| 1. |
- Frainer, André, 1982-, et al.
(författare)
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When does diversity matter? : Species functional diversity and ecosystem functioning across habitats and seasons in a field experiment
- 2014
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656. ; 83:2, s. 460-469
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Tidskriftsartikel (refereegranskat)abstract
- Despite ample experimental evidence indicating that biodiversity might be an important driver of ecosystem processes, its role in the functioning of real ecosystems remains unclear. In particular, the understanding of which aspects of biodiversity are most important for ecosystem functioning, their importance relative to other biotic and abiotic drivers, and the circumstances under which biodiversity is most likely to influence functioning in nature, is limited. We conducted a field study that focussed on a guild of insect detritivores in streams, in which we quantified variation in the process of leaf decomposition across two habitats (riffles and pools) and two seasons (autumn and spring). The study was conducted in six streams, and the same locations were sampled in the two seasons. With the aid of structural equations modelling, we assessed spatiotemporal variation in the roles of three key biotic drivers in this process: functional diversity, quantified based on a spe- cies trait matrix, consumer density and biomass. Our models also accounted for variability related to different litter resources, and other sources of biotic and abiotic variability among streams. All three of our focal biotic drivers influenced leaf decomposition, but none was important in all habitats and seasons. Functional diversity had contrasting effects on decomposition between habitats and seasons. A positive relationship was observed in pool habitats in spring, associated with high trait dispersion, whereas a negative relationship was observed in riffle habitats during autumn. Our results demonstrate that functional biodiversity can be as significant for functioning in natural ecosystems as other important biotic drivers. In particular, variation in the role of functional diversity between seasons highlights the importance of fluctuations in the relative abundances of traits for ecosystem process rates in real ecosystems.
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| 2. |
- Mckie, Brendan
(författare)
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Trophic complexity enhances ecosystem functioning in an aquatic detritus-based model system
- 2013
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 82, s. 1042-1051
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Tidskriftsartikel (refereegranskat)abstract
- 4. Our results thus highlight the importance of interactive effects of simultaneous species loss within multiple trophic levels on ecosystem functioning. If a common phenomenon, this outcome suggests that functional ecosystem impairment resulting from widespread biodiversity loss could be more severe than inferred from previous experiments confined to varying diversity within single trophic levels.
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| 3. |
- Sarremejane, Romainyuuii, et al.
(författare)
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Stochastic processes and ecological connectivity drive stream invertebrate community responses to short-term drought
- 2021
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656. ; 90:4, s. 886-898
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Tidskriftsartikel (refereegranskat)abstract
- 1. Community responses to and recovery from disturbances depend on local (e.g. presence of refuges) and regional (connectivity to recolonization sources) factors. Droughts are becoming more frequent in boreal regions, and are likely to constitute a severe disturbance for boreal stream communities where organisms largely lack adaptations to such hydrological extremes.2. We conducted an experiment in 24 semi-natural stream flumes to assess the effects of local and regional factors on the responses of benthic invertebrate communities to a short-term drought. We manipulated flow (drought vs. constant-flow), spatial arrangement of leaf litter patches (aggregated vs. evenly distributed) and colonization from regional species pool (enhanced vs. ambient connectivity) to test the combined effects of disturbance, resource arrangement and connectivity on the structural and functional responses of benthic invertebrate communities.3. We found that a drought as short as 1 week reduced invertebrate taxonomic richness and abundance, mainly through stochastic extinctions. Such changes in richness were not reflected in functional diversity. This suggests that communities were characterized by a high degree of functional redundancy, which allowed maintenance of functional diversity despite species losses. Feeding groups responded differently to drought, with organic matter decomposers responding more than scrapers and predators.4. Three weeks were insufficient for complete invertebrate community recovery from drought. However, recovery was greater in channels subjected to enhanced connectivity, which increased taxonomic diversity and abundance of certain taxa. Spatial configuration of resources explained the least variation in our response variables, having a significant effect only on invertebrate abundance and evenness (both sampling occasions) and taxonomic richness (end of recovery period).5. Even a short drought, if occurring late in the season, may not allow communities to recover before the onset of winter, thus having a potentially long-lasting effect on stream communities. For boreal headwaters, extreme dewatering poses a novel disturbance regime that may trigger substantial and potentially irreversible changes. An improved understanding of such changes is needed to underpin adaptive management strategies in these increasingly fragmented and disturbed ecosystems.
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| 4. |
- McKie, Brendan, et al.
(författare)
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Ecosystem functioning in stream assemblages from different regions : contrasting responses to variation in detritivore richness, evenness and density.
- 2008
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Ingår i: Journal of Animal Ecology. - : Wiley. - 1365-2656 .- 0021-8790. ; 77:3, s. 495-504
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Tidskriftsartikel (refereegranskat)abstract
- 1. The diversity of species traits characterising a biological assemblage reflects not only its species richness but also its species evenness and total density, which together influence the concentration of traits within functional guilds, and is ultimately constrained by the regional species pool. Implications of such variation for spatio-temporal variability in biodiversity-ecosystem functioning relationships are potentially complex, but poorly understood.2. In separate microcosm experiments maintained at laboratories in Sweden, Romania and Ireland, we investigated effects of the species richness, evenness and density of stream-living detritivores on two related processes: detritivore leaf processing efficiency (LPE) and growth. Assemblage composition varied among the laboratories, with only one taxonomic order (Plecoptera) investigated in Sweden, whereas two orders, encompassing wider trait variation, were studied in Romania (Trichoptera and Plecoptera) and Ireland (Trichoptera and Isopoda).3. Relationships between density and both LPE and growth ranged from negative to positive across all the study species, highlighting the potential for density-dependent variation in process rates to alter ecosystem functioning, but indicating that such effects vary with species identity.4. Increased diversity was associated with 25-50% higher LPE in the two more heterogeneous assemblages, but whereas LPE in the Romanian study was generally enhanced as richness increased, LPE in the Irish study only increased in less even species mixtures dominated by particular species. Mechanisms underlying these diversity effects also contrasted. The Romanian results were predominantly attributable to the selection effect, whereas there was evidence for positive complementarity among species in Ireland.5. Growth was elevated in Romanian species mixtures, reflecting positive complementarity among species, but lower than expected growth in some Swedish mixtures was associated with negative complementarity.6. Our results emphasize the potential importance of detritivore diversity for stream ecosystem functioning across multiple contrasting assemblages, but variability in both the effects of diversity on the studied processes, and the mechanisms underlying those effects, highlight challenges in generalizing impacts of diversity change for the functional integrity of naturally dynamic stream ecosystems in situ.
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