Effects of root mass and soil carbon stocks in old awn grasslands after artificial afforestation and grassland regeneration.

Abstract

Recent years have seen an increase in frequent, large-scale landslides causing significant damage annually. Traditionally, forests were believed better than grasslands at controlling landslides due to their deeper roots. However, recent research (Koyanagi et al., 2018) suggests that forests may actually experience deeper collapses and produce more sediment due to their greater root depth. A study conducted in Japan's Minonohara Highlands Plateau compared 'old grasslands' (maintained for over 100 years), 'forests' planted post-war, and 'new grasslands' (forests cleared less than 100 years ago). Various methods, including soil cross-sections and core samples, were used to assess root mass and soil carbon stocks. Results indicated that grasslands generally had more surface roots and potentially lower landslide susceptibility compared to forests. A novel soil carbon assessment method, accounting for roots, was proposed for improved accuracy, particularly in surface layers. Borehole and cross-sectional sampling methods showed similar efficiency in assessing root volume, suggesting practical options for future assessments.