Work

Soil bacterial communities and co-occurrence patterns across soil types and land uses in a typical karst region of Southwest China

Year: 2026

Type: article

Abstract: Soil microorganisms play a vital role in maintaining ecosystem stability in fragile karst landscapes. However, how edaphic properties and anthropogenic land use correspond to microbial assembly processes, network architectures, and functional potential remains insufficiently understood. This study evaluated the variations in soil bacterial communities across distinct soil types (limestone vs. red soil) and land-use systems (natural forest, eucalyptus plantation, citrus orchard, and paddy field) in a typical karst region of southwest China. Soil type accounted for 48% of the bacterial community variation, exhibiting a substantially stronger association with community structure than land use. Notably, Bacterial diversity and network complexity showed contrasting patterns: limestone soils harbored higher diversity, whereas red soils exhibited larger and more complex co-occurrence networks, reflecting divergent microbial community patterns across distinct edaphic contexts. These differences corresponded to contrasting community assembly processes, with homogenizing selection predominating in limestone soils and heterogeneous selection being more prevalent in red soils. Environmental modeling revealed that while pH, organic carbon, and calcium negatively correlated with network topology, available phosphorus stood out as the only parameter exhibiting a highly significant positive relationship with network connectivity ( p < 0.001), indicating that phosphorus availability is an important edaphic factor correlated with microbial network expansion in karst soils. Functionally, red soil bacterial communities were characterized by a higher relative abundance of pathways associated with cell motility and antimicrobial competition, whereas limestone soil communities showed higher representation of pathways related to specialized nitrogen turnover (nitrate reduction). Overall, these findings reveal that karst soil microbiomes and their co-occurrence networks are closely coupled with baseline geochemical characteristics, highlighting the importance of considering baseline soil types when designing ecosystem management and restoration strategies.

Source: Ecological Indicators

DOI: 10.1016/j.ecolind.2026.115629