Complementarity and selection effects in early and mid‐successional plant communities are differentially affected by plant–soil feedbackJournal of Ecology - Tập 103 Số 3 - Trang 641-647 - 2015
Jingying Jing, Т. Martijn Bezemer, Wim H. van der Putten
Summary
Many studies that provided evidence for a positive relationship between plant diversity and productivity have proposed that this effect may be explained by complementarity among species in resources utilization, or selection of particularly productive species in high‐diversity plant communities. Recent studies have related the higher productivity in diverse plant communities to suppression of pathogenic soil biota. If soil biota plays a role in diversity–productivity relationships, the question remains about how they may influence complementarity and selection effects.
Here we examine how complementarity and selection effects may depend on soil biota using a plant–soil feedback approach. We used monocultures and mixtures of early successional plant species, which are known to have mostly negative plant–soil feedback effects, and mid‐successional plant species, which generally have neutral plant–soil feedback.
We found that plant–soil feedback effects differed between monocultures and mixed plant communities, as well as between early and mid‐successional plants. This resulted in a significant interaction effect between diversity and successional stage. In monocultures, plant–soil feedback tended to be negative for early and positive for mid‐successional plant species. Interestingly, the community feedback responses of the mixed communities were opposite, being positive for early and negative for mid‐successional community.
Plant–soil feedback differentially affected complementarity and selection effects of early and mid‐successional plant communities: it enhanced complementarity effects of early and decreased selection effects of mid‐successional species.
Synthesis. Soil biota that drive plant–soil feedback effects can influence the diversity–productivity relationship not only through decreased biomass production in monocultures compared to mixtures, but also through influencing complementarity and selection effects among species in mixed plant communities. Our results reveal that biodiversity–productivity relationships depend on plant–soil feedback interactions, which depend on the successional position of the plant. We propose that including successional position and trait‐based analyses of plant–soil feedback in diversity‐functioning studies will enhance understanding consequences of biodiversity loss for productivity and other ecosystem processes.
Conspecific plant–soil feedbacks reduce survivorship and growth of tropical tree seedlingsJournal of Ecology - Tập 98 Số 2 - Trang 396-407 - 2010
Sarah McCarthy‐Neumann, Richard K. Kobe
Summary 1. The Janzen–Connell (J–C) Model proposes that host‐specific enemies maintain high tree species diversity by reducing seedling performance near conspecific adults and promoting replacement by heterospecific seedlings. Support for this model often comes from decreased performance for a species at near versus far distances from conspecific adults. However, the relative success of conspecific versus heterospecific seedlings recruiting under a given tree species is a critical, but untested, component of the J–C Model.
2. In a shade‐house experiment, we tested plant–soil feedbacks as a J–C mechanism in six tropical tree species. We assessed effects of conspecific versus heterospecific cultured soil extracts on seedling performance for each species, and we compared performance of conspecific versus heterospecific seedlings grown with soil extract cultured by a particular tree species. Additionally, we tested whether soil microbes were creating these plant–soil feedbacks and whether low light increased species vulnerability to pathogens.
3. Among 30 potential comparisons of survival and mass for seedlings grown in conspecific versus heterospecific soil extracts, survival decreased in seven and increased in two, whereas mass decreased in 13 and increased in 1. To integrate survival and growth, we also examined seedling performance [(mean total mass × mean survival time)/(days of experiment)], which was lower in 16 and higher in 2 of 30 comparisons between seedlings grown with soil extract cultured by conspecific versus heterospecific individuals. Based on performance within a soil extract, conspecific seedlings were disadvantaged in 15 and favoured in 7 of 30 cases relative to heterospecific seedlings.
4. Species pairwise interactions of soil modification and seedling performance occurred regardless of sterilization, suggesting chemical mediation. Microbes lacked host‐specificity and reduced performance regardless of extract source and irradiance.
5. Synthesis. These results, along with parallel research in temperate forests, suggest that plant–soil feedbacks are an important component of seedling dynamics in both ecosystems. However, negative conspecific feedbacks were more prevalent in tropical than temperate species. Thus, negative plant–soil feedbacks appear to facilitate species coexistence via negative distance‐dependent processes in tropical but not temperate forests, but the feedbacks were mediated through chemical effects rather than through natural enemies as expected under the J–C Model.
