Temperature variability at local scale in a mountain vineyard

Abstract

Over the past ten years, climate studies at local scale have been developed in winegrowing areas to improve terroir characterization. In this project, such a study was undertaken in the mountain vineyard of Irouleguy in cooperation with the local cooperative cellar. A network of 31 temperature sensors has been set up inside the region at the beginning of the 2016 vintage. To assess the impact of the different terroir parameters, ecophysiology measurements were carried out on 104 plots located near the temperature sensors. Great spatial thermal variability was measured, especially for minimum temperatures with an amplitude of up to 11°C on a given day. This result is close to the values obtained in a similar study in the Saint-Emilion region (Bordeaux), but days with large amplitudes are less frequent in the Irouleguy region. Winkler index showed a maximum difference of 289°C.day among the sensors which can induce one month delay in maturity. A similar difference was measured in the Saint-Emilion project which is characterized by a larger area but lower in altitude. Regarding grape composition analyses, grape sugar and acidity are significantly related to altitude. The spatial distribution of the temperature related to other variables like soil parameters and relief will allow to classify the influence of these parameters on vine behavior and grape quality potential. The final objective for the cooperative cellar is to better adapt plant material, vineyard management practices and harvest dates to each parcel for improving quality, which is of particular importance in a context of climate change.