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Luz Boyero - One of the best experts on this subject based on the ideXlab platform.
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Microplastics have lethal and sublethal effects on stream invertebrates and affect stream ecosystem functioning.
Environmental Pollution, 2020Co-Authors: Naiara López-rojo, Javier Pérez, Francisco Correa-araneda, Alberto Alonso, Luz BoyeroAbstract:Abstract Microplastics (MPs) are contaminants of increasing concern due to their abundance, ubiquity and persistence over time. However, knowledge about MP distribution in fresh waters and their effects on freshwater organisms is still scarce, and there is virtually no information about their potential influence on ecosystem functioning. We used a microcosm experiment to examine the effects of MPs (fluorescent, 10-μm polystyrene microspheres) at different concentrations (from 0 to 103 particles mL−1) on leaf litter decomposition (a key process in stream ecosystems) and associated organisms (the caddisfly detritivore Sericostoma pyrenaicum), and the extent to which MPs were attached to leaf litter and ingested and egested by Detritivores, thus assessing mechanisms of MP trophic transfer. We found that MPs caused detritivore mortality (which increased 9-fold at the highest concentration) but did not affect their growth. Analysis of fluorescence in samples suggested that MPs were rapidly ingested (most likely through ingestion of particles attached to leaf litter) and egested. Leaf litter decomposition was reduced as a result of increasing MP concentrations; the relationship was significant only in the presence of Detritivores, but microbially-mediated decomposition showed a similar trend. Our findings provide novel evidence of harmful effects of MPs on aquatic insects and stream ecosystem functioning, and highlight the need for the standardization of methods in future experiments with MPs in order to allow comparisons and generalizations.
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Joint effects of temperature and litter quality on detritivore-mediated breakdown in streams
Aquatic Sciences, 2018Co-Authors: Andrea Landeira-dabarca, Javier Pérez, Manuel A S Graca, Luz BoyeroAbstract:Global warming causes concomitant changes in several environmental factors that often have synergistic effects on populations and ecosystem processes. We examined how increased water temperature and reduced litter quality affected a leaf-shredding detritivore’s performance and its effect on litter breakdown. Detritivores were exposed in microcosms at two temperatures (10 and 15 °C) and four categories of litter quality (based on nitrogen and condensed tannin concentrations). We hypothesized that (1) high-quality litter mixtures would breakdown faster, improving detritivore performance; (2) differences would occur regardless of which plant species in the mixture were preferentially consumed; and (3) litter quality effects on detritivore-mediated breakdown and performance would be intensified at higher temperatures. Unexpectedly, we found faster breakdown at intermediate litter quality and lower temperature. Additionally, we found cases of detritivore selection and rejection of different resources driven by litter traits other than nitrogen and tannin concentrations. Detritivore performance increased with temperature, regardless of litter quality. Our results support non-additive and unpredictable joint effects of temperature and litter quality, suggesting that these concomitant changes may affect stream functioning.
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Leaf traits drive plant diversity effects on litter decomposition and FPOM production in streams - Fig 3
2018Co-Authors: Naiara López-rojo, Javier Pérez, Aingeru Martínez, Ana Basaguren, Jesús Pozo, Luz BoyeroAbstract:Changes in mean (± SE) (A-D) litter decomposition (mg leaf mg detritivore-1), (E-H) FPOM production (mg FPOM mg detritivore-1) and (I-L) detritivore growth (%) with plant diversity loss from 3 to 1 species in the different 3-species litter mixtures. A: Alnus glutinosa; C: Corylus avellana; Q: Quercus robur; I: Ilex aquifolium), in microcosms with Detritivores. Different lower-case letters represent significant differences across treatments (p < 0.05).
