Abstract
Plant-soil feedback is increasingly recognized as a vital framework to analyze multi-trophic interactions involving herbivores, plants and microbes, but research is still lacking on understanding such feedback in the context of global change. In grasslands, patterns of herbivory are expected to be affected by global change, further modifying existing plant-soil feedbacks. We tested this by evaluating the individual and combined impacts of aboveground herbivory by a generalist leaf-chewer and nitrogen (N) eutrophication, simulating elevated N deposition, on soil microbial communities and root colonization of arbuscular mycorrhizal fungi and related these to existing data on plant functional types and community composition. We found that colonization of arbuscular mycorrhizal fungi in the plant roots responded differently to treatments depending on host plant species in patterns consistent with the changes in the plant community composition and biomass. Further, the effect of aboveground herbivory on plant-soil interactions was comparable and even exceeded that of N-eutrophication, with the additive effects of herbivory and N-eutrophication on the soil microbiome being stronger than each factor separately. Our results suggest that plant-soil feedback in response to N-eutrophication is contingent on biotic variables such as herbivory and plant species, and that biotic and abiotic disturbances may have additive effects on the soil microbiome structure.
Highlights
Global change entails significant impacts on terrestrial ecosystems in the form of increased warming and increased loads of reactive nitrogen (N) from atmospheric deposition
This appeared to stem from the interaction between plant species and treatment, where colonization of A. capillaris roots was reduced under the single impact of N eutrophication but not when combined with herbivory (Fig. 1)
In this study we demonstrate that the arbuscular mycorrhizal fungi (AMF) response, as measured by root colonization, to herbivory and N eutrophication is contingent on plant species and on the interactions of these
Summary
Global change entails significant impacts on terrestrial ecosystems in the form of increased warming and increased loads of reactive nitrogen (N) from atmospheric deposition. Invertebrate herbivores tend to target certain plant func tional groups over others by preferentially feeding on fast-growing species such as grasses before perennial forbs, thereby altering the plant community composition of grassland ecosystems (Huntly, 1991). Under stable conditions plant herbivory induces several mutually antagonistic processes that might synchronously alter plant commu nities in opposite directions, increased N loadings may affect plant community composition and litter production. Plant-herbivore interactions are connected to the soil microbiome as plants and rhizosphere-associated microbiota live in intimate feedback with each other (Tedersoo et al, 2020). These feedbacks help to regulate plant nutrient uptake and plant defense mechanisms (Bever et al, 2012; Babikova et al, 2013). Accumulating evidence indicates that differing plant functional groups shape soil and root-associated micro bial communities directly or indirectly by altering soil conditions over multiple plant generations (Bezemer et al, 2005; Bais et al, 2006; Bahram et al, 2020), and that this constitutes a significant driver of aboveground community responses to herbivory (Bezemer et al, 2005; Kardol et al, 2007; Eisenhauer et al, 2011)
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