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A framework for identifying plant species to be used as 'ecological engineers' for fixing soil on unstable slopes.

Ghestem M, Cao K, Ma W, Rowe N, Leclerc R, Gadenne C, Stokes A - PLoS ONE (2014)

Bottom Line: Significant differences between all factors were found, depending on species.We then combined these results with those concerning root physiological traits, which were used as a proxy for root metabolic activity.We also propose a conceptual model describing how to position plants on an unstable site, based on root system traits.

View Article: PubMed Central - PubMed

Affiliation: AgroParis Tech, UMR AMAP, Montpellier, France.

ABSTRACT
Major reforestation programs have been initiated on hillsides prone to erosion and landslides in China, but no framework exists to guide managers in the choice of plant species. We developed such a framework based on the suitability of given plant traits for fixing soil on steep slopes in western Yunnan, China. We examined the utility of 55 native and exotic species with regard to the services they provided. We then chose nine species differing in life form. Plant root system architecture, root mechanical and physiological traits were then measured at two adjacent field sites. One site was highly unstable, with severe soil slippage and erosion. The second site had been replanted 8 years previously and appeared to be physically stable. How root traits differed between sites, season, depth in soil and distance from the plant stem were determined. Root system morphology was analysed by considering architectural traits (root angle, depth, diameter and volume) both up- and downslope. Significant differences between all factors were found, depending on species. We estimated the most useful architectural and mechanical traits for physically fixing soil in place. We then combined these results with those concerning root physiological traits, which were used as a proxy for root metabolic activity. Scores were assigned to each species based on traits. No one species possessed a suite of highly desirable traits, therefore mixtures of species should be used on vulnerable slopes. We also propose a conceptual model describing how to position plants on an unstable site, based on root system traits.

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Description of the root systems of the nine studied species.Root systems of the nine species and their rooting depth (m). A. americana's root system was composed of an underground stem from which emerged thin roots; A. hispidus's root system comprised only a few thin roots emerging from the plant collar; A. codonocephala possessed a root system with long lateral roots turning downwards over time; B. championii had long and deep roots, which deviated on encountering an obstacle and which were densely branched; C. anomala possessed a tufted and shallow root system; vertical roots of F. tikoua emerged from creeping stems; J. curcas and P. stricta both possessed taproot systems, but roots of P. stricta were deeper and more densely branched; R. chinensis had a sprouting root system comprising long, deep and scarcely branched roots. Note that the scale for soil depth (y axis) differs between species for easier viewing.
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pone-0095876-g003: Description of the root systems of the nine studied species.Root systems of the nine species and their rooting depth (m). A. americana's root system was composed of an underground stem from which emerged thin roots; A. hispidus's root system comprised only a few thin roots emerging from the plant collar; A. codonocephala possessed a root system with long lateral roots turning downwards over time; B. championii had long and deep roots, which deviated on encountering an obstacle and which were densely branched; C. anomala possessed a tufted and shallow root system; vertical roots of F. tikoua emerged from creeping stems; J. curcas and P. stricta both possessed taproot systems, but roots of P. stricta were deeper and more densely branched; R. chinensis had a sprouting root system comprising long, deep and scarcely branched roots. Note that the scale for soil depth (y axis) differs between species for easier viewing.

Mentions: For each of the nine species, 12 individuals were chosen i.e. six at each site. All individuals were chosen within the same size range. Plant height and stem basal diameter were measured (Table 3), but are not indicative of age because of occasional cattle grazing. By comparing these individuals with reference plants that germinated during the 3 years we worked at the site, we estimated that the individuals we studied were 3–6 years old. Root systems were excavated by hand (Figure 3). Excavations were carried out with extreme caution, so as to not damage root systems (Table 3).


A framework for identifying plant species to be used as 'ecological engineers' for fixing soil on unstable slopes.

Ghestem M, Cao K, Ma W, Rowe N, Leclerc R, Gadenne C, Stokes A - PLoS ONE (2014)

Description of the root systems of the nine studied species.Root systems of the nine species and their rooting depth (m). A. americana's root system was composed of an underground stem from which emerged thin roots; A. hispidus's root system comprised only a few thin roots emerging from the plant collar; A. codonocephala possessed a root system with long lateral roots turning downwards over time; B. championii had long and deep roots, which deviated on encountering an obstacle and which were densely branched; C. anomala possessed a tufted and shallow root system; vertical roots of F. tikoua emerged from creeping stems; J. curcas and P. stricta both possessed taproot systems, but roots of P. stricta were deeper and more densely branched; R. chinensis had a sprouting root system comprising long, deep and scarcely branched roots. Note that the scale for soil depth (y axis) differs between species for easier viewing.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126646&req=5

pone-0095876-g003: Description of the root systems of the nine studied species.Root systems of the nine species and their rooting depth (m). A. americana's root system was composed of an underground stem from which emerged thin roots; A. hispidus's root system comprised only a few thin roots emerging from the plant collar; A. codonocephala possessed a root system with long lateral roots turning downwards over time; B. championii had long and deep roots, which deviated on encountering an obstacle and which were densely branched; C. anomala possessed a tufted and shallow root system; vertical roots of F. tikoua emerged from creeping stems; J. curcas and P. stricta both possessed taproot systems, but roots of P. stricta were deeper and more densely branched; R. chinensis had a sprouting root system comprising long, deep and scarcely branched roots. Note that the scale for soil depth (y axis) differs between species for easier viewing.
Mentions: For each of the nine species, 12 individuals were chosen i.e. six at each site. All individuals were chosen within the same size range. Plant height and stem basal diameter were measured (Table 3), but are not indicative of age because of occasional cattle grazing. By comparing these individuals with reference plants that germinated during the 3 years we worked at the site, we estimated that the individuals we studied were 3–6 years old. Root systems were excavated by hand (Figure 3). Excavations were carried out with extreme caution, so as to not damage root systems (Table 3).

Bottom Line: Significant differences between all factors were found, depending on species.We then combined these results with those concerning root physiological traits, which were used as a proxy for root metabolic activity.We also propose a conceptual model describing how to position plants on an unstable site, based on root system traits.

View Article: PubMed Central - PubMed

Affiliation: AgroParis Tech, UMR AMAP, Montpellier, France.

ABSTRACT
Major reforestation programs have been initiated on hillsides prone to erosion and landslides in China, but no framework exists to guide managers in the choice of plant species. We developed such a framework based on the suitability of given plant traits for fixing soil on steep slopes in western Yunnan, China. We examined the utility of 55 native and exotic species with regard to the services they provided. We then chose nine species differing in life form. Plant root system architecture, root mechanical and physiological traits were then measured at two adjacent field sites. One site was highly unstable, with severe soil slippage and erosion. The second site had been replanted 8 years previously and appeared to be physically stable. How root traits differed between sites, season, depth in soil and distance from the plant stem were determined. Root system morphology was analysed by considering architectural traits (root angle, depth, diameter and volume) both up- and downslope. Significant differences between all factors were found, depending on species. We estimated the most useful architectural and mechanical traits for physically fixing soil in place. We then combined these results with those concerning root physiological traits, which were used as a proxy for root metabolic activity. Scores were assigned to each species based on traits. No one species possessed a suite of highly desirable traits, therefore mixtures of species should be used on vulnerable slopes. We also propose a conceptual model describing how to position plants on an unstable site, based on root system traits.

Show MeSH
Related in: MedlinePlus