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Results of linear models exploring effects of plant diversity loss (from 4 to 1 species in ACQI, or from 3 to 1 species in ACQ, ACI, AQI and CQI) on litter decomposition (mg mg detritivore-1), FPOM production (mg mg detritivore-1) and detritivore gro
2018Co-Authors: Naiara López-rojo, Javier Pérez, Aingeru Martínez, Ana Basaguren, Jesús Pozo, Luz BoyeroAbstract:Results of linear models exploring effects of plant diversity loss (from 4 to 1 species in ACQI, or from 3 to 1 species in ACQ, ACI, AQI and CQI) on litter decomposition (mg mg detritivore-1), FPOM production (mg mg detritivore-1) and detritivore growth (percentage) for different litter mixtures in microcosms with Detritivores.
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A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration
Ecology Letters, 2011Co-Authors: Luz Boyero, Richard G. Pearson, Manuel A S Graca, Marcos Callisto, Mark O. Gessner, David Dudgeon, Leon A. Barmuta, Verónica Ferreira, Andrew J M Boulton, Eric ChauvetAbstract:The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from Detritivores to microbes in warm climates would likely increase CO(2) production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback.
Loreto Rossi - One of the best experts on this subject based on the ideXlab platform.
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interactions between Detritivores and microfungi during the leaf detritus decomposition in a volcanic lake lake vico central italy
Hydrobiologia, 2000Co-Authors: L. Sabetta, Maria Letizia Costantini, Oriana Maggi, Anna Maria Persiani, Loreto RossiAbstract:The role of biota in the mass loss of Phragmites australis (Cav.) Trin. ex Steud was studied in the littoral belt of a central Italy volcanic lake. The research focussed on the feeding interactions between Detritivores and decomposing fungi as drivers of the leaf litter decomposition. The litterbag technique was used to assess the leaf mass loss, the number of colonizing fungi and the patterns of leaf colonization by Detritivores during 40 days of submersion in 16 sampling sites. Cores of bottom sediment were collected to estimate the organic content and ergosterol concentration as measure of fungal mass. The rate of leaf mass loss showed significant variability among the sampling sites and was non-linearly related to the quantity of organic depositions onto the lake bottom, peaking at about 40% of the dry matter. The rate was also positively correlated with the density of detritivore mass relative to the leaf unit mass, which increased with time. On the 20th day of litterbag immersion, when 40% of the initial leaf litter remained, we observed the best accordance between the two measures as well as the lowest difference in the detritivore mass density among sampling sites. In the absence of animals, the decomposition rate was positively related to the number of fungi on the decaying litter. The feeding activity of Detritivores changed both the species richness and composition of the fungal community on the litter. The substrate reduction due to intense animal feeding appeared to limit the ability of fungi to regrow after grazing. As a result, an inverse relationship between the number of fungi and the decomposition rate was observed.
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Interactions between Detritivores and microfungi during the leaf detritus decomposition in a volcanic lake (Lake Vico – central Italy)
Hydrobiologia, 2000Co-Authors: L. Sabetta, Maria Letizia Costantini, Oriana Maggi, Anna Maria Persiani, Loreto RossiAbstract:The role of biota in the mass loss of Phragmites australis (Cav.) Trin. ex Steud was studied in the littoral belt of a central Italy volcanic lake. The research focussed on the feeding interactions between Detritivores and decomposing fungi as drivers of the leaf litter decomposition. The litterbag technique was used to assess the leaf mass loss, the number of colonizing fungi and the patterns of leaf colonization by Detritivores during 40 days of submersion in 16 sampling sites. Cores of bottom sediment were collected to estimate the organic content and ergosterol concentration as measure of fungal mass. The rate of leaf mass loss showed significant variability among the sampling sites and was non-linearly related to the quantity of organic depositions onto the lake bottom, peaking at about 40% of the dry matter. The rate was also positively correlated with the density of detritivore mass relative to the leaf unit mass, which increased with time. On the 20th day of litterbag immersion, when 40% of the initial leaf litter remained, we observed the best accordance between the two measures as well as the lowest difference in the detritivore mass density among sampling sites. In the absence of animals, the decomposition rate was positively related to the number of fungi on the decaying litter. The feeding activity of Detritivores changed both the species richness and composition of the fungal community on the litter. The substrate reduction due to intense animal feeding appeared to limit the ability of fungi to regrow after grazing. As a result, an inverse relationship between the number of fungi and the decomposition rate was observed.
