Does drought alter hydrological functions in forest soils?

Abstract. Climate change is expected to impact the water cycle and severely affect precipitation patterns across central Europe and in other parts of the world, leading to more frequent and severe droughts. Usually when projecting drought impacts on hydrological systems, it is assumed that system properties, like soil properties, remain stable and will not be affected by drought events. To study if this assumption is appropriate, we address the effects of drought on the infiltration behavior of forest soils using dye tracer experiments on six sites in three regions across Germany, which were forced into drought conditions. The sites cover clayey-, loamy- and sandy-textured soils. In each region, we compared a deciduous and a coniferous forest stand to address differences between the main tree species. The results of the dye tracer experiments show clear evidence for changes in infiltration behavior at the sites. The infiltration changed at the clayey plots from regular and homogeneous flow to fast preferential flow. Similar behavior was observed at the loamy plots, where large areas in the upper layers remained dry, displaying signs of strong water repellency. This was confirmed by water drop penetration time (WDPT) tests, which revealed, in all except one plot, moderate to severe water repellency. Water repellency was also accountable for the change of regular infiltration to fingered flow in the sandy soils. The results of this study suggest that the drought history or, more generally, the climatic conditions of a soil in the past are more important than the actual antecedent soil moisture status regarding hydrophobicity and infiltration behavior; furthermore, drought effects on infiltration need to be considered in hydrological models to obtain realistic predictions concerning water quality and quantity in runoff and groundwater recharge.

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Does drought alter hydrological functions in forest soils? An infiltration experiment

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-7689-2015 ◽

2015 ◽

Vol 12 (8) ◽

pp. 7689-7725 ◽

Cited By ~ 4

Author(s):

K. F. Gimbel ◽

H. Puhlmann ◽

M. Weiler

Keyword(s):

Forest Soils ◽

Preferential Flow ◽

Water Cycle ◽

Coniferous Forest ◽

Water Repellency ◽

Climatic Conditions ◽

Antecedent Soil Moisture ◽

Dye Tracer ◽

Infiltration Behavior ◽

Tracer Experiments

Abstract. The water cycle is expected to change in future and severely affect precipitation patterns across central Europe and in other parts of the world, leading to more frequent and severe droughts. Usually, it is assumed that system properties, like soil properties, remain stable and will not be affected by drought events. To study if this assumption is appropriate, we address the effects of drought on the infiltration behavior of forest soils using dye tracer experiments on six sites in three regions across Germany, which were forced into drought conditions. The sites cover clayey, loamy and sandy textured soils. In each region, we compared a deciduous and a coniferous forest stand to address differences between the main tree species. The results of the dye tracer experiments show clear evidence for changes in infiltration behavior at the sites. The infiltration changed at the clayey plots from regular and homogeneous flow to fast preferential flow. Similar behavior was observed at the loamy plots, where large areas in the upper layers remained dry, displaying signs of strong water repellency. This was confirmed by WDPT tests, which revealed, in all except one plot, moderate to severe water repellency. Water repellency was also accountable for the change of regular infiltration to fingered flow in the sandy soils. The results of this study suggest that the "drought-history" or generally the climatic conditions in the past of a soil are more important than the actual antecedent soil moisture status regarding hydrophobicity and infiltration behavior; and also, that drought effects on infiltration need to be considered in hydrological models to obtain realistic predictions concerning water quality and quantity in runoff and groundwater recharge.

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Variability of water repellency in sandy forest soils under broadleaves and conifers in north-western Jutland/Denmark

Soil and Water Research ◽

10.17221/1407-swr ◽

2008 ◽

Vol 3 (Special Issue No. 1) ◽

pp. S155-S164 ◽

Cited By ~ 13

Author(s):

N.A Wahl

Keyword(s):

Soil Water ◽

Preferential Flow ◽

Water Drop ◽

Water Repellency ◽

Climatic Conditions ◽

Tree Age ◽

Critical Surface ◽

Soil Water Repellency ◽

Wide Range ◽

North Western

Soil water repellency has important consequences for ecological and hydrological properties of soils and usually retards infiltration capacity and induces preferential flow. This phenomenon has been known to occur on a wide range of sites under a variety of climatic conditions. The objective of this study was to investigate and characterize soil water repellency on forest sites with identical substrate and climatic conditions, differing in tree age and species. In the Vester Torup Klitplantage, an area comprising a conifer dominated forest plantation stocking on sandy deposits in a coastal setting near the Jammer Bay in north-western Jutland/Denmark, four different forest plots were investigated for water repellency effects four times in 2005. To measure soil water repellency, the water drop penetration time test and the critical surface tension test were carried out. Both tests revealed a seasonal variability in water repellency, exhibiting the highest water repellency for the upper 10 cm of the soil during the summer months, whereas the variability between the different plots seems to be less significant. There was no coherence between humus forms, thickness of litter layer and water repellency.

