The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Sandrine Petit - One of the best experts on this subject based on the ideXlab platform.
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Crop type and within-Field location as sources of intraspecific variations in the phenology and the production of floral and fruit resources by weeds
Agriculture Ecosystems & Environment, 2020Co-Authors: Séverin Yvoz, Stéphane Cordeau, Camille Zuccolo, Sandrine PetitAbstract:In arable farming, weeds provide important floral and seed resources that have the potential to support the provision of ecosystem services such as pollination or pest control. Estimating the production of these weed resources in the landscape is however not trivial as large-scale surveys of weed communities are usually con- ducted once in the season with a timing that may not coincide with the flowering and fruiting stages of all weed species. More, intraspecific variation in the mortality and phenology of individual weed species may arise from differences in the quality of the growing environment of each plant. In this study, we monitored the phenology of 30 common weed species in the Field Core and the Field edge of 64 commercial Fields grown with 6 crop types. Our hypothesis was that the production of resources by an individual plant would be modulated by its within- Field location and by the crop type where it grows. We quantified floral (proportion, starting date and duration of flowering, dry biomass at flowering as a proxy for the amount of flowers) and seed resource production (pro- portion and starting date of fruiting). For most species, flowering and fruiting success were higher in Field edges than in Field Cores and were lower in cereal crops than in other crops. Weeds flowered and fruited earlier and the flowering period was longer in Field edges, except those of cereal crops. Dry biomass at flowering varied with Field location either way, depending on the weed species, but tended to be lower in cereal crops than in other crops. This important intraspecific phenological variability in the production of seed and/or flower or resources should be considered when evaluating the contribution of weed communities to ecosystem services. It also suggests that within an agricultural landscape, the amount, timing and duration of provision of services by weeds could be enhanced by maintaining sufficient lengths of Field edges and by growing a diversity of crop types.
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The impact of sown grass strips on the spatial distribution of weed species in adjacent boundaries and arable Fields
Agriculture Ecosystems and Environment, 2012Co-Authors: Stéphane Cordeau, Sandrine Petit, Xavier Reboud, Bruno ChauvelAbstract:Surveys were performed along paired transects running from the boundary to the Field Core and with and without sown grass strips. Their presence affected weed assemblages in the boundaries and over the first metre of the Field margins as well as the patterns of weed species distribution. Sown grass strip effect always significantly explained the weed species assemblage in boundaries (23.6%), crop edges (28.4%) and Field margins (8.1%) but not in Field Cores. Sown grass strips enlarged the habitat of boundary species (Plantago lanceolata, Arrhenatherum elatius, Carex sp.). They limited the spread of some species into the Field (e.g. Sonchus asper, Anagallis arvensis). Some species were favoured by the establishment of sown grass strips (e.g. Cirsium arvense, Bromus sp., Elytrigia repens). However, sown grass strips acted as a buffer zone for arable species (Alopecurus myosuroides, Viola tricolor, Capsella bursa-pastoris), preventing them to extend their habitat from the Fields to the boundaries. With short-term consideration, the establishment of sown grass strips puts areas of arable land aside, but offers an opportunity for many plant species to enlarge their habitat without increasing weediness
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Arable weed decline in Northern France: Crop edges as refugia for weed conservation?
Biological Conservation, 2009Co-Authors: Guillaume Fried, Sandrine Petit, Fabrice Dessaint, Xavier ReboudAbstract:Abstract The maintenance of biodiversity in agro-ecosystems is often viewed as an insurance against an uncertain future, yet, there is increasing evidence of biodiversity loss in agricultural landscapes. Here, we examined long term trends in the arable weed flora of North-East France by revisiting 158 arable Fields initially surveyed in the 1970s. We assessed changes in species richness, density and frequency of occurrence in weed communities as well as for subgroups that are recognised for their conservation value. We also evaluated the importance of crop edges as potential refugia for the threatened arable weeds. Among the 121 species recorded in both surveys, 40% had significantly declined in frequency while 10% had significantly increased. At the Field level, we recorded a 42% decline in species richness and a 67% decline in species density. Trends were comparable for weed species of particular conservation value. In the 2000s survey, crop edges harboured levels of weed diversity that were intermediate between those found in Field Cores in the 1970s and in the 2000s survey. Our results indicated that many species of conservation value had disappeared or seriously decreased in the Field Core but still persisted in the crop edge. The consequences of this general decline and possible conservation options are discussed in the light of the results.
