Publications by authors named "Gerlinde B De Deyn"

30 Publications

  • Page 1 of 1

Leachates from plants recently infected by root-feeding nematodes cause increased biomass allocation to roots in neighbouring plants.

Sci Rep 2021 Jan 27;11(1):2347. Epub 2021 Jan 27.

Terrestrial Ecology Unit, Department of Biology, Ghent University, Karel Lodewijk Ledeganckstraat 35, 9000, Ghent, Belgium.

Plants can adjust defence strategies in response to signals from neighbouring plants attacked by aboveground herbivores. Whether similar responses exist to belowground herbivory remains less studied, particularly regarding the spatiotemporal dynamics of such belowground signalling. We grew the grass Agrostis stolonifera with or without root-feeding nematodes (Meloidogyne minor). Leachates were extracted at different distances from these plants and at different times after inoculation. The leachates were applied to receiver A. stolonifera plants, of which root, shoot, and total biomass, root/shoot ratio, shoot height, shoot branch number, maximum rooting depth and root number were measured 3 weeks after leachate application. Receiver plants allocated significantly more biomass to roots when treated with leachates from nematode-inoculated plants at early infection stages. However, receiver plants' root/shoot ratio was similar when receiving leachates collected at later stages from nematode-infected or control plants. Overall, early-collected leachates reduced growth of receiver plants significantly. Plants recently infected by root-feeding nematodes can thus induce increased root proliferation of neighbouring plants through root-derived compounds. Possible explanations for this response include a better tolerance of anticipated root damage by nematodes or the ability to grow roots away from the nematode-infected soil. Further investigations are still needed to identify the exact mechanisms.
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http://dx.doi.org/10.1038/s41598-021-82022-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7840926PMC
January 2021

Root traits as drivers of plant and ecosystem functioning: current understanding, pitfalls and future research needs.

New Phytol 2020 Nov 7. Epub 2020 Nov 7.

Geobotany, Faculty of Biology, University of Freiburg, Schänzlestr. 1, Freiburg, 79104, Germany.

The effects of plants on the biosphere, atmosphere and geosphere are key determinants of terrestrial ecosystem functioning. However, despite substantial progress made regarding plant belowground components, we are still only beginning to explore the complex relationships between root traits and functions. Drawing on the literature in plant physiology, ecophysiology, ecology, agronomy and soil science, we reviewed 24 aspects of plant and ecosystem functioning and their relationships with a number of root system traits, including aspects of architecture, physiology, morphology, anatomy, chemistry, biomechanics and biotic interactions. Based on this assessment, we critically evaluated the current strengths and gaps in our knowledge, and identify future research challenges in the field of root ecology. Most importantly, we found that belowground traits with the broadest importance in plant and ecosystem functioning are not those most commonly measured. Also, the estimation of trait relative importance for functioning requires us to consider a more comprehensive range of functionally relevant traits from a diverse range of species, across environments and over time series. We also advocate that establishing causal hierarchical links among root traits will provide a hypothesis-based framework to identify the most parsimonious sets of traits with the strongest links on functions, and to link genotypes to plant and ecosystem functioning.
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http://dx.doi.org/10.1111/nph.17072DOI Listing
November 2020

Can flooding-induced greenhouse gas emissions be mitigated by trait-based plant species choice?

Sci Total Environ 2020 Jul 10;727:138476. Epub 2020 Apr 10.

Soil Biology Group, Wageningen University & Research, PO Box 47, 6700 AA Wageningen, the Netherlands; Department of Agroecology - Soil Fertility, Aarhus University, Blichers Allé 20, 8830 Tjele, Denmark.

Intensively managed grasslands are large sources of the potent greenhouse gas nitrous oxide (NO) and important regulators of methane (CH) consumption and production. The predicted increase in flooding frequency and severity due to climate change could increase NO emissions and shift grasslands from a net CH sink to a source. Therefore, effective management strategies are critical for mitigating greenhouse gas emissions from flood-prone grasslands. We tested how repeated flooding affected the NO and CH emissions from 11 different plant communities (Festuca arundinacea, Lolium perenne, Poa trivialis, and Trifolium repens in monoculture, 2- and 4-species mixtures), using intact soil cores from an 18-month old grassland field experiment in a 4-month greenhouse experiment. To elucidate potential underlying mechanisms, we related plant functional traits to cumulative NO and CH emissions. We hypothesized that traits related with fast nitrogen uptake and growth would lower NO and CH emissions in ambient (non-flooded) conditions, and that traits related to tissue toughness would lower NO and CH emissions in flooded conditions. We found that flooding increased cumulative NO emissions by 97 fold and cumulative CH emissions by 1.6 fold on average. Plant community composition mediated the flood-induced increase in NO emissions. In flooded conditions, increasing abundance of the grass F. arundinacea was related with lower NO emissions; whereas increases in abundance of the legume T. repens resulted in higher NO emissions. In non-flooded conditions, NO emissions were not clearly mediated by plant traits related with nitrogen uptake or biomass production. In flooded conditions, plant communities with high root carbon to nitrogen ratio were related with lower cumulative NO emissions, and a lower global warming potential (CO equivalent of NO and CH). We conclude that plant functional traits related to slower decomposition and nitrogen mineralization could play a significant role in mitigating NO emissions in flooded grasslands.
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http://dx.doi.org/10.1016/j.scitotenv.2020.138476DOI Listing
July 2020

Increased arbuscular mycorrhizal fungal colonization reduces yield loss of rice (Oryza sativa L.) under drought.

Mycorrhiza 2020 May 15;30(2-3):315-328. Epub 2020 Apr 15.

Department of Environmental Sciences, Soil Biology Group, Wageningen University & Research, P.O. Box 47, 6700 AA, Wageningen, The Netherlands.