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Effects of macro-Detritivores density on leaf detritus processing rate: a macrocosm experiment
Hydrobiologia, 2000Co-Authors: Stefano Fazi, Loreto RossiAbstract:The effect of macroinvertebrate detritivore density on the mass loss rates of leaf litter of Alnus glutinosa (alder) was assessed. Experimental freshwater macrocosms, with increasing densities of four species of macroinvertebrate Detritivores belonging to two functional groups (shredders and scrapers), were set up outdoors. The litter bag technique was used to assess decomposition rates of alder leaves. Indirect effects of increasing density of macroinvertebrates on phytoplankton standing crop in the water column were investigated by analysing Chlorophyll a concentration. Decomposition rate increased as animal density increased, although a continuous increase in Detritivores density resulted in a discrete, step-wise increase of the decomposition rates. Animal colonisation followed an exponential pattern in low-medium density treatments versus a typical `bell-shape' curve in high density treatments; animals started to leave the consumed patches when about 60% of the initial leaf mass was lost (35th day in high-density treatments). Diversity (Hs) of the simplified detritivore community decreased as decomposition proceeded, with a dominance of shredders during the last phase of decomposition. Faster decomposition rate of detritus in the benthic compartment lead to a higher microalgae standing crop in the water column emphasising the role of allochthonous detritus as a source of nutrients for algae primary production in coastal freshwater ecotones.
Eric Chauvet - One of the best experts on this subject based on the ideXlab platform.
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Biodiversity and litter decomposition: a case study in a Mediterranean stream
Freshwater Science, 2015Co-Authors: Jérémy Jabiol, Eric ChauvetAbstract:The importance of riparian diversity for the functioning of headwater streams has been demonstrated repeatedly. For example, mixing litter from different riparian tree species can influence their decomposition rates, an effect that is contingent on both the litter assemblage and the detritivore community. However, the effects of mixing litter species have been studied mostly in temperate streams, and very few studies have been done in non- temperate streams. Mediterranean streams are often subjected to recurrent flow intermittency, and their riparian tree and stream detritivore communities have unique sets of species and traits, which probably influence the effects of litter mixtures on decomposition. We hypothesized that high dissimilarity in litter traits could promote effects of litter mixtures on decomposition that would be counteracted by the low abundance and small body size of Detritivores in Mediterranean streams. We manipulated litter diversity and the size-class and presence/absence of Detritivores in a 2nd-order Mediterranean stream in a 46-d experiment and found substantial but contingent effects on litter mixtures. Mixture effects were not significant on average, but both negative and positive effects of litter mixtures occurred. For instance, mixing soft and nutrient-rich litter species led to up to 9.6% increase in leaf mass loss. Microbial activity accounted for 85% of total leaf mass loss, and no effect of litter mixture was observed when Detritivores were excluded. In contrast, the presence of Detritivores, despite their relatively low abundance and diversity, was a key factor for litter decomposition and promoted effects of litter mixture. These results suggest that the extinction of a few key taxa (riparian tree species or large Detritivores) could impair nutrient and C cycling in Mediterranean streams with potential consequences for stream food webs.