Phylogenetic relatedness, phenotypic similarity and plant–soil feedbacksJournal of Ecology - Tập 105 Số 3 - Trang 786-800 - 2017
Connor R. Fitzpatrick, Laura Gehant, Peter M. Kotanen, Marc T. J. Johnson
Summary
Plant–soil feedbacks contribute to species invasions, the maintenance of biodiversity and climate change impacts on terrestrial ecosystems. Despite their far‐reaching importance, we lack a general understanding of the ecological and evolutionary determinants of plant–soil feedbacks.
We conducted a large‐scale plant–soil feedback experiment using 49 co‐occurring plant species from southern Ontario, Canada, representing a wide phylogenetic range. We tested whether the effects of soil conditioning vary among these species and whether different focal species respond similarly to the same soil conditioning. Next, we investigated whether plant traits and soil feedbacks depend on phylogenetic similarity and which plant traits affect plant–soil feedbacks between pairs of plant species. Finally, we used our experimental results to test whether soil feedbacks affect co‐occurrence of species in the field.
We found evidence of both strong positive and negative soil feedbacks between pairs of plant species. Our soil‐conditioning treatment explained nearly 20% of the variation in focal species performance.
Phylogenetic relatedness and phenotypic similarity between plant species were unrelated to the strength of their soil feedback. However, numerous plant traits of the conditioning species influenced the strength of soil feedbacks on focal species, including specific leaf area and total above‐ground productivity. Trait differences between species were also predictive of plant–soil feedbacks, though for some pairs of species, increased trait differences were associated with positive plant–soil feedbacks and for others, trait differences were associated with negative plant–soil feedbacks.
Plant species co‐occurrence in the field was related to their experimentally determined soil feedbacks but only for particular plant species.
Synthesis. Our results illustrate how evolutionary history and phenotypic variation shape plant–soil feedbacks and highlight the need for trait‐based studies. Due to the unique evolutionary history of individual traits and the variability in their importance across all possible interacting species, we show that indices of overall phenotypic and phylogenetic relatedness are poor predictors of plant–soil feedbacks at large phylogenetic scales. We conclude that a detailed trait‐based approach can be used to predict plant–soil feedbacks, and laboratory measures of soil feedbacks can explain patterns of co‐occurrence in nature.
Plant–soil feedbacks: role of plant functional group and plant traitsJournal of Ecology - Tập 104 Số 6 - Trang 1608-1617 - 2016
Roeland Cortois, Thomas Schröder‐Georgi, Alexandra Weigelt, Wim H. van der Putten, Gerlinde B. De Deyn
Summary
Plant–soil feedback (PSF), plant trait and functional group concepts advanced our understanding of plant community dynamics, but how they are interlinked is poorly known.
To test how plant functional groups (FGs: graminoids, small herbs, tall herbs, legumes) and plant traits relate to PSF, we grew 48 grassland species in sterilized soil, sterilized soil with own species soil inoculum and sterilized soil with soil inoculum from all species, and quantified relative growth rate (RGR), specific leaf area (SLA), specific root length (SRL) and per cent arbuscular mycorrhizal fungi colonization (%AMF).
Plant growth response to the plant species' own soil biota relative to sterilized soil (PSFsterilized) reflects net effects of all (generalist + specialized) soil biota. Growth response to the plant species' own soil biota relative to soil biota of all plant species (PSFaway) reveals effects of more specialized soil organisms.
PSFsterilized showed that graminoids and small herbs have a negative and tall herbs a positive response to their own soil biota, whereas legumes responded neutrally. However, PSFaway showed that on average, all plant FGs benefitted from growing with other species' soil biota, suggesting that pathogens are more specialized than plant growth‐promoting soil biota. Feedback to plant growth from all soil biota (PSFsterilized) was stronger than from more specialized soil biota (PSFaway) and could be predicted by SRL and especially by %AMF colonization. Species with high SRL and low %AMF colonization when grown in away soil experienced most negative soil feedback.
