Biogeographical patterns and mechanisms of microbial community assembly that underlie successional biocrusts across northern China

Yuanlong Li,Chunxiang Hu

doi:10.1038/s41522-021-00188-6

Abstract

Biocrusts play critical eco-functions in many drylands, however it is challenging to explore their community assembly, particularly within patched successional types and across climate zones. Here, different successional biocrusts (alga, lichen, and moss-dominated biocrusts) were collected across the northern China, and assembly of biocrust microbial communities was investigated by high-throughput sequencing combined with measurements of soil properties and microclimate environments. Bacterial and eukaryotic communities showed that the maximum and minimum community variation occurred across longitude and latitude, respectively. In the regions where all three stages of biocrusts were involved, the highest community difference existed between successional stages, and decreased with distance. The community assembly was generally driven by dispersal limitation, although neutral processes have controlled the eukaryotic community assembly in hyperarid areas. Along the succession, bacterial community had no obvious patterns, but eukaryotic community showed increasing homogeneity, with increased species sorting and decreased dispersal limitation for community assembly. Compared to early successional biocrusts, there were higher microbial mutual exclusions and more complex networks at later stages, with distinct topological features. Correlation analysis further indicated that the balance between deterministic and stochastic processes might be mediated by aridity, salinity, and total phosphorus, although the mediations were opposite for bacteria and eukaryotes.

Highlights

A major goal in microbial community ecology is to understand assembly processes and their mechanisms across spatial–temporal scales[1,2]
The orders of presentation and analysis that we defined for this study were according to sample successional stages from A to C to M, longitude location from West to Mid-longitude to East, latitude location from North to Mid-latitude to South, and mean annual precipitation (MAP) from Low to Middle to High, characterized by the gradual changes from severe to medium to mild environment
PH, oxidation-reduction potential (ORP), MAP, and mean annual sunshine duration (MASD) were only related to species sorting in bacteria, water content (WC), NH4+, and PO43+ were only related to species sorting in eukaryotes

Summary

INTRODUCTION

A major goal in microbial community ecology is to understand assembly processes and their mechanisms across spatial–temporal scales[1,2]. It is well recognized that deterministic and stochastic processes played different roles in microbial assembly, which further requires us to explore their respective regulation mechanisms on a given microbial community[4]. They play critical ecological functions as they contribute to stabilizing the soil against wind and water erosion and promoting the development of regional environments, influence soil bacterial composition and diversity in these ecosystems[48] It can be mainly classified into alga (A), lichen (C), and moss (M)dominated biocrusts, according to the dominant taxa (cyanobacteria, lichens, or mosses), representing the different successional stages of soil micro-environments/ecosystems[5,6,7]. We hypothesized that the biogeographical patterns in biocrusts with successional stages would not be influenced solely by spatial factors, and that there would be specific species interactions in a given successional stage of biocrust community

RESULTS

DISCUSSION

METHOD

CODE AVAILABILITY