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Sainte-Foy-lès-Lyon, France

Dufour A.,Isara Lyon | Dedieu B.,French National Institute for Agricultural Research
Cahiers Agricultures | Year: 2010

Society puts pressure on working time as does the rationalisation movement in dairy farms. Farmers need to de- and re-construct their relationships to time, work and organisation. This paper analyses the diversity of dairy farmers' conceptions of work based on 30 interviews conducted in the Segala Region, SW France, a natural area of small and medium-sized family dairy units. Farmers describe diversified conceptions which combine the standardisation of livestock farming norms at various levels, clearly influenced by industrial production, as well as societal norms based on a well-controlled working time management and the breeders' passion for their work and their animals. Three conceptions are highlighted: "creative and impassionate," whose principal characteristic is a continuous learning process, "mastered and efficient" and a "difficult" approach which differs from the other two in that it reflects work as an inflicted activity. The organisational modes which are related to these approaches are described in this paper: technical models, equipment, labour division. This variety of conceptions leads us to examine the role and working methods of experts and advisors as changes are under way. Source

Stokes A.,French National Institute for Agricultural Research | Mine F.-X.,Isara Lyon | Mao Z.,French National Institute for Agricultural Research | Brancheriau L.,CIRAD - Agricultural Research for Development
Journal of Vegetation Science | Year: 2012

Question: Many woody plants persist in a temporal 'persistence' niche, through resprouting after disturbance events. Will multi-stemming (as a consequence of resprouting or life form) and biomechanical traits enable certain species to survive disturbance and occupy a persistence niche? Location: A 1200-m long avalanche corridor in the French Alps, with disturbance events ca. every 2 yr. Methods: We measured tree/shrub size and multi-stemming in transects along and around the avalanche corridor. The mechanical traits, wood density, modulus of elasticity (E d), bending strength (σ) and stiffness (EI), along stems of several subalpine tree/shrub species were measured to test for differences in flexibility and strength. Results: The multi-stemmed pioneer shrubs Alnus viridis, Salix appendiculata and to a lesser extent, Corylus avellana, were more abundant where disturbance was most severe. Multi-stemming broadleaf species, in particular Fagus sylvatica, had more tapered, shorter and more numerous stems in severely disturbed zones. Single-stemmed conifers were usually found furthest from the avalanche track. A. viridis, codominant at the centre of the track, had the lowest E d, σ and EI. In A. viridis, Alnus incana, F. sylvatica and Betula pendula, E d was lower at the stem base and increased with height up the stem. Alnus viridis and C. avellana stems were most flexible (low EI), whereas single-stem tree forms, Picea abies and B. pendula, were stiffest. Corylus avellana had the highest σ and lowest wood mechanical construction cost (ρ) per unit function (E d), whereas P. abies had highest construction cost. Conclusions: High flexibility of A. viridis, and to a lesser extent C. avellana and the multi-stemmed form of F. sylvatica, allows individuals to bend during snow loading, before an avalanche; therefore, stem damage and uprooting during an avalanche are minimized. Increased stem basal flexibility in these species will also facilitate bending during snow loading. More rigid distal sections will confer extra mechanical advantage to stems that need to grow quickly upwards, dominate and maintain their position in the canopy during the growing season. © 2011 International Association for Vegetation Science. Source

Ripoche A.,Montpellier SupAgro | Celette F.,Isara Lyon | Cinna J.-P.,French National Institute for Agricultural Research | Gary C.,Montpellier SupAgro
European Journal of Agronomy | Year: 2010

Designing intercrop management plans (IMP) to meet objectives related to both crop production and environmental impacts is a challenge for farmers. A multiple criteria decision analysis is thus needed to evaluate and rate various cropping systems in different soil and climate conditions. Different intercrop management plans in vineyards were analysed in this study so as to classify them in relation to their ability to fulfil a particular set of objectives and to deal with climatic variability. The method included five steps. A set of intercrop management plans was defined by combining the type of grass, the covered soil surface ratio, and the intercropping duration. Four evaluation criteria were chosen: grapevine vegetative development, yield, product quality and runoff. Corresponding indicators were identified and the range of values that would be desirable or not were defined. A water balance model designed for row crops was run to simulate the behaviour of the grapevine-intercrop-soil system under different management plans and at various soil depths. The model was used to calculate, for each management plan and soil depth, the four indicators and evaluate the overall agreement and discordance with various weights assigned to the four criteria. A frequency analysis on 30 years of weather data was carried out to estimate the robustness of the most satisfactory intercrop management plans. The most satisfactory intercrop management plans differed according to the priority given to managing production or reducing environmental impacts and depended on the soil depth. This confirms the conclusions drawn on the basis of various experiments assessing a limited range of intercropping policies. Overall, giving priority to the environmental criterion was favourable for cropping systems with a long intercrop period regardless of the soil type. Few management plans were suitable for all years. The observed yearly rainfall varied from 330 to 1200 mm during the 1975-2003 period, which generated marked variations in the water balance of the grapevine-intercrop-soil system. The lack of robustness of the explored intercrop management plans could be a consequence of the poor description of the management plans due to the limited combinations of technical options considered. Strategic or tactical adjustments could be introduced by farmers. We assume that more robust intercrop management plans could be developed by introducing such rules in a decision model combined with the present biophysical model. © 2009 Elsevier B.V. All rights reserved. Source

