Ecological engineering of ground cover vegetation enhances the diversity and stability of peach orchard canopy arthropod communities

Ecological engineering of ground cover vegetation in agro-ecosystem may affect the diversity and stability of arthropod communities. Factors affecting the stability of arthropod community in turn influence the relationship between arthropod diversity and stability, which has been rarely investigated. We conducted a 2-year field-experiment in Shanghai and Jiangsu province in eastern China, examining the effects of the ecological engineering of ground cover plant Trifolium repens on the diversity and stability of canopy arthropod community in peach orchards. The results indicated that five diversity indices (abundance, species richness, Simpson's index, Shannon-Wiener index and Pielou's evenness index) and four stability indices (Nn/Np, Sn/Sp, (Nn + Nd)/Np and (Sn + Sd)/Sp) were all significantly higher but the coefficient of variation (ds/dm) was significantly lower in ground cover areas than control areas. The results of Pearson's correlations were significantly negative for abundance/richness and the above four stability indices both in ground cover areas and control ones in both sites; correlations between Pielou evenness index and the above four stability indices were all positive in control areas, while those in ground cover areas were not the same. Our study provides a more comprehensive understanding for arthropod community stability, suggesting that regulating harmful arthropods by beneficial and neutral arthropods was the basic implication of arthropod stability, and demonstrates that the ecological engineering of ground cover T. repens can enhance the diversity and stability of canopy arthropod communities but increased arthropod diversity will not always positively affect arthropod stability.