Jacques Baudry

On the contribution of modelling to multifunctional agriculture: Learning from comparisons

In this paper a set of criteria is proposed for the evaluation of the potential contribution of modelling tools to strengthening the multifunctionality of agriculture. The four main areas of evaluation are (1) policy relevance, (2) the temporal resolution and scope, (3) the degree to which spatial and socio-institutional scales and heterogeneity are addressed and (4) the level of integration in the assessment of scientific dimensions and of the multiple functions of agriculture. The evaluative criteria are applied to the portfolio of modelling approaches developed and applied in a joint project of the French research institute INRA and the Dutch Wageningen University & Research Centre. The CLUE-S model focuses on prediction of changes in multifunctional land-use at regional scale, given a set of predetermined scenarios or policy variants, e.g. for ex-ante policy assessment and initiation of discussions on regional development. The two other modelling approaches are complementary and aim to address multifunctional farming activities. The Landscape IMAGES framework generates a range of static images of possible but sometimes distant futures for multifunctional farming activities in a small region or landscape. It supports the exploration of trade-offs between financial returns from agriculture, landscape quality, nature conservation and restoration, and environmental quality. Co-Viability Analysis generates trajectories of states and farming decisions fulfilling a given set of ecological and productive constraints representing a desired and sustainable future. The three modelling approaches differ in their policy relevance, in the ways that spatial and socio-institutional scales are addressed and in their degree of explicitation of interaction between the various functions of agriculture, but jointly cover most of the desired capabilities for assessment of multifunctionality. Caveats were particularly identified in the integration of the socio-institutional dimension and the related heterogeneity. Although the model portfolio did not completely satisfy the demands of the set of evaluative criteria, it is concluded that, due to their complementarities, in combination the three models could significantly contribute to further development and strengthening of multifunctionality.

Nutrient dynamics in interstitial habitats of low-order rural streams with different bedrock geology

We Studied water exchange, nutrient dynamics, and microbial activities between the Surface and interstitial habitats of six low-order streams with catchments dominated by agriculture during high and low water periods. In each stream, surface (open) water and interstitial water form downwelling and Upwelling zones were considered. Interstitial habitats of most streams acted as a sink for nitrate, but as a source for ammonium and soluble reactive phosphorus (SRP). The nitrate sink persisted in shallow sediments of downwelling zones, while the source of ammonium and SRP persisted in deeper sediments of upwelling zones, where organic matter was decomposed and microbial uptake was lower than the production of nutrients. Geology (granite versus schist substratum) was the main variable controlling the nutrient contents and the microbial activity within interstitial habitats due to varying sediment grain size and hydraulic properties. Schist streams had the finest sediment grain size and lowest hydrologic connectivity between Surface water and interstitial habitats, and had the highest potential microbial activities, especially for denitrification. Land-use of the catchments (percentage of forested area), channel morphology (river incision), and local characteristics of the benthic sediment (partial clogging) also influenced nutrient concentrations and microbial activities irrespectively of the geology of the catchment.

Crop patterns and habitat preferences of the grey partridge farmland bird

Agricultural changes such as intensification and specialization are thought to be the major source of the severe decline of farmland bird populations observed on large spatial scales and over long time spans in Europe. We studied farmers’ practices at a local level on 22 farms from the Beauce area, France, with regard to habitat preferences of grey partridge, Perdix perdix L. We focused on the study of vegetation cover because it influences grey partridge’s reproduction and survival. The results revealed a high diversity of vegetation cover over the municipal territory. This high diversity can be explained by (1) the difference in the crops cultivated by the farmers, only wheat being cultivated by all the farmers; (2) the diversity of elementary crop sequences implemented, as many as 51 having been identified; and (3) the field size, which varies from 0.5 ha to 57 ha, with 54% of fields smaller than 10 ha. Altogether, this potentially creates six different habitat types, 32% of the arable land surveyed being a likely suitable habitat for the grey partridge. We found that irrigation was the main driving factor of vegetation cover diversity. Indeed irrigation controls the farms’ crop acreage, the crop sequences and their spatial pattern and field size. Nonetheless, irrigation practices show both positive, e.g. crop diversity, and negative aspects, e.g. large fields and clutch failure, for ground-nesting birds such as the grey partridge. Based on these results, a GIS modeling of the municipal landscape related to grey partridge’s habitat requirements is possible and would allow a deeper analysis of the impact of crop diversity on grey partridge populations.

Pourquoi s'intéresser à la notion d' « evidence-based policy » ?

