Comparisons of soil suction induced by evapotranspiration and transpiration of S. heptaphylla

For a given evapotranspiration (ETr), both soil evaporation and plant transpiration (Tr) would induce soil suction. However, the relative contribution of these two processes to the amount of suction induced is not clear. The objective of this study is to quantify ETr- and Tr-induced suction by a selected tree species, Scheffllera heptaphylla, in silty sand. The relative contribution of transpiration and evaporation to the responses of suction is then explored based on observed differences in Tr- and ETr-induced suction. In total, 12 test boxes were used for testing: 10 for vegetated soil with different values of leaf area index (LAI) and root area index (RAI), while two were for bare soil as references. Each box was exposed to identical atmospheric conditions controlled in a plant room for monitoring suction responses over a week. Due to the additional effects of soil evaporation, ETr-induced suction could be 3%–47% higher than Tr-induced suction, depending on LAI. The significance of evaporation reduced ...

[1]  Hervé Rey,et al.  Using a 3-D virtual sunflower to simulate light capture at organ, plant and plot levels: contribution of organ interception, impact of heliotropism and analysis of genotypic differences. , 2007, Annals of botany.

[2]  Charles Wang Wai Ng,et al.  Investigation of soil density effect on suction induced due to root water uptake by Schefflera heptaphylla , 2015 .

[3]  Charles Wang Wai Ng,et al.  Field study on influence of root characteristics on soil suction distribution in slopes vegetated with Cynodon dactylon and Schefflera heptaphylla , 2015 .

[4]  Richard S. Ladd,et al.  Specimen Preparation and Cyclic Stability of Sands , 1977 .

[5]  Buddhima Indraratna,et al.  Bioengineering ground improvement considering root water uptake model , 2010 .

[6]  Y. Cui,et al.  Development of a Large-Scale Environmental Chamber for Investigating Soil Water Evaporation , 2013 .

[7]  S. Sabaté,et al.  Vertical distribution of fine root density, length density, area index and mean diameter in a Quercus ilex forest. , 2001, Tree physiology.

[8]  Y. Cui,et al.  Thermo-hydro-mechanical modelling of soil settlements induced by soil-vegetation-atmosphere interactions , 2012 .

[9]  T. Illangasekare,et al.  Evaporation from soils under thermal boundary conditions: Experimental and modeling investigation to compare equilibrium‐ and nonequilibrium‐based approaches , 2010 .

[10]  D. Tennant,et al.  Root length density and water uptake in cereals and grain legumes: how well are they correlated , 1987 .

[11]  Van Genuchten,et al.  A closed-form equation for predicting the hydraulic conductivity of unsaturated soils , 1980 .

[12]  C. Lévi-Strauss,et al.  Experimental investigation , 2013 .

[13]  Charles Wang Wai Ng,et al.  Effects of plant roots on soil-water retention and induced suction in vegetated soil , 2015 .

[14]  Li Min Zhang,et al.  Evaluating suction profile in a vegetated slope considering uncertainty in transpiration , 2015 .

[15]  R. Corlett,et al.  Factors Affecting the Early Survival and Growth of Native Tree Seedlings Planted on a Degraded Hillside Grassland in Hong Kong, China , 2003 .

[16]  D. Fredlund,et al.  Soil Mechanics for Unsaturated Soils , 1993 .

[17]  A. Galston.  Plant Physiology , 1967, Nature.

[18]  C. Ng,et al.  Measurements of drying and wetting permeability functions using a new stress-controllable soil column , 2012 .

[19]  Joe T. Ritchie,et al.  Model for predicting evaporation from a row crop with incomplete cover , 1972 .

[20]  Jan Mikulka.  Evaluation of Errors in Manual Image Processing , 2011 .

[21]  R. Feddes,et al.  Simulation of field water use and crop yield , 1978 .

[22]  Charles Wang Wai Ng,et al.  Effects of soil density on grass-induced suction distributions in compacted soil subjected to rainfall , 2014 .

[23]  A. Srivastava,et al.  Quantitative Separation of Roots from Compacted Soil Profiles by the Hydropneumatic Elutriation System1 , 1982 .

[24]  Delwyn G. Fredlund,et al.  Coupled soil-atmosphere modelling for soil evaporation , 1994 .

[25]  D. Leitner,et al.  Root induced changes of effective 1D hydraulic properties in a soil column , 2014, Plant and Soil.

[26]  H. L. Penman.  Natural evaporation from open water, bare soil and grass , 1948, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[27]  Charles Wang Wai Ng,et al.  Effects of the roots of Cynodon dactylon and Schefflera heptaphylla on water infiltration rate and soil hydraulic conductivity , 2015 .

[28]  S. Plantureux,et al.  Effect of root mucilage and modelled root exudates on soil structure , 2000 .

[29]  D. Fredlund,et al.  Soil Mechanics for Unsaturated Soils: Fredlund/Soil Mechanics for Unsaturated Soils , 1993 .

[30]  A. Tang,et al.  Experimental and numerical investigation of soil-atmosphere interaction , 2013 .

[31]  L. Pagano,et al.  Investigation of soil–atmosphere interaction in pyroclastic soils , 2014 .

[32]  Charles Wang Wai Ng,et al.  Transpiration Reduction and Root Distribution Functions for a Non-crop Species Schefflera Heptaphylla , 2015 .

[33]  K. X. Woon,et al.  Experimental investigation of induced suction distribution in a grass-covered soil , 2013 .

[34]  S. Grayston,et al.  Rhizosphere carbon flow in trees, in comparison with annual plants: the importance of root exudation and its impact on microbial activity and nutrient availability , 1997 .