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Top‐down and bottom‐up control of litter decomposers in streams
Freshwater Biology, 2014Co-Authors: Ana Lúcia Gonçalves, Manuel A S Graca, Eric Chauvet, Felix Bärlocher, Cristina CanhotoAbstract:1. Detritivores preferentially consume certain aquatic hyphomycete species while rejecting others. Fungal identity may therefore be a crucial factor determining stream food-web structure and complexity and extend the impact of microbial diversity to effects up through the food web. 2. In this study, we examined if shredder feeding is affected by the identity of fungi on leaves (bottom-up effects) and if preferences of shredders for particular fungi affect the composition of fungal assemblages (top-down effects). Oak leaf discs were conditioned in microcosms with six individual fungal species previously reported as highly palatable (P), unpalatable/rejected (R) and intermediate (I). Additionally, three microcosms were inoculated with three mixtures of four fungal species, each consisting of a different subset of the six species. 3. Colonised discs were offered to three Detritivores with different feeding strategies: Proasellus sp. (Isopoda), Echinogammarus meridionalis (Amphipoda) and Schizopelex festiva (Trichoptera). When offered leaves colonised by single fungal species, consumption rates by E. meridionalis and S. festiva were higher on I, followed by P and, finally, R species. Consumption rates by Proasellus sp. were sim- ilar across fungal treatments. Consumption rates by the three invertebrates were also similar across all fungal multispecies treatments, suggesting that invertebrate preferences for, or rejection of, a given fungal species may be masked when it grows in proximity to other fungi. Composition and structure of fungal communities were not significantly affected by the feeding of any of the three invertebrates. 4. Our results suggest that certain combinations of fungal and detritivore species result in unpredictable bottom-up and top-down effects in stream food webs.
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Top-down and bottom-up control of litter decomposers in streams
Freshwater Biology, 2014Co-Authors: Ana Lúcia Gonçalves, Manuel A S Graca, Eric Chauvet, Felix Bärlocher, Cristina CanhotoAbstract:1. Detritivores preferentially consume certain aquatic hyphomycete species while rejecting others. Fungal identity may therefore be a crucial factor determining stream food-web structure and complexity and extend the impact of microbial diversity to effects up through the food web. 2. In this study, we examined if shredder feeding is affected by the identity of fungi on leaves (bottom-up effects) and if preferences of shredders for particular fungi affect the composition of fungal assemblages (top-down effects). Oak leaf discs were conditioned in microcosms with six individual fungal species previously reported as highly palatable (P), unpalatable/rejected (R) and intermediate (I). Additionally, three microcosms were inoculated with three mixtures of four fungal species, each consisting of a different subset of the six species. 3. Colonised discs were offered to three Detritivores with different feeding strategies: Proasellus sp. (Isopoda), Echinogammarus meridionalis (Amphipoda) and Schizopelex festiva (Trichoptera). When offered leaves colonised by single fungal species, consumption rates by E. meridionalis and S. festiva were higher on I, followed by P and, finally, R species. Consumption rates by Proasellus sp. were sim- ilar across fungal treatments. Consumption rates by the three invertebrates were also similar across all fungal multispecies treatments, suggesting that invertebrate preferences for, or rejection of, a given fungal species may be masked when it grows in proximity to other fungi. Composition and structure of fungal communities were not significantly affected by the feeding of any of the three invertebrates. 4. Our results suggest that certain combinations of fungal and detritivore species result in unpredictable bottom-up and top-down effects in stream food webs.
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Litter identity mediates predator impacts on the functioning of an aquatic detritus-based food web
Oecologia, 2014Co-Authors: Jérémy Jabiol, Julien Cornut, Michaël Danger, Marion Jouffroy, Arnaud Elger, Eric ChauvetAbstract:During past decades, several mechanisms such as resource quality and habitat complexity have been proposed to explain variations in the strength of trophic cascades across ecosystems. In detritus-based headwater streams, litter accumulations constitute both a habitat and a resource for detritivorous macroinvertebrates. Because litter edibility (which promotes trophic cascades) is usually inversely correlated with its structural complexity (which weakens trophic cascades), there is a great scope for stronger trophic cascades in litter accumulations that are dominated by easily degradable litter species. However, it remains unclear how mixing contrasting litter species (conferring both habitat complexity and high quality resource) may influence top–down controls on communities and processes. In enclosures exposed in a second-order stream, we manipulated litter species composition by using two contrasting litter (alder and oak), and the presence–absence of a macroinvertebrate predator (Cordulegaster boltonii larvae), enabling it to effectively exert predation pressure, or not, on Detritivores (consumptive versus non-consumptive predation effects). Leaf mass loss, detritivore biomass and community structure were mostly controlled independently by litter identity and mixing and by predator consumption. However, the strength of predator control was mediated by litter quality (stronger on alder), and to a lesser extent by litter mixing (weaker on mixed litter). Refractory litter such as oak leaves may contribute to the structural complexity of the habitat for stream macroinvertebrates, allowing the maintenance of detritivore communities even when strong predation pressure occurs. We suggest that considering the interaction between top–down and bottom–up factors is important when investigating their influence on natural communities and ecosystem processes in detritus-based ecosystems.
