Afforestation works on seadikes along the coastal line in China aid soil erosion control and help to maintain the stability of seadikes. Tree species currently used in the afforestation are black locust, cryptomeria, water fir, bamboo, and a few chinese fir. In this connection, various laboratory tests and field researches were conducted to study the effect of roots of the different tree species on soil stability, and to know which type of tree species is the most appropriate for soil erosion control on seadikes.
Results of research works show that the tree roots, particularly those with diameter smaller than 1mm, known as “rootlets” increase soil anti-erosivity efficiently. Soil anti-scouribility raises with the increase in rootlet length and weight. The correlation coefficients between soil anti-scouring index and the rootlet length and weight is found to be 0.93 and 0.83, respectively. Soil with more tree roots usually has higher porosity, thereby having higher infiltration capacity. The correlation coefficient between soil non-capillary porosity and steady infiltration rate is 0.86.
Among the tree species tested, black locust forest has the smallest function on soil erosion control, and bamboo has the largest function. The main afforestation tree species which functions most in soil erosion control are in the order, bamboo>;cryptomeria>water fir>black locust.
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