Subsoil root activity in tree-based cropping systems

Lehmann, Johannes

doi:10.1023/a:1026195527076

Cited by 101 publications

(28 citation statements)

References 30 publications

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“…"Dry" is Tswalu NR, "Intermediate" is Venetia-Limpopo NR and "Wet" is Andover GR. nutrient availability to under-tree canopy grasses (Dinkelmeyer et al, 2003;Lehmann, 2003;Ludwig et al, 2001;Sternberg et al, 2004). In another study, we experimentally showed that savanna trees are able to redistribute subsoil N to the under-tree canopy grasses throughout the year (Priyadarshini et al, 2014) which is consistent with the idea that facilitation rather than competition between trees and grasses may be operating at all the three sites.…”

Section: Effect Of Treessupporting

confidence: 87%

Competition with trees does not influence root characteristics of perennial grasses in semi-arid and arid savannas in South Africa

Priyadarshini

Bie

Heitkönig

et al. 2016

Journal of Arid Environments

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Section: Effect Of Treessupporting

confidence: 87%

Competition with trees does not influence root characteristics of perennial grasses in semi-arid and arid savannas in South Africa

Priyadarshini

Bie

Heitkönig

et al. 2016

Journal of Arid Environments

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“…This simple agro-ecosystem (with only 1 plant species growing in highly weathered soils without root growth barriers) provides an opportunity to investigate the belowground growth strategy of fast-growing trees in tropical regions. Most of the current information on tropical forests comes from indirect estimates of root activity from soil moisture monitoring (Calder et al, 1997; Robinson et al, 2006; Mendham et al, 2011) or tracer uptake (Lehmann, 2003; McCulley et al, 2004; da Silva et al, 2011). Spatial patterns of soil water depletion by Eucalyptus trees in Australian agroforests showed that Eucalyptus roots can take up water from the top soil up to 20 m from the tree belts and down to at least 8–10 m within 7 years after planting (Robinson et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of soil exploration by fine roots down to a depth of 10 m throughout the entire rotation in Eucalyptus grandis plantations

Laclau¹,

Silva²,

Lambais³

et al. 2013

Front. Plant Sci.

123

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Although highly weathered soils cover considerable areas in tropical regions, little is known about exploration by roots in deep soil layers. Intensively managed Eucalyptus plantations are simple forest ecosystems that can provide an insight into the belowground growth strategy of fast-growing tropical trees. Fast exploration of deep soil layers by eucalypt fine roots may contribute to achieving a gross primary production that is among the highest in the world for forests. Soil exploration by fine roots down to a depth of 10 m was studied throughout the complete cycle in Eucalyptus grandis plantations managed in short rotation. Intersects of fine roots, less than 1 mm in diameter, and medium-sized roots, 1–3 mm in diameter, were counted on trench walls in a chronosequence of 1-, 2-, 3.5-, and 6-year-old plantations on a sandy soil, as well as in an adjacent 6-year-old stand growing in a clayey soil. Two soil profiles were studied down to a depth of 10 m in each stand (down to 6 m at ages 1 and 2 years) and 4 soil profiles down to 1.5–3.0 m deep. The root intersects were counted on 224 m2 of trench walls in 15 pits. Monitoring the soil water content showed that, after clear-cutting, almost all the available water stored down to a depth of 7 m was taken up by tree roots within 1.1 year of planting. The soil space was explored intensively by fine roots down to a depth of 3 m from 1 year after planting, with an increase in anisotropy in the upper layers throughout the rotation. About 60% of fine root intersects were found at a depth of more than 1 m, irrespective of stand age. The root distribution was isotropic in deep soil layers and kriged maps showed fine root clumping. A considerable volume of soil was explored by fine roots in eucalypt plantations on deep tropical soils, which might prevent water and nutrient losses by deep drainage after canopy closure and contribute to maximizing resource uses.

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“…Concentrations of exchangeable cations usually decrease markedly with depth (Jackson et al 2000;Krishnaswamy & Richter 2002) and a decrease in nutrient uptake with soil depth has been shown in temperate forests (Burton, Pregitzer & Hendrick 2000;Bennett, Andrew & Prescott 2002;Go¨ransson, Ingerslev & Wallander 2008) and tropical agroforestry systems (Lehmann & Muraoka 2001;Lehmann 2003). However, the highest concentrations of nutrients can be found in depth in some specific areas (Stone & Kalisz 1991;Moroni, Smethurst & Holz 2004), and the subsoil may temporarily contain a significant proportion of available nutrients when low soil moistures limit nutrient uptake in surface layers (Lehmann 2003) or when hydraulic redistribution and soil water recharge occur at depth (McCulley et al 2004). Deep roots are also likely to provide a safety-net service, taking up nutrients leached from the topsoil and transferring nutrients available in deep layers to the soil surface (Allen et al 2004;Mulia & Dupraz 2006).…”

Section: Introductionmentioning

confidence: 99%

Functional specialization of Eucalyptus fine roots: contrasting potential uptake rates for nitrogen, potassium and calcium tracers at varying soil depths

Silva¹,

Bouillet

Gonçalves³

et al. 2011

Functional Ecology

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Summary 1.Little is known about the role of deep roots in the nutrition of forest trees and their ability to provide a safety-net service taking up nutrients leached from the topsoil. 2. To address this issue, we studied the potential uptake of N, K and Ca by Eucalyptus grandis trees (6 years of age -25 m mean height), in Brazil, as a function of soil depth, texture and water content. We injected NO ) tracers simultaneously in a solution through plastic tubes at 10, 50, 150 and 300 cm in depth in a sandy and a clayey Ferralsol soil. A complete randomized design was set up with three replicates of paired trees per injection depth and soil type. Recently expanded leaves were sampled at various times after tracer injection in the summer, and the experiment was repeated in the winter. Soil water contents were continuously monitored at the different depths in the two soils. 3. Determination of foliar Rb and Sr concentrations and 15 N atom % made it possible to estimate the relative uptake potential (RUP) of tracer injections from the four soil depths and the specific RUP (SRUP), defined as RUP, per unit of fine root length density in the corresponding soil layer. 4. The highest tracer uptake rates were found in the topsoil, but contrasting RUP distributions were observed for the three tracers. Whilst the RUP was higher for NO À 3 -15 N than for Rb + and Sr 2+ in the upper 50 cm of soil, the highest SRUP values for Sr 2+ and Rb + were found at a depth of 300 cm in the sandy soil, as well as in the clayey soil when gravitational solutions reached that depth. 5. Our results suggest that the fine roots of E. grandis trees exhibit contrasting potential uptake rates with depth depending on the nutrient. This functional specialization of roots might contribute to the high growth rates of E. grandis trees, efficiently providing the large amounts of nutrients required throughout the development of these fast-growing plantations.

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Subsoil root activity in tree-based cropping systems

Cited by 101 publications

References 30 publications

Competition with trees does not influence root characteristics of perennial grasses in semi-arid and arid savannas in South Africa

Competition with trees does not influence root characteristics of perennial grasses in semi-arid and arid savannas in South Africa

Dynamics of soil exploration by fine roots down to a depth of 10 m throughout the entire rotation in Eucalyptus grandis plantations

Functional specialization of Eucalyptus fine roots: contrasting potential uptake rates for nitrogen, potassium and calcium tracers at varying soil depths

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