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A global experiment suggests climate warming will not accelerate litter decomposition in streams but might reduce carbon sequestration
Ecology Letters, 2011Co-Authors: Luz Boyero, Richard G. Pearson, Manuel A S Graca, Marcos Callisto, Mark O. Gessner, David Dudgeon, Leon A. Barmuta, Verónica Ferreira, Andrew J M Boulton, Eric ChauvetAbstract:The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from Detritivores to microbes in warm climates would likely increase CO(2) production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback.
Frank Berendse - One of the best experts on this subject based on the ideXlab platform.
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Leaf litter quality drives litter mixing effects through complementary resource use among Detritivores.
Oecologia, 2013Co-Authors: Veronique C. A. Vos, Matty P. Berg, Jasper Van Ruijven, Edwin T. H. M. Peeters, Frank BerendseAbstract:To comprehend the potential consequences of biodiversity loss on the leaf litter decomposition process, a better understanding of its underlying mechanisms is necessary. Here, we hypothesize that positive litter mixture effects occur via complementary resource use, when litter species complement each other in terms of resource quality for Detritivores. To investigate this, monocultures and mixtures of two leaf litter species varying in quality were allowed to decompose with and without a single macro-detritivore species (the terrestrial woodlice Oniscus asellus). Resource quality of the mixture was assessed by the mean concentration, the dissimilarity in absolute and relative concentrations, and the covariance between nitrogen (N), phosphorus (P) and calcium (Ca) supply. Our results clearly show that litter mixing effects were driven by differences in their resource quality for Detritivores. In particular, complementary supply of N and P was a major driver of litter mixing effects. Interestingly, litter mixing effects caused by the addition of woodlice were predominantly driven by N dissimilarity, whereas in their absence, increased P concentration was the main driver of litter mixing effects. These results show that ultimately, litter diversity effects on decomposition may be driven by complementary resource use of the whole decomposer community (i.e., microbes and macro-Detritivores).
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Macro-detritivore identity drives leaf litter diversity effects
Oikos, 2010Co-Authors: Veronique C. A. Vos, Matty P. Berg, Jasper Van Ruijven, Edwin T. H. M. Peeters, Frank BerendseAbstract:The importance of leaf litter diversity for decomposition, an important process in terrestrial ecosystems, is much debated. Previous leaf litter-mixing studies have shown that non-additive leaf litter diversity effects can occur, but it is not clear why they occurred in only half of the studies and which underlying mechanisms can explain these conflicting results. We hypothesized that incorporating the role of macro-Detritivores could be important. Although often ignored, macro-Detritivores are known to strongly influence decomposition. To better understand the importance of macro-Detritivores for leaf litter mixing effects during decomposition, four common leaf litter species were added separately and in two and four species combinations to monocultures of three different macro-Detritivores and a control without fauna. Our results clearly show that leaf litter-mixing effects occurred only in the presence of two macro-Detritivores (earthworms and woodlice). Application of the additive partitioning method revealed that in the specific combination of woodlice and the presence of a slow-decomposing leaf litter species in the mixture, leaf litter mixing effects were strongly driven by a selection effect. This was caused by food preference of the isopod: the animals avoided the slow decomposing species when given the choice. However, most leaf litter mixing effects were caused by complementarity effects. The potential mechanisms underlying the complementarity effects are discussed. Our results clearly show that that both leaf litter and macro-detritivore identity can affect litter diversity. This may help to explain the conflicting results obtained in previous experiments.
