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IVES 9 IVES Conference Series 9 Étude de la composante climatique du terroir viticole en Val de Loire : relation avec les facteurs physiques du milieu

Étude de la composante climatique du terroir viticole en Val de Loire : relation avec les facteurs physiques du milieu

Abstract

Les recherches conduites par l’U.R.V.V. du centre I.N.R.A. d’Angers ont pour but d’élaborer une méthodologie de caractérisation intégrée des facteurs naturels des terroirs viticoles, représentative des conditions de fonctionnement de la vigne et des différences sensorielles des vins. Dans ce cadre, le concept d’Unité Terroir de Base (U.T.B.) a été développé. L’U.T.B. représente une surface viticole d’extension géographique variable, définie comme l’association en un lieu donné d’une composante géologique, pédologique et paysagère, Morlat (1989), Riou et al. (1995).

La géopédologie oriente la morphologie et les conditions nutritionnelles du système racinaire, (Morlat et Jacquet, 1993), et influence profondément le fonctionnement de la vigne, (Morlat, 1989). Parallèlement, on ne peut ignorer l’effet du climat sur la qualité du raisin dans une étude globale des terroirs viticoles (Branas, 1946 ; Nigond, 1957 ; Huglin, 1978 ; Riou et al., 1994). L’environnement paysager d’un terroir peut engendrer des variations locales du climat régional (mésoclimat), suffisantes pour modifier la réponse de la vigne. Cette hypothèse a été testée avec succès par Nigond (1971) et Lebon (1993) pour des reliefs accentués ou semi-montagneux soumis à des climats tranchés (semi-continental pour Lebon, méditerranéen pour Nigond).

La plupart des éléments constitutifs d’un terroir, potentiellement modificateurs du climat, ont été étudiés isolément et le plus souvent en zones accidentée. Les effets des brise-vent ont été largement analysés et décrits par Guyot (1963) et Guyot et al. (1976). le rôle de la nature de la surface du sol sur les températures a été abordé (Branas, 1946 ; Verbrugghe, 1991). Godard (1949), Guyot et al (1976), Varlet Grancher (1975) se sont intéressés aux effets climatiques des versants, des pentes et de l’altitude. Tous ces auteurs sont d’accord sur le fait que les mésoclimats se forment principalement par ciel clair et temps calme.

La transposition de leurs résultats, indispensable pour comprendre les phénomènes climatiques locaux, est insuffisante pour prédire un mésoclimat, car celui qui se forme en un endroit résulte de l’action conjointe (convergente ou opposée) de ces multiples variables. Il est donc important d’inclure à la même échelle, et en lui donnant une dimension spatiale, la composante climatique du terroir viticole, au même titre que la composante édaphique (sol, roche géologique).

Ce travail devrait aider à hiérarchiser les facteurs locaux du climat, en vue de déceler les variables utilisables pour une cartographie climatique applicable aux zones tempérées de faible altitudes dont le relief est peu accidenté. Ce dernier objectif est fondamental pour la caractérisation intégrée des terroirs et comme outil de gestion agroviticole des vignobles.

DOI:

Publication date: March 25, 2022

Type: Poster

Issue: Terroir 1996

Authors

A. JACQUET (1), (2), R. MORLAT (1)

(1) I.N.R.A.. U.R.V.V., Angers, France
(2) Adresse actuelle : INRA – L.A.P.B.V., Université de Caen, esplanade de la paix, 14032 Caen cedex. France

Tags

IVES Conference Series | Terroir 1996

Citation

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