Local community assembly processes shape β‐diversity of soil phoD‐harbouring communities in the Northern Hemisphere steppes

Abstract

Aim The contemporary coexistence theory suggests that species pool, environmental filtering, dispersal assembly processes, ecological drift and biotic interactions collectively determine the β‐diversity of communities. However, we know little about the biogeographical patterns of the β‐diversity of microbial communities harbouring the alkaline phosphatase phoD gene (phoD communities, hereafter) and whether these mechanisms are all‐important in shaping phoD communities’ β‐diversity in natural steppe ecosystems. Location Northern Hemisphere steppes. Time period July to August 2018. Major taxa studied Alkaline phosphatase (phoD gene) encoding community. Methods Using the high throughput amplicon sequencing method, soil phoD communities were comparatively studied along three representative regions of the Northern Hemisphere steppes, namely the Qinghai‐Tibetan Plateau, Inner Mongolian Plateau and the Loess Plateau. Each region harbours three types of steppes (habitats): meadow, typical and desert steppes. Results We observed significantly higher phoD β‐diversity in the Qinghai‐Tibetan than in the Loess and Inner Mongolian Plateaus and significantly lower β‐diversity in the typical steppes than in other steppe types. The decay rates of phoD β‐diversity with geographical distance varied in different steppe regions and types. The phoD β‐diversity was not significantly influenced by species pool; instead, environmental filtering, dispersal assembly processes, ecological drift and biotic interactions jointly shaped the β‐diversity patterns. The β‐deviation variations (β‐diversity excluding the effects of species pool) were influenced by spatial and environmental factors and biotic interactions, among which soil pH was the key environmental determinant. The soil pH driving β‐diversity mechanism was steppe region and habitat specific. Main conclusions The biogeographical patterns of phoD β‐diversity were mainly driven by local community assembly processes in the Northern Hemisphere steppes.

Afforestation can lower microbial diversity and functionality in deep soil layers in a semiarid region

“…The homogenized resource was found to decrease variation in beta diversity of soil bacterial communities (Jiao et al, 2018; Leibold & McPeek, 2006). Additionally, we found that the homogeneous enrichment of bacteria in deep soils contributed a large fraction to bacterial community assembly (Figure 4a), which will ultimately result in lower beta diversity (Stegen et al, 2015; Xu et al, 2021). These explanations were supported by the strong dependence of beta diversity in deep layer on soil moisture variation (Table S2) and by the significant correlation between Bray–Curtis dissimilarity and potential biotic interactions based on co‐occurrence network observed in this study (Figure S11b) and previous studies (Wang et al, 2021; Xu et al, 2021).…”

Revisiting Janzen's mountain passes hypothesis from a microbial perspective: why tropical mountains are so biodiverse?

“…In each climatic zone, we also calculated the difference of climatic factors (both temperature and humidity) and soil properties (the rst three axes of PCA of soil properties) between paired plots (hereafter climatic distance and soil distance). Comparisons between climatic distance, soil distance and Bray-Curtis community similarity across the three study sites were done using Wilcoxon test [37]. The relationship between β-diversity (Bray-Curtis similarity) and geographic (elevation, latitude and longitude) or elevational distance was analyzed using loess regression.…”

“…Presumably higher levels of functional redundancy would increase neutrality and make these functionally redundant taxa more vulnerable to drift. The high proportion of ecological drift in forest ecosystems is a special case when compared with other ecosystems such as grassland or steppe ecosystems [37], which indicates that the high levels of competition among species as well as tight nutrient cycling dynamics in a forest environment seem to be important considerations for soil bacterial and fungal functions and understanding these environmental modulators could be a starting point for future work.…”

The adjustment of life history strategies drives the ecological adaptations of soil microbiota to aridity

“…Detailed information about each site (soil type, plant community, etc.) was described in a previous study (Xu et al, 2021).…”