Matty P. Berg - One of the best experts on this subject based on the ideXlab platform.
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Desiccation resistance determines distribution of woodlice along forest edge-to-interior gradients
European Journal of Soil Biology, 2018Co-Authors: Pallieter De Smedt, Matty P. Berg, Lander Baeten, Emilie Gallet-moron, Jorg Brunet, Sara A. O. Cousins, Guillaume Decocq, Martin Diekmann, Brice Giffard, Pieter De FrenneAbstract:Forest edges show strong abiotic and biotic gradients potentially altering community composition and ecosystem processes such as nutrient cycling. While abiotic gradients are well studied, short-scale biotic gradients, like detritivore species composition and their associated trait distribution remains a poorly explored research-field. We sampled woodlice in 160 forest patches across Europe at varying distances from the forest edge and discovered that species desiccation resistance determines distribution along forest edge-to-interior gradients. Forest edges are warmer and dryer compared to interiors and favour drought-tolerant species, while abundance and activity of drought-sensitive species is reduced at the edge. Key ecological factors for litter-dwelling Detritivores (i.e. humidity) act as environmental filter, because of species-specific differences in desiccation resistance. Future research should focus on quantifying the consequences of a changing detritivore community and their associated functional traits for nutrient cycling.
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Diversity of macro-Detritivores in dead wood is influenced by tree species, decay stage and environment
Soil Biology and Biochemistry, 2014Co-Authors: Juan Zuo, Myrthe Fonck, Jurgen Van Hal, J. Hans C. Cornelissen, Matty P. BergAbstract:Diplopoda (millipedes) and Isopoda (woodlice) are among the most abundant macro-Detritivores in temperate forests. These key regulators of plant litter decomposition are influenced by habitat and substrate quality, including that of dead wood. Dead wood provides shelter and resources to macro-Detritivores, but the relative effects of tree species, wood decay stage, forest environment and their interactions on macro-detritivore communities are poorly known. To unravel these effects, we combined a reciprocal field incubation experiment and direct field sampling to compare the Diplopoda and Isopoda communities in logs of silver birch (Betula pendula) and Norway spruce (Picea abies) in two contrasting sites in terms of soil texture, pH, fertility and microclimate. We found: (1) a curvilinear relationship between wood decay stage and abundance of Diplopoda and Isopoda, by using wood density as a measure for the decay stage; (2) the pH of dead wood was a good predictor of wood decay stage in a site with pH close to neutrality but not in an acidic site; (3) Diplopoda and Isopoda community composition on different tree species converged during the decay process, consequently tree species are more important in the substrate selection of macro-Detritivores at the beginning of their dead wood decomposition; (4) tree species, the growing environment of the trees and the decomposition environment of the logs strongly determined Diplopoda and Isopoda community composition in dead wood, these drivers of macro-detritivore communities interacted with each other and with the wood decay stage. Thus, when trying to understand and predict future patterns of macro-detritivore diversity under regimes of changing land-use and climate, these interactions should be taken into account. An important next step will be to quantify the feedback of macro-detritivore community composition to dead wood decomposition itself. This feedback may be better understood from the combination of (1) the complex interactions of tree species, wood decay stage and forest environment on the macro-detritivore community and (2) the functional traits of these macro-detritivore species. A better knowledge about these feedbacks can help in predicting carbon storage and nutrient cycling functions of dead wood in forests differing or changing in tree species composition and abiotic environment.
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Leaf litter quality drives litter mixing effects through complementary resource use among Detritivores.
