Lucie Allart

Les prairies permanentes sont multifonctionnelles et rendent ainsi de nombreux services écosystémiques à la société. Elles sont menacées par le changement climatique et par l'intensification des pratiques agricoles qui les menacent de dégradation (i.e. baisse de biodiversité et de leur capacité à fournir des services). Elles reculent sous l'effet de la conversion de leurs surfaces au profit des cultures. Deux enjeux sont alors à concilier: i) maintenir la diversité de services que les prairies permanentes rendent à la société et ii) adapter les systèmes fourragers au changement climatique. La cadre des systèmes d'élevage qui combine un système biotechnique et un système décisionnel est ici utilisé pour analyser les effets directs et indirects du changement climatique sur les prairies permanentes. Les effets directs sont les évolutions des prairies sous l'effet de variations du climat, et les effets indirects sont les évolutions des prairies en réponse aux adaptations des éleveurs au changement climatique.Afin de comprendre les effets directs du changement climatique sur les prairies permanentes, nous avons utilisé les relevés botaniques précédemment réalisés pour établir une typologie fonctionnelle des prairies du Massif central. Leur distribution le long de gradients d'altitude et de latitude, indépendamment des facteurs de gestion, nous a permis d'étudier l'effet du changement climatique sur la multifonctionnalité des prairies permanentes selon les modes de fertilisation et leur richesse spécifique. Grâce à un modèle d'équation structurelle, nous avons identifié la richesse spécifique comme variable pivot des effets de la fertilisation et du climat. L'élévation de la température annuelle moyenne conditionne la baisse de leur biodiversité et de leur multifonctionnalité.Par la suite, nous avons interrogé 15 éleveurs bovins laitiers du Massif central sur leurs perceptions du changement climatique, de leurs prairies permanentes et analysé comment ces perceptions influencent leurs stratégies d'adaptation au changement climatique. Nous avons observé un effet marqué du contexte climatique avec un fort contraste entre les zones collinéennes du sud du Massif central, où les éleveurs font déjà face à des sécheresses prononcées et à des températures estivales élevées, et les autres zones. Dans ces dernières, la perception des prairies permanentes reste positive et leur diversité inter- et intra-parcelle est à la base des stratégies d'adaptation mises en œuvre par les éleveurs. Au sud du Massif central, les éleveurs insistent plus sur les dis-services liés à l'utilisation des prairies permanentes, et fondent leur stratégie d'adaptation sur un assolement dans lequel ils ont intégré des prairies temporaires, des cultures fourragères et des arbres.Enfin, grâce à notre modèle d'équation structurale, nous avons simulé l'effet d'une élévation de la température moyenne de 1,5°C sur l'évolution de la multifonctionnalité de prairies permanentes que les éleveurs jugeaient représentatives de leur système. Nous avons également distingué les exploitations selon la part de prairies permanentes dans la surface agricole. Cette analyse révèle que les phénomènes de dégradation et de conversion des prairies permanentes au profit des cultures ne touchent pas toutes les exploitations de la même manière. Dans certaines, la conversion de certaines parcelles préserve des prairies permanentes peu fertilisées sur une autre partie du parcellaire.Cette thèse met en évidence l'importance de combiner des approches écologiques et socio-cognitives pour comprendre les voies par lesquelles le changement climatique influence la gestion des écosystèmes prairiaux. Les apports de notre travail sur la perception qu'ont les éleveurs herbagers des prairies permanentes, et sur les freins à l'adaptation pourront être mobilisés par le conseil aux éleveurs, afin de les accompagner dans les transitions permettant de faire face aux défis climatiques et écologiques.

It is crucial that biodiversity conservation initiatives in agriculture take into account how farmers understand and value their relationships with nature. However, while highly relevant for pan‐European conservation work, insight into differences and commonalities in farmers' views across socio‐ecologically different European regions is still lacking. Therefore, we studied how farmers describe the relationship between how they farm and biodiversity in two contrasting regions: the Netherlands and the French Massif Central. In both regions, we included two specific study areas. We focused on dairy farming, as it is a key sector in terms of socio‐economic importance and biodiversity impact in both regions. In each area, we conducted 15 in‐depth interviews focusing on the impacts of the farm on biodiversity and vice versa, as well as on the relational importance of biodiversity to the farmer. We allowed farmers to use the term ‘biodiversity’ in their own words. We analysed our data using the Integrated Nature Futures Framework (I‐NFF), a recently proposed framework for analysing what people value positively and negatively about nature‐related matters. Six main narratives emerged, which we named ‘farming WITH biodiversity’, ‘farming FROM biodiversity—valorising what is there’, ‘farming FROM biodiversity—innovating for sustainability’, ‘farming FOR biodiversity’, ‘farming SEPARATE from biodiversity—out of necessity’ and ‘farming SEPARATE from biodiversity—out of conviction’. These narratives vary in how farmers conceptualise biodiversity, perceive and value interactions between farming and biodiversity, and define problems and solutions. Although we encountered partly the same narratives in the Dutch and Massif Central areas, we also noted considerable differences. In the Dutch areas, we frequently encountered ‘FOR’, which strongly depicts biodiversity as an additional service that requires payment, and ‘SEPARATE—out of conviction’, which argues for production‐intensive systems. In the Massif Central areas, we virtually never encountered these narratives and instead more often encountered ‘WITH’, which depicts farming as naturally integrated with biodiversity. Moreover, the narratives had strong region‐specific details. We close by discussing how better insight into such differences and commonalities can help foster more understanding engagement with farmers on the topic of biodiversity. Read the free Plain Language Summary for this article on the Journal blog.

