Effects of the roots of Cynodon dactylon and Schefflera heptaphylla on water infiltration rate and soil hydraulic conductivity

TY - JOUR

T1 - Effects of the roots of Cynodon dactylon and Schefflera heptaphylla on water infiltration rate and soil hydraulic conductivity

AU - Leung, A. K.

AU - Garg, A.

AU - Coo, J. L.

AU - Ng, C. W. W.

AU - Hau, B. C. H.

PY - 2015/7/15

Y1 - 2015/7/15

N2 - Water infiltration rate and hydraulic conductivity in vegetated soil are two vital hydrological parameters for agriculturists to determine availability of soil moisture for assessing crop growths and yields, and also for engineers to carry out stability calculations of vegetated slopes. However, any effects of roots on these two parameters are not well-understood. This study aims to quantify the effects of a grass species, Cynodon dactylon, and a tree species, Schefflera heptaphylla, on infiltration rate and hydraulic conductivity in relation to their root characteristics and suction responses. The two selected species are commonly used for ecological restoration and rehabilitation in many parts of the world and South China. A series of in-situ double-ring infiltration tests was conducted during a wet summer, while the responses of soil suction were mointored by tensiometers. When compared to bare soil, the vegetated soil has lower infiltration rate and hydraulic conductivity, due to the clogging of soil pore by plant roots. This results in at least 50% higher suction retained in the vegetated soil. It is revealed that the effects of root-water uptake by the selected species on suction were insignificant due to the small evapotranspiration (< 0.2 mm) when the tests were conducted under the wet climate. There appears to have no significant difference (less than 10%) of infiltration rates, hydraulic conductivity and suction retained between the grass-covered and the tree-covered soil. However, the grass and tree species having deeper root depth and greater Root Area Index (RAI) retained higher suction.

AB - Water infiltration rate and hydraulic conductivity in vegetated soil are two vital hydrological parameters for agriculturists to determine availability of soil moisture for assessing crop growths and yields, and also for engineers to carry out stability calculations of vegetated slopes. However, any effects of roots on these two parameters are not well-understood. This study aims to quantify the effects of a grass species, Cynodon dactylon, and a tree species, Schefflera heptaphylla, on infiltration rate and hydraulic conductivity in relation to their root characteristics and suction responses. The two selected species are commonly used for ecological restoration and rehabilitation in many parts of the world and South China. A series of in-situ double-ring infiltration tests was conducted during a wet summer, while the responses of soil suction were mointored by tensiometers. When compared to bare soil, the vegetated soil has lower infiltration rate and hydraulic conductivity, due to the clogging of soil pore by plant roots. This results in at least 50% higher suction retained in the vegetated soil. It is revealed that the effects of root-water uptake by the selected species on suction were insignificant due to the small evapotranspiration (< 0.2 mm) when the tests were conducted under the wet climate. There appears to have no significant difference (less than 10%) of infiltration rates, hydraulic conductivity and suction retained between the grass-covered and the tree-covered soil. However, the grass and tree species having deeper root depth and greater Root Area Index (RAI) retained higher suction.

KW - water infiltration rate

KW - hydraulic conductivity

KW - vegetation

KW - soil suction

U2 - 10.1002/hyp.10452

DO - 10.1002/hyp.10452

M3 - Article

SN - 0885-6087

VL - 29

SP - 3342

EP - 3354

JO - Hydrological Processes

JF - Hydrological Processes

IS - 15

ER -