Mickovski S.B.,Jacobs Engineering |
Stokes A.,French National Institute for Agricultural Research |
van Beek R.,University Utrecht |
Ghestem M.,AgroParis Technology |
Fourcaud T.,CIRAD - Agricultural Research for Development
Ecological Engineering | Year: 2011
The finite element (FE) method has been used in recent years to simulate overturning processes in trees and to better comprehend plant anchorage mechanics. We aimed at understanding the fundamental mechanisms of root-soil reinforcement by simulating direct shear of rooted and non-rooted soil. Two- (2D) and three-dimensional (3D) FE simulations of direct shear box tests were carried out using readily available software for routine strength assessment of the root-soil composite. Both rooted and non-rooted blocks of soil were modelled using a simplified model of root distribution and root material properties representative of real roots. Linear elastic behaviour was assumed for roots and the soil was modelled as an ideally plastic medium. FE analysis showed that direct shear tests were dependent on the material properties specified for both the soil and roots. 2D and 3D simulations of direct shear of non-rooted soil produced similar results and any differences between 2D and 3D simulations could be explained with regard to the spatial complexity of roots used in the root distribution model. The application of FE methods was verified through direct shear tests on soil with analogue roots and the results compared to in situ tests on rooted soil in field conditions. © 2011 Elsevier B.V.
Ghestem M.,AgroParis Technology |
Veylon G.,IRSTEA |
Bernard A.,IRSTEA |
Vanel Q.,EPHE Paris |
Stokes A.,French National Institute for Agricultural Research
Plant and Soil | Year: 2014
Background and aims: Vegetation can be used to stabilise slopes with regard to shallow landslides, but the optimal plant architecture for conferring resistance is not known. This study aims at identifying root morphological traits which confer the most resistance to soil during shearing. Methods: Three species used for slope stabilisation (Ricinus communis L., Jatropha curcas L. and Rhus chinensis Mill.) were grown for 10 months in large shear boxes filled with silty clay similar to that found in Yunnan, China. Direct shear tests were then performed and compared to fallow soil. Root systems were excavated and a large number of traits measured. Results: Shear strength and deformation energy were enhanced by the presence of roots. Regardless of confining pressure, R. communis conferred most resistance due to its taprooted system with many vertical roots. J. curcas possessed oblique and vertical roots which created fragile zones throughout the soil profile. The least efficient root system was R. chinensis which possessed many horizontal lateral roots. Soil mechanical properties were most influenced by (i) density of roots crossing the shear plane, (ii) branching density throughout the soil profile, (iii) total length of coarse roots above the shear plane and (iv) total volume of coarse roots and fine root density below the shear plane. During failure, fine, short and branched roots slipped through soil rather than breaking. Conclusion: Root morphological traits such as density, branching, length, volume, inclination and orientation influence significantly soil mechanical properties. © 2013 Springer Science+Business Media Dordrecht.
Verrier E.,AgroParis Technology |
Verrier E.,French National Institute for Agricultural Research |
Saint-Dizier M.,AgroParis Technology |
Saint-Dizier M.,French National Institute for Agricultural Research
Productions Animales | Year: 2011
After an overview of ruminant stocks in France and the European Union, The characteristics of the species acting on the possibilities to develop breeding programs and their efficiency are shown. Emphasis is put on the impact of the efficiency of reproduction, the need for a strict organization and the diversity of cases among species, breeds, territories and market chains. The perspectives opened by the ongoing development of genomic selection are briefly evoked.
Chelle M.,French National Institute for Agricultural Research |
Liu S.,AgroParis Technology |
Mathieu A.,AgroParis Technology |
Ney B.,AgroParis Technology
Plant Growth Modeling, Simulation, Visualization and Applications, Proceedings - PMA09 | Year: 2010
Function-Structure Plant models (FSPM) seem attractive to better understand the complex interactions between plant growth, canopy morphogenesis, and epidemics. Epidemics are driven by climate factors and among them, temperature is known to play a major role. Thus, weather station measurement is commonly used to drive epidemics models. However, the relationship between climate and within-canopy microclimate is mainly affected by the canopy architecture. Thus, the general question addressed in this study is: where air temperature should be measured as input of FSPM for sick plants? © 2010 IEEE.
Ghestem M.,AgroParis Technology |
Cao K.,CAS Xishuangbanna Tropical Botanical Garden |
Cao K.,Guangxi University |
Ma W.,CAS Kunming Institute of Botany |
And 4 more authors.
PLoS ONE | Year: 2014
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. © 2014 Ghestem et al.
PubMed | Agro ParisTech, AgroParis Technology, CAS Kunming Institute of Botany, CAS Xishuangbanna Tropical Botanical Garden and 2 more.
Type: Journal Article | Journal: PloS one | Year: 2014
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.
PubMed | CNRS Physiology of Reproduction and Behaviors, French National Institute for Agricultural Research, University of Caen Lower Normandy, AgroParis Technology and 2 more.