Arthaud F.,CNRS Ecology of Natural and Anthropized Hydrosystems Laboratory | Mousset M.,CNRS Ecology of Natural and Anthropized Hydrosystems Laboratory | Vallod D.,CNRS Ecology of Natural and Anthropized Hydrosystems Laboratory | Robin J.,CNRS Ecology of Natural and Anthropized Hydrosystems Laboratory | And 2 more authors.
Freshwater Biology | Year: 2012

The way light stress controls the recruitment of aquatic plants (phanerogams and charophytes) is a key process controlling plant biodiversity, although still poorly understood. Our aim was to investigate how light stress induced by phytoplankton, that is, independent from the aquatic plants themselves, determines the recruitment and establishment of plant species from the propagule bank. The hypotheses were that an increase in light stress (i) decreases abundance and species richness both of established aquatic plants and of propagules in the bank and (ii) decreases the recruitment success of plants from this bank. These hypotheses were tested in 25 shallow lakes representing a light stress gradient, by sampling propagule banks before the recruitment phase and when the lakes are devoid of actively growing plants (i.e. at the end of winter), established vegetation at the beginning of the summer and phytoplankton biomass (chlorophyll a) during the recruitment and establishment phase. The phytoplankton biomass was negatively correlated with the richness and abundance of established vegetation but was not correlated with the propagule bank (neither species richness nor propagule abundance). The similarity between the propagule bank and established vegetation decreased significantly with increasing phytoplankton biomass. The contrast in species composition between the vegetation and the propagule bank at the highest light stress suggests poor recruitment from the propagule bank but prompts questions about its origin. It could result from dispersal of propagules from neighbouring systems. Propagules could also originate from a persistent propagule bank formerly produced in the lake, suggesting strong year-to-year variation in light stress and, as a consequence, in recruitment and reproductive success of plants. © 2012 Blackwell Publishing Ltd. Source

Arthaud F.,University Claude Bernard Lyon 1 | Vallod D.,University Claude Bernard Lyon 1 | Robin J.,University Claude Bernard Lyon 1 | Wezel A.,Isara Lyon | Bornette G.,University Claude Bernard Lyon 1
Journal of Vegetation Science | Year: 2013

Questions: The highest species richness is usually expected at an intermediate stage of development since the last major disturbance event, but some studies have shown that ecosystem productivity and dispersal may modify this pattern, suggesting the need for further studies on the effects of productivity and dispersal on the dynamics of species richness through succession. In this study, we analysed aquatic plant species richness in relation to (1) succession stage, measured as numbers of years since the last disturbance that affected the ecosystems; (2) lake productivity, measured as the chlorophyll a concentration; and (3) connectivity to similar nearby ecosystems, a proxy for the potential input of diaspores. Location: Shallow lakes of the Dombes region, France. Methods: Every 5-7 yr these shallow lakes are emptied and left to dry out for 1 yr. These drought disturbances lead to complete destruction of the submerged aquatic plant communities. Sixty lakes arranged along a gradient of productivity were selected. The probability of diaspore input was considered to increase from upstream to downstream, as lakes are organized in hydrologically connected networks via ditches, through which the downstream lakes receive water from the upstream lakes. For each lake, the aquatic plant species richness (from systematic summer vegetation sampling), time since the last disturbance (last summer drying), productivity (estimated as chlorophyll a concentration) and probability of diaspore input (assessed from position in the network) were recorded. Results: The aquatic plant species richness decreased with the time since the last disturbance for all of the lakes, but there was a significant interaction with the chlorophyll a concentration and position of the lake in the network. At the lowest ecosystem productivities, the relationship between successional stage and species richness was hump-shaped, whereas the species richness decreased with increasing time since the last disturbance when productivity increased. The lake's position in the network did not influence species richness during the first 2 yr after disturbance, but from year 3 and thereafter, lakes connected to high numbers of upstream lakes consistently exhibited decreased richness, contradicting the expected trend of increasing species richness with increasing diaspore inputs. Conclusions: This study indicates that both ecosystem productivity and connectivity strongly affected the relationship between aquatic plant species richness and succession, and that these factors should be taken into account in further developments of the intermediate disturbance hypothesis. In this study, we analysed the effect of the lake productivity and the lake connectivity on the relationship between aquatic plant species richness and the succession stage. These factors affected the dynamics of species richness through succession and they should be taken into account in further developments of the intermediate disturbance hypothesis. © 2012 International Association for Vegetation Science. Source

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