Biology subjects

Wagg, C.

Publications and source records attributed to Wagg, C..

5 recordsLinked to original sources

bioRxiv2018

Diversity-dependent plant-soil feedbacks underlie long-term plant diversity effects on primary productivity

Although diversity-dependent plant-soil feedbacks (PSFs) may contribute significantly to plant diversity effects on ecosystem functioning, the influence of underlying abiotic and biotic mechanistic pathways have been little explored to date. Here, we assessed such pathways with a PSF experiment using soil conditioned for [≥]12 years from two grassland biodiversity experiments. Model plant communities differing in diversity were grown in soils conditioned by plant communities with either low- or high-diversity (soil history). Our results reveal that plant diversity can modify plant productivity through both diversity-mediated plant-plant and plant-soil interactions, with the main driver (current plant diversity or soil history) differing with experimental context. The underlying mechanisms of PSFs were explained to a significant extent by both abiotic and biotic pathways (specifically, nematode richness and soil nitrogen availability). Thus, effects of plant diversity loss on ecosystem functioning may persist or even increase over time because of biotic and abiotic soil legacy effects.

ecology↗

bioRxiv2018

Rhizosphere bacterial community composition depends on plant diversity legacy in soil and plant species identity

Soil microbes are known to be involved in a number of 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 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 timeframe plants with a monoculture or mixture history changed in the microbial communities they associated with. For eight species, we grew offspring of plants that had been grown for 11 years in the same monocultures or mixtures (monoculture- or mixture-type plants) in pots inoculated with microbes extracted from the monoculture and mixture soils. After five 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. Microbial community structure in the plant rhizosphere was primarily determined by soil legacy (monoculture vs. mixture soil) and by plant species identity, but not by plant legacy (monoculture- vs. mixture-type plants). In seven out of the eight plant species bacterial abundance was larger when inoculated with microbes from mixture soil. We conclude that plant diversity can strongly affect belowground community composition and diversity, feeding back to the assemblage of rhizosphere microbial communities in newly establishing plants. Thereby our work demonstrates that concerns for plant biodiversity loss are also concerns for soil biodiversity loss.

ecology↗

bioRxiv2018

Evolution increases ecosystem temporal stability and recovery from a flood in grassland communities

Understanding factors that increase ecosystem stability is critical in the face of environmental change. Experiments simulating species loss from grassland ecosystems have shown that losing biodiversity decreases the ability of ecosystems to buffer negative effects of disturbances. However, as the originally sown experimental communities with reduced biodiversity develop, plant evolutionary processes or the assembly of interacting soil organisms may allow them to develop stability and resilience over time. We explored such effects in a long-term grassland biodiversity experiment with plant communities with either a history of co-occurrence (selected communities) or no such history (naive communities) over a four-year period in which a major flood disturbance occurred. We found selected communities had temporally more stable biomass than the same communities of naive plants, especially at low species richness. Furthermore, selected communities showed greater short-term biomass recovery after flooding, resulting in more stable post-flood productivity. In contrast to a previous study, the positive diversity-stability relationship was maintained after the flooding. Our results were consistent across three soil treatments simulating the presence or absence of co-selected microbial communities. We suggest that prolonged exposure of plant populations to a particular community context and abiotic site conditions can increase ecosystem temporal stability and resistance to disturbance. We argue that selection during the course of a biodiversity experiment is the most parsimonious explanation for these effects. A history of co-occurrence can in part compensate for species loss, as can high plant diversity in part compensate for the missing opportunity of such adaptive adjustments.

ecology↗

bioRxiv2017

Testing for co-adaptation of plants and arbuscular mycorrhizal fungi in a biodiversity experiment

O_LIBiodiversity loss not only impairs ecosystem functioning but can also alter the selection for traits in plant communities. At high diversity selection favours traits that allow for greater niche partitioning, whereas at low diversity selection may favour greater defence against pathogens. However, it is unknown whether changes in plant diversity also select for altered interactions with soil organisms.\nC_LIO_LIWe assessed whether the responses in plant growth and functional traits to their local arbuscular mycorrhizal fungal (AMF) communities have been altered by the diversity of the plant communities from which both plants and AMF communities were obtained. We grew plants with AMF communities that originated from either plant monocultures or mixtures in a fully factorial design that included both negative and positive controls, by inoculating no AMF or a foreign AMF respectively.\nC_LIO_LIWe found that AMF from plant mixtures were more beneficial than monoculture AMF for two out of five plant species. Plants from mixtures generally grew better than those from monocultures, but suffered greater damage by leaf pathogens. Although plant growth and phenotypic responses were dependent on the AMF communities with which they associated, we found little evidence for plant growth responses specific to their local AMF communities and results differed between species and traits.\nC_LIO_LIOur results show that plants from mixtures were selected for increased growth at the expense of reduced defence and vice versa for plants from monocultures, providing evidence for plant diversity-dependent selection on competitive growth vs. defence. Furthermore, our study suggests that effects of a common history between plants and AMF do not follow a general pattern leading to increased or decreased mutualism.\nC_LIO_LISynthesis: Here we provide evidence that biodiversity loss can alter evolutionary trajectories of plant phenotypes and responses to their local AMF communities. However, the selection for altered plant-AMF interactions differ between plant species. To understand how plant communities respond and evolve under a changing environment requires further knowledge about life strategies of plant species and their above-belowground interactions.\nC_LI

ecology↗

bioRxiv2017

Community selection increases biodiversity effects

Species extinctions from local communities can 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 the effects of biodiversity 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 (\"naive communities\"). Monocultures and in particular mixtures of two to four co-selected species were more productive than their corresponding naive communities over four 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 that simulated additional co-evolutionary processes between plants and soil organisms.

ecology↗