Factors shaping the interspecific variations in herbivory have puzzled ecologists for decades and several hypotheses have been proposed to explain interspecific variation in leaf herbivory. However, we still lack a clear evaluation on the direction and relative contribution of plant size, species’ richness, community composition and growth strategy to the variations in herbivory.

In a study published in Ecology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) and Research Center for EcoEnvironmental Sciences evaluated the effects of canopy height, neighbors’ species richness and composition and leaf traits on leaf herbivory in a tropical rainforest.  

With the help of an 80-m-tall forest canopy crane, the researchers collected 6732 leaves from 129 species with canopy heights ranging from 1.6？m to 65.0？m above the ground in a tropical rainforest in Bubeng, Xishuangbanna.  

Through an observational study of the variations in leaf herbivory across 129 plant species, they found that herbivory varied with plant morphological (canopy height, leaf size) and growth strategy trait. 

Parameter estimation of the full model found that among the seven variables, three(canopy height, leaf size, and specific leaf area) showed significant effects on herbivory, while the other four variables (neighbor species richness, conspecific neighbor abundance, total neighbor abundance, and the standard deviation of neighbor tree heights) showed no association with herbivory.  

The researchers detected a clear negative effect of canopy height on herbivory. Leaf herbivory decreased with canopy height and specific leaf area and increased with leaf size. Species with lower canopy heights and larger leaves tend to have higher herbivory levels.  

However, they found no effect of neighboring species richness, composition, and structural heterogeneity on the variations in herbivory. Therefore, no evidence of associational resistance or associational susceptibility was detected.  

“Our findings provided new insights into the interspecific variations of herbivory in higher diversity and structural complexity forest ecosystems. The vertical variation in plant-herbivore interaction and its ecological effects in maintaining diversity in tropical forests should not be overlooked,” said XU Guorui, co-lead author of the study. 

Contact 

XU Guorui Ph.D 

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China     

E-mail: xuguorui@xtbg.ac.cn    

Forest canopy crane in Xishuangbanna tropical rainforest. (Image by XTBG)