Individual Plant-Soil Feedback Effects Influence Tree Growth and Rhizosphere Fungal Communities in a Temperate Forest Restoration Experiment

Abstract

Plant-soil feedbacks have important implications for community composition and restoration. However, relatively few field trials test the influence of plant-soil feedbacks, especially on longer-lived species, such as trees. Here we present a field restoration experiment with 10 ectomycorrhizal fungal tree species native to eastern North America. Trees were inoculated with soils collected from conspecifics in the field or from a heterospecific: Quercus rubra. Following 16 months of growth in the field, Carya ovata diameter increase was significantly greater in trees receiving the heterospecific inoculant. This plant-soil feedback is consistent with C. ovata's natural co-occurrence with Q. rubra. Conversely, Quercus macrocarpa diameter increase and Carya cordiformis height increase were significantly greater when inoculated with conspecific soils, and this positive plant-soil feedback is consistent with their numerical dominance in natural communities. We found no evidence for phylogenetic Janzen-Connell effects or conservation of soil mutualists across tree species. We also quantified differences in soil fungal community structure with next generation sequencing methods (Illumina MiSeq) following 16 months in the field. Shannon's diversity of fungal taxa was greater in heterospecific soils of seven of our nine experimental species, consistent with a diversifying influence of Quercus rubra soil inocula. However, only one genus, Ulmus, exhibited differences in fungal community composition derived from conspecific and heterospecific sources, suggesting a stronger effect of focal tree species than of soil inocula source. The relatedness among focal tree species also influenced fungal community composition, with tree families and genera displaying different fungal communities. We suggest that future experiments should determine whether more diverse tree and fungal communities might have enhanced ecosystem functioning in tree restoration sites.

Contrasting plant–soil–microbial feedbacks stabilize vegetation types and uncouple topsoil C and N stocks across a subarctic–alpine landscape

“…Particularly, the plant rooting zone selects for microorganisms that may generate either negative or positive feedbacks to plant growth (Wardle, 2002; Van der Putten et al ., 2013). Negative feedbacks involve nutrient competition and pathogenic activities (Bell et al ., 2006; Mangan et al ., 2010), while positive feedbacks involve enhanced nutrient acquisition, for example, through mycorrhizal symbioses, and pathogen suppression (Bennett et al ., 2017; Lance et al ., 2020). While negative feedbacks may prevent dominance by single plant species (Mangan et al ., 2010), positive feedbacks may stabilize vegetation types (Van der Putten et al ., 2013).…”

Plant–soil feedbacks among boreal forest species

“…The type of feedback mechanism determines inter‐ and intraspecific dynamics in forests. Positive feedbacks, where tree‐mediated changes in soil biota aid conspecific seedling establishment, often result in the dominance of one tree species over the others (Lance et al., 2020). Conversely, negative PSFs, which promote the establishment of heterospecific seedlings, can result in either the coexistence of two or more species or compositional shifts.…”

Alteration of the tree–soil microbial system triggers a feedback loop that boosts holm oak decline

“…For instance, microbial metabolism is the great engine of carbon and nutrient cycling contributing to the availability of soil nutrients (Willey et al, 2008). Overall, alterations of these mechanisms at the soil level may exert positive or negative effects on plant growth and fitness (Bezemer et al, 2020) and hence on species composition and ecosystem functioning (Png et al, 2023). Disentangling the individual contribution of the different processes involved in these plant-soil feedback and its responses to natural and anthropogenic disturbances associated with climate change (van der Putten et al, 2016) may further facilitate the implementation of effective climate-adaptive forest management (Refsland et al, 2023).…”