Is mowing effective in reducing rodent damage to forest plantations?

Forest trees, particularly at a young age in afforestation, are susceptible to bark gnawing by herbivorous rodents such as voles. Few preventive measures for vole damage exist, although mowing to control herbaceous vegetation is often suggested. However, no empirical evidence supports the claim that mowing prevents or inhibits rodent damage to seedlings in a forest ecosystem. We examined the effects of single mowing on rodent population dynamics and the amount of damage they cause. The study was conducted in 2019 - 2021 at 34 randomly selected European beech forest plantations in Poland, with half manually mowed in late summer. Methods Rodent damage to treesTo assess the duration and intensity of bark damage caused by small rodents, European beech saplings on 20 forest plantations were monitored monthly from December to April. Tree gnawing intensity was conducted from December 2019 to April 2021. During the tree survey, 150 beech saplings were inspected for signs of gnawing marks in each selected plantation. Any newly gnawed trees were recorded and marked. The proportion of gnawed trees to unaffected trees per month was used to measure damage intensity. Small rodent abundanceTo estimate rodent abundance, small rodent surveys were conducted on 30 of the plantations. Surveys for rodents and tree damage were carried out in 16 plantations. Trapping lasted from January 2020 to August 2021. The small rodent’s community structure and population dynamics were surveyed using a catch-mark-release method during 5-day live-trapping sessions conducted eight times approximately every three months. Trapping sites were designated randomly within the plantations. At each site, 15 wooden boxes baited with oats and apples were placed in three rows 10 m apart and checked every 12 hours. Captured rodents were identified to species, marked non-individually by fur clipping at first capture, or recorded as a recapture.