Evaluation of the Effects of Forest on Slope Stability and Its Implications for Forest Management: A Case Study of Bailong River Basin, China

Abstract

Previous studies have shown that the mechanical effects of vegetation roots on slope stability can be classified as additional cohesion effects and anchorage effects. The present study investigated the combined mechanical effects (additional cohesion effects and anchorage effects) of vegetation on a slope with coarse-grained soil in the mountainous region (significantly prone to slope failure) of Gansu Province, China. A detailed survey of tree density, root system morphology and slope profiles was conducted, and we also assessed the soil cohesion provided by the root systems of monospecific stands of Robinia pseudoacacia growing in different locations on the slope. The measured data were incorporated into a numerical slope model to calculate the stability of the slope under the influence of trees. The results indicated that it was necessary to consider the anchoring effect of coarse roots when estimating the mechanical effects of trees on slope stability. In particular, the FoS (factor of safety) of the slope was increased by the presence of trees. The results also demonstrated that vegetation increased slope stability. The reinforcing effects were most significant when the trees were planted along the entire slope. Although the reinforcing effects contributed by trees were limited (only 4–11%), they were essential for making optimal use of vegetation for enhancing slope stability. Overall, vegetation development can make a major contribution to ecosystem restoration in the study region.

Scaling the Roots Mechanical Reinforcement in Plantation of Cunninghamia R. Br in Southwest China

“…The upslope grown roots also provide good anchorage to the slope compared to roots on the downslope direction [57]. Wang et al [36] also showed that the additional cohesion provided by the roots was almost the same on different slope directions of the tree. Further, Genet et al [17] reported that a significant difference was not observed in RD measured in a different direction around the same tree.…”

“…Only those roots were considered, which were in the cross-sectional area (a × h (Figure 3b)), assuming all these roots play a role in providing additional root cohesion. If a root was branched inside the excavated area, the branched roots were not counted, as only the roots crossing the cross-sectional area (a × h) will play a role in root cohesion at that profile [36]. From these roots counting and roots diameter, the roots area (A r ) was calculated.…”

A Study on the Influence of Vegetation Growth on Slope Stability

“…Roots of the vegetation can reach up to the depths of 3m [4,7,9]. The zone of Soil with roots is represented in terms of root reinforced soil properties with anchors [8,10] and only as root reinforced soil [8].…”

Stability Reinforcement of Slopes Using Vegetation Considering the Existence of Soft Rock

“…Due to the catastrophic consequence caused by slope failure, many reinforcement methods have been developed, such as drainage systems [7], stabilizing piles [8], reinforcement of vegetation, among others. Due to its environmentally friendly characteristics compared to soil nails, geosynthetics, retaining structures, gabions and shotcrete, the reinforcement of vegetation, such as grass and shrubs, on the slope stability, has been gradually recognized [9][10][11][12][13][14][15][16][17][18][19][20], and there are an increasing number of slope protection engineering with vegetation grew on the slope in recent years [19][20][21][22][23][24][25][26][27][28]. In fact, vegetation-soil interaction and plant-soil-atmosphere interaction are rather complex, thus the mechanism and effectiveness of vegetation reinforcement on slope stability are significant and it has attracted much attention of researchers.…”