Danièle Magda

THE EVOLVING GENETIC HISTORY OF A POPULATION OF LATHYRUS SYLVESTRIS : EVIDENCE FROM TEMPORAL AND SPATIAL GENETIC STRUCTURE

We analyze patterns of genetic microdifferentiation within a natural population of Lathyrus sylvestris, a perennial herb with both sexual reproduction and clonal growth. In a population from the northern foothills of the Pyrénées in southwestern France, a combined demographic and genetic investigation enabled the study not only of spatial genetic structure of the population, but also of the history of the populations spatial genetic structure over time. Excavation of all individuals allowed identification of clonemates. Age of each individual was determined by counting annual growth rings in the taproot, a method tested with individuals of known age planted in experimental gardens. Each individual was mapped, and genotypes of all individuals were determined using allozyme markers for a number of polymorphic loci. Distribution patterns and spatial genetic structure, both for all individuals and for different age classes, were analyzed using spatial autocorrelation statistics (Gearys Index, Morans Index). Patterns of gene flow within the population were also studied using F‐statistics and tests for random associations of alleles. Because age, allele frequencies, and location were known for each individual, it was possible to study how spatial genetic structure changed over time. Results from all these diverse approaches are consistent with one another, and clearly show the following: (1) founder effects, with the study transect being first colonized by individuals at either end of the transect that were homozygous for different alleles at one marker locus; (2) a difference in spatial distribution of individuals originated from sexual reproduction (seedlings) and from clonal growth (connected individuals); (3) restricted gene flow, due to inbreeding among related, clumped individuals; and (4) increase in heterozygote deficit within the youngest cohort of individuals. The results indicate that genetic differentiation in time was much less marked than differentiation in space. Nevertheless, the results revealed that the studied population is experiencing demographic and genetic variation in time, suggesting that it is not at equilibrium. On the one hand, spatial structuring is becoming less marked due to the recombination of founder genotypes; on the other hand, as establishment of new individuals increases, a new spatial structure emerges due to mating between relatives.

Categorising farming practices to design sustainable land-use management in mountain areas

In European mountain areas, shrub encroachment resulting from farmland abandonment is most often managed by mechanical operations such as roller chopping or controlled burning, which have proved to be ineffective and unsustainable. Recent agroecological findings highlight the potential impact of grazing on long-term shrub dynamics. We thus explored the potential contribution of livestock farms to the management of shrub encroachment. We studied the diversity of livestock practices and strategies on the scale of a small mountain valley in France where a land-use management plan was initiated. We interviewed 33 livestock farmers with a comprehensive approach and analysed the data in partnership with local land-use managers. To categorise farming practices, we used an innovative constructivist method based on knowledge engineering techniques and tools such as repertory grids. Our results show that the diversity of land-use practices can be summed up by ten practices related to three management domains: (i) livestock management, that is, splitting herds into batches, leading animals to pasture and breeding choices; (ii) the feeding system, including indoor feeding during the year, the hierarchy between haymaking and grazing in spring and the system’s forage autonomy; and (iii) farmland utilisation and maintenance, which comprises hillside use, spatial configuration of grazed areas, maintenance practices and technical choices to cut meadows. We also show that farmers combine these practices within six types of strategies: ensuring feeding security and simplifying labour (type A), maintaining farmland heritage (type B), taking advantage of hillsides (type C), focusing on animal care (type D), combining areas, periods and batches (type E), or selling on local markets (type F). This makes it possible to identify: (1) farmers’ strategies that have the greatest impact on shrub encroachment; and (2) practices that may develop into more sustainable management of shrub encroachment. Our work is thus a first step in developing sustainable land-use management plans in rural areas threatened by shrub encroachment. In return, this deep understanding of farmers’ strategies allowed us to address socially pertinent scientific issues related to the dynamics of grazed plant communities.

Defining management rules for grasslands using weed demographic characteristics

Abstract The study objective was to use demographic information to adjust forage production practices to control the invasive weeds golden chervil and yellow-rattle without herbicides by defining the population dynamics traits that are directly involved in weed responses to farming practices. The principal population traits are capacity for dominance, sensitivity and accessibility of targeted developmental stages, and variation in weed population reactions from year to year. On the basis of demographic surveys of these two weed species when subjected experimentally to various cutting regimes (by date and number), we used matrix simulation models to describe each weed in terms of these traits and to construct species-specific management strategies. Management strategies for golden chervil need to prevent new recruitment by focusing on limiting or eliminating seed production and seedling survival because adult mortality is insensitive to cutting. Grazing to a low residual height is proposed in spring, when seedling emergence is maximal, or when adults reach their apex height to prevent the development of reproductive stems. Cutting before flowering may also efficiently limit seed production. The annual life cycle of yellow-rattle allows more flexibility in its management, even when density fluctuates and is unpredictable. If cutting is scheduled to coincide with peak juvenile height, this can drastically reduce population density the next year, and the population can be eradicated within 3 yr. Nomenclature: Golden chervil, Chaerophyllum aureum L.; yellow-rattle, Rhinanthus minor L.