Stéphane Cordeau - One of the best experts on this subject based on the ideXlab platform.
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Crop type and within-Field location as sources of intraspecific variations in the phenology and the production of floral and fruit resources by weeds
Agriculture Ecosystems & Environment, 2020Co-Authors: Séverin Yvoz, Stéphane Cordeau, Camille Zuccolo, Sandrine PetitAbstract:In arable farming, weeds provide important floral and seed resources that have the potential to support the provision of ecosystem services such as pollination or pest control. Estimating the production of these weed resources in the landscape is however not trivial as large-scale surveys of weed communities are usually con- ducted once in the season with a timing that may not coincide with the flowering and fruiting stages of all weed species. More, intraspecific variation in the mortality and phenology of individual weed species may arise from differences in the quality of the growing environment of each plant. In this study, we monitored the phenology of 30 common weed species in the Field Core and the Field edge of 64 commercial Fields grown with 6 crop types. Our hypothesis was that the production of resources by an individual plant would be modulated by its within- Field location and by the crop type where it grows. We quantified floral (proportion, starting date and duration of flowering, dry biomass at flowering as a proxy for the amount of flowers) and seed resource production (pro- portion and starting date of fruiting). For most species, flowering and fruiting success were higher in Field edges than in Field Cores and were lower in cereal crops than in other crops. Weeds flowered and fruited earlier and the flowering period was longer in Field edges, except those of cereal crops. Dry biomass at flowering varied with Field location either way, depending on the weed species, but tended to be lower in cereal crops than in other crops. This important intraspecific phenological variability in the production of seed and/or flower or resources should be considered when evaluating the contribution of weed communities to ecosystem services. It also suggests that within an agricultural landscape, the amount, timing and duration of provision of services by weeds could be enhanced by maintaining sufficient lengths of Field edges and by growing a diversity of crop types.
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Field margin grass strips: opportunity or threat for the weed management in arable landscapes?
Agricultural Research and Technology, 2017Co-Authors: Stéphane CordeauAbstract:Sown grass strips could be an opportunity (refuge) or a threat (source of crop infestation) for weed management in arable landscapes. Firstly, our Field surveys recorded 187 weed species, among which 90% were arable species, mostly perennial and wind dispersing species, here mostly represented by the Asteraceae family. Even if sown grass strips harboured a high richness of unsown species (26 weed species/grass strip), the richness did not vary according to the time since establishment. Weed community composition drastically changed over time, with a quick shift (within the 2 first years) from annual to perennial species, and from common agricultural weeds to non-arable species. Secondly, flora surveys performed with continuous transects from the Field margin to the Field centre showed clear plant spatial patterns. The sown grass strips acted as an ecotone with a sharp vegetation transition. Weeds occurring within the centre of the sown grass strips radically differed from species occurring within the first 0.5m of the cultivated area (only 15% of similarity between communities occuring in both habitats). Moreover, classical Field margins influenced the weed composition up to 4.5m in the Field whereas sown grass strips influenced the weed composition only up to 2m. We concluded that sown grass strips could be an opportunity to maintain plant diversity at the landscape scale and to decrease weed dispersion from the Field margin to the Field Core in the short term. However, we discussed the long term impacts, especially to maintaining high level of annual species and segetal species in these perennial semi-natural habitats.
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The impact of sown grass strips on the spatial distribution of weed species in adjacent boundaries and arable Fields
Agriculture Ecosystems and Environment, 2012Co-Authors: Stéphane Cordeau, Sandrine Petit, Xavier Reboud, Bruno ChauvelAbstract:Surveys were performed along paired transects running from the boundary to the Field Core and with and without sown grass strips. Their presence affected weed assemblages in the boundaries and over the first metre of the Field margins as well as the patterns of weed species distribution. Sown grass strip effect always significantly explained the weed species assemblage in boundaries (23.6%), crop edges (28.4%) and Field margins (8.1%) but not in Field Cores. Sown grass strips enlarged the habitat of boundary species (Plantago lanceolata, Arrhenatherum elatius, Carex sp.). They limited the spread of some species into the Field (e.g. Sonchus asper, Anagallis arvensis). Some species were favoured by the establishment of sown grass strips (e.g. Cirsium arvense, Bromus sp., Elytrigia repens). However, sown grass strips acted as a buffer zone for arable species (Alopecurus myosuroides, Viola tricolor, Capsella bursa-pastoris), preventing them to extend their habitat from the Fields to the boundaries. With short-term consideration, the establishment of sown grass strips puts areas of arable land aside, but offers an opportunity for many plant species to enlarge their habitat without increasing weediness
Sabrina Gaba - One of the best experts on this subject based on the ideXlab platform.
