Use of fallen dead trees by Japanese squirrels within cedar plantations in northeastern Japan

Abstract

Deadwood in forests plays a critical role in maintaining the ecological functions. Small mammals use deadwood, and thus deadwood can mitigate the negative impacts of plantation on small mammals. This study focused on fallen dead trees in planted forests, and aimed to verify whether fallen dead trees affect behavioral patterns of Japanese squirrels. To clarify the use of fallen dead trees by Japanese squirrels in a Japanese cedar plantation, we observed squirrel behavior by camera trap surveys at 61 survey sites. Our findings showed that fallen dead trees play a crucial role in the behavior of Japanese squirrels, serving as landmarks for movement, vigilance, resting, and hoarding sites. These functions are critical for the survival of Japanese squirrels, suggesting that fallen dead trees in planted forests have positive impacts on their microenvironment use. The increase of deadwood due to disturbances such as heavy rainfall and snowfall resulting from climate change may provide benefits to arboreal small mammals in poorly managed planted forests. Additionally, leaving some of the deadwood generated during the harvesting process in properly managed forests can improve the quality of habitat for arboreal small mammals.