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Water repellency in Japanese coniferous forest soils as affected by drying temperature and moisture

Biologia ◽

10.2478/s11756-018-0157-8 ◽

2018 ◽

Vol 74 (2) ◽

pp. 127-137 ◽

Cited By ~ 4

Author(s):

D. A. L. Leelamanie ◽

Junko Nishiwaki

Keyword(s):

Forest Soils ◽

Coniferous Forest ◽

Water Repellency ◽

Drying Temperature

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Plants and biological soil crust influence the hydrophysical parameters and water flow in an aeolian sandy soil / Vplyv rastlín a biologického pôdneho pokryvu na hydrofyzikálne parametre a prúdenie vody v piesočnatej pôde

Journal of Hydrology and Hydromechanics ◽

10.2478/v10098-012-0027-y ◽

2012 ◽

Vol 60 (4) ◽

pp. 309-318 ◽

Cited By ~ 40

Author(s):

Ľubomír Lichner ◽

Ladislav Holko ◽

Natalia Zhukova ◽

Karsten Schacht ◽

Kálmán Rajkai ◽

...

Keyword(s):

Water Flow ◽

Sandy Soil ◽

Forest Soils ◽

Preferential Flow ◽

Biological Soil Crust ◽

Water Repellency ◽

Pine Forest ◽

Wetting Front ◽

Soil Water Repellency ◽

Grassland Soil

This study tested the hypothesis that the changes in hydrophysical parameters and heterogeneity of water flow in an aeolian sandy soil have the same trend as the process of succession. Three sub-sites were demarcated at the area of about 50 m x 50 m. The first sub-site was located at the pine-forest glade covered with a biological soil crust and represented the initial stage of succession. The second sub-site was located at the grassland and represented more advanced stage of succession. The third sub-site was located at the pine forest with 30-year old Scots pines and represented advanced stage (close to climax) of succession. The sandy soil at the surface was compared to the soil at the pine-forest glade at 50 cm depth, which served as a control because it had a similar texture but limited impact of vegetation or organic matter. It was found that any type of vegetation cover studied had a strong influence on hydrophysical parameters and heterogeneity of water flow in an aeolian sandy soil during hot and dry spells. The changes in some hydrophysical parameters (WDPT, R, k(-2 cm), Sw(-2 cm), ECS and DPF) and heterogeneity of water flow in an aeolian sandy soil had the same trend as the process of succession, but it was not so in the case of Ksand Se(-2 cm), probably due to the higher content of smaller soil particles in grassland soil in comparison with that content at other sub-sites. Both the persistence and index of water repellency of pure sand differed significantly from those of grassland, glade and forest soils. The highest repellency parameter values in forest soil resulted in the lowest value of both the water sorptivity and hydraulic conductivity in this soil in comparison with other soils studied. The highest value of ethanol sorptivity and the lowest value of saturated hydraulic conductivity in the grassland soil in comparison with other soils studied were due to the higher content of fine-grained (silt and clay) particles in the grassland soil. The effective cross section and the degree of preferential flow of pure sand differed significantly from those of grassland, glade and forest soils. The change in soil hydrophysical parameters due to soil water repellency resulted in preferential flow in the grassland, glade and forest soils, while the wetting front in pure sand area exhibited a form typical of that for stable flow. The latter shape of the wetting front can be expected in the studied soils in spring, when soil water repellency is alleviated substantially. The columnar shape of the wetting front, which can be met during heavy rains following long dry and hot spells, was attributed to redistribution of applied water on the surface to a series of micro-catchments, which acted as runon and runoff zones.

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The impact of vegetation on hydraulic conductivity of sandy soil

Soil and Water Research ◽

10.17221/2115-swr ◽

2008 ◽

Vol 2 (No. 2) ◽

pp. 59-66 ◽

Cited By ~ 10

Author(s):

L. Lichner ◽

T. Orfánus ◽

K. Novákova ◽

M. Šír ◽

M. Tesař

Keyword(s):

