Adaptation au changement climatique au Vietnam avec les mangroves et le riz
Author: Trung Vo, Hung
Under the direction of: Michel Simioni
SupAgro, Montpellier
English text
Keywords: Economy, Vietnam, Ecosystem, Climate change, Agriculture.
Abstract
Chapter 1 gives a brief introduction to this thesis which discusses the context of climate change at the global level and in Vietnam. Chapter 2 and 3 aim at valuing mangrove ecosystem services in Xuan Thuy National Park (XTNP), Red River Delta that are being degraded aggressively under environmental pressures. Conservation for protected areas, especially biodiversity, is a necessity for the livelihoods of the poor. These two chapters consider different scenarios of investments in conservation activities at XTNP that present a vision of long-term mangrove ecosystem health and examine factors that go into the decision-making framework. In chapter 2, contingent valuation with a double-bounded dichotomous-choice question survey is used to elicit local willingness to pay (WTP) for the total non-use values of mangroves. Findings indicate that income appears as the only significant sociodemographic factor when explaining WTP. Respondents’ perceived knowledge of mangrove benefits and interest in conservation activities also influence WTP. Non-parametric and parametric estimates of lump sum mean WTP per household are reported from the empirical analysis. In chapter 3, a discrete choice experiment is used to provide finer values for different components of a mangrove conservation project. Mangrove coverage area and storm prevention capacity are found to be greatly discerned attributes whereas biodiversity benefits are of minor importance. Results from the random parameter models (RPL) confirms that local preference heterogeneity exists and that observed preference 2 heterogeneity could be explained by respondents’ economic dependency on mangroves, education, occupation and knowledge of mangrove benefits. Unobserved preference heterogeneity and the degree of certainty of choices across individuals are further captured by estimating the generalized multinomial logit model (GMNL). Marginal household WTPs are reported given a change in each attribute level across econometric specifications. In chapter 4, climate impacts on rice yields are addressed in order to create lasting solutions in a sustainable food system for the coming years. The food system in Vietnam has entered a critical time when the adaptation solutions implemented by farmers today will determine how crop yields will flourish in the future. The panel model in this study, called mean observation ordinary least squares (MO-OLS), has intercepts as well as the slope coefficients on the climate variables change over space and time to capture the heterogeneity of rice yield responses under adaptation. The results affirm there exists regional heterogeneity of rice yield responses, meaning Vietnamese rice farmers are highly adaptable to shifts in various local weather conditions in the long-run. The decline in the adverse effect of high temperature on yield over the period from 1986 to 2020 is also consistent with this long-run adaptation.
