| Summary: | Vegetation has an important influence on slope hydrology and hence slope stability via plant transpiration. Little is known about the relative merit of evergreen versus deciduous shrubs in maintaining suctions through the year. This study aims to quantify the soil-plant-water relations of two shrub species and to identify relevant plant traits that correlate with hydro-mechanical properties of vegetated soil. Corylus avellana L. (Hazel) and Ilex aquifolium L. (Holly) were chosen as contrasting deciduous and evergreen broadleaf species. For each species, three replicates were planted in separated pots of sandy loam soil. Each pot was irrigated until the soil was saturated and then was left to transpire for 20 days. Soil suction, leaf conductance to water vapour (gL) and soil penetration resistance were recorded. After testing, some key plant traits were determined. It was found that Hazel dried soil faster than Holly. The mean suction induced by Hazel (82.9±1.5 kPa) was 2.7 times greater than that induced by Holly (30.6±8.2 kPa), as Hazel has significantly higher gL and specific leaf area. Both suction and soil penetration resistance were strongly correlated with the total leaf area, but not the total leaf biomass.
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