Controls on diversity of core and indicative microbial subcommunities in Tibetan Plateau grassland soils

Core subcommunity represents the less diversity but high abundance, while indicative subcommunity is highly diverse but low abundance in soils. The core subcommunity fundamentally maintains ecosystem stability, while the indicative plays important roles in vital ecosystem functions and is more sensitive to environmental change. However, their environmental driving factors and responses to human disturbances remain less defined. Herein, we explored the patterns of core and indicative soil microbes and their responses to animal grazing in dry grasslands across the Tibetan Plateau, using the Illumina sequencing of 16S rRNA gene. The results revealed that the core subcommunity diversity and richness were lower than the indicative in soils. The indicative subcommunity diversity exhibited substantially stronger correlations with nutrient-associated factors than the core diversity, including soil organic carbon, nitrogen, and plant biomass. The core and indicative microbial subcommunities both strongly varied with grassland ecosystems, while the latter was also significantly influenced by grazing. The variation partitioning analysis revealed that indicative microbial subcommunity was explained less by environmental factors than core subcommunity (34.5% vs 73.0%), but more influenced by grazing (2.6% vs 0.1%). Our findings demonstrated that the indicative microbes were particularly sensitive to soil nutrient-associated factors and human disturbances in alpine dry grasslands. This manuscript compared the diversity and structure of core and indicative subcommunities and their driving factors in grassland soils, highlighting that the indicative diversity is more sensitive than the core diversity to soil nutrient-associated factors.

Automated summary

The core subcommunity in soils has less diversity but high abundance, while the indicative subcommunity is highly diverse but low abundance. The core subcommunity is essential for maintaining ecosystem stability, while the indicative subcommunity plays a vital role in ecosystem functions and is more sensitive to environmental change. However, their responses to environmental factors and human disturbances are not well-defined. In this study, we investigated the distribution patterns of core and indicative soil microbes and their responses to animal grazing in dry grasslands across the Tibetan Plateau using Illumina sequencing of 16S rRNA gene. The results showed that the core subcommunity had lower diversity and richness compared to the indicative subcommunity in soils. The diversity of the indicative subcommunity was strongly correlated with nutrient-associated factors, such as soil organic carbon, nitrogen, and plant biomass. Both the core and indicative microbial subcommunities showed significant variations in different grassland ecosystems, with the indicative subcommunity being more affected by grazing. The analysis revealed that the indicative microbial subcommunity was influenced less by environmental factors but more by grazing compared to the core subcommunity. These findings highlight the sensitivity of indicative microbes to soil nutrient-associated factors and human disturbances in alpine dry grasslands. This study provides insights into the diversity and structure of core and indicative subcommunities in grassland soils and their driving factors.