TY - JOUR

T1 - Variation in root morphology amongst tree species influences soil hydraulic conductivity and macroporosity

AU - Webb, Bid

AU - Robinson, David

AU - Marshall, Miles

AU - Ford, Hilary

AU - Pagella, Tim

AU - Healey, John

AU - Smith, Andy

PY - 2022/11/1

Y1 - 2022/11/1

N2 - Natural approaches to flood risk management are gaining interest as sustainable flood mitigation options. Targeted tree planting has the potential to reduce local flood risk, however attention is generally focused on the hydrological impacts of catchment afforestation linked to generic tree features, whilst the species-specific impacts of trees on soil hydrology remain poorly understood. This study compared effects of different tree species on soil hydraulic properties. Monocultures of Alnus glutinosa (common alder), Fraxinus excelsior (European ash), Fagus sylvatica (European beech), Betula pendula (silver birch), Castanea sativa (sweet chestnut), Quercus robur (English oak) and Acer pseudoplatanus (sycamore maple) were used to determine effects of tree species identity on soil hydraulic properties (near-saturated K and soil water retention) in a sandy loam soil, North Wales, United Kingdom. The interaction of F. excelsior root properties and soil class on hydraulic conductivity was also examined in four different soils (Rendzic Leptosol, Haplic Luvisol, Dystric Fluvic Cambisol and Dystric Gleysol) across England and Wales. Fine root biomass (FRB) and morphological characteristics were determined at three depths (0-0.1, 0.1-0.2 and 0.2-0.3 m) and complemented by in situ surface measurement of soil hydraulic conductivity. Root morphological traits were closely associated with species identity and pore-size distribution, and FRB was strongly correlated with soil hydraulic conductivity (R2=0.64 for 0-0.1 m depth FRB; R2=0.69 for 0.1-0.2 m depth FRB). Fine root biomass of F. excelsior was six-fold greater than C. sativa (p<0.001), and the frequency of 0.01 mm radius soil pores under F. excelsior was twice that of Q. robur. Near-saturated hydraulic conductivity under F. excelsior was 7.91 ± 1.23 cm day-1, double the mean rate of the other species. Soil classification did not significantly influence FRB (p = 0.056) or near-saturated hydraulic conductivity (p = 0.076) in the 0.0-0.1 m depth soil, but soil water retention varied with depth. Species-specific traits of trees should be considered in landscape design to maximise the local hydrological benefits of trees.

AB - Natural approaches to flood risk management are gaining interest as sustainable flood mitigation options. Targeted tree planting has the potential to reduce local flood risk, however attention is generally focused on the hydrological impacts of catchment afforestation linked to generic tree features, whilst the species-specific impacts of trees on soil hydrology remain poorly understood. This study compared effects of different tree species on soil hydraulic properties. Monocultures of Alnus glutinosa (common alder), Fraxinus excelsior (European ash), Fagus sylvatica (European beech), Betula pendula (silver birch), Castanea sativa (sweet chestnut), Quercus robur (English oak) and Acer pseudoplatanus (sycamore maple) were used to determine effects of tree species identity on soil hydraulic properties (near-saturated K and soil water retention) in a sandy loam soil, North Wales, United Kingdom. The interaction of F. excelsior root properties and soil class on hydraulic conductivity was also examined in four different soils (Rendzic Leptosol, Haplic Luvisol, Dystric Fluvic Cambisol and Dystric Gleysol) across England and Wales. Fine root biomass (FRB) and morphological characteristics were determined at three depths (0-0.1, 0.1-0.2 and 0.2-0.3 m) and complemented by in situ surface measurement of soil hydraulic conductivity. Root morphological traits were closely associated with species identity and pore-size distribution, and FRB was strongly correlated with soil hydraulic conductivity (R2=0.64 for 0-0.1 m depth FRB; R2=0.69 for 0.1-0.2 m depth FRB). Fine root biomass of F. excelsior was six-fold greater than C. sativa (p<0.001), and the frequency of 0.01 mm radius soil pores under F. excelsior was twice that of Q. robur. Near-saturated hydraulic conductivity under F. excelsior was 7.91 ± 1.23 cm day-1, double the mean rate of the other species. Soil classification did not significantly influence FRB (p = 0.056) or near-saturated hydraulic conductivity (p = 0.076) in the 0.0-0.1 m depth soil, but soil water retention varied with depth. Species-specific traits of trees should be considered in landscape design to maximise the local hydrological benefits of trees.

KW - Land use

KW - Infiltration

KW - Hymenoscyphus fraxineus

KW - Hydrology

KW - Soil porosity

KW - Soil classification

U2 - 10.1016/j.geoderma.2022.116057

DO - 10.1016/j.geoderma.2022.116057

M3 - Article

VL - 425

JO - Geoderma

JF - Geoderma

SN - 0016-7061

M1 - 116057

ER -