Synergistic effects of primates and dung beetles on soil seed accumulation in snow regions

Abstract

This study aimed to reveal the soil seed accumulation processes for endozoochorous plants in the heavy‐snowfall forests of Japan, where seed dispersal agents are few when compared to tropical forests. We assessed (1) primary seed dispersal by Japanese macaques (Macaca fuscata) by identifying dispersed seeds found in their feces, and (2) secondary seed dispersal by dung beetles by using beads (as seeds mimics) of different sizes, to quantify the frequency of seed burial and burial depths. We studied this diplochorous system in different forest types (undisturbed beech forest, conifer plantation, and secondary beech‐oak forest) and during the spring and summer seasons. The key findings were as follows: (1) macaques dispersed the seeds of 11 and 14 plant species during spring and summer, respectively; (2) seeds dispersed by macaques in the spring were smaller and twice as abundant than those dispersed in the summer; (3) although no differences were observed in the amount of beads buried by beetles between seasons, all bead sizes tended to be buried in deeper soil layers in the spring than in the summer; and (4) the seed supply to the soil in undisturbed beech forest and conifer plantation was greater than the one in secondary beech‐oak forest. Similar to what has been observed in tropical forests, seeds defecated by frugivorous mammals can be successfully incorporated into the underground soil seed bank through a diplochorous macaque‐beetle system in temperate forests of deep snow regions.

A simple technique to assess resource use in dung beetle breeding studies

“…Previous incorporation of foreign objects into dung has not been shown to have major effects on brood ball production or dung beetle functioning (Moczek & Cochrane, 2006; Santos‐Heredia et al, 2011). Industrial dyes and vermiculite have been used to understand brood ball parasitism (Moczek & Cochrane, 2006) and digestion in larvae (Rohner & Moczek, 2021), while the incorporation of small beads into dung has been used to gain insight into secondary seed dispersal (Enari & Sakamaki‐Enari, 2014; Feer et al, 2013; Santos‐Heredia et al, 2011). Glitter particle sizes can range from 50 to 6250 μm (0.05–6.25 mm), though most glitters are around 100–200 μm (Blackledge & Jones, 2007).…”

“…Tracking resources or individuals using indigestible markers has previously been used to understand a wide range of ecological processes in animals, including movement rates, territory use and species interactions within spatial and social networks (Delahay et al, 2000; Jackson et al, 1999; Rösner & Selva, 2005; Ruiz‐Aizpurua et al, 2013). There has been frequent work on secondary seed dispersal using plastic beads, but less work on broader aspects of dung beetle ecology (Andresen, 2002; Andresen & Levey, 2004; Enari & Sakamaki‐Enari, 2014; Feer et al, 2013; Koike et al, 2012; Manns et al, 2020; Santos‐Heredia et al, 2011). Moczek and Cochrane (2006) used dung containing vermiculite to investigate the rate of intraspecific brood ball parasitism in Onthophagus taurus .…”

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

“…The shift in such succession patterns could also be due to the fact that most of the pioneer species bear fleshy fruits, of which macaques serve as efficient seed dispersers. In fact, macaques potentially contribute to seed dispersal for half of all the tree species consumed during winter (Table ; Enari & Sakamaki‐Enari, 2014; Tsuji et al, 2011).…”