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Weed diversity is driven by complex interplay between multi-scale dispersal and local filtering
Proceedings of the Royal Society B: Biological Sciences, 2020Co-Authors: Bérenger Bourgeois, Sabrina Gaba, Christine Plumejeaud, Vincent BretagnolleAbstract:Arable weeds are key organisms for biodiversity maintenance and ecosystem service provision in agroecosystems. Disentangling the drivers of weed diversity is critical to counteract the global decline of farmland biodiversity. Even if distinct scale-dependent processes were alternatively proposed, no general framework unifying the multi-scale drivers of weed dynamics has yet emerged. Here, we investigate the joint effects of Field- and landscape-scale processes on weed assemblages in 444 arable Fields. First, Field margins sheltered greater weed diversity than Field Core, evidencing their role as biodiversity refugia. Second, community similarity between Field Core and margin decreased with the distance to margin, highlighting a major role of local dispersal. Third, weed diversity at Field margins increased with organic Field cover in the landscape, pointing out massive regional dispersal. Fourth, while both local and landscape dispersal explained up to 41% of Field Core weed diversity, crop type strongly modulated their strength, depicting an intense filtering effect by agricultural management. This study sheds new light on the complex multi-scale interactions shaping weed diversity, Field margins playing a key role by strengthening regional dispersal and sustaining local dispersal. Land-sharing strategies improving habitat heterogeneity both locally and regionally should largely promote agroecosystem multifunctionality and sustainability.
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Ecological mechanisms shaping weed assembly in intensive farmland landscapes
2017Co-Authors: Bérenger Bourgeois, Sabrina Gaba, Christine Plumejeaud, Vincent BretagnolleAbstract:The ecological mechanisms shaping plants assemblages are multiple and scale-dependent. While the differentiation of resource patches may govern assembly rules at intermediate scales, the role dispersal processes is expected to decrease and the one of species interaction to increase from large to fine spatial scale. In this study, we investigate the contribution of these three processes to weed assembly based on a hierarchical sampling design conducted in 454 arable Fields of the LTSER Zone Atelier ‘Plaine & Val de Sèvre’ from 2014 to 2016 . Using multiplicative diversity partitioning, the total Field weed diversity was decomposed into four metrics, corresponding to differences in species richness between sampling scales (subplots, plots, Field Core-margin) and mean subplot richness. Between-plot difference in species richness was the main component of weed diversity, but its contribution decreased when the total Field weed diversity increased while between-subplot difference in species richness and mean subplot richness increased. Even if plots within Field Core corresponded to similar resources patches (according to Ellenberg indices), we showed that the dispersion of plant height within subplots increased with the total Field diversity. Furthermore, Field Core weed richness strongly increased with the richness of Field margin, and to a lesser extent with the cover of organic Fields within 1000m. All together, these results demonstrate that the increase of Field weed diversity is related to small-scale (i.e. subplot) community diversification due mainly to niche-partitioning and short-distance dispersal from margin, and provide new insights on the assembly rules of weed communities.
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Ecological mechanisms shaping weed assembly in intensive farmland landscapes
2017Co-Authors: Bérenger Bourgeois, Sabrina Gaba, Christine Plumejeaud, Vincent BretagnolleAbstract:The ecological mechanisms shaping plants assemblages are multiple and scale-dependent. While the differentiation of resource patches may govern assembly rules at intermediate scales, the role dispersal processes is expected to decrease and the one of species interaction to increase from large to fine spatial scale. In this study, we investigate the contribution of these three processes to weed assembly based on a hierarchical sampling design conducted in 454 arable Fields of the LTSER Zone Atelier ‘Plaine & Val de Sevre’ from 2014 to 2016 . Using multiplicative diversity partitioning, the total Field weed diversity was decomposed into four metrics, corresponding to differences in species richness between sampling scales (subplots, plots, Field Core-margin) and mean subplot richness. Between-plot difference in species richness was the main component of weed diversity, but its contribution decreased when the total Field weed diversity increased while between-subplot difference in species richness and mean subplot richness increased. Even if plots within Field Core corresponded to similar resources patches (according to Ellenberg indices), we showed that the dispersion of plant height within subplots increased with the total Field diversity. Furthermore, Field Core weed richness strongly increased with the richness of Field margin, and to a lesser extent with the cover of organic Fields within 1000m. All together, these results demonstrate that the increase of Field weed diversity is related to small-scale (i.e. subplot) community diversification due mainly to niche-partitioning and short-distance dispersal from margin, and provide new insights on the assembly rules of weed communities.