Drought reduces the availability of soil water and the mobility of nutrients, thereby limiting the growth and productivity of rice. Under drought, arbuscular mycorrhizal fungi (AMF) increase P uptake and sustain rice growth. However, we lack knowledge of how the AMF symbiosis contributes to drought tolerance of rice. In the greenhouse, we investigated mechanisms of AMF symbiosis that confer drought tolerance, such as enhanced nutrient uptake, stomatal conductance, chlorophyll fluorescence, and hormonal balance (abscisic acid (ABA) and indole acetic acid (IAA)). Two greenhouse pot experiments comprised three factors in a full factorial design with two AMF treatments (low- and high-AMF colonization), two water treatments (well-watered and drought), and three rice varieties. Soil water potential was maintained at 0 kPa in the well-watered treatment. In the drought treatment, we reduced soil water potential to - 40 kPa in experiment 1 (Expt 1) and to - 80 kPa in experiment 2 (Expt 2). Drought reduced shoot and root dry biomass and grain yield of rice in both experiments. The reduction of grain yield was less with higher AMF colonization. Plants with higher AMF colonization showed higher leaf P concentrations than plants with lower colonization in Expt 1, but not in Expt 2. Plants with higher AMF colonization exhibited higher stomatal conductance and chlorophyll fluorescence than plants with lower colonization, especially under drought. Drought increased the levels of ABA and IAA, and AMF colonization also resulted in higher levels of IAA. The results suggest both nutrient-driven and plant hormone-driven pathways through which AMF confer drought tolerance to rice.
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http://dx.doi.org/10.1007/s00572-020-00953-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7228911PMC
May 2020

Biodiversity increases multitrophic energy use efficiency, flow and storage in grasslands.

Nat Ecol Evol 2020 03 24;4(3):393-405. Epub 2020 Feb 24.

Department of Biosciences, University of Salzburg, Salzburg, Austria.

The continuing loss of global biodiversity has raised questions about the risk that species extinctions pose for the functioning of natural ecosystems and the services that they provide for human wellbeing. There is consensus that, on single trophic levels, biodiversity sustains functions; however, to understand the full range of biodiversity effects, a holistic and multitrophic perspective is needed. Here, we apply methods from ecosystem ecology that quantify the structure and dynamics of the trophic network using ecosystem energetics to data from a large grassland biodiversity experiment. We show that higher plant diversity leads to more energy stored, greater energy flow and higher community-energy-use efficiency across the entire trophic network. These effects of biodiversity on energy dynamics were not restricted to only plants but were also expressed by other trophic groups and, to a similar degree, in aboveground and belowground parts of the ecosystem, even though plants are by far the dominating group in the system. The positive effects of biodiversity on one trophic level were not counteracted by the negative effects on adjacent levels. Trophic levels jointly increased the performance of the community, indicating ecosystem-wide multitrophic complementarity, which is potentially an important prerequisite for the provisioning of ecosystem services.
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http://dx.doi.org/10.1038/s41559-020-1123-8DOI Listing
March 2020

Soil fauna diversity increases CO but suppresses N O emissions from soil.

Glob Chang Biol 2020 03 4;26(3):1886-1898. Epub 2019 Nov 4.

Soil Biology Group, Wageningen University, Wageningen, The Netherlands.

Soil faunal activity can be a major control of greenhouse gas (GHG) emissions from soil. Effects of single faunal species, genera or families have been investigated, but it is unknown how soil fauna diversity may influence emissions of both carbon dioxide (CO , end product of decomposition of organic matter) and nitrous oxide (N O, an intermediate product of N transformation processes, in particular denitrification). Here, we studied how CO and N O emissions are affected by species and species mixtures of up to eight species of detritivorous/fungivorous soil fauna from four different taxonomic groups (earthworms, potworms, mites, springtails) using a microcosm set-up. We found that higher species richness and increased functional dissimilarity of species mixtures led to increased faunal-induced CO emission (up to 10%), but decreased N O emission (up to 62%). Large ecosystem engineers such as earthworms were key drivers of both CO and N O emissions. Interestingly, increased biodiversity of other soil fauna in the presence of earthworms decreased faunal-induced N O emission despite enhanced C cycling. We conclude that higher soil fauna functional diversity enhanced the intensity of belowground processes, leading to more complete litter decomposition and increased CO emission, but concurrently also resulting in more complete denitrification and reduced N O emission. Our results suggest that increased soil fauna species diversity has the potential to mitigate emissions of N O from soil ecosystems. Given the loss of soil biodiversity in managed soils, our findings call for adoption of management practices that enhance soil biodiversity and stimulate a functionally diverse faunal community to reduce N O emissions from managed soils.
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http://dx.doi.org/10.1111/gcb.14860DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7078878PMC
March 2020

Feedbacks of plant identity and diversity on the diversity and community composition of rhizosphere microbiomes from a long-term biodiversity experiment.

Mol Ecol 2019 02;28(4):863-878

Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zürich, Switzerland.

Soil microbes are known to be key drivers of several essential ecosystem processes such as nutrient cycling, plant productivity and the maintenance of plant species diversity. However, how plant species diversity and identity affect soil microbial diversity and community composition in the rhizosphere is largely unknown. We tested whether, over the course of 11 years, distinct soil bacterial communities developed under plant monocultures and mixtures, and if over this time frame plants with a monoculture or mixture history changed in the bacterial communities they associated with. For eight species, we grew offspring of plants that had been grown for 11 years in the same field monocultures or mixtures (plant history in monoculture vs. mixture) in pots inoculated with microbes extracted from the field monoculture and mixture soils attached to the roots of the host plants (soil legacy). After 5 months of growth in the glasshouse, we collected rhizosphere soil from each plant and used 16S rRNA gene sequencing to determine the community composition and diversity of the bacterial communities. Bacterial community structure in the plant rhizosphere was primarily determined by soil legacy and by plant species identity, but not by plant history. In seven of the eight plant species the number of individual operational taxonomic units with increased abundance was larger when inoculated with microbes from mixture soil. We conclude that plant species richness can affect below-ground community composition and diversity, feeding back to the assemblage of rhizosphere bacterial communities in newly establishing plants via the legacy in soil.
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http://dx.doi.org/10.1111/mec.14987DOI Listing
February 2019

The Future of Complementarity: Disentangling Causes from Consequences.

