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

Abstract The stability and serviceability of geotechnical infrastructure may be affected by plant-induced 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 is rarely studied. The objectives of this study are to (1) quantify suction induced by a non-crop 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.

[1]  M. Raupach,et al.  Maximum conductances for evaporation from global vegetation types , 1995 .

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

[3]  C. Fan,et al.  Effect of soil moisture content on the deformation behaviour of root-reinforced soils subjected to shear , 2009, Plant and Soil.

[4]  A. Simon,et al.  Quantifying the mechanical and hydrologic effects of riparian vegetation on streambank stability , 2002 .

[5]  J. M. Norman,et al.  Plant Canopies: Their Growth, Form and Function: The description and measurement of plant canopy structure , 1989 .

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

[7]  Li Zhang,et al.  Modelling hydrological processes in created freshwater wetlands: an integrated system approach , 2005, Environ. Model. Softw..

[8]  R. Lemeur,et al.  Extinction of net radiation in different crop canopies , 1969 .

[9]  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 .

[10]  W. Mitsch,et al.  Nutrient and hydrologic budgets of a great lakes coastal freshwater wetland during a drought year , 1992, Wetlands Ecology and Management.

[11]  A. Rosenfeld,et al.  Residential cooling loads and the urban heat island—the effects of albedo , 1988 .

[12]  J. D. Hanson,et al.  Root Length Growth of Eight Crop Species in Haplustoll Soils , 2002 .

[13]  H. Ross,et al.  Sensitivity of Seed Germination and Seedling Radicle Growth to Moisture Stress in Some Vegetable Crop Species , 1979 .

[14]  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 .

[15]  D. A. Sampson,et al.  Light attenuation in a 14-year-old loblolly pine stand as influenced by fertilization and irrigation , 1998, Trees.

[16]  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 .

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

[18]  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.

[19]  M. Qadir,et al.  Crop and irrigation management strategies for saline-sodic soils and waters aimed at environmentally sustainable agriculture. , 2003, The Science of the total environment.

[20]  Charles Wang Wai Ng,et al.  Comparisons of soil suction induced by evapotranspiration and transpiration of S. heptaphylla , 2015 .

[21]  Decheng Zhou,et al.  A meta-analysis of the canopy light extinction coefficient in terrestrial ecosystems , 2014, Frontiers of Earth Science.

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

[23]  William Powrie,et al.  Seasonal changes in pore water pressure in a grass covered cut slope in London clay , 2006 .

[24]  D. Vetterlein,et al.  Plasticity of rhizosphere hydraulic properties as a key for efficient utilization of scarce resources. , 2013, Annals of botany.

[25]  S. Running,et al.  Numerical Terradynamic Simulation Group 12-1988 Rapid Estimation of Coniferous Forest Leaf Area Index Using a Portable Integrating Radiometer , 2018 .

[26]  C. Ng,et al.  Centrifuge modelling of the effects of root geometry on transpiration-induced suction and stability of vegetated slopes , 2016, Landslides.

[27]  N. Barbier,et al.  Estimates and relationships between aboveground and belowground resource exchange surface areas in a Sitka spruce managed forest. , 2010, Tree physiology.

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

[29]  J. Caron,et al.  Plant-induced Changes in Soil Structure: Processes and Feedbacks , 1998 .

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

[31]  William Powrie,et al.  Factors controlling the seasonal variation in soil water content and pore water pressures within a lightly vegetated clay slope , 2012 .

[32]  Pietro Alessandro Brivio,et al.  Principi e metodi di Telerilevamento , 2006 .

[33]  Murielle Ghestem,et al.  Influence of plant root system morphology and architectural traits on soil shear resistance , 2012, Plant and Soil.

[34]  Frederick R. Adler,et al.  Limitation of plant water use by rhizosphere and xylem conductance: results from a model , 1998 .

[35]  P. Reich.  Root–Shoot Relations: Optimality in Acclimation and Adaptation or the ‘‘Emperor’s New Clothes’’? , 2002 .

[36]  Natasha Pollen-Bankhead,et al.  Hydrologic and hydraulic effects of riparian root networks on streambank stability: is mechanical root-reinforcement the whole story? , 2010 .

[37]  A. Stokes,et al.  Quantification of mechanical and hydric components of soil reinforcement by plant roots , 2015 .

[38]  Marnik Vanclooster,et al.  Intraseasonal dynamics of soil moisture variability within a small agricultural maize cropped field , 2002 .

[39]  Changsheng Li,et al.  An integrated model of soil, hydrology, and vegetation for carbon dynamics in wetland ecosystems , 2002 .

[40]  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.

[41]  W. Schlesinger,et al.  The global carbon dioxide flux in soil respiration and its relationship to vegetation and climate , 1992 .