Response Strategies of Five Common Warm Temperate Species to Insect Defoliation

Under the background of global climate change, the insect herbivory phenomenon has been frequent, which significantly affects the growth, survival, and regeneration of forest plants in the warm temperate zone of China. Plants can adopt defense responses to adapt to insect defoliation. Therefore, field experiments were conducted on five common warm temperate species, Quercus acutissima , Quercus serrata , Quercus aliena , Quercus dentata , and Robinia pseudoacacia . We measured the leaf traits of healthy trees and insect defoliated trees, to explore the response strategies of common species in warm temperate zones to insect defoliation. Our results showed that native species stored more carbon in extreme environments for survival rather than growth, while alien species tended to adopt active resource acquisition strategies and were more inclined towards growth. Then the content of tannins and flavonoids in the alien species R. pseudoacacia did not significantly increase after leaf damage, while the content of secondary metabolites such as tannins, flavonoids, and total phenols in the native species Q. acutissima , Q. serrata , Q. aliena , Q. dentata increased significantly after leaf damage. This indicated that compared to alien species, native species would invest more resources in defense, which might reduce resource allocation for growth. Thus, the native Quercus species have stronger resistance than the alien species R. pseudoacacia after insect defoliation.