Trends Ecol Evol 2019 02 4;34(2):167-180. Epub 2018 Dec 4.

Systematic Botany and Functional Biodiversity, Institute of Biology, Leipzig University, Johannisallee 21-23, 04103 Leipzig, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany.

Evidence suggests that biodiversity supports ecosystem functioning. Yet, the mechanisms driving this relationship remain unclear. Complementarity is one common explanation for these positive biodiversity-ecosystem functioning relationships. Yet, complementarity is often indirectly quantified as overperformance in mixture relative to monoculture (e.g., 'complementarity effect'). This overperformance is then attributed to the intuitive idea of complementarity or, more specifically, to species resource partitioning. Locally, however, several unassociated causes may drive this overperformance. Here, we differentiate complementarity into three types of species differences that may cause enhanced ecosystem functioning in more diverse ecosystems: (i) resource partitioning, (ii) abiotic facilitation, and (iii) biotic feedbacks. We argue that disentangling these three causes is crucial for predicting the response of ecosystems to future biodiversity loss.
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http://dx.doi.org/10.1016/j.tree.2018.10.013DOI Listing
February 2019

Spatial heterogeneity in root litter and soil legacies differentially affect legume root traits.

Plant Soil 2018 11;428(1):253-264. Epub 2018 May 11.

1Department of Soil Quality, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.

Background And Aims: Plants affect the soil environment via litter inputs and changes in biotic communities, which feed back to subsequent plant growth. Here we investigated the individual contributions of litter and biotic communities to soil feedback effects, and plant ability to respond to spatial heterogeneity in soil legacy.

Methods: We tested for localised and systemic responses of to soil biotic and root litter legacy of seven grassland species by exposing half of a root system to control soil and the other half to specific inoculum or root litter.

Results: Soil inoculation triggered a localised reduction in root length while litter locally increased root biomass independent of inoculum or litter species identity. Nodule formation was locally suppressed in response to soil conditioned by another legume ( and showed a trend towards systemic reduction in response to conspecific soil. litter also caused a systemic response with thinner roots produced in the part of the root system not directly exposed to the litter.

Conclusions: Spatial heterogeneity in root litter distribution and soil communities generate distinct local and systemic responses in root morphology and nodulation. These responses can influence plant-mutualist interactions and nutrient cycling, and should be included in plant co-existence models.
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http://dx.doi.org/10.1007/s11104-018-3667-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6435190PMC
May 2018

Plant-Soil Feedback: Bridging Natural and Agricultural Sciences.

Trends Ecol Evol 2018 02 11;33(2):129-142. Epub 2017 Dec 11.

Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, 90183, Umeå, Sweden. Electronic address:

In agricultural and natural systems researchers have demonstrated large effects of plant-soil feedback (PSF) on plant growth. However, the concepts and approaches used in these two types of systems have developed, for the most part, independently. Here, we present a conceptual framework that integrates knowledge and approaches from these two contrasting systems. We use this integrated framework to demonstrate (i) how knowledge from complex natural systems can be used to increase agricultural resource-use efficiency and productivity and (ii) how research in agricultural systems can be used to test hypotheses and approaches developed in natural systems. Using this framework, we discuss avenues for new research toward an ecologically sustainable and climate-smart future.
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http://dx.doi.org/10.1016/j.tree.2017.11.005DOI Listing
February 2018

Community evolution increases plant productivity at low diversity.

Ecol Lett 2018 Jan 16;21(1):128-137. Epub 2017 Nov 16.

URPP Global Change and Biodiversity and Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.

Species extinctions from local communities negatively affect ecosystem functioning. Ecological mechanisms underlying these impacts are well studied, but the role of evolutionary processes is rarely assessed. Using a long-term field experiment, we tested whether natural selection in plant communities increased biodiversity effects on productivity. We re-assembled communities with 8-year co-selection history adjacent to communities with identical species composition but no history of co-selection ('naïve communities'). Monocultures, and in particular mixtures of two to four co-selected species, were more productive than their corresponding naïve communities over 4 years in soils with or without co-selected microbial communities. At the highest diversity level of eight plant species, no such differences were observed. Our findings suggest that plant community evolution can lead to rapid increases in ecosystem functioning at low diversity but may take longer at high diversity. This effect was not modified by treatments simulating co-evolutionary processes between plants and soil organisms.
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http://dx.doi.org/10.1111/ele.12879DOI Listing
January 2018

What plant functional traits can reduce nitrous oxide emissions from intensively managed grasslands?

Glob Chang Biol 2018 Jan 17;24(1):e248-e258. Epub 2017 Aug 17.

Department of Soil Quality, Wageningen University, Wageningen, The Netherlands.

