Modelling of root reinforcement and erosion control by ‘Veronese’ poplar on pastoral hill country in New Zealand

Schwarz, Massimiliano; Phillips, Chris; Marden, Michael; McIvor, Ian; Douglas, Grant; Watson, A. J.

doi:10.1186/s40490-016-0060-4

Cited by 29 publications

(35 citation statements)

References 46 publications

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“…The authors of this work obtained, for the "Veronese" poplars with a diameter at breast height of 0.15 m at a distance of about 1 m from the trunk, the increase in shear strength of the soil by approximately 12 kPa. Taking into account that the diameter of the root collar of the studied black poplar was on average 0.09 m, it can be admitted that the obtained results do not differ much from the results of Schwarz et al [32].…”

Section: Root Cohesionsupporting

confidence: 56%

“…However, it should be emphasized that the authors conducted the research for older trees with a measurement range limited to a depth of 0.5 m and to small distances from trunks (0.25 and 0.5 m), and the obtained values of tensile strength were greater than those obtained in this work. Information on the effect of the root system of poplar plants on soil reinforcement can be found in the work of Schwarz et al [32], in which the method of estimating the value of root cohesion was the same as in the present research. The authors of this work obtained, for the "Veronese" poplars with a diameter at breast height of 0.15 m at a distance of about 1 m from the trunk, the increase in shear strength of the soil by approximately 12 kPa.…”

Section: Root Cohesionmentioning

confidence: 99%

“…On the other hand, the results of Kalliokoski et al [30] and Day et al [31] indicate that the ratio of the radial extension of the tree root system to the diameter of the root collar exceeds the value of 40, especially in the case of trees with a small value of DBH. For 1-and 2-year-old Veronese poplar seedlings, Schwarz et al [32] obtained values of the a 0 parameter in the range of 74-88. For silver birch, Norway spruce and Scots pine with a DBH diameter of about 0.08 m Kalliokoski et al [30] observed that, in extreme cases, the root system extension exceeded 5 m and was close to the height of the trees.…”

Section: Distribution Of Roots In the Soilmentioning

confidence: 99%

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Spatial Variability of Reinforcement Provided by Juvenile Root Systems of Black Locust and Black Poplar

Zydroń¹,

Gruchot²,

Kluba³

2019

Pol. J. Environ. Stud.

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The impact of tree vegetation on the subsoil is complex and its influence on slope stability can be both positive and negative. Vegetation, for life processes, needs water, which is retained during precipitation within the crown, and retrieved from soil through the root system. These processes reduce the soil moisture content and pore water pressure [1-3], and as a consequence an increase in shear strength occurs, which is beneficial from a geotechnical point of view. In an extreme case, excessive intensity of water transpiration Pol. AbstractOur work aimed to determine the spatial distribution of the root cohesion of the roots of 8-year-old black locust and black poplar trees. The scope of our research and analyses included determining characteristics of root systems of the studied tree species by profiling the walls of a trench with a width and a depth of 1.0 m at a distance of 0.5 and 1.0 m from the trunks. Laboratory tests comprised determining the tensile strength of the selected root classes. A modified Schwarz model (RDM) was used to describe the horizontal distribution of roots in the soil. The increase in shear strength of the root-reinforced soil was determined by a strain bundle model in which the value of the force mobilized by the roots is described by the Weibull survival function (RBMw). The results of the root system measurements have shown that the black locust is characterized by a greater number of roots, while the roots of black poplar are thicker, which makes the relative surface of its roots larger. Calculations of root cohesion using the modified bundle model, taking into account the root system displacement, showed that the maximum value for the black locust was 9.4 and 6.4 kPa, and for the black poplar 6.4 and 6.2 kPa respectively at a distance of 0.5 and 1.0 m from the trunk. It was also shown that the optimal spacing of the trees of these species, necessary to achieve effective reinforcement of the soil, was approximately 4 m.

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Section: Root Cohesionsupporting

confidence: 56%

Section: Root Cohesionmentioning

confidence: 99%

Section: Distribution Of Roots In the Soilmentioning

confidence: 99%

See 1 more Smart Citation

Spatial Variability of Reinforcement Provided by Juvenile Root Systems of Black Locust and Black Poplar

Zydroń¹,

Gruchot²,

Kluba³

2019

Pol. J. Environ. Stud.

