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

Abstract

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.

Canopy and Understory Nitrogen Addition Alters Organic Soil Bacterial Communities but Not Fungal Communities in a Temperate Forest

“…Second, compared to fungi, bacteria have a shorter turnover time and can respond more quickly to environmental changes (Yin et al, 2010;Li et al, 2019); thus, bacterial communities are more sensitive to N addition than fungal communities in this study. Third, compared to bacteria, fungal communities are often thought to be even more strongly coupled with plant community (van der Linde et al, 2018;Liu et al, 2021) and soil nutrients (Gilliam et al, 2011;Chen et al, 2018;He et al, 2021). In this study, we identified fungal diversity and community composition were closely related to soil moisture and nutrient availability (such as DOC, DON, AP, NH + 4 , and NO − 3 ) (P < 0.05, Table 2; Figure 4), and soil nutrients, nutrient availability, and soil moisture explained the main variations of fungal community composition in the litter layer, organic soil layer, and mineral soil layer, respectively (Figures 5D-F), indicating that the fungal community was mainly regulated by soil moisture and nutrient availability.…”

“…Microbial diversity and community composition are key determinants of their ecological functions (Nannipieri et al, 2003;Philippot et al, 2013). It has been recognized that the elevated N deposition could influence soil microbial diversity and community composition (Freedman et al, 2015;Zhou et al, 2017;Dai et al, 2018;Liu et al, 2020b;He et al, 2021). For the bacterial community, most studies have shown that N addition generally reduces bacterial diversity and alters bacterial community composition (Freedman et al, 2015;Zeng et al, 2016;Nie et al, 2018;Wang et al, 2018c;Wu et al, 2019).…”

“…(Mueller et al, 2014;Zhao et al, 2020). Some studies found that N addition could enhance or reduce fungal diversity and alter fungal community composition (Freedman et al, 2015;Kaspari et al, 2017;Chen et al, 2018;He et al, 2021), but others showed no effect of N addition on fungal diversity and community composition (Carrara et al, 2018;Li et al, 2019;Liu et al, 2021). Several environmental factors have been used to explain the responses of soil bacterial and fungal communities to N addition, such as soil pH and N availability (Rousk et al, 2010;Lladó et al, 2017;Nie et al, 2018;Wang et al, 2018a;Liu et al, 2021).…”

“…Several environmental factors have been used to explain the responses of soil bacterial and fungal communities to N addition, such as soil pH and N availability (Rousk et al, 2010;Lladó et al, 2017;Nie et al, 2018;Wang et al, 2018a;Liu et al, 2021). Soil pH is widely recognized as an important predictor of soil bacterial communities under N addition (Rousk et al, 2010;Maestre et al, 2015;Fierer, 2017;Liu et al, 2021), whereas N availability is often thought to be a key regulator of soil fungal communities under N addition (Gilliam et al, 2011;Chen et al, 2018;He et al, 2021). To understand the implications of N deposition on soil ecosystem processes under future global change scenarios, general patterns and mechanisms in both bacterial and fungal communities in response to N deposition need to be investigated simultaneously (Baldrian et al, 2012;Romanowicz et al, 2016).…”

Soil Microbial Community Response to Nitrogen Application on a Swamp Meadow in the Arid Region of Central Asia

“…The soil microbial community is an important biotic component of soil and an important driving force of many soil ecological processes ( Wang et al, 2021 ). Due to the high sensitivity of soil microbes, the increase in N deposition is bound to have a significant impact on the soil microbial community; however, the response to N deposition often differs in different ecosystems, and the relationship between the soil microbial community and soil factors is uncertain ( Xiao et al, 2020 ; He et al, 2021 ). Therefore, monitoring the response of soil microorganisms to N application is helpful to evaluate the changes of ecosystem processes driven by soil microbiota.…”