Effects of plant roots on soil-water retention and induced suction in vegetated soil

Leung, Anthony Kwan; Garg, Ankit; Ng, Charles Wang Wai

doi:10.1016/j.enggeo.2015.04.017

Cited by 203 publications

(95 citation statements)

References 51 publications

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“…5). The laboratory study conducted by Leung et al (2015b) also showed that the effects of vegetation on the change in soil hydraulic properties, including not only soil hydraulic conductivity but also soil water retention curve (SWRC), played a more significant role in the suction responses under rainfall, compared to the effects of ET.…”

Section: Effects Of Tree Spacing On Suction Responses During Rainfallmentioning

confidence: 99%

“…Grass that has relatively shallow root system may be effective for soil erosion control, while tree has relatively stronger and deeper root system which may be used for mechanical soil stabilisation. Despite of rather different root systems, transpiration would happen for both types of species, causing a change in matric suction (Pollen-bankhead and Simon 2010; Garg et al 2015b; Leung et al 2015b;Ng et al 2013Ng et al , 2014Ng et al , 2016a and consequently the soil hydrology (Simon and Collison 2002;Smethurst et al 2015;Ng et al 2016c). The increase in matric suction due to plant transpiration would result in a decrease in soil hydraulic conductivity (Ng and Leung 2012) and also an increase in soil shear strength (Ng and Menzies 2007).…”

Section: Introductionmentioning

confidence: 99%

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Investigation of plant growth and transpiration-induced matric suction under mixed grass–tree conditions

Leung

et al. 2017

Can. Geotech. J.

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Investigation of plant growth and transpiration-induced matric suction under mixed grass-tree conditions Ni, J. J.; Leung, Anthony; Ng, C. W. W.; So, P. S. General rightsCopyright and moral rights for the publications made accessible in Discovery Research Portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from Discovery Research Portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain.• You may freely distribute the URL identifying the publication in the public portal. Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractAlthough evapotranspiration-induced matric suction for single species has been widely studied, little is known about how mixed-species planting would affect the plant growth and induced matric suction. This study aims to explore the effects of grass-tree interaction on their growth and induced matric suction during evapotranspiration (ET) and rainfalls. Field monitoring was carried out to measure matric suction responses in compacted soil that was vegetated with (i) single tree species, Schefflera heptaphylla and (ii) mixed species of the trees and a grass species, Cynodon dactylon. In each condition, three tree spacings (120, 180 and 240 mm) were planted. When tree spacing increased from 120 to 240 mm, the peak tree root area index (RAI, for fine roots with diameter < 2 mm) decreased by 16%, but the peak grass RAI increased by 29%. At mixed planting plots, the ET-induced peak matric suction for tree spacing of 240 mm was 20% higher than that for spacing of 180 mm because of increased contribution of grass root-water uptake as the trees were more widely spaced. Without grass, a reverse trend was observed as tree-tree interaction reduced at wide spacings. The peak ET-induced matric suction had a significant linear correlation with RAI. During rainfalls, the highest matric suction was preserved for the case of 240 mm spacing due to the greatest reduction of soil hydraulic conductivity by roots.

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Section: Effects Of Tree Spacing On Suction Responses During Rainfallmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation of plant growth and transpiration-induced matric suction under mixed grass–tree conditions

Leung

et al. 2017

Can. Geotech. J.

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“…x 10 -7 m/s (Leung et al, 2015b). In each test box, a 280 mm thick layer of SC was compacted to a dry density of 1500 kg m -3 ± 2% (i.e., equivalent to 80% of the maximum dry density) at water content of 12% (by mass) using the undercompaction method (Ladd, 1977).…”

Section: Soil Type and Box Preparationmentioning

confidence: 99%

Relationships between leaf and root area indices and soil suction induced during drying–wetting cycles

Garg

Leung

et al. 2016

Ecological Engineering

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The stability and serviceability of geotechnical infrastructure may be affected by plantinduced soil suction during drying-wetting cycles, because an increase in suction would reduce hydraulic conductivity and also increase shear strength. Recent studies have been conducted to quantify suction induced during evapotranspiration (ET) and ponding in soil vegetated with non-crop species that are used for the ecological restoration of geotechnical infrastructure. However, induced suction distribution under drying-wetting cycles has not been investigated. The objectives of this study are to (1) quantify suction induced by a noncrop tree species, Schefflera heptaphylla, under ponding-drying-ponding cycles and (2) correlate intercepted radiant energy, tree leaf area index (LAI), extinction coefficient (k) and root area index (RAI) with suction. In total, 18 vegetated soil samples with LAI ranging from 0.9 to 3.1 and three bare soil samples (control) were tested and subjected to identical cycles of ET and ponding. Energy balance calculation was performed to determine the percentage of interception of radiant energy. An almost linear relationship can be seen between the percentage of energy intercepted (from 7% to 42% ± 4%) and LAI (from 0.9 to 3.1 ± 0.09) for S. heptaphylla. The measured value of k for S. heptaphylla (0.13) was found to be much lower than that of some crop species (0.4-1.6) reported in the literature. Peak suction is always identified at the depth, where RAI is maximum. It was further demonstrated that the tree-induced suction has a strong linear correlation with both the RAI and LAI.

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“…Extensive field and laboratory studies have shown that transpiration-induced suction could be maintained in the soil during and after rainfall Ng et al 2014;Rahardjo et al 2014;Leung et al 2015a;Ng et al in press). Recent research also argues that the presence of roots could affect the soil water retention properties and hence the suction responses (Bengough 2012;Carminati and Vetterlein 2013;Scholl et al 2014;Leung et al 2015b;Ng et al 2016aNg et al , 2016b. The ability of plants to preserve/maintain suction has important implications for slope stability.…”

Section: Introductionmentioning

confidence: 99%

Correlating hydrologic reinforcement of vegetated soil with plant traits during establishment of woody perennials

2017

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Background and aims Vegetation stabilizes slopes via root mechanical reinforcement and hydrologic reinforcement induced by transpiration. Most studies have focused on mechanical reinforcement and its correlation with plant biomechanical traits. The correlations however generally ignore the effects of hydrologic reinforcement. This study aims to quantify the hydrologic reinforcement associated with ten woody species and identify correlations with relevant plant traits. Methods Ten species widespread in Europe, which belong to Aquifoliaceae, Betulaceae, Buxaceae, Celastraceae, Fabaceae, Oleaceae and Salicaceae families, were planted in pots of sandy loam soil. Each planted pot was irrigated and then left to transpire. Soil strength, matric suction and plant traits were measured. Results Transpiration-induced suction was linearly correlated with soil penetration resistance for the ten species due to their different transpiration rates i.e. both suction and soil penetration resistance induced by Hazel and Blackthorn (deciduous) were five times greater than those by Holly and European Box (evergreens). Specific leaf area and root length density correlated with hydrologic reinforcement. The root:shoot ratio correlated best with the hydrologic reinforcement. Conclusions Specific leaf area, root length density and root:shoot ratio explained the tenfold differences in hydrologic reinforcement provided by the ten different species.

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Effects of plant roots on soil-water retention and induced suction in vegetated soil

Cited by 203 publications

References 51 publications

Investigation of plant growth and transpiration-induced matric suction under mixed grass–tree conditions

Investigation of plant growth and transpiration-induced matric suction under mixed grass–tree conditions

Relationships between leaf and root area indices and soil suction induced during drying–wetting cycles

Correlating hydrologic reinforcement of vegetated soil with plant traits during establishment of woody perennials

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