Shrub Hydropedology: Preferential Water Availability to Deep Soil Layer

Abstract

The complex interactions between shrub traits, soil structure, and soil water dynamics are not well understood yet. This study investigated rainfall partition by C. microphylla L., spatial soil water pattern, soil hydraulic conductivity, and soil macropores to ascertain preferential water flow to deep soil layer by shrub. Results indicated that high variability in throughfall existed within individual shrub stand: average coefficient of variation was 0.36 ± 0.13 for shrub and 0.15 ± 0.13 for interspace grass. Throughfall was less at the center of the shrub patch (30–60% of rainfall) than the outward positions at the edges of the canopy (70–90% of rainfall). Soil water responded differently to rainfall, soil depth, and vegetation type and showed high variability within shrub patches and on the slope. Greater and deeper infiltration was observed beneath C. microphylla L. canopy than interspaces grass after rainfall with large amount and high intensity, suggesting that macropore flow dominated in shrub patches. X‐ray CT showed that macroporosity was over six times greater in soil under C. microphylla L. than interspace grass. Soil hydraulic conductivity for shrub at saturation and the pressure heads of −30, −60, and −150 mm were 3, 2, 2.5, and 2 times than those of grass, respectively. Shrub patches had a significant lower bulk density and higher porosity than grass patches at the top 0‐ to 30‐cm depth. Soil hydraulic conductivity was significantly correlated to organic matter content, total N, bulk density, and porosity. This study suggests that rainfall partition by shrub's canopy and subsurface soil macropores induced by root architecture results in preferential water flow into deep soil layer, which might favor competitive advantages for water by shrubs under arid conditions.

Comparisons of stemflow and its bio-/abiotic influential factors between two xerophytic shrub species

“…Note: BA is the branch inclined angle; P is the precipitation amount; CK and SP are the abbreviations of C. korshinskii and S. psammophila, respectively. available moisture in dryland ecosystems (Dunkerley, 2000;Yang, 2010;Návar, 2011;Li et al, 2013). That agreed with the findings of Dong and Zhang (2001) that S. psammophila belonged to the water-spending paradigm from the aspect of leaf water relations and anatomic features, and the finding of Ai et al (2015) that C. korshinskii belonged to the watersaving paradigm and had larger drought tolerance ability than S. psammophila from the aspect of root anatomical structure and hydraulic traits.…”

“…Dryland shrubs generally experienced several wetting-drying cycles (Cui and Caldwell, 1997) when rains were sporadic. As an important source of rhizosphere soil moisture at dryland ecosystems (Dunkerley, 2000;Yang, 2010;Návar, 2011;Li et al, 2013), a considerable amount of stemflow could be produced by various species and infiltrated into deep soil during heavier rains. However, during lighter rains, the larger amount stemflow produced in more efficient manner might benefit xerophytic shrubs, as more soil moisture could be recharged especially at the root zone.…”

Rainfall partitioning into throughfall, stemflow and interception loss by two xerophytic shrubs within a rain-fed re-vegetated desert ecosystem, northwestern China

“…An understanding of the hydrologic balance induced by desert vegetation is crucial for assessing the spatial patterns, establishment and permanence of vegetation in vast desert areas (Reynolds et al, 1999;Rietkerk et al, 2004). Shrubs are the dominant vegetation and play an important role in the desert ecosystems by altering the hydrological, physical and biological soil environment induced by their canopies (Li et al, 2013;McKell, 1975). Therein, from a hydrologic point of view, individual shrub canopies exert a significant control by modifying both evaporation and redistribution of incident rainfall (Domingo et al, 1998).…”

The native shrub, Piliostigma reticulatum , as an ecological “resource island” for mango trees in the Sahel

“…Previous studies have shown that resource islands, compared to interspaces, modify soil water properties that can lead to changes that serve as a positive biophysical feedback to plant establishment and growth (Bhark and Small, 2003;Kizito et al, 2012;Rango et al, 2006). Plant-soilhydrological processes in resource islands are complex, varying greatly across spatiotemporal scales, by depth, and an area of incipient research (Aguilera et al, 1999;Jury et al, 2011;Li et al, 2013;Schade and Hobbie, 2005). In our study, soils of native shrubs had significantly greater soil water content (SWC) than bare soil at 10 cm depth, however, no significant difference in SWC was found among soils from interspaces, mango alone, and intercropped mango + shrub.…”