Impact of thinning and contour-felled logs on overland flow, soil erosion, and litter erosion in a monoculture Japanese cypress forest plantation

• Main Authors: Moein Farahnak, Takanori Sato, Nobuaki Tanaka, Anand Nainar, Ibtisam Mohd Ghaus, Koichiro Kuraji
• Format: Article
• Language: English; English
• Published: MDPI Multidisciplinary Digital Publishing Institute 2024
• Subjects: SD1-669.5 Forestry; SD390-390.43 Forest soils
• Online Access: https://eprints.ums.edu.my/id/eprint/42194/1/ABSTRACT.pdf; https://eprints.ums.edu.my/id/eprint/42194/2/FULL%20TEXT.pdf; https://eprints.ums.edu.my/id/eprint/42194/; https://doi.org/10.3390/w16202874

This study investigated the impact of thinning and felled logs (random- and contour-felled logs) on overland flow, soil erosion, and litter erosion in a Japanese cypress forest plantation (2400 tree ha−1) with low ground cover, from 2018 to 2023 in central Japan. Monthly measurements of overland flow and soil and litter erosion were carried out using small-sized traps across three plots (two treatments and one control). In early 2020, a 40% thinning (tree ha−1) was conducted in the two treatment plots. Overland flow increased in the plot with random-felled logs during the first year post-thinning (from 139.1 to 422.0 L m−1), while it remained stable in the plot with contour-felled logs (from 341.8 to 337.1 L m−1). A paired-plot analysis showed no change in overland flow in the contour-felled logs plot compared to the control plot from the pre- to post-thinning periods (pre-thinning Y = 0.41X − 0.69, post-thinning Y = 0.5X + 5.46, ANCOVA: p > 0.05). However, exposure to direct rainfall on uncovered ground areas post-thinning led to increased soil and litter erosion in both treatment plots. These findings suggest that thinning combined with contour-felled logs effectively stabilizes overland flow. Therefore, thinning with contour-felled logs can be considered a viable method for mitigating overland flow in monoculture plantations with low ground cover.