Dynamics of soil reinforcement by roots in a regenerating coppice stand of Quercus serrata and effects on slope stability
Dynamics of soil reinforcement by roots in a regenerating coppice stand of Quercus serrata and effects on slope stability
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DOI：
10.1016/j.ecoleng.2021.106169
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发表时间：
2021-04
影响因子：
3.8
通讯作者：
K. Yamase;C. Todo;N. Torii;T. Tanikawa;Tomonori Yamamoto;H. Ikeno;M. Ohashi;M. Dannoura;Y. Hirano
中科院分区：
文献类型：
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作者：
K. Yamase;C. Todo;N. Torii;T. Tanikawa;Tomonori Yamamoto;H. Ikeno;M. Ohashi;M. Dannoura;Y. Hirano
次生林萌芽更新不仅是森林资源利用的必要手段，也是通过更新维持森林健康和避免因地上生物量过大而引起边坡失稳的必要手段。在森林砍伐过程中，如皆伐，根系对土壤的加固作用一般会在树木死亡过程中减弱，而在砍伐后再生发芽的树木中，根系强度会暂时减弱。然而，在更新过程中减少根系对土壤的加固和边坡稳定性的定量评价还没有进行。在这项研究中，我们评估了根的数量和根分布的变化，3年后，在更新过程ofQuercus serrata，一个主要的优势种，在日本的暖温带和冷温带次生林砍伐。我们还估计了土壤加固根：根束模型，从根的附加凝聚力和边坡稳定性的基础上的安全系数分为垂直和水平的凝聚力与土壤的物理性质的树根系统的影响。在约0.2m的高度切割后，地上发芽的枝条立即再生，而地下根系逐渐腐烂。采伐前树木根系的附加粘聚力为34.6kPa，采伐后3年活伐桩的附加粘聚力显著下降至21.7kPa。在采伐前，饱和土层厚度为0.7m时，树下土壤的安全系数为1.20，而采伐后3年，活树桩下土壤的安全系数显著下降至1.11。伐后3年内不能再生新芽的死伐根下土壤的安全系数为0.99。我们得出的结论是，边坡破坏的概率是显着更大的死树桩比活树桩，并可能会有所不同，这取决于地上和地下部分，包括细根的动态。
Regeneration by sprouting in secondary forests is a necessary technique not only for the utilization of forest resources, but also for maintaining forest health by regrowth and avoiding slope instability caused by over-sized aboveground biomass. The strength of soil reinforcement by roots generally decreases during the tree death process in deforestation, such as clear-cutting, whereas root system strength temporarily decreases in trees that regenerate sprouting after cutting. However, quantitative evaluation of decreasing soil reinforcement by roots and slope stability has not been conducted during regeneration. In this study, we evaluated changes in the number of roots and root distribution up to 3 years after cutting in the regeneration process ofQuercus serrata, a major dominant species of secondary forests in warm and cool temperate zones in Japan. We also estimated soil reinforcement by roots: additional cohesion from roots using the root bundle model, and slope stability based on a factor of safety by dividing the effect of the tree root system into vertical and horizontal cohesion with soil physical properties. After cutting at the height of approximately 0.2 m, the aboveground sprouting branches immediately regenerated, whereas the belowground root system gradually decayed. The additional cohesion from roots in trees before cutting was calculated as 34.6 kPa, whereas it decreased significantly to 21.7 kPa in living stumps 3 years after cutting. The value for the factor of safety with a saturated soil thickness of 0.7 m was calculated as 1.20 in soil under trees before cutting, whereas it decreased significantly to 1.11 in soil under living stumps in the 3 years after cutting. The safety factor's value to 0.99 in soil under dead stumps, which did not regenerate sprouts within 3 years after cutting. We concluded that the probability of slope failure was significantly greater in the dead stumps than in the living stumps and could vary depending on the dynamics of above- and below-ground parts, including fine roots.