Tree Roots Anchoring and Binding Soil: Reducing Landslide Risk in Indonesian Agroforestry
Tree root systems stabilize hillslopes and riverbanks, reducing landslide risk, but related data for the humid tropics are scarce. We tested fractal allometry hypotheses on differences in the vertical and horizontal distribution of roots of trees commonly found in agroforestry systems and on shear s...
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doaj-816a9606f41d48a98e8c7e66700e96d92020-11-25T03:52:05ZengMDPI AGLand2073-445X2020-08-01925625610.3390/land9080256Tree Roots Anchoring and Binding Soil: Reducing Landslide Risk in Indonesian AgroforestryKurniatun Hairiah0Widianto Widianto1Didik Suprayogo2Meine Van Noordwijk3Faculty of Agriculture, Brawijaya University, Jl Veteran, Malang 65145, IndonesiaFaculty of Agriculture, Brawijaya University, Jl Veteran, Malang 65145, IndonesiaFaculty of Agriculture, Brawijaya University, Jl Veteran, Malang 65145, IndonesiaFaculty of Agriculture, Brawijaya University, Jl Veteran, Malang 65145, IndonesiaTree root systems stabilize hillslopes and riverbanks, reducing landslide risk, but related data for the humid tropics are scarce. We tested fractal allometry hypotheses on differences in the vertical and horizontal distribution of roots of trees commonly found in agroforestry systems and on shear strength of soil in relation to root length density in the topsoil. Proximal roots of 685 trees (55 species; 4–20 cm stem diameter at breast height, dbh) were observed across six landscapes in Indonesia. The Index of Root Anchoring (IRA) and the Index of Root Binding (IRB) were calculated as D<sub>v</sub><sup>2</sup>/dbh<sup>2</sup> and as D<sub>h</sub><sup>2</sup>/dbh<sup>2</sup>, respectively, where D<sub>v</sub> and D<sub>h</sub> are the diameters of vertical (angle >45°) and horizontal (angle <45°) proximal roots. High IRA values (>1.0) were observed in coffee and several common shade trees. Common fruit trees in coffee agroforestry had low medium values, indicating modest ‘soil anchoring’. Where root length density (L<sub>rv</sub>) in the topsoil is less than 10 km m<sup>−3</sup> shear strength largely depends on texture; for L<sub>rv</sub> > 10 shear strength was >1.5 kg m<sup>−2</sup> at the texture tested. In conclusion, a mix of tree species with deep roots and grasses with intense fine roots provides the highest hillslope and riverbank stability.https://www.mdpi.com/2073-445X/9/8/256coffeefruit treesindex of root anchoringslope stabilitysoil shear strengthroot length density |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Kurniatun Hairiah Widianto Widianto Didik Suprayogo Meine Van Noordwijk |
spellingShingle |
Kurniatun Hairiah Widianto Widianto Didik Suprayogo Meine Van Noordwijk Tree Roots Anchoring and Binding Soil: Reducing Landslide Risk in Indonesian Agroforestry Land coffee fruit trees index of root anchoring slope stability soil shear strength root length density |
author_facet |
Kurniatun Hairiah Widianto Widianto Didik Suprayogo Meine Van Noordwijk |
author_sort |
Kurniatun Hairiah |
title |
Tree Roots Anchoring and Binding Soil: Reducing Landslide Risk in Indonesian Agroforestry |
title_short |
Tree Roots Anchoring and Binding Soil: Reducing Landslide Risk in Indonesian Agroforestry |
title_full |
Tree Roots Anchoring and Binding Soil: Reducing Landslide Risk in Indonesian Agroforestry |
title_fullStr |
Tree Roots Anchoring and Binding Soil: Reducing Landslide Risk in Indonesian Agroforestry |
title_full_unstemmed |
Tree Roots Anchoring and Binding Soil: Reducing Landslide Risk in Indonesian Agroforestry |
title_sort |
tree roots anchoring and binding soil: reducing landslide risk in indonesian agroforestry |
publisher |
MDPI AG |
series |
Land |
issn |
2073-445X |
publishDate |
2020-08-01 |
description |
Tree root systems stabilize hillslopes and riverbanks, reducing landslide risk, but related data for the humid tropics are scarce. We tested fractal allometry hypotheses on differences in the vertical and horizontal distribution of roots of trees commonly found in agroforestry systems and on shear strength of soil in relation to root length density in the topsoil. Proximal roots of 685 trees (55 species; 4–20 cm stem diameter at breast height, dbh) were observed across six landscapes in Indonesia. The Index of Root Anchoring (IRA) and the Index of Root Binding (IRB) were calculated as D<sub>v</sub><sup>2</sup>/dbh<sup>2</sup> and as D<sub>h</sub><sup>2</sup>/dbh<sup>2</sup>, respectively, where D<sub>v</sub> and D<sub>h</sub> are the diameters of vertical (angle >45°) and horizontal (angle <45°) proximal roots. High IRA values (>1.0) were observed in coffee and several common shade trees. Common fruit trees in coffee agroforestry had low medium values, indicating modest ‘soil anchoring’. Where root length density (L<sub>rv</sub>) in the topsoil is less than 10 km m<sup>−3</sup> shear strength largely depends on texture; for L<sub>rv</sub> > 10 shear strength was >1.5 kg m<sup>−2</sup> at the texture tested. In conclusion, a mix of tree species with deep roots and grasses with intense fine roots provides the highest hillslope and riverbank stability. |
topic |
coffee fruit trees index of root anchoring slope stability soil shear strength root length density |
url |
https://www.mdpi.com/2073-445X/9/8/256 |
work_keys_str_mv |
AT kurniatunhairiah treerootsanchoringandbindingsoilreducinglandslideriskinindonesianagroforestry AT widiantowidianto treerootsanchoringandbindingsoilreducinglandslideriskinindonesianagroforestry AT didiksuprayogo treerootsanchoringandbindingsoilreducinglandslideriskinindonesianagroforestry AT meinevannoordwijk treerootsanchoringandbindingsoilreducinglandslideriskinindonesianagroforestry |
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