Soil Phosphorus Availability Controls Deterministic and Stochastic Processes of Soil Microbial Community along an Elevational Gradient in Subtropical Forests

Abstract

Revealing the assembly mechanisms of the soil microbial community, which is crucial to comprehend microbial biodiversity, is a central focus in ecology. The distribution patterns of microbial elevational diversity have been extensively studied, but their assembly processes and drivers remain unclear. Therefore, it is essential to unravel the relationship between the deterministic and stochastic processes of the microbial community assembly and elevational gradients. Here, our study built upon previous physicochemical analyses of soil samples collected along an elevational gradient (900–1500 m) in Daiyun mountain, a subtropical forest located in southeastern China. Using the phylogenetic-bin-based null model analysis (icamp) and multiple regression on matrices approach, we explored the major drivers that influence the assembly processes of soil bacterial and fungal community across elevations. The results showed that: (1) bacterial rare taxa exhibited a broad habitat niche breadth along the elevational gradient; (2) homogeneous selection and homogenizing dispersal proved to be the most important assembly processes for the bacterial and fungal community; (3) soil phosphorus availability mediated the relative importance of deterministic and stochastic processes in the soil microbial community. Notably, the relative abundance of dominant microbial taxa controlled by homogeneous selection and homogenizing dispersal increased with increasing soil phosphorus availability. Collectively, the assembly processes of microbial elevational communities of the subtropical mountains in China can be explained to some extent by variations in the soil phosphorus availability. This conclusion provides valuable insights into the prediction of soil microbial diversity and phosphorus nutrient cycling in subtropical montane forests.

Soil Environments Regulate Dominant Soil Fungal Communities along an Elevational Gradient in Subtropical Forests

“…The elevation ranges from 650 to 1856 m, with precipitation ranging from 1700 to 2000 mm, and relative humidity is consistently above 80%. The nature reserve stands out with a forest coverage rate of 93.4% [19]. It is home for many ancient plants, serves as a focal point for natural biodiversity, and ranks as one of the largest plant repositories in Fujian Province [20,21].…”

“…In July 2018, we carefully selected a region with relatively consistent conditions and minimal anthropogenic disturbances in the southern slope of Daiyun Mountain to establish sample plots. Following the Center for Tropical Forest Science standard [18,19], seven permanent sample plots were established along an elevation range of 900-1500 m (Table S3), with intervals of 100 m. Three standard plots of 10 m × 20 m were set up at each elevation gradient. Soil samples were collected from each standard plot using the five-point sampling method.…”

“…He et al demonstrated the changes in elevations and seasons affect soil properties, influencing the soil microbial nutrient cycle and, consequently, the functional diversity of soil microbial community [18]. Chen et al illuminated the assembly mechanisms of the soil microbial community along an elevational gradient in subtropical forests [19]. On a local scale, homogeneous ecological processes predominantly influence microbial community assembly.…”

“…On a local scale, homogeneous ecological processes predominantly influence microbial community assembly. Soil available phosphorus moderates the relative significance of homogeneous selection and homogeneous dispersal in soil bacterial and fungal community assembly [19]. Nevertheless, the comprehension of the dominant soil fungal community along an elevational gradient in Daiyun Mountain remains limited.…”

“…Our objective is to elucidate the primary driving factors influencing the variations in soil fungal communities. Thus, we hypothesized: (i) based on previous studies indicating a moderately humped pattern of plant diversity along the elevational gradient of 1200-1300 m [18,19], we predict that soil fungal diversity would show a similar moderate expansion pattern across this elevation range. (ii) Soil temperature and available phosphorus have been shown to change with elevation.…”