Plant species exert a dominant control over the nitrogen (N) cycle of natural and managed grasslands. Although in intensively managed systems that receive large external N inputs the emission of the potent greenhouse gas nitrous oxide (N O) is a crucial component of this cycle, a mechanistic relationship between plant species and N O emissions has not yet been established. Here we use a plant functional trait approach to study the relation between plant species strategies and N O emissions from soils. Compared to species with conservative strategies, species with acquisitive strategies have higher N uptake when there is ample N in the soil, but also trigger N mineralization when soil N is limiting. Therefore, we hypothesized that (1) compared to conservative species, species with acquisitive traits reduce N O emissions after a high N addition; and (2) species with conservative traits have lower N O emissions than acquisitive plants if there is no high N addition. This was tested in a greenhouse experiment using monocultures of six grass species with differing above- and below-ground traits, growing across a gradient of soil N availability. We found that acquisitive species reduced N O emissions at all levels of N availability, produced higher biomass and showed larger N uptake. As such, acquisitive species had 87% lower N O emissions per unit of N uptake than conservative species (p < .05). Structural equation modelling revealed that specific leaf area and root length density were key traits regulating the effects of plants on N O emission and biomass productivity. These results provide the first framework to understand the mechanisms through which plants modulate N O emissions, pointing the way to develop productive grasslands that contribute optimally to climate change mitigation.
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http://dx.doi.org/10.1111/gcb.13827DOI Listing
January 2018

Symbiotic soil fungi enhance ecosystem resilience to climate change.

Glob Chang Biol 2017 12 11;23(12):5228-5236. Epub 2017 Jul 11.

Plant-Soil Interactions, Research Division of Agroecology and Environmental Science, Agroscope, CH - 8046, Zürich, Switzerland.

Substantial amounts of nutrients are lost from soils through leaching. These losses can be environmentally damaging, causing groundwater eutrophication and also comprise an economic burden in terms of lost agricultural production. More intense precipitation events caused by climate change will likely aggravate this problem. So far it is unresolved to which extent soil biota can make ecosystems more resilient to climate change and reduce nutrient leaching losses when rainfall intensity increases. In this study, we focused on arbuscular mycorrhizal (AM) fungi, common soil fungi that form symbiotic associations with most land plants and which increase plant nutrient uptake. We hypothesized that AM fungi mitigate nutrient losses following intensive precipitation events (higher amount of precipitation and rain events frequency). To test this, we manipulated the presence of AM fungi in model grassland communities subjected to two rainfall scenarios: moderate and high rainfall intensity. The total amount of nutrients lost through leaching increased substantially with higher rainfall intensity. The presence of AM fungi reduced phosphorus losses by 50% under both rainfall scenarios and nitrogen losses by 40% under high rainfall intensity. Thus, the presence of AM fungi enhanced the nutrient interception ability of soils, and AM fungi reduced the nutrient leaching risk when rainfall intensity increases. These findings are especially relevant in areas with high rainfall intensity (e.g., such as the tropics) and for ecosystems that will experience increased rainfall due to climate change. Overall, this work demonstrates that soil biota such as AM fungi can enhance ecosystem resilience and reduce the negative impact of increased precipitation on nutrient losses.
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http://dx.doi.org/10.1111/gcb.13785DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5697572PMC
December 2017

Differential responses of soil bacteria, fungi, archaea and protists to plant species richness and plant functional group identity.

Mol Ecol 2017 Aug 2;26(15):4085-4098. Epub 2017 Jun 2.

Department of Soil Quality, Wageningen University, Wageningen, The Netherlands.

Plants are known to influence belowground microbial community structure along their roots, but the impacts of plant species richness and plant functional group (FG) identity on microbial communities in the bulk soil are still not well understood. Here, we used 454-pyrosequencing to analyse the soil microbial community composition in a long-term biodiversity experiment at Jena, Germany. We examined responses of bacteria, fungi, archaea, and protists to plant species richness (communities varying from 1 to 60 sown species) and plant FG identity (grasses, legumes, small herbs, tall herbs) in bulk soil. We hypothesized that plant species richness and FG identity would alter microbial community composition and have a positive impact on microbial species richness. Plant species richness had a marginal positive effect on the richness of fungi, but we observed no such effect on bacteria, archaea and protists. Plant species richness also did not have a large impact on microbial community composition. Rather, abiotic soil properties partially explained the community composition of bacteria, fungi, arbuscular mycorrhizal fungi (AMF), archaea and protists. Plant FG richness did not impact microbial community composition; however, plant FG identity was more effective. Bacterial richness was highest in legume plots and lowest in small herb plots, and AMF and archaeal community composition in legume plant communities was distinct from that in communities composed of other plant FGs. We conclude that soil microbial community composition in bulk soil is influenced more by changes in plant FG composition and abiotic soil properties, than by changes in plant species richness per se.
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http://dx.doi.org/10.1111/mec.14175DOI Listing
August 2017

Plant diversity and root traits benefit physical properties key to soil function in grasslands.

Ecol Lett 2016 09 26;19(9):1140-9. Epub 2016 Jul 26.

Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK.

Plant diversity loss impairs ecosystem functioning, including important effects on soil. Most studies that have explored plant diversity effects belowground, however, have largely focused on biological processes. As such, our understanding of how plant diversity impacts the soil physical environment remains limited, despite the fundamental role soil physical structure plays in ensuring soil function and ecosystem service provision. Here, in both a glasshouse and a long-term field study, we show that high plant diversity in grassland systems increases soil aggregate stability, a vital structural property of soil, and that root traits play a major role in determining diversity effects. We also reveal that the presence of particular plant species within mixed communities affects an even wider range of soil physical processes, including hydrology and soil strength regimes. Our results indicate that alongside well-documented effects on ecosystem functioning, plant diversity and root traits also benefit essential soil physical properties.
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http://dx.doi.org/10.1111/ele.12652DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988498PMC
September 2016

Plant selection and soil legacy enhance long-term biodiversity effects.