Evidence-based medicine” approaches began to be formalized in the early 1990s to promote a conscientious, explicit and judicious use of current best evidence in decision-making on care for individual patients. These approaches were subsequently extended to other spheres of public decision (education, justice, environment, poverty alleviation, etc.), giving birth to the concept of evidence-based policy” (EBP). In the Francophone world, with the exception of the medical sector, these approaches are not well known. This is partly a problem of translation. In French, no concept associates the idea of empirical corroboration with that of proof, unlike English where they are both encapsulated in the word evidence. The lack of familiarity with EBP also results from an intellectual tradition that is suspicious of simplistic pragmatisms in public action, which are believed to favour a principle of immediate effectiveness, regardless of the multiple dimensions of such action. The increasing use of the EBP concept is consequently often equated to mere rhetoric or to an attempt to depoliticize the debate by defending a normative model of decision-making grounded in the rational choice theory. This article presents a critical analysis of the debates on EBP. It shows how these debates argue for a renewal of positive approaches to public decision-making, primarily by proposing methods that facilitate circulation within the realm of existing knowledge, and that assess the quality of the empirical content of that knowledge. The article emphasizes the point that such debates contributes to offering an alternative to the increasing use of knowledge models based too exclusively on expert opinions or simulations that disclaim empirical validation tests. Finally, it suggests the need for more in-depth reflection on the types of evidence and the levels of proof that could support the design, implementation and evaluation of public policies, and points to some paths in that direction.

Framework and Tools for Agricultural Landscape Assessment Relating to Water Quality Protection

While many scientific studies show the influence of agricultural landscape patterns on water cycle and water quality, only a few of these have proposed scientifically based and operational methods to improve water management. Territ’eau is a framework developed to adapt agricultural landscapes to water quality protection, using components such as farmers’ fields, seminatural areas, and human infrastructures, which can act as sources, sinks, or buffers on water quality. This framework allows us to delimit active areas contributing to water quality, defined by the following three characteristics: (i) the dominant hydrological processes and their flow pathways, (ii) the characteristics of each considered pollutant, and (iii) the main landscape features. These areas are delineated by analyzing the flow connectivity from the stream to the croplands, by assessing the buffer functions of seminatural areas according to their flow pathways. Hence, this framework allows us to identify functional seminatural areas in terms of water quality and assess their limits and functions; it helps in proposing different approaches for changing agricultural landscape, acting on agricultural practices or systems, and/or conserving or rebuilding seminatural areas in controversial landscapes. Finally, it allows us to objectivize the functions of the landscape components, for adapting these components to new environmental constraints.

Monitoring effects of GM crops on butterflies: the use of multiscale approaches for general surveillance

Abstract.According to EU Directive 2001/18/EC, a general surveillance monitoring must be implemented to detect possible unexpected effects of genetically modified (GM) crops on the environment. Butterflies have been proposed to be suitable indicators for monitoring environmental changes in agricultural landscapes. Using such mobile organisms as indicators for general surveillance is a challenge as their populations vary according to many environmental factors acting at the field, landscape and regional scales. They might thus not be appropriate to detect unexpected effects of GM crops, unless the sources of variation in their populations can be identified and accounted for. In the present study we use a multiscale approach to describe the interactions between butterfly populations, the environment and farming activities. We analysed existing butterfly data from several Swiss agricultural landscapes in order to identify the sources of variation in butterfly populations and to give guidelines for the design of general surveillance protocols for butterflies.

Influence of edge effects on common vole population abundance in an agricultural landscape of eastern France

Vole demographics are often modified close to wooded environments. Population monitoring in such settings reveals substantial edge effects, although these have seldom been quantified. This study compares the abundance of common voleMicrotus arvalis (Pallas, 1778) populations at various distances from three types of wooded environment (hedgerow, copse and forest) and in two types of habitat (temporary and permanent grassland). In temporary grassland, substantial edge effects were detected along the boundaries of forests and hedgerows. At 100 m from the forest edge, voles were twice more abundant than at 50 m, four times more than at 25 m and eight times more than at 5 m. In permanent grassland, the edge effect was such that voles were practically absent up to 100 m from the forest edge. For both types of grassland, the edge effect was more pronounced for forest habitat than for hedgerows, that is, for elements with a large surface area of wooded environment. Our results suggest that landscape context may greatly affect the local abundance of voles. Given the considerable damage done byM. arvalis, the presence of wooded patches in grassland areas leads to lower vole densities in adjacent areas and this might be an alternative method to controlM. arvalis as a pest species.