Resilience analysis in viticulture: an approach based on expert knowledge elicitation

Abstract

The study aims to address the issue of resilience to climate change in viticulture through the adoption of the expert knowledge elicitation (EKE) approach. Elicitation consists of the application of techniques to extract knowledge or information from expert people on a specific topic. Specifically, elicitation consists of the process of expressing expert knowledge in a quantitative way, obtaining numbers and probability distributions. The study involved some experts operating in Franciacorta, an important wine-growing area in northern Italy. The experts were interviewed, subjecting to their evaluation the effect of different management strategies and their interaction on the ability of the vineyard system to cope with different pressures deriving from abiotic and biotic stressors, maximizing quantity and quality of production. To conduct the elicitation it was necessary to define the investigation context and different scenarios of years, that combined elements of water supply with elements of risk of the onset of phytopathologies. Technical management paths were also identified that combined soil management practices (fertilization and tillage) with canopy management practices (defoliation, shoots topping and thinning). The study, through the adoption of the EKE approach, allowed to summarize the results obtained from the shared opinion of the various experts, generating a system of synthesis of knowledge and translation of this in a quantitative key. Starting from the uncertainty distributions defined by the experts, the statistical approach adopted led to obtain a dataset of 96,000 observations. Statistical models were applied to this dataset allowing to detect the management variables which, within those included in the set of scenarios, were considered significant in influencing the yields and quality of the grapes. In particular, the positive effect on productivity of organic and mineral fertilizations, as well as inter-row and sub-row tillage, emerged as particularly significant. As regards the canopy management, the effect of shoots thinning, the method and timing of topping and defoliation had a significant effect only in some vintages and with diversified effects based on the specific scenario of year. This work has allowed us to carry out an integrated analysis of the effect of different management practices and their interaction on resilience in viticulture by enhancing the knowledge of experts through the EKE technique. This made it possible to enhance the role of different technical management paths in improving the resilience of the vineyard system by mitigating the negative effects of the stressors of the different vintages.