Ecology 2016 Apr;97(4):918-28

Plant-plant and plant-soil interactions can help maintain plant diversity and ecosystem functions. Changes in these interactions may underlie experimentally observed increases in biodiversity effects over time via the selection of genotypes adapted to low or high plant diversity. Little is known, however, about such community-history effects and particularly the role of plant-soil interactions in this process. Soil-legacy effects may occur if co-evolved interactions with soil communities either positively or negatively modify plant biodiversity effects. We tested how plant selection and soil legacy influence biodiversity effects on productivity, and whether such effects increase the resistance of the communities to invasion by weeds. We used two plant selection treatments: parental plants growing in monoculture or in mixture over 8 yr in a grassland biodiversity experiment in the field, which we term monoculture types and mixture types. The two soil-legacy treatments used in this study were neutral soil inoculated with live or sterilized soil inocula collected from the same plots in the biodiversity experiment. For each of the four factorial combinations, seedlings of eight species were grown in monocultures or four-species mixtures in pots in an experimental garden over 15 weeks. Soil legacy (live inoculum) strongly increased biodiversity complementarity effects for communities of mixture types, and to a significantly weaker extent for communities of monoculture types. This may be attributed to negative plant-soil feedbacks suffered by mixture types in monocultures, whereas monoculture types had positive plant-soil feedbacks, in both monocultures and mixtures. Monocultures of mixture types were most strongly invaded by weeds, presumably due to increased pathogen susceptibility, reduced biomass, and altered plant-soil interactions of mixture types. These results show that biodiversity effects in experimental grassland communities can be modified by the evolution of positive vs. negative plant-soil feedbacks of plant monoculture vs. mixture types.
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April 2016

Plant selection and soil legacy enhance long-term biodiversity effects.

Ecology 2016 Apr;97(4):918-928

Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.

Plant-plant and plant-soil interactions can help maintain plant diversity and ecosystem functions. Changes in these interactions may underlie experimentally observed increases in biodiversity effects over time via the selection of genotypes adapted to low or high plant diversity. Little is known, however, about such community-history effects and particularly the role of plant-soil interactions in this process. Soil-legacy effects may occur if co-evolved interactions with soil communities either positively or negatively modify plant biodiversity effects. We tested how plant selection and soil legacy influence biodiversity effects on productivity, and whether such effects increase the resistance of the communities to invasion by weeds. We used two plant selection treatments: parental plants growing in monoculture or in mixture over 8 yr in a grassland biodiversity experiment in the field, which we term monoculture types and mixture types. The two soil-legacy treatments used in this study were neutral soil inoculated with live or sterilized soil inocula collected from the same plots in the biodiversity experiment. For each of the four factorial combinations, seedlings of eight species were grown in monocultures or four-species mixtures in pots in an experimental garden over 15 weeks. Soil legacy (live inoculum) strongly increased biodiversity complementarity effects for communities of mixture types, and to a significantly weaker extent for communities of monoculture types. This may be attributed to negative plant-soil feedbacks suffered by mixture types in monocultures, whereas monoculture types had positive plant-soil feedbacks, in both monocultures and mixtures. Monocultures of mixture types were most strongly invaded by weeds, presumably due to increased pathogen susceptibility, reduced biomass, and altered plant-soil interactions of mixture types. These results show that biodiversity effects in experimental grassland communities can be modified by the evolution of positive vs. negative plant-soil feedbacks of plant monoculture vs. mixture types.
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http://dx.doi.org/10.1890/15-0599.1DOI Listing
April 2016

Plant diversity and identity effects on predatory nematodes and their prey.

Ecol Evol 2015 Feb 23;5(4):836-47. Epub 2015 Jan 23.

Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW) PO Box 50, Wageningen, 6700 AB, The Netherlands.

There is considerable evidence that both plant diversity and plant identity can influence the level of predation and predator abundance aboveground. However, how the level of predation in the soil and the abundance of predatory soil fauna are related to plant diversity and identity remains largely unknown. In a biodiversity field experiment, we examined the effects of plant diversity and identity on the infectivity of entomopathogenic nematodes (EPNs, Heterorhabditis and Steinernema spp.), which prey on soil arthropods, and abundance of carnivorous non-EPNs, which are predators of other nematode groups. To obtain a comprehensive view of the potential prey/food availability, we also quantified the abundance of soil insects and nonpredatory nematodes and the root biomass in the experimental plots. We used structural equation modeling (SEM) to investigate possible pathways by which plant diversity and identity may affect EPN infectivity and the abundance of carnivorous non-EPNs. Heterorhabditis spp. infectivity and the abundance of carnivorous non-EPNs were not directly related to plant diversity or the proportion of legumes, grasses and forbs in the plant community. However, Steinernema spp. infectivity was higher in monocultures of Festuca rubra and Trifolium pratense than in monocultures of the other six plant species. SEM revealed that legumes positively affected Steinernema infectivity, whereas plant diversity indirectly affected the infectivity of HeterorhabditisEPNs via effects on the abundance of soil insects. The abundance of prey (soil insects and root-feeding, bacterivorous, and fungivorous nematodes) increased with higher plant diversity. The abundance of prey nematodes was also positively affected by legumes. These plant community effects could not be explained by changes in root biomass. Our results show that plant diversity and identity effects on belowground biota (particularly soil nematode community) can differ between organisms that belong to the same feeding guild and that generalizations about plant diversity effects on soil organisms should be made with great caution.
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http://dx.doi.org/10.1002/ece3.1337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4338967PMC
February 2015

Selection for niche differentiation in plant communities increases biodiversity effects.

Nature 2014 11 15;515(7525):108-11. Epub 2014 Oct 15.

1] Institute of Evolutionary Biology and Environmental Studies &Zurich-Basel Plant Science Center, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland [2] Arnold Arboretum, Harvard University, Boston, Massachusetts 02131, USA.

