Abstract: The rock tea-producing regions have diverse soil types and significant variations in terrain. Understanding the contents of soil organic carbon (SOC) and its active components, as well as the characteristics of carbon-fixing microorganisms in the soils across different rock tea-producing regions can reveal the dynamics in SOC and its influencing factors, offering a theoretical foundation for optimizing rock tea cultivation. In this study, we measured the contents of SOC and its active components, as well as the relative abundance and diversity of carbon-fixing bacterial communities in Zhengyan tea, Banyan tea, and Zhou tea producing regions in Wuyi Mountain, Fujian Province. The results showed that: (1) The contents of SOC active components varied significantly across rock tea-producing regions, with the highest contents in the Banyan tea region, followed by the Zhou tea region, and the lowest in the Zhengyan  tea region. In the Banyan and Zhou tea regions, the upper soil layers exhibited higher contents of easily oxidizable organic carbon (EOC) and microbial biomass carbon (MBC) than the lower layers, while in the Zhengyan and Banyan tea regions, dissolved organic carbon (DOC) was significantly higher in the lower soil layer (P<0.05). (2) SOC and its active components in Wuyi Mountain rock tea-producing regions were closely correlated with soil physical and chemical factors. Total phosphorus content (TP) and soil water content (WC) had significant positive impacts on the contents of SOC, DOC, MBC, and EOC (P<0.05), while total potassium content (TK) had a significant negative impact (P<0.05). (3) Nitrobacter was the most abundant in the Zhengyan and Banyan tea regions, while Thioalkalivibrio dominated in the Zhou tea region. (4) The relative abundance of soil carbon-fixing bacteria was mainly affected by soil physicochemical factors, which in turn affected SOC accumulation. Soil pH was significantly positively correlated with Thioalkalivibrio and Mycobacterium (P<0.05). Soil TP was significantly positively correlated with Pseudonocardia (P<0.01). Soil electrical conductivity and bulk density were significantly negatively correlated with Nitrobacter (P<0.05). In addition, Mycobacterium was the major genus affecting the content of DOC and MBC (P<0.05). In summary, SOC content and relative abundance of carbon-fixing microorganisms vary across different rock tea-producing regions and are influenced by environmental factors. These findings provide a scientific basis for developing high-carbon sequestration tea gardens.

Key words: soil organic carbon, soil active carbon component, carbon-fixing microorganisms, tea garden, Wuyi Mountain