Spatial characteristics of soil enzyme activity and bacterial diversity in Chinese egret habitat

The egret activities, including the deposition of feces and feathers, significantly alter soil properties and the local ecosystem. Two villages of Hainan Province serve as "the haven of egret," a crucial habitat along the migratory route of egrets in China, where tens of thousands of egrets flock to breed. To explore the spatial dynamics of soil bacterial diversity in egret nesting areas, soil samples of three layers (0-10 cm, 10-20 cm, and 20-30 cm) were collected from five long-term nesting sites. Soil enzyme activity, microbial community composition, and their interaction network were analyzed. Additionally, functional bacteria capable of degrading uric acid were isolated from the surface soil (0-10 cm) to obtain novel strains. The results revealed that soil enzyme activities, including soil urease, acid phosphatase, and sucrase, decreased significantly with increasing soil depth. Among the bacterial communities, Acidobacteriota and Proteobacteria were the dominant microbial phyla (>40%), with Chloroflexi showing increasing abundance with depth, while Verrucomicrobiota and Bacteroidota decreased. Surface soil (0-10 cm) demonstrated significantly higher bacterial alpha and beta diversity than deeper layers (20-30 cm); notably, the Shannon index exhibited a positive correlation with soil pH, urease, and sucrase activities, highlighting the strong association between bacterial diversity and soil properties. Furthermore, five highly effective uric acid-degrading bacterial strains belonging to Cellulosimicrobium sp., Paracoccus sp., Arthrobacter sp. (two strains), and Paenibacillus sp. were identified, which highlights their potential in ecological and economic applications. These findings enhance our understanding of soil bacterial community characteristics in egret colonies and provide a foundation for the habitat protection of egrets and island ecosystems.

Egret colony activities have a significant impact on soil bacterial community structure, which is essential for maintaining soil nutrient dynamics and ecological functions. Understanding the spatial distribution characteristics of bacterial communities is fundamental to effective ecological monitoring and conservation. Both alpha and beta diversity exhibited significant variations across different soil layers and showed a strong positive correlation with soil enzyme activity, indicating that soil bacterial diversity is a key driver of nutrient efficiency.