Preliminary Study on the Diversity of Soil Oribatid Mite (Acari: Oribatida) Community Reveals Both Longitudinal and Latitudinal Patterns in Paddy Fields along the Middle and Lower Reaches of Yangtze River, China

Abstract

Soil biodiversity plays an important role in maintaining soil fertility and agricultural health. Exploring the patterns of soil fauna diversity across geographical gradients is a fundamental and crucial scientific topic for understanding the mechanisms of soil biodiversity in farmlands. However, the spatial pattern of soil fauna diversity across longitudinal gradients has received far less attention. In order to explore the longitudinal pattern (west to east) of the composition and diversity of the soil oribatid mite community in paddy fields along the middle and lower reaches of the Yangtze River (MLYR), an investigation was carried out in July 2021 at nine sites spanning a longitudinal range of 8.86° (906 km) in southeastern China. In total, 19 taxa and 2392 individuals were observed with a density of 1535.47/m2. Protoribates and Ceratozetes were the most dominant and widely distributed genera along MLYR. The distribution patterns of the richness, abundance, and diversity index were obvious across the longitudinal and latitudinal gradients. The longitudinal pattern showed a quadratic distribution of first increasing and then decreasing, while the latitudinal pattern showed an increasing pattern with the increase in latitude (unimodal pattern). The influence of latitude on the abundance of the soil oribatid mite community was greater than that of longitude, and the influence of longitude on richness and the corresponding diversity index was greater. The dominance index did not show a distribution pattern in the longitudinal and latitudinal directions, while the evenness index showed only the distribution pattern in the longitudinal direction, and the latitudinal pattern was not significant. The results of this study suggest that the diversity of the soil oribatid mite community along MLYR displays both longitudinal and latitudinal patterns in paddy fields. Moreover, we highlighted the importance of integrating longitudinal and latitudinal patterns into spatial patterns of the soil fauna community in farmlands at a regional scale.