In experimental plant communities, relationships between biodiversity and ecosystem functioning have been found to strengthen over time, a fact often attributed to increased resource complementarity between species in mixtures and negative plant-soil feedbacks in monocultures. Here we show that selection for niche differentiation between species can drive this increasing biodiversity effect. Growing 12 grassland species in test monocultures and mixtures, we found character displacement between species and increased biodiversity effects when plants had been selected over 8 years in species mixtures rather than in monocultures. When grown in mixtures, relative differences in height and specific leaf area between plant species selected in mixtures (mixture types) were greater than between species selected in monocultures (monoculture types). Furthermore, net biodiversity and complementarity effects were greater in mixtures of mixture types than in mixtures of monoculture types. Our study demonstrates a novel mechanism for the increase in biodiversity effects: selection for increased niche differentiation through character displacement. Selection in diverse mixtures may therefore increase species coexistence and ecosystem functioning in natural communities and may also allow increased mixture yields in agriculture or forestry. However, loss of biodiversity and prolonged selection of crops in monoculture may compromise this potential for selection in the longer term.
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http://dx.doi.org/10.1038/nature13869DOI Listing
November 2014

Earthworms increase plant production: a meta-analysis.

Sci Rep 2014 Sep 15;4:6365. Epub 2014 Sep 15.

Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona 86011, USA.

To meet the challenge of feeding a growing world population with minimal environmental impact, we need comprehensive and quantitative knowledge of ecological factors affecting crop production. Earthworms are among the most important soil dwelling invertebrates. Their activity affects both biotic and abiotic soil properties, in turn affecting plant growth. Yet, studies on the effect of earthworm presence on crop yields have not been quantitatively synthesized. Here we show, using meta-analysis, that on average earthworm presence in agroecosystems leads to a 25% increase in crop yield and a 23% increase in aboveground biomass. The magnitude of these effects depends on presence of crop residue, earthworm density and type and rate of fertilization. The positive effects of earthworms become larger when more residue is returned to the soil, but disappear when soil nitrogen availability is high. This suggests that earthworms stimulate plant growth predominantly through releasing nitrogen locked away in residue and soil organic matter. Our results therefore imply that earthworms are of crucial importance to decrease the yield gap of farmers who can't -or won't- use nitrogen fertilizer.
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http://dx.doi.org/10.1038/srep06365DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5376159PMC
September 2014

Plant species identity surpasses species richness as a key driver of N(2)O emissions from grassland.

Glob Chang Biol 2014 Jan;20(1):265-75

Grassland ecosystems worldwide not only provide many important ecosystem services but they also function as a major source of the greenhouse gas nitrous oxide (N2O), especially in response to nitrogen deposition by grazing animals. To explore the role of plants as mediators of these emissions, we tested whether and how N2O emissions are dependent on grass species richness and/or specific grass species composition in the absence and presence of urine deposition. We hypothesized that: (i) N2O emissions relate negatively to plant productivity; (ii) four-species mixtures have lower emissions than monocultures (as they are expected to be more productive); (iii) emissions are lowest in combinations of species with diverging root morphology and high root biomass; and (iv) the identity of the key species that reduce N2O emissions is dependent on urine deposition. We established monocultures and two- and four-species mixtures of common grass species with diverging functional traits: Lolium perenne L. (Lp), Festuca arundinacea Schreb. (Fa), Phleum pratense L. (Php) and Poa trivialis L. (Pt), and quantified N2O emissions for 42 days. We found no relation between plant species richness and N2O emissions. However, N2O emissions were significantly reduced in specific plant species combinations. In the absence of urine, plant communities of Fa+Php acted as a sink for N2O, whereas the monocultures of these species constituted a N2O source. With urine application Lp+Pt plant communities reduced (P < 0.001) N2O emissions by 44% compared to monocultures of Lp. Reductions in N2O emissions by species mixtures could be explained by total biomass productivity and by complementarity in root morphology. This study shows that plant species composition is a key component underlying N2O emissions from grassland ecosystems. Selection of specific grass species combinations in the context of the expected nitrogen deposition regimes may therefore provide a key for mitigation of N2O emissions.
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http://dx.doi.org/10.1111/gcb.12350DOI Listing
January 2014

Soil biotic legacy effects of extreme weather events influence plant invasiveness.

Proc Natl Acad Sci U S A 2013 Jun 28;110(24):9835-8. Epub 2013 May 28.

Department of Terrestrial Ecology, Netherlands Institute of Ecology, 6700 AB Wageningen, The Netherlands.

Climate change is expected to increase future abiotic stresses on ecosystems through extreme weather events leading to more extreme drought and rainfall incidences [Jentsch A, et al. (2007) Front Ecol Environ 5(7):365-374]. These fluctuations in precipitation may affect soil biota, soil processes [Evans ST, Wallenstein MD (2012) Biogeochemistry 109:101-116], and the proportion of exotics in invaded plant communities [Jiménez MA, et al. (2011) Ecol Lett 14:1277-1235]. However, little is known about legacy effects in soil on the performance of exotics and natives in invaded plant communities. Here we report that drought and rainfall effects on soil processes and biota affect the performance of exotics and natives in plant communities. We performed two mesocosm experiments. In the first experiment, soil without plants was exposed to drought and/or rainfall, which affected soil N availability. Then the initial soil moisture conditions were restored, and a mixed community of co-occurring natives and exotics was planted and exposed to drought during growth. A single stress before or during growth decreased the biomass of natives, but did not affect exotics. A second drought stress during plant growth resetted the exotic advantage, whereas native biomass was not further reduced. In the second experiment, soil inoculation revealed that drought and/or rainfall influenced soil biotic legacies, which promoted exotics but suppressed natives. Our results demonstrate that extreme weather events can cause legacy effects in soil biota, promoting exotics and suppressing natives in invaded plant communities, depending on the type, frequency, and timing of extreme events.
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http://dx.doi.org/10.1073/pnas.1300922110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683719PMC
June 2013

Soil invertebrate fauna affect N2 O emissions from soil.

Glob Chang Biol 2013 Sep 14;19(9):2814-25. Epub 2013 Jul 14.

