<abstract xmlns="http://www.w3.org/1999/xhtml">

Changes in hydrological processes and water resources required to sustain vegetation for ecological restoration of landfill covers and post mining sites in arid environments pose challenges in the context of extended droughts. Knowledge of actual threshold and wilting suction values based on tree morphological feature or plant age is essential for understanding the variation of root water uptake with drought stress and numerically predict the pore water pressure profile in root zone. The objective of this study is to quantify the transpiration reduction function (TRF; in terms of stomatal conductance (SC) and xylem sap flow (SF)) of <italic>Schefflera arboricola,</italic> considering the effects of tree morphology. Continuous drought condition was applied on the plant quantified with leaf area index (LAI) values at 0.5, 2 and 3.5, wherein each LAI represent tree age. The soil matric suction (ψ) and volumetric water content were measured by embedded sensors in the root zone. Based on the TRF obtained from SC values, a unique threshold suction (<italic>ψ</italic>NTRt) ranging from 30 to 50 kPa was identified. Beyond this <italic>ψ</italic>NTRt, measured leaf abscisic acid concentration increased up to 35 ng/mL, indicating the start of water stress avoidance mechanism. It is evident that <italic>ψ</italic>NTRt is independent of tree morphological parameter- leaf area to root length ratio (LA/RL). On the contrary, a threshold suction (<italic>ψ</italic>SAPt), depending on LA/RL ratio, can be determined, indicating the start of xylem cavitation. This <italic>ψ</italic>SAPt values ranging from 80 to 500 kPa depending on the LA/RL value, imply that the plant could significantly resist xylem embolization at higher LA/RL. In contrast, the plant with low LA/RL values have less tolerance of drought stress and hence low survivability. The results from this research study can be vital for devising and predicting plant available water in water scarce arid environments by a flux-based approach which is dependent on the tree age.
</abstract>

Changes in hydrological processes and water resources required to sustain vegetation for ecological restoration of landfill covers and post mining sites in arid environments pose challenges in the context of extended droughts. Knowledge of actual threshold and wilting suction values based on tree morphological feature or plant age is essential for understanding the variation of root water uptake with drought stress and numerically predict the pore water pressure profile in root zone. The objective of this study is to quantify the transpiration reduction function (TRF; in terms of stomatal conductance (SC) and xylem sap flow (SF)) of Schefflera arboricola, considering the effects of tree morphology. Continuous drought condition was applied on the plant quantified with leaf area index (LAI) values at 0.5, 2 and 3.5, wherein each LAI represent tree age. The soil matric suction (ψ) and volumetric water content were measured by embedded sensors in the root zone. Based on the TRF obtained from SC values, a unique threshold suction (ψNTRt) ranging from 30 to 50 kPa was identified. Beyond this ψNTRt, measured leaf abscisic acid concentration increased up to 35 ng/mL, indicating the start of water stress avoidance mechanism. It is evident that ψNTRt is independent of tree morphological parameter- leaf area to root length ratio (LA/RL). On the contrary, a threshold suction (ψSAPt), depending on LA/RL ratio, can be determined, indicating the start of xylem cavitation. This ψSAPt values ranging from 80 to 500 kPa depending on the LA/RL value, imply that the plant could significantly resist xylem embolization at higher LA/RL. In contrast, the plant with low LA/RL values have less tolerance of drought stress and hence low survivability. The results from this research study can be vital for devising and predicting plant available water in water scarce arid environments by a flux-based approach which is dependent on the tree age.

Tree morphology dependent transpiration reduction function of <italic>Schefflera arboricola</italic> for landfill cover restoration

Department of Civil and Environmental Engineering

Hong Kong University of Science and Technology

Journal of Hydrology and Hydromechanics

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Tree morphology dependent transpiration reduction function of  for landfill cover restoration

Changes in hydrological processes and water resources required to sustain vegetation for ecological restoration of landfill covers and post mining sites in...

Tree morphology dependent transpiration reduction function of Schefflera arboricola for landfill cover restoration

Published Online: Feb 08, 2024

Page range: 1 - 14

Received: Mar 20, 2023

Accepted: May 10, 2023

DOI: https://doi.org/10.2478/johh-2023-0038

Keywords
Vegetation, Suction, Transpiration, Partial saturation, Drought

© 2023 Sanandam Bordoloi et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Tree morphology dependent transpiration reduction function of Schefflera arboricola for landfill cover restoration

Published Online: Feb 08, 2024

Page range: 1 - 14

Received: Mar 20, 2023

Accepted: May 10, 2023

DOI: https://doi.org/10.2478/johh-2023-0038

KeywordsVegetation, Suction, Transpiration, Partial saturation, Drought

© 2023 Sanandam Bordoloi et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
Vegetation, Suction, Transpiration, Partial saturation, Drought