Abstract:

Aims: Millipedes play diverse roles as consumers, decomposers, and soil engineers, exerting critical influences on carbon and nitrogen cycling and greenhouse gas emissions in ecosystems. However, the current paucity of studies on the seasonal dynamics of millipede communities hinders a systematic understanding of their ecological functions. 

Methods: This study investigated the seasonal variations in millipede community composition, structure, and diversity in the limestone tropical monsoon forests of Xishuangbanna, and analyzed the relationships between these variables and the plant community, microbial biomass, and soil physicochemical properties. 

Results: (1) A total of 268 millipedes were collected, belonging to six orders and six families. The composition and diversity of the millipede community showed significant seasonal variations. In the wet season, the total density of millipedes and the densities of the dominant groups Zephroniidae and Pseudospirobolellidae were 2.76, 2.80, and 6.29 times those in the dry season, respectively. The total number of millipede family-level groups, the Margalef richness index, and the Shannon-Wiener diversity index were 1.95, 1.80, and 1.41 times those in the dry season, respectively. (2) The partial correlation analysis revealed that the total density of millipedes was positively associated with the number of tree layer species, shrub layer species, and herbaceous layer species, litter thickness, soil water content, and total nitrogen (P < 0.05, 0.01, or 0.001). Moreover, both the total number of millipede groups and the Margalef richness index showed positive correlations with soil organic carbon and microbial biomass carbon (P < 0.05). By contrast, the total number of millipede groups and the Shannon-Wiener diversity index exhibited negative correlations with air temperature (P < 0.05 or 0.01). (3) The results of redundancy analysis (RDA) demonstrated that soil water content, litter thickness, and number of herbaceous layer species were the main factors regulating millipede community composition, with contributions of 88.6%, 3.8%, and 1.4%, respectively. In contrast, air temperature and microbial biomass carbon were the dominant factors driving millipede diversity, accounting for 77.8% and 5.7% of the explained variation, respectively. 

Conclusion: Seasonal variations in the surface-active millipede community in the limestone tropical monsoon forests of Xishuangbanna are primarily driven by the combined effects of biotic and abiotic factors, including microclimate, litter, and microorganisms. The findings of this study provide critical support for research on tropical millipede biogeography and its underlying mechanisms.

Key words: millipedes, diversity, seasonal differences, biotic factors, abiotic factors, tropical monsoon forests