Synthesis. Plant species from all plant FGs grow better in soil from other species because of less net negative effects of soil biota (in graminoids), or because of more net positive soil biota effects (in tall herbs). Explorative plant species (high SRL, low %AMF colonization) suffer most from negative feedback of all soil biota, whereas more resource conservative species (low SRL, high %AMF colonization) benefit from soil feedback of all soil biota. These findings help to understand replacement of explorative species during succession. Moreover, we suggest a potentially larger role for species with positive feedback than for species with negative feedback to contribute to maintain plant community productivity of diverse communities over time.
Plant diversity improves protection against soil‐borne pathogens by fostering antagonistic bacterial communitiesJournal of Ecology - Tập 100 Số 3 - Trang 597-604 - 2012
Ellen Latz, Nico Eisenhauer, Björn C. Rall, Eric Allan, Christiane Roscher, Stefan Scheu, Alexandre Jousset
Summary1. Rhizosphere bacteria antagonistic to fungal pathogens improve plant performance by preventing infection. In temperate grasslands, primary productivity often increases with plant diversity, and we hypothesized that this effect may in part rely on the interactions between plants and antagonistic bacteria.
2. We investigated the impact of plant diversity and functional group composition on soil bacteria producing the antifungal compounds 2,4‐diacetylphloroglucinol (DAPG) and pyrrolnitrin (PRN) in a long‐term grassland biodiversity experiment, as well as their impact on soil suppressiveness. Soil suppressiveness was investigated in a model infection assay with Beta vulgaris and the pathogen Rhizoctonia solani.
3. The abundance of DAPG and PRN producers increased with plant diversity and that of PRN also increased in the presence of grasses. Moreover, legume species richness and coverage decreased the abundance of DAPG and PRN producers, respectively, contrary to beneficial effects of legumes on soil microorganisms reported previously. In turn, soil suppressiveness was at maximum when DAPG and PRN producer abundance was high.
4. Synthesis. Our results suggest that plant diversity contributes to plant community resistance against pathogens by fostering beneficial bacterial communities. This indirect soil feedback mechanism may contribute to the positive relationship between plant diversity and productivity and could also help the development of more sustainable and environmentally friendly agricultural management strategies.
Root traits are multidimensional: specific root length is independent from root tissue density and the plant economic spectrumJournal of Ecology - Tập 104 Số 5 - Trang 1299-1310 - 2016
Kris R. Kramer‐Walter, Peter J. Bellingham, Timothy R. Millar, Rob D. Smissen, Sarah J. Richardson, Daniel C. Laughlin
Summary
Root, stem and leaf traits are thought to be functionally coordinated to maximize the efficiency of acquiring and using limited resources. However, evidence is mixed for consistent whole‐plant trait coordination among woody plants, and we lack a clear understanding of the adaptive value of root traits along soil resource gradients. If fine roots are the below‐ground analogue to leaves, then low specific root length (SRL) and high tissue density should be common on infertile soil. Here, we test the prediction that root, stem and leaf traits and relative growth rate respond in unison with soil fertility gradients.
We measured fine root, stem and leaf traits and relative growth rate on individual seedlings of 66 tree species grown in controlled conditions. Our objectives were (i) to determine whether multiple root traits align with growth rate, leaf and stem traits and with each other and (ii) to quantify the relationships between community‐weighted mean root traits and two strong soil fertility gradients that differed in spatial extent and community composition.
At the species level, fast growth rates were associated with low root and stem tissue density and high specific leaf area. SRL and root diameter were not clearly related to growth rate and loaded on a separate principal component from the plant economic spectrum.
At the community level, growth rate was positively related to soil fertility, and root tissue density (RTD) and branching were negatively related to soil fertility. SRL was negatively related and root diameter was positively related to soil fertility on the large‐scale gradient that included ectomycorrhizal angiosperms.
Synthesis. Root, stem and leaf tissue traits of tree seedlings are coordinated and influence fitness along soil fertility gradients. RTD responds in unison with above‐ground traits to soil fertility gradients; however, root traits are multidimensional because SRL is orthogonal to the plant economic spectrum. In contrast to leaves, trees are not constrained in the way they construct fine roots: plants can construct high or low SRL roots of any tissue density. High RTD is the most consistent below‐ground trait that reflects adaptation to infertile soil.
