Differences in Extracellular Enzyme Activities and Microbial Community Structure Between Rhizosphere and Non-rhizosphere Soils of Zanthoxylum bungeanum. ‘Fengcai’ in Marginal Habitats

To clarify the soil ecological adaptability of Zanthoxylum bungeanum. 'Fengcai' in non-suitable areas, we investigated rhizosphere and non-rhizosphere (0～30 cm) soils of Zanthoxylum bungeanum. 'Fengcai' seedlings cultivated at an altitude of 1000 m, and systematically analyzed differences in soil nutrient content, extracellular enzyme activities, and microbial community structures.Soil nutrient content, extracellular enzyme activities, and the abundance and community composition of bacterial 16S rRNA and fungal 18S rRNA genes were determined using high-throughput sequencing and fluorescence methods. Correlation analyses were further performed to explore the relationships among soil microbial diversity, extracellular enzyme activities, and environmental factors(1) Rhizosphere soils had higher levels of organic carbon, total nitrogen, C:N, and N:P ratios, and lower total phosphorus and C:P ratios compared to non-rhizosphere soils, though differences were not statistically significant ; (2) Enzyme activities of BG, CBH, NAG, LAP, ACP, as well as E_C:P and E_N:P ratios, were higher in rhizosphere soils, yet not significant. VL ranged from 0.73 to 0.81, with non-rhizosphere soil values 4.43% lower than rhizosphere, indicating slightly higher carbon limitation in the rhizosphere. VA ranged from 54.28° to 58.98°, suggesting phosphorus limitation in both soil types, with slightly higher limitation in the rhizosphere; (3) Bacterial abundance greatly exceeded fungal abundance. Rhizosphere soils showed increased relative abundances of Actinobacteriota and Chloroflexota, and higher levels of Mucoromycota among fungi. Bacterial diversity was significantly higher in rhizosphere soils, whereas fungal diversity was higher in non-rhizosphere soils; (4) Correlation analysis revealed that bacterial Chao1 index and observed species were positively correlated with N:P (P<0.05), while fungal Chao1 and observed species were negatively correlated with N:P (P<0.05). NAG, LAP, and ACP were significantly positively correlated with soil (P<0.05); while LAP and ACP were significantly negatively correlated with C:P (P<0.05). This study revealed the rhizosphere microenvironmental regulation characteristics of Zanthoxylum bungeanum. 'Fengcai' in non-suitable areas and elucidated the interrelationships among soil nutrients, microbial communities, and extracellular enzyme activities. These findings not only provide a scientific basis for precision fertilization and cultivation management of Zanthoxylum bungeanum. 'Fengcai', but also offer theoretical support for understanding the soil ecological mechanisms and sustainable expansion strategies of economic tree species beyond their suitable habitats.