Stochastic processes drive bacterial and fungal community assembly in sustainable intensive agricultural soils of Shanghai, China

The assembly mechanisms and drivers of abundant and rare fungi in dryland montane forest soils remain underexplored. Therefore, in this study, we compared the distribution patterns of abundant and rare fungi and explored the factors determining their assembly processes in a dryland montane forest in China. Stronger distance-decay relationships (DDRs) were found in abundant sub-communities than in rare sub-communities. In addition, abundant fungi exhibited greater presence and wider habitat niche breadth than rare fungi. Both the null model and variation partitioning analysis indicated that dispersal limitation and environmental selection work together to govern both abundant and rare fungal assembly, while dispersal limitation plays a dominant role. Meanwhile, the relative influence of dispersal limitation and environmental selection varied between abundant and rare sub-communities, where dispersal limitation showed greater dominance in abundant fungal assembly. Mantel tests demonstrated that soil pH and phosphorus played critical roles in mediating abundant and rare fungi assembly processes, respectively. Our findings highlight that the distinct biogeographic patterns of abundant and rare fungi are driven by different assembly mechanisms, and the assembly processes of abundant and rare fungi are determined by diverse ecological drivers in dryland montane forest soils.

Section: Discussionsupporting

confidence: 91%

Section: Dominant Role Of Dispersal Limitation In Abundant and Rare F...contrasting

confidence: 99%

Dispersal limitation dominates the community assembly of abundant and rare fungi in dryland montane forests

Wang

et al. 2022

“…However, some investigations have highlighted the implication of neutrality for certain fungal communities, arbuscular mycorrhizal (AM) and ectomycorrhizal fungi (EM) in soil and roots ( Caruso et al, 2012 ; Davison et al, 2016 ; Schröter et al, 2019 ). Our observation in the context of different habitats is in line with the results of recent large-scale studies in natural soil from different habitats across Scotland ( Powell et al, 2015 ), suburban agricultural districts of Shanghai, China ( Li et al, 2021 ), and a wine-growing region of Italy ( Larsen et al, 2022 ). In contrast to our finding, however, Birch et al (2022) , who reported that deterministic processes, particularly homogenizing selection, dominated fungal communities along an 1,800 km transect of North America across Pseudotsuga forests.…”

Section: Discussionsupporting

confidence: 90%

Fungal diversities and community assembly processes show different biogeographical patterns in forest and grassland soil ecosystems

Wang

et al. 2023

Soil fungal community has been largely explored by comparing their natural diversity. However, there is a relatively small body of literature concerned with fungal community assembly processes and their co-occurrence network correlations carried out across large spatial–temporal scales with complex environmental gradients in natural ecosystems and different habitats in China. Thus, soil fungal community assembly processes were assessed to predict changes in soil function in 98 different forest and grassland sites from the Sichuan, Hubei, and Hebei Provinces of China using high-throughput sequencing of nuclear ribosomal internal transcribed spacer 2 (ITS-2). The 10 most abundant fungal phyla results showed that Ascomycota was the most abundant phylum in forests from Sichuan province (64.42%) and grassland habitats from Hebei province (53.46%). Moreover, core fungal taxa (487 OTUs) represented 0.35% of total fungal OTUs. We observed higher fungal Shannon diversity and richness (the Chao1 index) from diverse mixed forests of the Sichuan and Hubei Provinces than the mono-cultured forest and grassland habitats in Hebei Province. Although fungal alpha and beta diversities exhibited different biogeographical patterns, the fungal assembly pattern was mostly driven by dispersal limitation than selection in different habitats. Fungal co-occurrence analyses showed that the network was more intense at Saihanba National Forest Park (SNFP, Hebei). In contrast, the co-occurrence network was more complex at boundaries between forests and grasslands at SNFP. Additionally, the highest number of positive (co-presence or co-operative) correlations of fungal genera were inferred from grassland habitat, which led fungal communities to form commensalism relationships compared to forest areas with having higher negative correlations (mutual exclusion or competitive). The generalized additive model (GAM) analysis showed that the association of fungal Shannon diversity and richness indices with geographical coordinates did not follow a general pattern; instead, the fluctuation of these indices was restricted to local geographical coordinates at each sampling location. These results indicated the existence of a site effect on the diversity of fungal communities across our sampling sites. Our observation suggested that higher fungal diversity and richness of fungal taxa in a particular habitat are not necessarily associated with more complex networks.

“…Nitrogen enrichment can affect the processes underpinning fungal community assembly, but inconsistent results have been reported. For example, stochastic processes dominate under the fertilization treatment in cropland ecosystems (Shi et al, 2019;Li et al, 2021), whereas deterministic processes were found to have a larger relative importance with fertilization in plantation and grassland ecosystems (Chen et al, 2017;Guo et al, 2020). Moreover, N fertilization resulted in tightened network associations among fungal, bacterial, and protist communities in diverse agricultural soils (Zhao Z. et al, 2019), indicating an increased importance of deterministic biotic interactions in shaping microbiome.…”

Section: Introductionmentioning

confidence: 99%

Adaptation of Soil Fungal Community Structure and Assembly to Long- Versus Short-Term Nitrogen Addition in a Tropical Forest

Jiao

Tan

et al. 2021

Soil fungi play critical roles in ecosystem processes and are sensitive to global changes. Elevated atmospheric nitrogen (N) deposition has been well documented to impact on fungal diversity and community composition, but how the fungal community assembly responds to the duration effects of experimental N addition remains poorly understood. Here, we aimed to investigate the soil fungal community variations and assembly processes under short- (2 years) versus long-term (13 years) exogenous N addition (∼100 kg N ha–1 yr–1) in a N-rich tropical forest of China. We observed that short-term N addition significantly increased fungal taxonomic and phylogenetic α-diversity and shifted fungal community composition with significant increases in the relative abundance of Ascomycota and decreases in that of Basidiomycota. Short-term N addition also significantly increased the relative abundance of saprotrophic fungi and decreased that of ectomycorrhizal fungi. However, unremarkable effects on these indices were found under long-term N addition. The variations of fungal α-diversity, community composition, and the relative abundance of major phyla, genera, and functional guilds were mainly correlated with soil pH and NO3––N concentration, and these correlations were much stronger under short-term than long-term N addition. The results of null, neutral community models and the normalized stochasticity ratio (NST) index consistently revealed that stochastic processes played predominant roles in the assembly of soil fungal community in the tropical forest, and the relative contribution of stochastic processes was significantly increased by short-term N addition. These findings highlighted that the responses of fungal community to N addition were duration-dependent, i.e., fungal community structure and assembly would be sensitive to short-term N addition but become adaptive to long-term N enrichment.