Species‐specific disturbance tolerance, competition and positive interactions along an anthropogenic disturbance gradient

Villarreal-Barajas, Tania; Martorell, Carlos

doi:10.1111/j.1654-1103.2009.01101.x

Cited by 39 publications

(49 citation statements)

References 69 publications

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“…Our main focus is on the role of social information and heterospecific attraction in structuring the species community. As facilitative processes are expected to dominate over competitive processes in continuously perturbed environments (Bertness & Callaway 1994;Villarreal-Barajas & Martorell 2009), we predicted the predominance of positive co-occurrence patterns in this system. However, as some of the species have very similar niches and thus are likely to show strong competitive interactions, we predicted that the co-occurrence pattern could be negative for some pairs of species.…”

Section: Introductionmentioning

confidence: 93%

Testing the heterospecific attraction hypothesis with time-series data on species co-occurrence

et al. 2010

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The distributional patterns of actively moving animals are influenced by the cues that the individuals use for choosing sites into which they settle. Individuals may gather information about habitat quality using two types of strategies, either directly assessing the relevant environmental factors, or using the presence of conspecifics or heterospecifics as an indirect measure of habitat quality. We examined patterns of heterospecific attraction with observational time-series data on a community of seven waterbird species breeding in artificial irrigation ponds. We fitted to the data a multivariate logistic regression model, which attributes the presence -absence of each species to a set of environmental and spatial covariates, to the presence of con-and heterospecifics in the previous year and to the presence of heterospecifics in the same year. All species showed a clear tendency to continue breeding in the same sites where they were observed in the previous year. Additionally, the presence of heterospecifics, both in the previous year and in the same year, generally increased the probability that the focal species was found breeding on a given pond. Our data thus give support for the heterospecific attraction hypothesis, though causal inference should be confirmed with manipulative experiments.

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Section: Introductionmentioning

confidence: 93%

Testing the heterospecific attraction hypothesis with time-series data on species co-occurrence

et al. 2010

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“…In stressful systems that present sporadic resource pulses, stress drives plant growth over the scarcity period, while competition occurs during benign bouts (Fowler 1986;Briones et al 1998;Chesson et al 2004). In arid environments, shrub removal by CAD may increase water stress by reducing infiltration and increasing soil moisture loss (Valiente-Banuet and Ezcurra 1991; Rietkerk et al 1997;Adair et al 2008;Villarreal-Barajas and Martorell 2009). This may explain why, on most years, cactus' size became smaller in DS, where shrub cover was only 3% compared to 15% in NDS.…”

Section: Vital Rates and Population Dynamicsmentioning

confidence: 98%

Ruderality in extreme‐desert cacti? Population effects of chronic anthropogenic disturbance on Echinocereus lindsayi

2012

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Ruderal species, i.e., those that increase their numbers in the presence of disturbance, are not expected to occur in extreme environments. We test whether Echinocereus lindsayi, a cactus from an extreme desert, follows the ruderal trend observed in similar species from mild deserts, or, as theory suggests, it is a non ruderal. Contrary to expectations, its density and fraction of small individuals in the population increased with disturbance. This seemingly results from increased establishment, as it is nursed by rocks exposed by disturbance. A demographic model for two populations, one nearly pristine and another highly disturbed, showed that at the latter site recruitment was more frequent and likely. At the disturbed site the performance of E. lindsayi individuals was usually poor, except on favorable years. Then, competition release caused by disturbance apparently allowed for a better performance compared to the less disturbed site. Despite that this opportunistic behavior would suffice to maintain the population size stable, the large mortality produced by an insect outbreak in two of the four study years caused the population to diminish. In contrast, the population at the less disturbed site was near equilibrium. If the insect outbreak is associated to disturbance, E. lindsayi at the disturbed site would be already experiencing more disturbance than it tolerates. This agrees with the fact that no populations were found at greater disturbance intensities. While, contrary to our hypothesis, E. lindsayi is ruderal, this extreme desert species appears to tolerate far less disturbance than its counterparts from milder areas.

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“…We recorded the number of individuals of all species in 20 randomly chosen 0.1 9 0.1 m squares in each quadrat. This sampling unit was selected because it probably reflects the scale over which interactions occur given the extremely small sizes of plants in this grassland (Freckleton & Watkinson 2001b;Villareal-Barajas & Martorell 2009). Only presence-absence was recorded for three highly clonal species (Bouteloua polymorpha and Tripogon spicatus).…”

Section: A T Amentioning

confidence: 99%

Testing the roles of competition, facilitation and stochasticity on community structure in a species‐rich assemblage

2013

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Summary1. There is an ongoing debate about whether communities are closely integrated and bound together via interactions such as competition or facilitation, or are disintegrated and dominated by chance. We still lack community-wide data on the intensities of interactions and randomness, and measurements of their impacts on community structure. 2. Using a long-term data set, we sought to measure the effects of interactions and stochasticity in structuring a highly diverse (>100 species) semi-arid grassland plant community, testing for positive and negative interactions at different stages of population growth of all species. 3. During the colonization of new patches, most species were facilitated or inhibited by several others. These opposite effects can potentially have a large effect on species abundances, but they were correlated and cancelled out at the community level. Nevertheless, competition during colonization was strong enough to cause poor competitors to have small population sizes. 4. The subsequent phase of population growth (increase and subsequent change in numbers within occupied patches) was mainly driven by intraspecific density dependence, and we found little evidence for interspecific interactions. 5. Model results showed that stochasticity and recurrent colonization of transient, favourable patches maintained diversity, keeping poor competitors from becoming extinct. 6. Synthesis: Our results, taken together with recent studies on tropical forests, suggest that weak interactions among established plants may be a general phenomenon, but that local interactions during colonization are important drivers of community composition. Most of the variance in species abundance in our community was explained by intraspecific competition and stochasticity, with interspecific interactions playing a minor role due to their overall weakness, interaction changes over ontogeny, and the cancellation of opposite-sign interactions when all the species in the community are considered. Despite this, some species were rare seemingly because they cannot withstand interspecific competition. Thus, to untangle the effects of interactions on community structure, future research should focus on interactions occurring at different phases of population growth and on whole communities.

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Species‐specific disturbance tolerance, competition and positive interactions along an anthropogenic disturbance gradient

Cited by 39 publications

References 69 publications

Testing the heterospecific attraction hypothesis with time-series data on species co-occurrence

Testing the heterospecific attraction hypothesis with time-series data on species co-occurrence

Ruderality in extreme‐desert cacti? Population effects of chronic anthropogenic disturbance on Echinocereus lindsayi

Testing the roles of competition, facilitation and stochasticity on community structure in a species‐rich assemblage

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