Aronson, E. | Search bioRxiv

bioRxiv2018

Fungal community assembly in soils and roots under plant invasion and nitrogen deposition

Abstract Fungal community composition in the Anthropocene is driven by rapid changes in environmental conditions caused by human activities. This study examines the relative importance of two global change drivers - atmospheric nitrogen (N) deposition and annual grass invasion - on structuring fungal communities in a California chaparral ecosystem, with emphasis on arbuscular mycorrhizal fungi. We used molecular markers, functional groupings, generalized linear statistics and joint distribution modeling, to examine how environmental variables structure taxonomic and functional composition of fungal communities. Invasion of a chaparral ecosystem decreased richness and relative abundance of non-AMF symbionts and rhizophilic AMF (e.g. Glomeraceae) as well as the proportion of edaphophilic AMF (e.g. Gigasporaceae). We found increased richness and the proportion of rhizophilic and edaphophilic AMF with increasing soil NO3. Our findings suggest that invasive persistence may decrease the presence of multiple soil symbionts that native species depend on for pathogen protection and increased access to soil resources.

ecology↗

bioRxiv2018

Inoculation with Pisolithus tinctorius may ameliorate acid rain impacts on soil microbial communities associated with Pinus massoniana seedlings

Human activities accelerate acidification, particularly as acid rain, which may have lasting impacts on soil abiotic and biotic parameters. However, the effects of acidification on aboveground vegetation, belowground communities, and carbon cycling remains unresolved. We examined the effects of long-term acidic treatments and Pisolithus inoculation on plants, soils, and microbial communities in pine plantations and found that exposure to severely-acidic treatments diminished plant performance, altered microbial communities, and decreased organic matter, nitrate, and available phosphorus. Although we did not detect any benefits of Pisolithus inoculation for Pinus seedlings impacted by severely-acidic treatments, when these severe treatments were inoculated with Pisolithus, both soil properties and microbial community composition shifted. We posit that inoculation with Pisolithus may alleviate stressful environmental conditions, and change the structure of mycorrhizal fungal communities. Although acidification may alter biogeochemical cycles and constrain aboveground and belowground communities, Pisolithus inoculation may provide benefits to some components of forested ecosystems.

ecology↗