Endozoochory by granivorous rodents in seed dispersal of green fruits

Although the role of frugivores in seed dispersal has attracted scientific attention, it remains unclear whether granivorous rodents can act as frugivores to interact mutualistically with fruit-producing plants, especially those bearing green fruits inconspicuous to avian frugivores. In this study, we tracked fruit removal of the tara vine (Actinidia arguta (Siebold & Zucc.) Planch. Ex Miq.) and variegated kiwi vine (Actinidia kolomikta (Rupr. & Maxim.) Maxim.) in a temperate forest and presented fruits to the granivorous rodents Siberian chipmunk (Tamias sibiricus (Laxmann, 1769)), Korean field mouse (Apodemus peninsulae (Thomas, 1907)), and gray red-backed vole (Clethrionomys rufocanus (Sundevall, 1846) = Myodes rufocanus (Sundevall, 1846)) in the laboratory to answer this question. Seeds were collected from rodent feces to see the effects of gut passage on seed germination to determine the role of granivorous rodents in endozoochory of A. arguta and A. kolomikta. We presented clear evidence of endozoochory by granivorous rodents in seed dispersal of the two Actinidia species. Rodents appeared to play an alternative role in dispersing plants bearing green fruits. Moreover, we observed increased germination rates after gut ingestion by the granivorous rodents. Our study evidenced endozoochory of granivorous rodents and provided new insight into the mutualist interactions between rodents and plant species bearing fleshy fruits containing tiny seeds. We suggest future studies pay more attention to endozoochory of rodents and establish their mutualistic relationship with fruit-bearing plants in temperate forests.

Changes in species abundance after seven years of elevated atmospheric CO2 and warming in a Subarctic birch forest understorey, as modified by rodent and moth outbreaks

A seven-year long, two-factorial experiment using elevated temperatures (5 °C) and CO2 (concentration doubled compared to ambient conditions) designed to test the effects of global climate change on plant community composition was set up in a Subarctic ecosystem in northernmost Sweden. Using point-frequency analyses in permanent plots, an increased abundance of the deciduous Vaccinium myrtillus, the evergreens V. vitis-idaea and Empetrum nigrum ssp. hermaphroditum and the grass Avenella flexuosa was found in plots with elevated temperatures. We also observed a possibly transient community shift in the warmed plots, from the vegetation being dominated by the deciduous V. myrtillus to the evergreen V. vitis-idaea. This happened as a combined effect of V. myrtillus being heavily grazed during two events of herbivore attack—one vole outbreak (Clethrionomys rufocanus) followed by a more severe moth (Epirrita autumnata) outbreak that lasted for two growing seasons—producing a window of opportunity for V. vitis-idaea to utilize the extra light available as the abundance of V. myrtillus decreased, while at the same time benefitting from the increased growth in the warmed plots. Even though the effect of the herbivore attacks did not differ between treatments they may have obscured any additional treatment effects. This long-term study highlights that also the effects of stochastic herbivory events need to be accounted for when predicting future plant community changes.

A new species of Aspiculuris Schulz, 1924 (Nematoda, Heteroxynematidae) from the gray-sided vole, Clethrionomys rufocanus (Rodentia, Cricetidae), from Tianjin, China

Aspiculuris tianjinensis sp. nov. recovered from the intestine of Clethrionomys rufocanus from Tianjin, China is described and illustrated using light microscopy and scanning electron microscopy. The new species differs from congeners in the shape of the cervical alae, and the number and arrangement of caudal papillae.

Effect of cyclic and declining food supply on great grey owls in boreal Sweden

In this study of 35 years of data, we examine the short-term (cyclic) and long-term relationship between breeding success of great grey owls ( Strix nebulosa Forster, 1772) and their food supply (bank voles ( Clethrionomys glareolus (Schreber, 1780)), grey-sided voles ( Clethrionomys rufocanus (Sundevall, 1846)), and field voles ( Microtus agrestis (L., 1761))) in northern Sweden. Annual number of owl nests showed a 3 year cyclicity, which as predicted, corresponded to the length of the vole cycle in the region. Mean annual brood size also fluctuated and was positively dependent on the vole supply during the same spring. In this region, there has also been a decline in vole numbers in recent decades, from high-amplitude cycles in the 1970s to subsequent low-amplitude cycles. Correspondingly, and as predicted, mean annual brood size of the owls also declined, although only during the third years of the vole cycle when vole supply in spring and brood size of the owls is at its highest level in high-amplitude cycles. We predict that in the long run the vole decline, associated with increasingly milder winters, and the reduction of the brood size of the owls, especially in years of high owl breeding success, will have serious implications for the population of great grey owls in Scandinavia.