Department of Soil Quality, Wageningen University, Wageningen, The Netherlands.

Nitrous oxide (N2 O) emissions from soils contribute significantly to global warming. Mitigation of N2 O emissions is severely hampered by a lack of understanding of its main controls. Fluxes can only partly be predicted from soil abiotic factors and microbial analyses - a possible role for soil fauna has until now largely been overlooked. We studied the effect of six groups of soil invertebrate fauna and tested the hypothesis that all of them increase N2 O emissions, although to different extents. We conducted three microcosm experiments with sandy soil and hay residue. Faunal groups included in our experiments were as follows: fungal-feeding nematodes, mites, springtails, potworms, earthworms and isopods. In experiment I, involving all six faunal groups, N2 O emissions declined with earthworms and potworms from 78.4 (control) to 37.0 (earthworms) or 53.5 (potworms) mg N2 O-N m(-2) . In experiment II, with a higher soil-to-hay ratio and mites, springtails and potworms as faunal treatments, N2 O emissions increased with potworms from 51.9 (control) to 123.5 mg N2 O-N m(-2) . Experiment III studied the effect of potworm density; we found that higher densities of potworms accelerated the peak of the N2 O emissions by 5 days (P < 0.001), but the cumulative N2 O emissions remained unaffected. We propose that increased soil aeration by the soil fauna reduced N2 O emissions in experiment I, whereas in experiment II N2 O emissions were driven by increased nitrogen and carbon availability. In experiment III, higher densities of potworms accelerated nitrogen and carbon availability and N2 O emissions, but did not increase them. Overall, our data show that soil fauna can suppress, increase, delay or accelerate N2 O emissions from soil and should therefore be an integral part of future N2 O studies.
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http://dx.doi.org/10.1111/gcb.12232DOI Listing
September 2013

Effects of plant species identity, diversity and soil fertility on biodegradation of phenanthrene in soil.

Environ Pollut 2013 Feb 29;173:231-7. Epub 2012 Nov 29.

Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, United Kingdom.

The work presented in this paper investigated the effects of plant species composition, species diversity and soil fertility on biodegradation of (14)C-phenanthrene in soil. The two soils used were of contrasting fertility, taken from long term unfertilised and fertilised grassland, showing differences in total nitrogen content (%N). Plant communities consisted of six different plant species: two grasses, two forbs, and two legume species, and ranged in species richness from 1 to 6. The degradation of (14)C-phenanthrene was evaluated by measuring indigenous catabolic activity following the addition of the contaminant to soil using respirometry. Soil fertility was a driving factor in all aspects of (14)C-phenanthrene degradation; lag phase, maximum rates and total extents of (14)C-phenanthrene mineralisation were higher in improved soils compared to unimproved soils. Plant identity had a significant effect on the lag phase and extents of mineralisation. Soil fertility was the major influence also on abundance of microbial communities.
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http://dx.doi.org/10.1016/j.envpol.2012.09.020DOI Listing
February 2013

Increased plant carbon translocation linked to overyielding in grassland species mixtures.

PLoS One 2012 25;7(9):e45926. Epub 2012 Sep 25.

Soil and Ecosystem Ecology Laboratory, Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom.

Plant species richness and productivity often show a positive relationship, but the underlying mechanisms are not fully understood, especially at the plant species level. We examined how growing plants in species mixture influences intraspecific rates of short-term carbon (C-) translocation, and determined whether such short-term responses are reflected in biomass yields. We grew monocultures and mixtures of six common C3 grassland plant species in outdoor mesocosms, applied a (13)C-CO(2) pulse in situ to trace assimilated C through plants, into the soil, and back to the atmosphere, and quantified species-specific biomass. Pulse derived (13)C enrichment was highest in the legumes Lotus corniculatus and Trifolium repens, and relocation (i.e. transport from the leaves to other plant parts) of the recently assimilated (13)C was most rapid in T. repens grown in 6-species mixtures. The grass Anthoxanthum odoratum also showed high levels of (13)C enrichment in 6-species mixtures, while (13)C enrichment was low in Lolium perenne, Plantago lanceolata and Achillea millefolium. Rates of C loss through respiration were highest in monocultures of T. repens and relatively low in species mixtures, while the proportion of (13)C in the respired CO(2) was similar in monocultures and mixtures. The grass A. odoratum and legume T. repens were most promoted in 6-species mixtures, and together with L. corniculatus, caused the net biomass increase in 6-species mixtures. These plant species also had highest rates of (13)C-label translocation, and for A. odoratum and T. repens this effect was greatest in plant individuals grown in species mixtures. Our study reveals that short-term plant C translocation can be accelerated in plant individuals of legume and C3 grass species when grown in mixtures, and that this is strongly positively related to overyielding. These results demonstrate a mechanistic coupling between changes in intraspecific plant carbon physiology and increased community level productivity in grassland systems.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0045926PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3457971PMC
May 2013

Enhancement of late successional plants on ex-arable land by soil inoculations.

PLoS One 2011 8;6(7):e21943. Epub 2011 Jul 8.

Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands.