Type: Journal Article | Journal: PloS one | Year: 2015
In stud management, broodmares are commonly fed concentrates in late pregnancy. This practice, however, was shown to correlate with an increased incidence of osteochondrosis in foals, which may be related to insulin sensitivity. We hypothesized that supplementation of the mare with barley in the last trimester of pregnancy alters the pre-weaning foal growth, glucose metabolism and osteoarticular status. Here, pregnant multiparous saddlebred mares were fed forage only (group F, n=13) or both forage and cracked barley (group B, n=12) from the 7th month of pregnancy until term, as calculated to cover nutritional needs of broodmares. Diets were given in two daily meals. All mares and foals returned to pasture after parturition. Post-natal growth, glucose metabolism and osteoarticular status were investigated in pre-weaning foals. B mares maintained an optimal body condition score (>3.5), whereas that of F mares decreased and remained low (<2.5) up to 3 months of lactation, with a significantly lower bodyweight (-7%) than B mares throughout the last 2 months of pregnancy. B mares had increased plasma glucose and insulin after the first meal and after the second meal to a lesser extent, which was not observed in F mares. B mares also had increased insulin secretion during an intravenous glucose tolerance test (IVGTT). Plasma NEFA and leptin were only temporarily affected by diet in mares during pregnancy or in early lactation. Neonatal B foals had increased serum osteocalcin and slightly increased glucose increments and clearance after glucose injection, but these effects had vanished at weaning. Body measurements, plasma IGF-1, T4, T3, NEFA and leptin concentrations, insulin secretion during IVGTT, as well as glucose metabolism rate during euglycemic hyperinsulinemic clamps after weaning, did not differ between groups. Radiographic examination of joints indicated increased osteochondrosis relative risk in B foals, but this was not significant. These data demonstrate that B or F maternal nutrition has very few effects on foal growth, endocrinology and glucose homeostasis until weaning, but may induce cartilage lesions.
See L.,International Institute For Applied Systems Analysis |
Schepaschenko D.,International Institute For Applied Systems Analysis |
Lesiv M.,Lviv Polytechnic |
Lesiv M.,Polish Academy of Sciences |
And 23 more authors.
ISPRS Journal of Photogrammetry and Remote Sensing | Year: 2015
Land cover is of fundamental importance to many environmental applications and serves as critical baseline information for many large scale models e.g. in developing future scenarios of land use and climate change. Although there is an ongoing movement towards the development of higher resolution global land cover maps, medium resolution land cover products (e.g. GLC2000 and MODIS) are still very useful for modelling and assessment purposes. However, the current land cover products are not accurate enough for many applications so we need to develop approaches that can take existing land covers maps and produce a better overall product in a hybrid approach. This paper uses geographically weighted regression (GWR) and crowdsourced validation data from Geo-Wiki to create two hybrid global land cover maps that use medium resolution land cover products as an input. Two different methods were used: (a) the GWR was used to determine the best land cover product at each location; (b) the GWR was only used to determine the best land cover at those locations where all three land cover maps disagree, using the agreement of the land cover maps to determine land cover at the other cells. The results show that the hybrid land cover map developed using the first method resulted in a lower overall disagreement than the individual global land cover maps. The hybrid map produced by the second method was also better when compared to the GLC2000 and GlobCover but worse or similar in performance to the MODIS land cover product depending upon the metrics considered. The reason for this may be due to the use of the GLC2000 in the development of GlobCover, which may have resulted in areas where both maps agree with one another but not with MODIS, and where MODIS may in fact better represent land cover in those situations. These results serve to demonstrate that spatial analysis methods can be used to improve medium resolution global land cover information with existing products. © 2014 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).
Broyde H.,AgroParis Technology |
Dore T.,Agro ParisTech
Cahiers Agricultures | Year: 2013
Fungal species belonging to the Fusarium and Aspergillus genera are the main culprits of field contamination of agricultural commodities by mycotoxins. The toxicological consequences of such contaminations are currently managed through adaptations to cropping systems. Due to large gaps in the knowledge regarding the production of mycotoxins themselves, most strategies aim at minimizing fungal infection risks. For both Fusarium and Aspergillus, cultural techniques to inhibit survival of the innoculum, such as the use of uncontaminated seeds and crop succession management, as well as crop residue treatment for Fusarium infections, are crucial action levers. For both genera, infection may be avoided by moving the crop sowing date, and a lower crop density can attenuate fungal attacks on the crop. In contrast, attenuation via management of nitrogen nutrition or water status are more complex, as different pathosystems react differently to the nutritional status of plants. Similarly, chemical protection should be considered on a case-by-case basis, as its effects on fungal communities vary. Finally, selection of mycotoxin-resistant varieties, most notably in cereals and particularly wheat, has met with higher success for Fusarium than for Aspergillus diseases. These techniques can only function as part of a coherent combination of agricultural practices, the effects of which on mycotoxin accumulation in interaction with climate effects are still poorly understood. Nevertheless, at the present level of knowledge, organic agriculture systems appear to be similarly or less affected than conventional systems.
Paradelo R.,AgroParis Technology |
Barral M.T.,University of Santiago de Compostela
Spanish Journal of Soil Science | Year: 2014
Magnetic susceptibility can be used for assessing anthropogenic pollution in solid matrices, including soils and composts. This work studies the distribution of trace elements and magnetic susceptibility in the different size fractions of six composts, for the development of measures aimed at reducing compost pollution at the production stage. The results showed that magnetic susceptibility decreased with increasing particle size in all composts, and the same was true for most trace element concentrations. Magnetic susceptibility was significantly correlated with Fe, as well as with Cu, Zn, Pb, Cr and Ni, which proves the relationship between the presence of ferric particles and trace element contamination in compost. Our results suggest that the association of trace elements and magnetic susceptibility is a characteristic feature in municipal solid waste composts. © 2014, Universia. All rights reserved.