Abstract:
Populus ciliata also known as the Himalayan Poplar is being used extensively
for erosion control and the re-vegetation of eroded hilly areas in the developed
countries such as China, Japan, United States of America, and New Zealand. Two
samples of Populus ciliata were uprooted to study the root distribution of each of
trees for every ten cm thick layer. Evident from the excavation of both sample trees, it
is found that a majority of the roots are found at depths of 50-80cm. Trees and other
vegetation impart a roughness to water flow in channels, causing flow retardance,
which results in reduced flow and lower flow energy for detachment and transport of
the sediment. The data that was gathered revealed that the Populus ciliata is a stable
plant species and breaks new ground on steep eroded slopes with shallow soil that was
subjected the climatic movement of the area. The current study has also showed that
Populus ciliata has roots that have the ability to grow and stretch out to shallow soils,
unlike other tree species that may not have the ability to do so. Populus ciliata has
very fast growth rates and strong spreading root systems as examined in the current
study. A-type slope has a growth of tap roots which is restricted by bedrock resulting
in no reinforcing strength effect at the potential shear zone boundary. However, root
reinforcement is increased by the growing plant only to a depth of 70 to 80cm. In the
B-type slope, the roots invade and reinforce the transitional zone, and the change of
the occurrence of landslides begins to decrease as the plant becomes older. When the
plant begins to age or become older after about 25 years, the root reinforcement
becomes stronger than the soil shear strength and the shear stress of the rooted soil.
The potential shear zone also increase for the Type B slope as the age of the plant
increases between the ages of 25 to 40 years.