Integrating Agricultural and Ecological Goals into the Management of Species-Rich Grasslands: Learning from the Flowering Meadows Competition in France

Current agri-environmental schemes for reconciling agricultural production with biodiversity conservation are proving ineffective Europe-wide, increasing interest in results-based schemes (RBSs). We describe here the French “Flowering Meadows” competition, rewarding the “best agroecological balance” in semi-natural grasslands managed by livestock farmers. This competition, which was entered by about a thousand farmers in 50 regional nature parks between 2007 and 2014, explicitly promotes a new style of agri-environmental scheme focusing on an ability to reach the desired outcome rather than adherence to prescriptive management rules. Building on our experience in the design and monitoring of the competition, we argue that the cornerstone of successful RBSs is a collective learning process in which the reconciliation of agriculture and environment is reconsidered in terms of synergistic relationships between agricultural and ecological functioning. We present the interactive, iterative process by which we defined an original method for assessing species-rich grasslands in agroecological terms. This approach was based on the integration of new criteria, such as flexibility, feeding value, and consistency of use, into the assessment of forage production performance and the consideration of biodiversity conservation through its functional role within the grassland ecosystem, rather than simply noting the presence or abundance of species. We describe the adaptation of this methodology on the basis of competition feedback, to bring about a significant shift in the conventional working methods of agronomists and conservationists (including researchers).The potential and efficacy of RBSs for promoting ecologically sound livestock systems are discussed in the concluding remarks, and they relate to the ecological intensification debate.

Towards biodiversity-based livestock systems: review of evidence and options for improvement

A major challenge for livestock farming systems (LFSs) is to reconcile production with the management of natural resources, especially biodiversity and ecosystem services. Based on a review of research conducted on grassland- and rangeland-based LFSs, this paper addresses this challenge by analysing biodiversity as a product of and a key resource for LFSs. Although most studies reveal antagonisms between biodiversity and production, our findings show that it is possible to move towards synergies. The literature review sheds light on five points: (i) moving beyond an antagonistic view of biodiversity and production by considering biodiversity as a resource requires new criteria for biodiversity categorization from a taxonomic view to a functional one; (ii) functional biodiversity (both domestic and wild) considered as a resource provides beneficial properties (e.g. stability and resilience) to LFSs; (iii) links between production and biodiversity cannot be simply summarized as having a negative impact of production intensity as management practices have various impacts on the different components of biodiversity; (iv) impact assessment studies linking management of LFSs and biodiversity reveal complex multi-level interactions between grassland or rangeland management and biodiversity; (v) a large range of management options are available to move towards biodiversitybased LFSs. We conclude that future research should address the challenge of collective management of wild biodiversity at higher levels of organization (landscapes, territories, etc.) and that such collective management would greatly benefit from the experience of domestic biodiversity.

Interplay between Endophyte Prevalence, Effects and Transmission: Insights from a Natural Grass Population.

Two main mechanisms are thought to affect the prevalence of endophyte-grass symbiosis in host populations: the mode of endophyte transmission, and the fitness differential between symbiotic and non-symbiotic plants. These mechanisms have mostly been studied in synthetic grass populations. If we are to improve our understanding of the ecological and evolutionary dynamics of such symbioses, we now need to determine the combinations of mechanisms actually operating in the wild, in populations shaped by evolutionary history. We used a demographic population modeling approach to identify the mechanisms operating in a natural stand of an intermediate population (i.e. 50% of plants symbiotic) of the native grass Festuca eskia. We recorded demographic data in the wild over a period of three years, with manipulation of the soil resources for half the population. We developed two stage-structured matrix population models. The first model concerned either symbiotic or non-symbiotic plants. The second model included both symbiotic and non-symbiotic plants and took endophyte transmission rates into account. According to our models, symbiotic had a significantly higher population growth rate than non-symbiotic plants, and endophyte prevalence was about 58%. Endophyte transmission rates were about 0.67 or 0.87, depending on the growth stage considered. In the presence of nutrient supplementation, population growth rates were still significantly higher for symbiotic than for non-symbiotic plants, but endophyte prevalence fell to 0%. At vertical transmission rates below 0.10–0.20, no symbiosis was observed. Our models showed that a positive benefit of the endophyte and vertical transmission rates of about 0.6 could lead to the coexistence of symbiotic and non-symbiotic F. eskia plants. The positive effect of the symbiont on host is not systematically associated with high transmission rates of the symbiont over short time scales, in particular following an environmental change.

Analyzing Theory and Use of Management Tools for Sustainable Agri-environmental Livestock Practices: The Case of the Pastoral Value in the French Pyrenees Mountains

The aim of this paper is to contribute to the design of management tools for sustainable agricultural systems that are able to accompany farming practices in anticipating the long-term effects of practices on natural resources management. Its originality is to analyze tools on the basis of their cognitive content as well as their management philosophy and their organizational model. We applied this approach to the main tool (Pastoral Value) used to assess the potential of forage resources in France. Our findings show how the tool strongly shapes practices and how it is adapted by technicians to their situation within the context of the French Central Pyrenees, emphasizing the role of experiential knowledge.

Practicing Agroecology: Management Principles Drawn From Small Farming in Misiones (Argentina)

In face of sustainability challenges, agronomical research has focused on the design of new production systems, whereas ethnographic studies have put forward the traditional small production systems. A gap remains between such agroecological design and the practices of farms. Our objectives are to draw principles for agroecological management from the in-depth study of practices in ecologically based farms in Argentina. We extracted three principles: 1) adjustment and observation instead of control, 2) variable and flexible management in time and space, and 3) permanent at-home experimentation. After examining their generality, we discuss the paths to take these systems as models for the ecologization of conventional systems.