Oecologia, 2013Co-Authors: Veronique C. A. Vos, Matty P. Berg, Jasper Van Ruijven, Edwin T. H. M. Peeters, Frank BerendseAbstract:To comprehend the potential consequences of biodiversity loss on the leaf litter decomposition process, a better understanding of its underlying mechanisms is necessary. Here, we hypothesize that positive litter mixture effects occur via complementary resource use, when litter species complement each other in terms of resource quality for Detritivores. To investigate this, monocultures and mixtures of two leaf litter species varying in quality were allowed to decompose with and without a single macro-detritivore species (the terrestrial woodlice Oniscus asellus). Resource quality of the mixture was assessed by the mean concentration, the dissimilarity in absolute and relative concentrations, and the covariance between nitrogen (N), phosphorus (P) and calcium (Ca) supply. Our results clearly show that litter mixing effects were driven by differences in their resource quality for Detritivores. In particular, complementary supply of N and P was a major driver of litter mixing effects. Interestingly, litter mixing effects caused by the addition of woodlice were predominantly driven by N dissimilarity, whereas in their absence, increased P concentration was the main driver of litter mixing effects. These results show that ultimately, litter diversity effects on decomposition may be driven by complementary resource use of the whole decomposer community (i.e., microbes and macro-Detritivores).
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Potential macro-detritivore range expansion into the subarctic stimulates litter decomposition: a new positive feedback mechanism to climate change?
Oecologia, 2011Co-Authors: Koert G. Van Geffen, Matty P. Berg, Rien AertsAbstract:As a result of low decomposition rates, high-latitude ecosystems store large amounts of carbon. Litter decomposition in these ecosystems is constrained by harsh abiotic conditions, but also by the absence of macro-Detritivores. We have studied the potential effects of their climate change-driven northward range expansion on the decomposition of two contrasting subarctic litter types. Litter of Alnus incana and Betula pubescens was incubated in microcosms together with monocultures and all possible combinations of three functionally different macro-Detritivores (the earthworm Lumbricus rubellus, isopod Oniscus asellus, and millipede Julus scandinavius). Our results show that these macro-Detritivores stimulated decomposition, especially of the high-quality A. incana litter and that the macro-Detritivores tested differed in their decomposition-stimulating effects, with earthworms having the largest influence. Decomposition processes increased with increasing number of macro-detritivore species, and positive net diveristy effects occurred in several macro-detritivore treatments. However, after correction for macro-detritivore biomass, all interspecific differences in macro-detritivore effects, as well as the positive effects of species number on subarctic litter decomposition disappeared. The net diversity effects also appeared to be driven by variation in biomass, with a possible exception of net diversity effects in mass loss. Based on these results, we conclude that the expected climate change-induced range expansion of macro-Detritivores into subarctic regions is likely to result in accelerated decomposition rates. Our results also indicate that the magnitude of macro-detritivore effects on subarctic decomposition will mainly depend on macro-detritivore biomass, rather than on macro-detritivore species number or identity.
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Macro-detritivore identity drives leaf litter diversity effects
Oikos, 2010Co-Authors: Veronique C. A. Vos, Matty P. Berg, Jasper Van Ruijven, Edwin T. H. M. Peeters, Frank BerendseAbstract:The importance of leaf litter diversity for decomposition, an important process in terrestrial ecosystems, is much debated. Previous leaf litter-mixing studies have shown that non-additive leaf litter diversity effects can occur, but it is not clear why they occurred in only half of the studies and which underlying mechanisms can explain these conflicting results. We hypothesized that incorporating the role of macro-Detritivores could be important. Although often ignored, macro-Detritivores are known to strongly influence decomposition. To better understand the importance of macro-Detritivores for leaf litter mixing effects during decomposition, four common leaf litter species were added separately and in two and four species combinations to monocultures of three different macro-Detritivores and a control without fauna. Our results clearly show that leaf litter-mixing effects occurred only in the presence of two macro-Detritivores (earthworms and woodlice). Application of the additive partitioning method revealed that in the specific combination of woodlice and the presence of a slow-decomposing leaf litter species in the mixture, leaf litter mixing effects were strongly driven by a selection effect. This was caused by food preference of the isopod: the animals avoided the slow decomposing species when given the choice. However, most leaf litter mixing effects were caused by complementarity effects. The potential mechanisms underlying the complementarity effects are discussed. Our results clearly show that that both leaf litter and macro-detritivore identity can affect litter diversity. This may help to explain the conflicting results obtained in previous experiments.