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“…Worldwide, 24 billion tons of fertile soil are estimated to be lost every year due to erosion and mass wasting [1]. Vegetation, especially in the mountain regions, plays a remarkable role in stabilizing slopes and protecting soil from erosion and landslides [2,3]. Particularly for trees, roots are known to reinforce soil through three mechanisms [4][5][6][7]: basal root reinforcement, lateral root reinforcement, and increasing the stiffness of the root-soil composite material.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Characteristics of the Fine Roots of Two Broadleaved Tree Species from the Temperate Caspian Hyrcanian Ecoregion

Deljouei

Abdi

Schwarz

et al. 2020

Forests

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In view of the important role played by roots against shallow landslides, root tensile force was evaluated for two widespread temperate tree species within the Caspian Hyrcanian Ecoregion, i.e., Fagus orientalis L. and Carpinus betulus L. Fine roots (0.02 to 7.99 mm) were collected from five trees of each species at three different elevations (400, 950, and 1350 m a.s.l.), across three diameter at breast height (DBH) classes (small = 7.5–32.5 cm, medium = 32.6–57.5 cm, and large =57.6–82.5 cm), and at two slope positions relative to the tree stem (up- and down-slope). In the laboratory, maximum tensile force (N) required to break the root was determined for 2016 roots (56 roots per each of two species x three sites x three DBH classes x two slope positions). ANCOVA was used to test the effects of slope position, DBH, and study site on root tensile force. To obtain the power-law regression coefficients, a nonlinear least square method was used. We found that: 1) root tensile force strongly depends on root size, 2) F. orientalis roots are stronger than C. betulus ones in the large DBH class, although they are weaker in the medium and small DBH classes, 3) root mechanical resistance is higher upslope than downslope, 4) roots of the trees with larger DBH were the most resistant roots in tension in compare with roots of the medium or small DBH classes, and 5) the root tensile force for both species is notably different from one site to another site. Overall, our findings provide a fundamental contribution to the quantification of the protective effects of forests in the temperate region.

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“…This model contains four fitting parameters (µ, η, ψ, and γ ) that must be determined from data Schwarz et al, 2016).…”

Section: Root Density and Root-diameter Distributionmentioning

confidence: 99%

Tree-root control of shallow landslides

Cohen

Schwarz

2017

Earth Surf. Dynam.

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Abstract. Tree roots have long been recognized to increase slope stability by reinforcing the strength of soils. Slope stability models usually include the effects of roots by adding an apparent cohesion to the soil to simulate root strength. No model includes the combined effects of root distribution heterogeneity, stress-strain behavior of root reinforcement, or root strength in compression. Recent field observations, however, indicate that shallow landslide triggering mechanisms are characterized by differential deformation that indicates localized activation of zones in tension, compression, and shear in the soil. Here we describe a new model for slope stability that specifically considers these effects. The model is a strain-step discrete element model that reproduces the selforganized redistribution of forces on a slope during rainfall-triggered shallow landslides. We use a conceptual sigmoidal-shaped hillslope with a clearing in its center to explore the effects of tree size, spacing, weak zones, maximum root-size diameter, and different root strength configurations. Simulation results indicate that tree roots can stabilize slopes that would otherwise fail without them and, in general, higher root density with higher root reinforcement results in a more stable slope. The variation in root stiffness with diameter can, in some cases, invert this relationship. Root tension provides more resistance to failure than root compression but roots with both tension and compression offer the best resistance to failure. Lateral (slope-parallel) tension can be important in cases when the magnitude of this force is comparable to the slope-perpendicular tensile force. In this case, lateral forces can bring to failure tree-covered areas with high root reinforcement. Slope failure occurs when downslope soil compression reaches the soil maximum strength. When this occurs depends on the amount of root tension upslope in both the slope-perpendicular and slope-parallel directions. Roots in tension can prevent failure by reducing soil compressive forces downslope. When root reinforcement is limited, a crack parallel to the slope forms near the top of the hillslope. Simulations with roots that fail across this crack always resulted in a landslide. Slopes that did not form a crack could either fail or remain stable, depending on root reinforcement. Tree spacing is important for the location of weak zones but tree location on the slope (with respect to where a crack opens) is as important. Finally, for the specific cases tested here, intermediate-sized roots (5 to 20 mm in diameter) appear to contribute most to root reinforcement. Our results show more complex behaviors than can be obtained with the traditional slope-uniform, apparent-cohesion approach. A full understanding of the mechanisms of shallow landslide triggering requires a complete re-evaluation of this traditional approach that cannot predict where and how forces are mobilized and distributed in roots and soils, and how these control shallow landslides shape, size, loc...

show abstract

Modelling of root reinforcement and erosion control by ‘Veronese’ poplar on pastoral hill country in New Zealand

Cited by 29 publications

References 46 publications

Spatial Variability of Reinforcement Provided by Juvenile Root Systems of Black Locust and Black Poplar

Spatial Variability of Reinforcement Provided by Juvenile Root Systems of Black Locust and Black Poplar

Mechanical Characteristics of the Fine Roots of Two Broadleaved Tree Species from the Temperate Caspian Hyrcanian Ecoregion

Tree-root control of shallow landslides

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