoS ONE

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Amphibians are sensitive to anthropogenic habitat alterations but also respond to natural drivers of assemblage composition at many levels. Additionally, they are usually hard to detect in field inventories. We used a multiscale approach, from microhabitat to the landscape levels, to try to understand the effects of natural changes, and try to distinguish them from the effects of landscape level anthropogenic changes, on dynamic and diverse anuran assemblages, taking imperfect detection into account. We conducted thorough field inventories in 16 streams at Serra do Cipó, in the southern portion of Espinhaço Mountain Range, southeastern Brazil, during two time periods separated by 16 years. We compared species richness and diversity between periods, sampling both tadpoles and adult frogs. We quantified tadpole microhabitat availability, alterations in immediate riparian vegetation, and changes in classes of land cover within buffers around streams (adult habitats) to test for their effects on species composition. We also tested for effects of human occupancy around streams on nestedness and turnover components of species diversity. Microhabitats and riparian vegetation explained some of the changes in species composition (or detection) between time periods. Nestedness seemed to be influenced by the stability of the landscape. Detectabilities were too low to support robust occupancy estimates for most species. Natural changes in local habitats occupied by anurans in montane meadows are likely to influence species distribution. Some species with robust estimates experienced change in their occupancy over the studied 16-year interval, although no anthropogenic causes could be directly associated with such changes. The low detectability of most species, even with thorough sampling effort, makes it very hard to detect amphibian declines and possibly tell them apart from natural population fluctuations. New techniques are needed that improve species detectability in such diverse tropical habitats.

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“…Adjacent to the 0.5‐ha plot of three of the sites, there was an additional 0.5‐ha plot where livestock had been excluded since 2001 using electrified fences, altogether resulting in 25 0.5‐ha plots (22 unfenced plus three fenced 0.5‐ha exclosure plots). Data on grazing intensity were already available for these plots (Martínez‐Blancas et al, 2018). Sites were selected by isolation, so that even when distance between them was small, a geographic barrier such as a ravine would separate them.…”

Section: Methodsmentioning

confidence: 99%

The effects of livestock grazing on vegetation in a semiarid grassland: a test of three hypotheses

Vázquez‐Ribera

Martorell

2022

Applied Vegetation Science

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Questions: Livestock grazing is an important driver of plant diversity in grasslands.Different mechanisms summarized in three main hypotheses have been proposed to explain its varying effects depending on productivity. The insufficient compensation hypothesis (ICH) states that livestock causes the extinction of species that cannot compensate for biomass removal in unproductive sites, reducing species richness. The competitive release hypothesis (CRH) states that livestock increases plant diversity by attenuating competition, especially in productive environments. In the convergent evolution hypothesis (CEH), livestock has minor effects on diversity in unproductive sites because plants that endure stress are pre-adapted to grazing. These hypotheses have rarely been compared formally, and have mostly been tested on large spatial scales. Here we simultaneously test these hypotheses on a local scale.Location: Natural semi-arid grassland, Oaxaca, Mexico. Methods:We performed a long-term exclosure experiment, recording plant diversity annually over 17 years. In 2017 we measured species richness over a grazing intensity gradient. We used linear mixed-effects models, nestedness and beta-diversity analyses to evaluate diversity and composition in relation to grazing and productivity.Results: Plant diversity generally increased with grazing intensity. In line with CRH, species richness increased as grazing became more intensive due to a progressive incorporation of increasingly poor competitors to the community, with a seemingly stronger effect under high productivity. This suggests that herbivores limit competitive species and prevent competitive exclusion. ICH may play a secondary role because the effect was reversed in low productivity inside exclosures. Conclusions:Our finding implies that in productive sites, the exclusion of livestock can be detrimental to plant diversity as a lack of grazing accelerates competitive exclusion. By contrast, in limiting environments, grazing can preserve diversity if livestock are kept at low stocking densities. Our results show that small-scale variations in productivity need to be considered when designing livestock management.

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Related plant species respond similarly to chronic anthropogenic disturbance: Implications for conservation decision‐making

Cited by 15 publications

References 56 publications

Unraveling the drivers of plant taxonomic and phylogenetic β-diversity in a human-modified tropical dry forest

Unraveling the drivers of plant taxonomic and phylogenetic β-diversity in a human-modified tropical dry forest

Dynamic and diverse amphibian assemblages: Can we differentiate natural processes from human induced changes?

The effects of livestock grazing on vegetation in a semiarid grassland: a test of three hypotheses

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