The effects of carbonate rock surface microrelief on microbial community structure and gene function in moss biocrusts

This study investigated the effects of carbonate rock surface microrelief on the microbial community structure and functional gene distribution of moss-dominated biocrusts, testing two hypotheses: (1) microrelief morphology influences microbial community structure and diversity, and (2) microrelief shape affects the spatial distribution of carbon and nitrogen cycling functional genes. The dataset comprises two integrated components: morphometric measurements (length, width, depth) of 125 microrelief units across five types (honeycomb, solution pit, gully, sheet erosion, and near-planar; 25 replicates per type) collected from the Huajiang Karst Basin, Guizhou, China, and metagenomic sequencing data from 15 moss crust samples (3 per microrelief type), including taxonomic profiles, alpha/beta diversity indices, and abundances of functional genes associated with six carbon fixation pathways and six nitrogen cycling processes. Notable findings revealed that while microbial diversity did not differ significantly among microrelief types, community abundance did vary substantially; near-planar surfaces were hotspots for assimilatory nitrate reduction genes (nirA, nasA), whereas solution pit microreliefs promoted reductive tricarboxylic acid (rTCA) cycle genes (nifJ, accB, accD), likely due to anaerobic microenvironments. Correlation analyses further demonstrated that most carbon fixation gene abundances were negatively correlated with microrelief length and width, while certain genes were positively correlated with depth, indicating that morphological parameters constrain microbial metabolic potential by limiting photosynthetic area and accelerating water evaporation. This dataset provides the first quantitative link between carbonate rock microrelief morphology and the functional potential of attached biocrust microbial communities, serving as a valuable resource for modeling biogeochemical cycles in karst landscapes, guiding ecological restoration by identifying functional hotspots, and establishing a baseline for comparative studies of rock-surface microbial communities under climate change or land-use disturbance.