Taiwan field vole (Microtus kikuchii) herbivory facilitates Yushan cane (Yushania niitakayamensis) asexual reproduction in alpine meadows

Herbivores can sometimes benefit the plants they consume. We investigated the interaction between an herbivore species, the Taiwan field vole (Microtus kikuchii), and its major food plant, the Yushan cane (Yushania niitakayamensis) of alpine meadows. We observed consumption of Yushan canes by voles in the field and laboratory, performed 2 field manipulative experiments and 2 laboratory cafeteria feeding experiments, and carried out chemical analyses on different Yushan cane parts to test 2 hypotheses: Taiwan field voles feed preferentially on certain Yushan cane parts due to their different chemical constituents, which vary with season; and herbivory by the Taiwan field vole has positive effects on fitness of Yushan cane. Our results showed that, although Taiwan field voles could exert a strong herbivorous pressure on Yushan canes through their near year-round preference for feeding on Yushan cane leaves, the presence of Taiwan field voles actually increases the emergence of Yushan cane shoots over time. The feeding preference of voles for different plant parts can be explained by plant chemical constituents. We demonstrated that the consumption behavior of voles, which reduces the canopy and creates large litter piles, could facilitate the production of Yushan cane shoots by creating favorable shooting conditions. This study suggests a behavioral mechanism of overcompensation where the gain in asexual reproduction by Yushan cane more than compensates the loss to herbivory by the Taiwan field vole.