How does the 120-year cycle mast seeding of dwarf bamboo affect the rodent population?

Abstract

Background In 2017, large-scale flowering, seeding, and dying events of dwarf bamboo (Sasa borealis) occurred in a wide range in central Japan for the first time in 120 years. This phenomenon of S. borealis, like the mast seeding of trees, could be expected to provide a large amount of food for seed-eating rodents and gradually affect their ecology and population dynamics. We captured rodents in survey plots in a secondary broad-leaved forest with the phenomenon from 2018 to 2019 to investigate the species, the number of individuals, growing stage, sex, and body mass. In addition, we also compared the capture data for 2 years (2018–2019) with that for the mast seeding year (2017) and 6 years before it (2011–2016). Results The mast seeding of S. borealis greatly increased the population size of rodents, especially Apodemus speciosus and A. argenteus. Conversely, Eothenomys smithii did not show such an increase. Most of the captured rodent individuals were already adults at the time of new capture, and the proportion of male juveniles was extremely low. These results suggest that the mast seeding of S. borealis created unusually rich food availability for the population concentration of rodents due to their immigration. However, body mass was not significantly different before and after the mast seeding. In addition, the increased populations of the two Apodemus species did not decline 2 years after the S. borealis masting, contrary to the previously reported decrease of rodent populations after tree masting. Conclusions Our results indicate that the mast seeding of S. borealis affected the population dynamics of Apodemus species over a long time and their individual composition of different growth stages. However, it did not affect their body mass.

How much do field mice prefer dwarf bamboo seeds? Two‐choice experiments between seeds of Sasa borealis and several tree species on the forest floor

“…Then, foraging for S. borealis seeds was the same as that reported previously (Suzuki & Kajimura, 2023). These results support the hypothesis that the increase in their population after the mast seeding of S. borealis was due to increased food resources (Suzuki et al, 2022). In addition, foraging of S. borealis seeds by E. smithii, another rodent species, and N. procyonoides of the family Canidae, was newly identified.…”

“…Birds and rodents have been reported consuming bamboo seeds in the wild (Areta et al., 2009; Areta & Cockle, 2012; Franklin, 2005; Kitzberger et al., 2007; Lebbin, 2006). In particular, the mast seeding of Bambusoideae leads to a rapid outbreak of rodent populations (Bovendorp et al., 2020; González et al., 2000; Ito, 1975; Suzuki et al., 2022). Nevertheless, studies on rodents' preferences for bamboo seeds over other seeds are few, with only one reported from Argentina by Kitzberger et al.…”

Reproductive characteristics in an understory bamboo and gradual environmental changes after its dieback provide an extended opportunity for overstory tree regeneration in a mixed cool‐temperate forest in central Japan

“…2019; Suzuki et al . 2022). It bloomed gregariously from the end of May to early June in 2017 at the study site (Shimada et al .…”

“…1b). Sasa borealis is monocarpic, with an estimated flowering interval of 120 years and a synchronized mass flowering occurred nationwide in Korea in 2015 and in central Japan in 2017 (Cho et al 2017;Shimada et al 2019;Suzuki et al 2022). It bloomed gregariously from the end of May to early June in 2017 at the study site (Shimada et al 2019).…”