Ecological consequences of herbivory by Japanese macaques (Macaca fuscata) on succession patterns of tree assemblages: A case of snowy regions in Japan

Abstract

Apart from frugivory, we have limited knowledge of the ecological consequences of primate herbivory. We aimed to ascertain the effects of spring folivory and winter bark/bud herbivory by Japanese macaques (Macaca fuscata) on tree species and succession patterns of cool‐temperate forests with heavy snow. To evaluate the impact of herbivory on individual trees, we assessed the growth and mortality of trees consumed by simulating herbivory on nine tree species over 4 years. Additionally, we assessed the cumulative impacts of bark/bud herbivory observed at the tree community level by monitoring the patterns of natural herbivory for almost a decade and evaluating the structure of tree assemblages in places with different cumulative impacts of herbivory. The results of simulated herbivory showed that the mortality caused by both spring and winter herbivory was limited (<20%) for almost all tree species monitored; however, the simulated folivory led to delayed tree growth and/or weakening of tree architecture. In contrast, the simulated bark/bud herbivory sometimes resulted in overcompensation of the tree consumed. The multiyear monitoring of natural herbivory demonstrated that, while bark/bud herbivory did not reduced the diversity and biomass of tree assemblages, the cumulative impacts of natural herbivory could have affected the tree succession pattern, resulting in increasing the availability of bark/buds preferably fed by macaques. The key cause for this feedback effect of herbivory on available foods of macaques might be heavy snow conditions, which could physically and physiologically restrain the excessive bark/buds herbivory by macaques.

Optimizing habitat connectivity among macaque populations in modern Japan

“…Recent evidence has supported the observation that wild primates serve as a solid foundation for maintaining the structure and function of ecosystems that they occupy (Andresen et al, 2018;Chapman et al, 2013;Corlett, 2017;Enari & Enari, 2021a;Tsuji & Su, 2018). Unfortunately, most primates are typically severely threatened by human activities, such as increasing habitat loss through forest exploitation and illegal hunting, because their original habitats are mostly found in countries with rapid human population growth (Estrada et al, 2018).…”