Hydraulic Conductivity ◽

Forest Soil ◽

Sandy Soil ◽

Preferential Flow ◽

Water Drop ◽

Water Repellency ◽

Forest Site ◽

Meadow Soil ◽

Capillary Suction ◽

The Impact

The objective of this study was to assess the impact of vegetation on the hydraulic conductivity of sandy soil at the locality Mláky II at Sekule (southwest Slovakia). The measurements were taken on the surface of a meadow (Meadow site), a 30-year old Scots pine (Pinus sylvestris) forest (Forest site) and a glade (Glade site). In the glade, the measurements were also taken in the depth of 50 cm (Pure sand) to reduce the influence of vegetation on the soil properties. It was found that the unsaturated hydraulic conductivity kr(−2 cm) as reduced due to the soil water repellency increased in the same order: Forest soil < Glade soil ≈ Meadow soil < Pure sand, similarly as decreased the water drop penetration time tp: Forest soil > Glade soil ≈ Meadow soil > Pure sand, which could refer to an inverse proportionality between the capillary suction and hydrophobic coating of the soil particles. The saturated hydraulic conductivity Ks increased in the following order: Meadow soil < Glade soil ≈ Forest soil < Pure sand; more than two-times higher Ks at both the Forest and Glade sites than that at the Meadow site could be the result of both the patchy growth of vegetation with some areas of bare soil at the Glade site and the macropores (dead roots) in more homogeneous humic top-layer at the Forest site. The share Br of flux through the pores with radii r longer than approximately 0.5 mm decreased in the order: Forest soil » Meadow soil > Glade soil » Pure sand, revealing the prevalence of preferential flow through macropores (dead roots) in the Forest site and a negligible share of macropores in the Pure sand.

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Influence of Root Distribution on Preferential Flow in Deciduous and Coniferous Forest Soils

Forests ◽

10.3390/f10110986 ◽

2019 ◽

Vol 10 (11) ◽

pp. 986 ◽

Cited By ~ 1

Author(s):

Ziteng Luo ◽

Jianzhi Niu ◽

Baoyuan Xie ◽

Linus Zhang ◽

Xiongwen Chen ◽

...

Keyword(s):

Forest Soil ◽

Forest Soils ◽

Root Distribution ◽

Preferential Flow ◽

Deciduous Forest ◽

Coniferous Forest ◽

Soil Layer ◽

Extreme Rainfall ◽

Coarse Roots ◽

Rainfall Events

Root-induced channels are the primary controlling factors for rapid movement of water and solute in forest soils. To explore the effects of root distribution on preferential flow during rainfall events, deciduous (Quercus variabilis BI.) and coniferous forest (Platycladus orientalis (L.) Franco) sites were selected to conduct dual-tracer experiments (Brilliant Blue FCF and Bromide [Br−]). Each plot (1.30 × 1.30 m) was divided into two subplots (0.65 × 1.30 m), and two rainfall simulations (40 mm, large rainfall and 70 mm, extreme rainfall) were conducted in these. Vertical soil profiles (1.00 m × 0.40 m) were excavated, and preferential flow path features were quantified based on digital image analysis. Root (fine and coarse) abundance and Br− concentration were investigated for each soil profile. In deciduous forest, accumulated roots in the upper soil layer induce larger lateral preferential flow as compared to the coniferous forest soil during large rainfall events. Compared with deciduous forest, coniferous forest soil, with higher (horizontal and vertical) spatial variability of preferential flow paths, promotes higher percolation and solute leaching to deeper soil layers during extreme rainfall events. Fine roots, accounting for a larger proportion of total roots (compared to coarse roots), facilitate preferential flow in the 0–40 cm forest soil layer. Overall, our results indicate that the root distribution pattern of different tree species can exert diverse effects on preferential flow in forest soils.

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The effect of soil surfactants on soil hydrological behavior, the plant growth environment, irrigation efficiency and water conservation

Journal of Hydrology and Hydromechanics ◽

10.2478/v10098-010-0013-1 ◽

2010 ◽

Vol 58 (3) ◽

pp. 142-148 ◽

Cited By ~ 18

Author(s):

Demie Moore ◽

Stanley Kostka ◽

Thomas Boerth ◽

Mica Franklin ◽

Coen Ritsema ◽

...

Keyword(s):

Plant Growth ◽

Soil Water ◽

Water Conservation ◽

Preferential Flow ◽

Water Repellency ◽

Climatic Conditions ◽

Irrigation Efficiency ◽

Soil Water Repellency ◽

Growth Environment ◽

Growing Conditions

The effect of soil surfactants on soil hydrological behavior, the plant growth environment, irrigation efficiency and water conservationSoil water repellency causes at least temporal changes in the hydrological properties of a soil which result in, among other things, suboptimal growing conditions and increased irrigation requirements. Water repellency in soil is more widespread than previously thought and has been identified in many soil types under a wide array of climatic conditions worldwide. Consequences of soil water repellency include loss of wettability, increased runoff and preferential flow, reduced access to water for plants, reduced irrigation efficiency, increased requirement for water and other inputs, and increased potential for non-point source pollution. Research indicates that certain soil surfactants can be used to manage soil water repellency by modifying the flow dynamics of water and restoring soil wettability. This results in improved hydrological behavior of those soils. Consequently, the plant growth environment is also improved and significant water conservation is possible through more efficient functioning of the soil.

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