As part of the Social Sciences Seminar, Frédéric Richard and Greta Tommasi will present their book Rural Gentrification in France, forthcoming with the Presses Universitaires de Rennes (2025). Abstract: The revival of many French rural areas is largely driven by the settlement of individuals and households from diverse social backgrounds. These newcomers contribute to profound social, functional, and landscape transformations of rural territories. Many of them belong to the middle and upper classes, are highly educated, and generally possess economic, social, and cultural capital that is often greater than that of previously established populations, whom they tend to progressively replace in locally variable proportions. Often interpreted as amenity-led migration, these dynamics are sometimes praised by public institutions for their contribution to the revitalization of rural areas. Yet they also raise significant concerns. It is now crucial for researchers, elected officials, and practitioners to address the issues they generate in terms of social and political inequalities, power relations—sometimes forms of domination—and the processes of displacement and marginalization affecting the most disadvantaged populations, for whom access to land and housing has in some cases become impossible. Rural gentrification provides a conceptual framework that makes it possible to analyze these trajectories from a clearly critical perspective. Bringing together epistemological, theoretical, and empirical contributions, the book aims to present different facets of a key concept for understanding inequalities within French rural areas.

Title: Weed Management and Herbicide Resistance: An Economic Analysis Abstract: Agriculture has undergone a major transformation driven by the massive use of pesticides. This intensification has made it possible to increase yields and stabilize production, thereby addressing global food security concerns. However, the dependence on pesticides has generated worrying environmental and health consequences. Beyond these effects, the very effectiveness of pesticides is now being challenged by the growing emergence of resistant pest populations, which increase control costs and threaten the economic viability of many farms. In light of this situation, a more rational use of pesticides has become necessary. This dissertation, organized into three chapters, seeks to shed light on this issue by focusing on herbicides. Chapter 1 analyzes the factors influencing the willingness of farmers engaged in weed control to adopt new sustainable agricultural practices, particularly collective approaches such as collective agri-environmental schemes. We show that farmers who already use certain weed control methods—such as mechanical treatment, combined strategies (mechanical and chemical), and crop rotation—are more inclined to participate in these new collective frameworks. In Chapter 2, we first examine the potential of Integrated Pest Management (IPM) to mitigate the development of resistance in the presence of intertemporal production externalities, showing that IPM contributes to reducing the overall level of resistance. Second, we analyze two types of policy instruments designed to internalize the negative intertemporal production externality: one input-based (taxing each unit of herbicide use) and one output-based (taxing the overall level of resistance). We derive the conditions under which both policy approaches lead to socially optimal strategies. Chapter 3 evaluates the effect of lacking information on the level of weed development, more specifically the interaction between susceptible and resistant weeds, on farmers’ strategies when they adopt a mixed approach (combined herbicide and mechanical control). We show that the absence of information leads farmers to rely more heavily on both herbicide and mechanical treatments than necessary. We then assess a taxation mechanism based on the total stock of susceptible and resistant weeds. We show that such a tax encourages more rational use of herbicide and mechanical treatments. Keywords: Herbicide Resistance, Collective Agri-Environmental Measures, Integrated Pest Management (IPM), Information, Public Policies.

Alexandra Verlhiac will defend her dissertation on the analysis of how residential location preferences evolve and how these shifts affect real estate dynamics. Her work draws on three quasi-natural experiments: the Covid-19 crisis, wildfires, and the opening of new transport infrastructures. These shocks shed light on residential trade-offs and market adjustments. The originality of the dissertation lies in the use of data from the online real estate platforms Meilleurs Agents and SeLoger (AVIV Group), complemented by postal forwarding data and short-term rental records. Methodologically, the dissertation relies on discrete choice models and causal inference approaches (difference-in-differences, synthetic methods, and staggered treatment designs). The first chapter analyzes how households’ location preferences evolved during the Covid-19 crisis using discrete choice models. Based on real estate valuations produced by Meilleurs Agents, we reconstruct flows of intended residential mobility between January 2019 and September 2021. By estimating a dwelling both as sellers and as buyers, households reveal their underlying aspirations. The results show that the probability for an urban resident to search in an urban rather than a rural area decreases relative to the pre-Covid period. The likelihood of considering a move outside one’s functional area increases for both urban and rural residents. The second chapter assesses the impact of the 2022 wildfires in the Landes forest massif on residential intentions, residential choices, and the real estate market. Using synthetic difference-in-differences, we identify the causal impact through a rich dataset combining SeLoger listings, La Poste mail-forwarding contracts, property transactions (DV3F), and short-term rental data (AirDNA). Our findings reveal a sharp increase in the supply of properties for sale and for rent, accompanied by longer time-on-market durations. Demand, however, contracts—both in terms of intentions and actual mobility. Property transactions increase slightly, as does the use of short-term rentals, pointing to a reconfiguration of the market rather than a resurgence in dynamism. The third chapter evaluates the effects of the opening of new metro and tramway lines on the Île-de-France housing market. I separately identify their influence on supply, demand, and market tightness. User behavior data from SeLoger, combined with transaction records (DVF) and the Callaway and Sant’Anna (2021) estimator, allow the measurement of heterogeneous effects. The treated group (areas surrounding the new stations) is compared with three control groups to distinguish proximity effects, accessibility gains, and anticipation effects. The commissioning of a metro line increases market tightness through shorter selling times, higher demand, and higher listing prices. These effects reflect a valuation of proximity to stations and commissioning effects that exceed anticipation effects. The absence of effects on sale prices suggests anticipatory capitalization. Market transformations appear specific to metro lines, as the opening of tramway lines has no observable effect. Overall, this dissertation highlights how households adapt their residential choices and how the housing market reacts to shocks that reshape the decision-making environment. From the growing appeal of rural areas and the attractiveness of new metro lines, to the market adjustments triggered by climate-related risks, the insights from this dissertation are essential for informing planning strategies and supporting territorial adaptation to contemporary transformations.