Optimizing mowing practices can mitigate the short-term negative impacts of mowing on insect diversity

Urban meadows are an important component of urban green spaces and have substantial potential for biodiversity conservation. Conventional mowing can enhance plant diversity by altering the niches of dominant herbaceous species, yet it often adversely affects insect communities. Developing appropriate mowing strategies is therefore critical for conserving insects and maintaining multi-trophic biodiversity. In this study, we used a controlled experiment to assess the short-term effects of retaining flowering plants during mowing on plant and insect diversity. Four treatments were established: the Mowing group (M), the Medicago sativa L. retained group (MS), the Carduus nutans retained group (CN), and the Control group (CK). Cluster analysis was used to compare plant and insect community composition among the four treatments. Linear regression and redundancy analysis (RDA) were further performed to examine the effects of plant diversity and plant functional groups on insect diversity. Compared with CK, all three mowing treatments significantly increased plant diversity. Conversely, these treatments significantly reduced insect Shannon-Wiener diversity, driven largely by declines in the abundances of Diptera, Coleoptera, and Orthoptera. The cover and height of Fabaceae plants were positively correlated with insect Shannon-Wiener diversity. Partial least squares structural equation modeling (PLS-SEM) revealed that the effect of mowing on insect diversity was mediated by altering the community structure of Fabaceae plants. These findings suggest that retaining dominant flowering plants during mowing can mitigate short-term losses in insect diversity while simultaneously enhancing plant diversity.