When the dominant species in a plant community are palatable, many believe that large herbivores will reduce the dominant species and promote the proportion of previously suppressed species.  However, this view may not always hold true.  We conducted a 4-year yak grazing experiment on the Qinghai-Tibet Plateau and tracked the plant compositions of the rotational grazing (RG) and grazing exclusion (GE) grasslands during the four years.  The results showed that in the absence of yaks under GE, the plant community was dominated by two palatable species, Kobresia pygmaea and Stipa capillata, due to their small leaf area and rapid growth strategy.  The presence of yaks under RG significantly inhibited S. capillata and over half of the forbs, while the proportion of K. pygmaea increased and it became the absolute dominant species, contradicting the view that large herbivores inhibit palatable species.  Interannually, the dominance of K. pygmaea under RG decreased in the dry year, leading to an increase in the dominance of the other eight species.  Under GE, the dominance of K. pygmaea declined notably in the dry year, while S. capillata and seven other forbs increased substantially.  Overall, these results suggest that K. pygmaea is grazing-tolerant but not drought-tolerant, whereas the other eight species are drought-tolerant but not grazing-tolerant.  At the community level, community composition shifts resulting from succession after grazing exclusion exceeded those caused by drought, drought tends to induce community species turnover while grazing tends to induce species abundance variations.  In summary, our conclusions remind ranch managers that when considering the impact of livestock on plant community composition, they should factor in local conditions and climate change rather than simply assuming that livestock will suppress the palatable species.

The fall armyworm (FAW, Lepidoptera: Noctuidae), Spodoptera frugiperda (J. E. Smith), invaded China in mid-December 2018; since then, it has become a great threat to Chinese agricultural production.  Qinling Mountains–Huaihe River region (QM–HRR) is the transitional zone between northern and southern China, an important region for both corn and wheat production.  Based on the actual occurrence of QM–HRR invaded by FAW in 2019, daily mean surface air temperature and nocturnal wind conditions at 925 hPa were examined, and migratory routes of FAW moths originated in QM–HRR were modeled by a forward-trajectory-analysis approach.  The results indicated that migratory activities of FAW adults emerged in QM–HRR were initiated from late June.  The moths from western QM–HRR, where has complex topographic terrain, mainly flied to Ningxia and Inner Mongolia before mid September.  However, FAW moths from the eastern QM–HRR primarily engaged in high-altitude northward transport assisted by the prevailing southerly winds before mid August, and the North China Plain was identified as the main destination of FAW.  Meanwhile, the migration trajectories of FAW moths had a possibility to reach the Northeast China Plain.  From mid August, FAW moths in eastern QM–HRR largely migrated southward and returned to the Yangtze River Valley.  This study provides detailed information on the occurrence and migration routes of FAW moths from QM–HRR and will be helpful for early warning and development of integrated pest management strategies for the control of this exotic insect pest.