Restoration of species-rich grasslands on ex-arable land can help the conservation of biodiversity but faces three big challenges: absence of target plant propagules, high residual soil fertility and restoration of soil communities. Seed additions and top soil removal can solve some of these constraints, but restoring beneficial biotic soil conditions remains a challenge. Here we test the hypotheses that inoculation of soil from late secondary succession grasslands in arable receptor soil enhances performance of late successional plants, especially after top soil removal but pending on the added dose. To test this we grew mixtures of late successional plants in arable top (organic) soil or in underlying mineral soil mixed with donor soil in small or large proportions. Donor soils were collected from different grasslands that had been under restoration for 5 to 41 years, or from semi-natural grassland that has not been used intensively. Donor soil addition, especially when collected from older restoration sites, increased plant community biomass without altering its evenness. In contrast, addition of soil from semi-natural grassland promoted plant community evenness, and hence its diversity, but reduced community biomass. Effects of donor soil additions were stronger in mineral than in organic soil and larger with bigger proportions added. The variation in plant community composition was explained best by the abundances of nematodes, ergosterol concentration and soil pH. We show that in controlled conditions inoculation of soil from secondary succession grassland into ex-arable land can strongly promote target plant species, and that the role of soil biota in promoting target plant species is greatest when added after top soil removal. Together our results point out that transplantation of later secondary succession soil can promote grassland restoration on ex-arable land.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0021943PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3132286PMC
October 2011

Plant species richness, identity and productivity differentially influence key groups of microbes in grassland soils of contrasting fertility.

Biol Lett 2011 Feb 4;7(1):75-8. Epub 2010 Aug 4.

Soil and Ecosystem Ecology Laboratory, Lancaster Environment Centre, University of Lancaster, Lancaster LA1 4YQ, UK.

The abundance of microbes in soil is thought to be strongly influenced by plant productivity rather than by plant species richness per se. However, whether this holds true for different microbial groups and under different soil conditions is unresolved. We tested how plant species richness, identity and biomass influence the abundances of arbuscular mycorrhizal fungi (AMF), saprophytic bacteria and fungi, and actinomycetes, in model plant communities in soil of low and high fertility using phospholipid fatty acid analysis. Abundances of saprophytic fungi and bacteria were driven by larger plant biomass in high diversity treatments. In contrast, increased AMF abundance with larger plant species richness was not explained by plant biomass, but responded to plant species identity and was stimulated by Anthoxantum odoratum. Our results indicate that the abundance of saprophytic soil microbes is influenced more by resource quantity, as driven by plant production, while AMF respond more strongly to resource composition, driven by variation in plant species richness and identity. This suggests that AMF abundance in soil is more sensitive to changes in plant species diversity per se and plant species composition than are abundances of saprophytic microbes.
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http://dx.doi.org/10.1098/rsbl.2010.0575DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3030891PMC
February 2011

Plant functional traits and soil carbon sequestration in contrasting biomes.

Ecol Lett 2008 May 13;11(5):516-31. Epub 2008 Feb 13.

Institute of Environmental and Natural Sciences, Soil and Ecosystem Ecology, Lancaster University, Lancaster LA1 4YQ, UK.

Plant functional traits control a variety of terrestrial ecosystem processes, including soil carbon storage which is a key component of the global carbon cycle. Plant traits regulate net soil carbon storage by controlling carbon assimilation, its transfer and storage in belowground biomass, and its release from soil through respiration, fire and leaching. However, our mechanistic understanding of these processes is incomplete. Here, we present a mechanistic framework, based on the plant traits that drive soil carbon inputs and outputs, for understanding how alteration of vegetation composition will affect soil carbon sequestration under global changes. First, we show direct and indirect plant trait effects on soil carbon input and output through autotrophs and heterotrophs, and through modification of abiotic conditions, which need to be considered to determine the local carbon sequestration potential. Second, we explore how the composition of key plant traits and soil biota related to carbon input, release and storage prevail in different biomes across the globe, and address the biome-specific mechanisms by which plant trait composition may impact on soil carbon sequestration. We propose that a trait-based approach will help to develop strategies to preserve and promote carbon sequestration.
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http://dx.doi.org/10.1111/j.1461-0248.2008.01164.xDOI Listing
May 2008

Linking aboveground and belowground diversity.

Trends Ecol Evol 2005 Nov 8;20(11):625-33. Epub 2005 Sep 8.

Department of Integrative Biology, University of Guelph, Guelph, On, Canada, N1G 2W1.

Aboveground and belowground species interactions drive ecosystem properties at the local scale, but it is unclear how these relationships scale-up to regional and global scales. Here, we discuss our current knowledge of aboveground and belowground diversity links from a global to a local scale. Global diversity peaks towards the Equator for large, aboveground organisms, but not for small (mainly belowground) organisms, suggesting that there are size-related biodiversity gradients in global aboveground-belowground linkages. The generalization of aboveground-belowground diversity relationships, and their role in ecosystem functioning, requires surveys at scales that are relevant to the organisms and ecosystem properties. Habitat sizes and diversity gradients can differ significantly between aboveground and belowground organisms and between ecosystems. These gradients in biodiversity and plant community trait perception need to be acknowledged when studying aboveground-belowground biodiversity linkages.
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http://dx.doi.org/10.1016/j.tree.2005.08.009DOI Listing
November 2005

Soil invertebrate fauna enhances grassland succession and diversity.

Nature 2003 Apr;422(6933):711-3

Department of Multitrophic Interactions, Centre for Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 40, 6666 ZG, Heteren, The Netherlands.

One of the most important areas in ecology is to elucidate the factors that drive succession in ecosystems and thus influence the diversity of species in natural vegetation. Significant mechanisms in this process are known to be resource limitation and the effects of aboveground vertebrate herbivores. More recently, symbiotic and pathogenic soil microbes have been shown to exert a profound effect on the composition of vegetation and changes therein. However, the influence of invertebrate soil fauna on succession has so far received little attention. Here we report that invertebrate soil fauna might enhance both secondary succession and local plant species diversity. Soil fauna from a series of secondary grassland succession stages selectively suppress early successional dominant plant species, thereby enhancing the relative abundance of subordinate species and also that of species from later succession stages. Soil fauna from the mid-succession stage had the strongest effect. Our results clearly show that soil fauna strongly affects the composition of natural vegetation and we suggest that this knowledge might improve the restoration and conservation of plant species diversity.
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http://dx.doi.org/10.1038/nature01548DOI Listing
April 2003