Spatial heterogeneity and functional response: an experiment in microcosms with varying obstacle densities

Hauzy, Céline; Tully, Thomas N.; Spataro, Thierry; Paul, Gregory S.; Arditi, Roger

doi:10.1007/s00442-010-1585-5

Cited by 37 publications

(45 citation statements)

References 47 publications

(63 reference statements)

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“…Spatial structure has also been shown to be an important stabilizing factor of consumer-resource interactions (Murdoch et al 2003;Briggs and Hoopes 2004;Amarasekare 2008). Indeed, spatial structure increases consumerresource persistence by creating permanent or temporary refuges for the resource (Huffaker 1958;Ellner et al 2001;Neubert et al 2002;Brockhust et al 2006;Hauzy et al 2010b). Local extinctions can also be prevented by dispersal from other patches (Holyoak and Lawler 1996), and populations in unfavorable ecosystems (sinks) can be maintained by immigration from more favorable source ecosystems (Amezcua and Holyoak 2000;Casini et al 2012).…”

Section: Introductionmentioning

confidence: 96%

The Paradox of Enrichment in Metaecosystems

Gounand¹,

Mouquet²,

Canard³

et al. 2014

The American Naturalist

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The paradox of enrichment has been studied almost exclusively within communities or metacommunities, without explicit nutrient dynamics. Yet local recycling of materials from enriched ecosystems may affect the stability of connected ecosystems. Here we study the effect of nutrient, detritus, producer, and consumer spatial flows-combined with changes in regional enrichment-on the stability of a metaecosystem model. We considered both spatially homogeneous and heterogeneous enrichment. We found that nutrient and detritus spatial flows are destabilizing, whereas producer or consumer spatial flows are either neutral or stabilizing. We noticed that detritus spatial flows have only a weak impact on stability. Our study reveals that heterogeneity no longer stabilizes well-connected systems when accounting for explicit representation of nutrient dynamics. We also found that intermediate consumer diffusion could lead to multiple equilibria in strongly enriched metaecosystems. Stability can emerge from a top-down control allowing the storage of materials into inorganic form, a mechanism never documented before. In conclusion, local enrichment can be stabilized if spatial flows are strong enough to efficiently redistribute the local excess of enrichment to unfertile ecosystems. However, high regional enrichment can be dampened only by intermediate consumer diffusion rates.

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Section: Introductionmentioning

confidence: 96%

The Paradox of Enrichment in Metaecosystems

Gounand¹,

Mouquet²,

Canard³

et al. 2014

The American Naturalist

Self Cite

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“…Another lack of reality in laboratory studies is due to oversimplified environmental conditions that are typically provided within artificial arenas. There are only a limited number of studies focussing on the effects of habitat complexity on the functional response of terrestrial predators (Kaiser 1983; Munyaneza and Obrycki 1997; Pitt and Ritchie 2002; Hoddle 2003; Hohberg and Traunspurger 2005; Hauzy et al 2010; Vucic-Pestic et al 2010a). While some of these studies focussed on the fractal complexity of an artificially structured habitat (Kaiser 1983; Pitt and Ritchie 2002; Hoddle 2003) and others made qualitative comparisons of with-structure- versus non-structure-treatments (Hohberg and Traunspurger 2005; Vucic-Pestic et al 2010a), there is only one study to our knowledge with a qualitative comparison between a simplified, unstructured laboratory setting and field conditions (Munyaneza and Obrycki 1997).…”

Section: Introductionmentioning

confidence: 99%

Habitat structure alters top-down control in litter communities

2012

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The question whether top-down or bottom-up forces dominate trophic relationships, energy flow, and abundances within food webs has fuelled much ecological research with particular focus on soil litter ecosystems. Because litter simultaneously provides habitat structure and a basal resource, disentangling direct trophic and indirect non-trophic effects on different trophic levels remains challenging. Here, we focussed on short-term per capita interaction strengths of generalist predators (centipedes) on their microbi-detritivore prey (springtails) and addressed how the habitat structuring effects of the leaf litter modifies this interaction. We performed a series of laboratory functional response experiments where four levels of habitat structure were constructed by adding different amounts of leaf litter to the experimental arenas. We found that increased leaf litter reduced the consumption rate of the predator. We interpreted this as a dilution effect of the augmented habitat size provided by the increasing leaf litter surface available to the species. Dilution of the prey population decreased encounter rates, whereas the capture success was not affected. Interestingly, our results imply that top-down control by centipedes decreased with increasing resource supply for the microbi-detritivore prey (i.e. the leaf litter that simultaneously provides habitat structure). Therefore, effective top-down control of predators on microbi-detritvore populations seems unlikely in litter-rich ecosystems due to the non-trophic, habitat-structuring effect of the basal litter resource.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-012-2530-6) contains supplementary material, which is available to authorized users.

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“…Indeed, short term experiments investigating the effects of habitat complexity typically focus on predator-prey relationships (e.g. [8]) because predators are either hindered [9,34] or aided [35] in their search for prey when structure is present and ‘complex’.…”

Section: Discussionmentioning

confidence: 99%

Habitat Complexity in Aquatic Microcosms Affects Processes Driven by Detritivores

et al. 2016

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Habitat complexity can influence predation rates (e.g. by providing refuge) but other ecosystem processes and species interactions might also be modulated by the properties of habitat structure. Here, we focussed on how complexity of artificial habitat (plastic plants), in microcosms, influenced short-term processes driven by three aquatic detritivores. The effects of habitat complexity on leaf decomposition, production of fine organic matter and pH levels were explored by measuring complexity in three ways: 1. as the presence vs. absence of habitat structure; 2. as the amount of structure (3 or 4.5 g of plastic plants); and 3. as the spatial configuration of structures (measured as fractal dimension). The experiment also addressed potential interactions among the consumers by running all possible species combinations. In the experimental microcosms, habitat complexity influenced how species performed, especially when comparing structure present vs. structure absent. Treatments with structure showed higher fine particulate matter production and lower pH compared to treatments without structures and this was probably due to higher digestion and respiration when structures were present. When we explored the effects of the different complexity levels, we found that the amount of structure added explained more than the fractal dimension of the structures. We give a detailed overview of the experimental design, statistical models and R codes, because our statistical analysis can be applied to other study systems (and disciplines such as restoration ecology). We further make suggestions of how to optimise statistical power when artificially assembling, and analysing, ‘habitat complexity’ by not confounding complexity with the amount of structure added. In summary, this study highlights the importance of habitat complexity for energy flow and the maintenance of ecosystem processes in aquatic ecosystems.

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Spatial heterogeneity and functional response: an experiment in microcosms with varying obstacle densities

Cited by 37 publications

References 47 publications

The Paradox of Enrichment in Metaecosystems

The Paradox of Enrichment in Metaecosystems

Habitat structure alters top-down control in litter communities

Habitat Complexity in Aquatic Microcosms Affects Processes Driven by Detritivores

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