Climate change will increase average temperatures and the frequency and intensity of summertime droughts; those shifts will in turn affect forage production in grassland-based livestock farms. Farmers will accordingly likely have to implement adaptation strategies to cope with the effects of climate change. We hypothesized that farmers' resilience strategies would depend on (i) their intention to adapt to climate change, which partly results from previous climate risk exposure, (ii) how they perceive the values and disvalues of multi-species permanent grasslands (PGs), and (iii) that both of the aforementioned factors would vary according to the geographical context of each farm. We carried out 15 semi-structured interviews with dairy cattle farmers in the French Massif Central; the farms were distributed along a range of climatic and topographic conditions. We used (i) the Model of Proactive Private Adaptation to Climate Change to analyze farmers' individual process of adaptation, (ii) the Integrated Nature Futures Framework to analyze farmers' perception of multi-species PGs, and (iii) text analysis to identify the farmers' adaptation strategies. Nine of the farmers felt that they were already adapted to climate change or that they had a plan in place to implement new adaptations in the future. We observed straightforward relationships between these farmers' perception of PGs and their choice of adaptation strategy; those relationships varied, however, with the geographical context of each farm. Farmers in the northern Massif Central and southern uplands highlighted the values of PGs and considered PGs to be central to their adaption strategies. Conversely, farmers in the southern lowlands mostly referred to the disvalues of PGs; they based their adaptation strategies on temporary grasslands and forage crops. Three of the farmers believed that climate change posed a significant risk, but they foresaw little room to maneuver. Despite acknowledging the values of PGs, those individuals did not intend to use PGs to adapt to climate change. The final three farmers did not intend to adapt to climate change; their reasoning stemmed from either a mindset of fatalism or their acknowledged desire to retire soon. Extreme events such as the summertime drought of 2003 and human factors such as intergenerational transmission of farm can accordingly facilitate or inhibit climate change-related adaptation. It is accordingly important to take into account both socio-psychological and environmental factors when analyzing how grassland-based farmers transition to more climate change-resilient systems.

Temperate seminatural grasslands harbour unique biodiversity, support livestock farming through forage production, and deliver many essential ecosystem services (ESs) to human society; they are highly multifunctional. However, temperate grassland ecosystems are also among the most threatened ecosystems on earth due to land use and climate changes. Understanding how biodiversity, climate and land use intensification impact grassland multifunctionality through complex direct and indirect pathways is critical to better anticipate the future of these fragile ecosystems. Here, we evaluate how local plant species richness (SR) modulates the effect of land use intensification and climate on grassland multifunctionality (using six key ESs: biomass productivity and stability, forage quality, carbon storage, pollination and local plant rarity) in the French Massif Central, the largest grassland in Western Europe. We sampled 100 grasslands with contrasted fertilization rates and SR, over large elevational and latitudinal gradients related to variation in mean annual temperature (MAT), and drought severity (DS), two key climate change drivers predicted to increase in the future. Using a confirmatory path analysis, we found that SR was the main driver of multifunctionality. We also found significant SR × MAT and SR × fertilization interactions suggesting that warm climate and high fertilization rates alter the biodiversity–ecosystem multifunctionality relationships. Furthermore, increasing temperature and fertilization indirectly influenced multifunctionality by decreasing SR and consequent multifunctionality in warm lowland and highly fertilized grasslands compared to colder montane grasslands or less fertilized ones. DS only impacted some ES individually (e.g. forage quality). Synthesis and applications: We identified species richness (SR) as a pivotal factor mediating the effects of land use intensification and climate on multifunctionality through both direct and indirect pathways. Failing to account for changes in SR could thus bias any prediction of, or aggravate, the effects of land use intensification and climate change on ecosystem services delivery in temperate grassland ecosystems. Considering that SR, mean annual temperature and fertilization are major proxies of three main global change drivers (biodiversity loss, climate change and land use intensification) our study may help to better anticipate the effect of multiple interacting global change drivers on grassland ecosystems.