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The interspecific and intraspecific variation of functional traits in weeds: diversified ecological strategies within arable Fields
Acta Botanica Gallica, 2014Co-Authors: Rémi Perronne, Sabrina Gaba, Emilie Cadet, Valérie Le CorreAbstract:AbstractArable weeds are a key component of the biodiversity of agroecosystems, but have faced a marked decline due to agricultural intensification. Recently, the crop edge has been considered as a potential refugia for many species. Indeed, weed species richness and abundance are higher in the crop edge than in the Field margin and the Field Core. In this study we question whether weed functional diversity also varies among Field elements and whether it is higher in the crop edge. We studied the interspecific and intraspecific variation of three functional traits (specific leaf area, canopy height and above-ground biomass) related to the response of weeds to competition and to agricultural practices, for seven weed species sampled in the crop edge, the Field margin and the Field Core area in four winter-wheat Fields. We show that trait values varied significantly with the species, the Field element and their interaction. Within the Field, all species had high specific leaf area, low canopy height and bio...
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The interspecific and intraspecific variation of functional traits in weeds: diversified ecological strategies within arable Fields
Acta Botanica Gallica, 2014Co-Authors: Rémi Perrone, Sabrina Gaba, Emilie Cadet, Valérie Le CorreAbstract:Arable weeds are a key component of the biodiversity of agroecosystems, but have faced a marked decline due to agricultural intensification. Recently, the crop edge has been considered as a potential refugia for many species. Indeed, weed species richness and abundance are higher in the crop edge than in the Field margin and the Field Core. In this study we question whether weed functional diversity also varies among Field elements and whether it is higher in the crop edge. We studied the interspecific and intraspecific variation of three functional traits (specific leaf area, canopy height and above-ground biomass) related to the response of weeds to competition and to agricultural practices, for seven weed species sampled in the crop edge, the Field margin and the Field Core area in four winter-wheat Fields. We show that trait values varied significantly with the species, the Field element and their interaction. Within the Field, all species had high specific leaf area, low canopy height and biomass, suggesting a shade-tolerance syndrome that could be a strategy in response to both competition with the crop and the disturbances induced by agricultural practices. In the crop edge, where the functional variation was the highest, two distinct functional strategies were observed, suggesting a resource partitioning under the predominance of weed-weed competition. In conclusion, the crop edge plays a key role in sustaining weed diversity, mostly because of its intermediate environmental properties that allow the coexistence of weeds with different ecological strategies.
T L Walzak - One of the best experts on this subject based on the ideXlab platform.
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Effects of moisture on surface chemistry of steel slags and steel slag-asphalt paving mixes
Transportation Research Record, 1995Co-Authors: A Coomarasamy, T L WalzakAbstract:Random cracking and premature failure have been observed in some steel slag-asphalt pavements in Ontario. The causes of the failure were investigated. Surface chemistry and morphology of steel slags and asphalt mixes and the effect of moisture on these characteristics were studied using scanning electron microscopy, scanning electron microscopy coupled with energy-dispersive x-ray analysis, and optical microscopy. X-ray diffraction and electron microprobe analysis were used for mineralogical studies. Experiments were also performed to determine moisture uptake and volume expansivity of steel slags and steel slag-asphalt mixes. Basic oxygen furnace slags and an electric arc furnace slag were used in this investigation, and asphalt mixes were prepared from some samples. The results indicate that failure in steel slag-asphalt mixes in moist environments is due to the formation of calcium-rich deposits, mainly calcium carbonate, along the surface and the interface. This affects interfacial bonding and can cause excessive expansion of the slag leading to cracking of the mixture. This reactivity was also observed in Field Core samples, even after several years of service. The mineralogical data showed that the distribution and microstructure of the two main phases (an iron oxide-rich mixed oxide phase and a calcium silicate phase in steel slags) were different among the slags examined. The calcium silicate phase appears to be one of the sources responsible for the reactivity of steel slags in moist environments.
Vincent Bretagnolle - One of the best experts on this subject based on the ideXlab platform.