Plant–soil feedbacks: the past, the present and future challengesJournal of Ecology - Tập 101 Số 2 - Trang 265-276 - 2013
Wim H. van der Putten, Richard D. Bardgett, James D. Bever, Т. Martijn Bezemer, Brenda B. Casper, Tadashi Fukami, Paul Kardol, John N. Klironomos, Andrew Kulmatiski, Jennifer A. Schweitzer, Katharine N. Suding, Tess F. J. van de Voorde, David A. Wardle
Summary
Plant–soil feedbacks is becoming an important concept for explaining vegetation dynamics, the invasiveness of introduced exotic species in new habitats and how terrestrial ecosystems respond to global land use and climate change. Using a new conceptual model, we show how critical alterations in plant–soil feedback interactions can change the assemblage of plant communities. We highlight recent advances, define terms and identify future challenges in this area of research and discuss how variations in strengths and directions of plant–soil feedbacks can explain succession, invasion, response to climate warming and diversity‐productivity relationships.
While there has been a rapid increase in understanding the biological, chemical and physical mechanisms and their interdependencies underlying plant–soil feedback interactions, further progress is to be expected from applying new experimental techniques and technologies, linking empirical studies to modelling and field‐based studies that can include plant–soil feedback interactions on longer time scales that also include long‐term processes such as litter decomposition and mineralization.
Significant progress has also been made in analysing consequences of plant–soil feedbacks for biodiversity‐functioning relationships, plant fitness and selection.
To further integrate plant–soil feedbacks into ecological theory, it will be important to determine where and how observed patterns may be generalized, and how they may influence evolution.
Synthesis. Gaining a greater understanding of plant–soil feedbacks and underlying mechanisms is improving our ability to predict consequences of these interactions for plant community composition and productivity under a variety of conditions. Future research will enable better prediction and mitigation of the consequences of human‐induced global changes, improve efforts of restoration and conservation and promote sustainable provision of ecosystem services in a rapidly changing world.
Density‐dependent disease, life‐history trade‐offs, and the effect of leaf pathogens on a suite of co‐occurring close relativesJournal of Ecology - Tập 106 Số 5 - Trang 1829-1838 - 2018
Ingrid M. Parker, Gregory S. Gilbert
Abstract
Plant pathogens reduce the performance of their hosts and therefore may contribute to ecological mechanisms of coexistence. In Chesson’s framework, pathogens contribute to stabilizing mechanisms when they intensify negative intraspecific interactions, such as density‐dependent disease. Additionally, pathogens contribute to equalizing mechanisms when they reduce differences in performance among species. Life‐history trade‐offs predict higher susceptibility to pathogens in rapidly growing species, which could equalize performance among fast‐ and slow‐growing species in the presence of pathogens.
In a coastal prairie in California, we studied the impact of leaf diseases on the performance of 17 co‐occurring species of Trifolium and Medicago (“clovers”). We transplanted clovers in randomized arrays into the natural prairie community in 3 years of common garden experiments. We quantified infection rates by isolating fungi from leaves, and we measured disease severity as per cent leaf area damaged. In a fungicide experiment, we measured the impact of infection on biomass and survival. We assessed whether disease on transplants was positively related to natural abundance of that species in the surrounding community, which we monitored over 5 years. We assessed life‐history trade‐offs by testing whether more rapidly growing species were more susceptible to pathogens.
Rank abundance of clover species was stable over 5 years despite marked environmental fluctuations. Across hosts, fungal infection was not linearly related to density, although transplants of species that were locally absent showed lower and more variable infection. Disease severity was greater for more abundant species, but in only 1 of 3 years, and response to fungicide was not stronger in more abundant species. As predicted by life‐history trade‐offs, faster‐growing species experienced greater fungal infection. However, the impact of that infection was less negative, not more negative, on faster‐growing species.
Our results suggest that life‐history trade‐offs in plant–pathogen interactions may influence equalizing mechanisms among species in this guild, but the combined effects of greater infection with greater tolerance may limit rather than promote coexistence. We also found modest evidence that density‐dependent disease may contribute to stabilizing mechanisms. Lack of host specificity, rapid evolution of host use and temporal variation in climatic conditions may all influence the role that pathogens play in coexistence of these closely related plants.
