Ants determine plant herbivory along an elevational gradient

Background/Question/Methods

Herbivory has important impacts on a variety of ecological processes and functions, but in nature, factors determinate herbivory are controversial. Here in a deciduous temperate forest, we surveyed the herbivory of Quercus liaotungensis, the dominate species of the community, along an altitudinal gradient. We also monitored the abundances of predators, the leaf quality of Q. liaotungensis (Evaluated as the nutrient content and area of the leaf) and the plant community structure to evaluate the role of top-down and bottom-up factors and their interactions in shaping the variation of herbivory.

Results/Conclusions

 The results showed that herbivory tends to increase with altitude and all other tested factors varied with altitude. Among the predators, ants could significantly reduce herbivory rather than spiders and carnivorous beetles. The quality of the leaf had no significantly impacts on herbivory. Pathway analysis revealed that the important value (IV) of Q. liaotungensis has significant indirect positive impacts on herbivory through its negative influences on ants. Further more, the results also suggested that in community the abundances of carnivorous beetled are significantly suppressed by ants (mainly aphid-tending species), this could complicate the role of predators on shaping herbivory.  In general, we confirmed that the environmental (altitude) and top-down effects has significant impacts on herbivory; the composition of the community rather than species richness of the trees also impacts herbivory significantly through their influences on predators. Those results shed new light on the impacts of different factors on herbivory.