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Weed diversity is driven by complex interplay between multi-scale dispersal and local filtering
Proceedings of the Royal Society B: Biological Sciences, 2020Co-Authors: Bérenger Bourgeois, Sabrina Gaba, Christine Plumejeaud, Vincent BretagnolleAbstract:Arable weeds are key organisms for biodiversity maintenance and ecosystem service provision in agroecosystems. Disentangling the drivers of weed diversity is critical to counteract the global decline of farmland biodiversity. Even if distinct scale-dependent processes were alternatively proposed, no general framework unifying the multi-scale drivers of weed dynamics has yet emerged. Here, we investigate the joint effects of Field- and landscape-scale processes on weed assemblages in 444 arable Fields. First, Field margins sheltered greater weed diversity than Field Core, evidencing their role as biodiversity refugia. Second, community similarity between Field Core and margin decreased with the distance to margin, highlighting a major role of local dispersal. Third, weed diversity at Field margins increased with organic Field cover in the landscape, pointing out massive regional dispersal. Fourth, while both local and landscape dispersal explained up to 41% of Field Core weed diversity, crop type strongly modulated their strength, depicting an intense filtering effect by agricultural management. This study sheds new light on the complex multi-scale interactions shaping weed diversity, Field margins playing a key role by strengthening regional dispersal and sustaining local dispersal. Land-sharing strategies improving habitat heterogeneity both locally and regionally should largely promote agroecosystem multifunctionality and sustainability.
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Ecological mechanisms shaping weed assembly in intensive farmland landscapes
2017Co-Authors: Bérenger Bourgeois, Sabrina Gaba, Christine Plumejeaud, Vincent BretagnolleAbstract:The ecological mechanisms shaping plants assemblages are multiple and scale-dependent. While the differentiation of resource patches may govern assembly rules at intermediate scales, the role dispersal processes is expected to decrease and the one of species interaction to increase from large to fine spatial scale. In this study, we investigate the contribution of these three processes to weed assembly based on a hierarchical sampling design conducted in 454 arable Fields of the LTSER Zone Atelier ‘Plaine & Val de Sèvre’ from 2014 to 2016 . Using multiplicative diversity partitioning, the total Field weed diversity was decomposed into four metrics, corresponding to differences in species richness between sampling scales (subplots, plots, Field Core-margin) and mean subplot richness. Between-plot difference in species richness was the main component of weed diversity, but its contribution decreased when the total Field weed diversity increased while between-subplot difference in species richness and mean subplot richness increased. Even if plots within Field Core corresponded to similar resources patches (according to Ellenberg indices), we showed that the dispersion of plant height within subplots increased with the total Field diversity. Furthermore, Field Core weed richness strongly increased with the richness of Field margin, and to a lesser extent with the cover of organic Fields within 1000m. All together, these results demonstrate that the increase of Field weed diversity is related to small-scale (i.e. subplot) community diversification due mainly to niche-partitioning and short-distance dispersal from margin, and provide new insights on the assembly rules of weed communities.
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Ecological mechanisms shaping weed assembly in intensive farmland landscapes
2017Co-Authors: Bérenger Bourgeois, Sabrina Gaba, Christine Plumejeaud, Vincent BretagnolleAbstract:The ecological mechanisms shaping plants assemblages are multiple and scale-dependent. While the differentiation of resource patches may govern assembly rules at intermediate scales, the role dispersal processes is expected to decrease and the one of species interaction to increase from large to fine spatial scale. In this study, we investigate the contribution of these three processes to weed assembly based on a hierarchical sampling design conducted in 454 arable Fields of the LTSER Zone Atelier ‘Plaine & Val de Sevre’ from 2014 to 2016 . Using multiplicative diversity partitioning, the total Field weed diversity was decomposed into four metrics, corresponding to differences in species richness between sampling scales (subplots, plots, Field Core-margin) and mean subplot richness. Between-plot difference in species richness was the main component of weed diversity, but its contribution decreased when the total Field weed diversity increased while between-subplot difference in species richness and mean subplot richness increased. Even if plots within Field Core corresponded to similar resources patches (according to Ellenberg indices), we showed that the dispersion of plant height within subplots increased with the total Field diversity. Furthermore, Field Core weed richness strongly increased with the richness of Field margin, and to a lesser extent with the cover of organic Fields within 1000m. All together, these results demonstrate that the increase of Field weed diversity is related to small-scale (i.e. subplot) community diversification due mainly to niche-partitioning and short-distance dispersal from margin, and provide new insights on the assembly rules of weed communities.