Gang Zhou, Daniel F Petticord, Yao-Zhan Xu, Yuan-Zhi Qin, Biao Dong, Xiu-Juan Qiao, Ming-Xi Jiang
Mental stress elicited the largest global HRV reductions, pain affected only MeanNN, and noise produced no global changes. However, time-resolved analyses revealed distinct HRV dynamics across all stressors that were not captured by global averages. Chronic stress and noise sensitivity had little effects on global HRV but significantly moderated fine-grained responses to mental and noise stress during anticipation, stress, or recovery phases.
Herbivory is widely known to play a critical role in structuring plant communities. However, much less is known about what factors determine herbivory in forest ecosystems. Here, we monitored herbivory damage on more than 2000 seedlings in a subtropical forest (2022 and 2023), to identify the key biotic drivers of interspecific variation in seedling herbivory. We found a positive correlation between seedling height and herbivory, evidence for the "plant apparency" hypothesis. Both increasing proportion of herbivory on local conspecifics and conspecific adult density were associated with higher herbivory on focal seedlings, evidence for the Janzen-Connell hypothesis. Interestingly, interactions with ants, as an example of interspecific mutualisms, were found to increase herbivory damage, while decrease seedling mortality in the same research system, highlighting the pivotal role of biotic mutualisms in mediating plant-herbivore interactions. Furthermore, leaf functional traits accounted for the greatest proportion of variance in seedling herbivory, indicating that they served as the primary determinant regulating herbivory pressure at the seedling stage. Overall, our study provides insight into the intricate interplay of seedling height, Janzen-Connell effect and functional traits in determining seedling herbivory and consequently assembly of forest ecosystems. These findings advance our understanding of subtropical forest community dynamics and provide empirical support for evidence-based conservation strategies in such ecosystems.