Multiple soil reinforcement mechanisms during the initial phase of vegetation restoration: A case study of two plant species in Jinyun Mountain area of Chongqing
ZHU Jinqi1,2, LIU Yong3, WANG Dan1,2, ZHENG Bofu1, WANG Yujie4,5, JIANG Yihui1,2, WANG Yunqi4,5
1. Jiangxi Institute of Ecological Civilization, School of Resources and Environment, Nanchang University, 330031, Nanchang, China; 2. Insitute of Basin Carbon Neutality, Nanchang University, 330031, Nanchang, China; 3. Changjiang Survey, Planning, Design and Research Co., Ltd., 430010, Wuhan, China; 4. Three-Gorges Reservoir Area(Chongqing) Forest Ecosystem Research Station, School of Soil and Water Conservation, Beijing Forestry University, 100083, Beijing, China; 5. Three-Gorges Reservoir Area(Chongqing) Forest Ecosystem Research Station, Ministry of Education, School of Soil and Water Conservation, Beijing Forestry University, 100083, Beijing, China
Abstract：[Background] Plant is widely used in protecting soil and water from erosion and shallow landslide, is regarded as an important role in soil and water conservation measures. Plant roots can affect soil cohesion in two ways: Mechanical (root physically penetrate into the soil) and chemical (change the chemical composition of the soil) reinforcement. This study investigated and compared two benefits of plant roots working on soil cohesion with different species restoration in the initial period. [Methods] We selected tree (Symplocos setchuensis) and herb (Cynodon dactylon) as the research object and replanted them in a forest gap for 3 years in Jinyun of Chongqing. Soil shear strength, root distribution density, and root strength traits were evaluated, the benefits of vegetation restoration on soil were measured in different planting period and different soil layer. The chemical reinforcement was measured by direct shear tests, and mechanical reinforcement was measured using RBMw. [Results] 1) Both species strengthened soil through mechanical and chemical soil stabilization mechanisms, the mechanical reinforcement ranged from 5 to 15 kPa and chemical reinforcement ranged from 0 to 7 kPa. Both of these two effects decreased with soil depth. 2)The C. dactylonis only provided a higher increase in soil cohesion in the 0-20 cm soil layer than the tree by 12% in the second year of planting, due to its faster growth characteristic. After the third year, the increase in soil cohesion provided by the C. dactylonis was higher than the tree by 7%. 2) Both plant species demonstrated a higher effect of mechanical soil stabilization over chemical soil stabilization, with the mechanical effect of C. dactylonis being approximately 52% higher than the chemical effect, while S. setchuensis was 34%. [Conclusions] Compared with chemical reinforcement of root, root mechanical reinforcement plays a more important role on soil cohesion, but they varied with different soil layer and different species. More details, different species reinforced the soil via vary mechanisms, some had strong and high-density roots, that provided a higher mechanical reinforcement; while others affected the soil cohesion and internal friction angle via remold and change soil structure, soil organic carbon, and etc., that provided a higher chemical reinforcement. Thus, this study expands our acknowledge on the mechanism of vegetation works on soil reinforcement and helps us on plant selection for soil conservation.
朱锦奇, 刘勇, 王丹, 郑博福, 王玉杰, 江旖慧, 王云琦. 植被恢复初期的多重固土机制——以重庆缙云山地区2种植物为例[J]. 中国水土保持科学, 2023, 21(3): 17-24.
ZHU Jinqi, LIU Yong, WANG Dan, ZHENG Bofu, WANG Yujie, JIANG Yihui, WANG Yunqi. Multiple soil reinforcement mechanisms during the initial phase of vegetation restoration: A case study of two plant species in Jinyun Mountain area of Chongqing. SSWC, 2023, 21(3): 17-24.
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2023, Vol. 21 
