Short-term plant mixtures alter soil organic carbon components and microbial network characteristics

Restoring plant diversity is crucial to enhance soil organic carbon (SOC) storage and mitigate biodiversity loss and climate change. However, there is limited understanding of how plant diversity impacts biological SOC components and microbial communities in the short term, impeding informed agricultural management decisions. We conducted controlled experiments with various herbaceous plant mixtures to investigate the short-term effects of plant diversity on SOC components (e.g., amino sugars and lignin phenols) and associated microbial community. While soil physical and chemical properties remained relatively stable over one year, plant diversity significantly increased both microbial-derived and plant-derived carbon contents. The plant-derived carbon of two, three, and four-species mixture treatments was higher than 38 %, 59 %, and 80 %, respectively, compared to that of one species. Similarly, microbial-derived carbon increased by 68 %, 117 %, and 164 % for treatments with two, three, and four species mixtures compared to the one species treatment. While plant species richness did not influence bacterial & fungal diversity and community composition at the phylum level, it did affect community constitution at the genus level. Moreover, plant diversity decreased the total number of edges, the number of negatively related edges, and the mean degree of the fungal co-occurrence network. Hence, our results suggest that plant diversity may alter SOC composition by influencing soil microorganism interactions. The rapid response of organic carbon components to plant diversity could underpin total SOC accumulation in the long term. This study provides novel insights into how plant diversity shapes short-term SOC dynamics by influencing microbial interactions, potentially contributing to long-term SOC accumulation.