Multivariate clustering of viticultural terroirs in the Douro winemaking region

Abstract

The Douro Demarcated Region (DDR) is one of the most important winemaking regions in Portugal. Viticulture is historically and culturally tied to the DDR, having a strong impact on the local economy. This mountainous region, characterized by the steep slopes of the Douro Valley, provides a wide range of environmental characteristics for grapevine growth. Different climatic conditions, soil profiles, topography, grapevine varieties and management practices comprise the DDR terroir , resulting in the distinctiveness of the wines produced. In the present study, an assessment of the homogeneous zones of interest for viticultural activities is proposed for the DDR, by integrating different terroir elements (thermal, hydric, soils, topography and vegetation), using state-of-the-art high resolution datasets (1 km) and a large number of variables/indices. A multivariate zoning was carried out using a principal component analysis and a subsequent clustering methodology. A geospatial assessment of the terroir elements was also performed separately for each type of vegetation covering the DDR. The inter-connections of the different terroir elements that exist at a given location, were also innovatively assessed. The zoning may promote a more appropriate selection of vineyard sites, the selection of more locally-adapted varieties and rootstocks and the adoption of appropriate viticultural practices and management planning. After assessing the terroir conditions that exist at the current vineyard locations, possible expansion zones within the DDR were also evaluated. The present study may also be used as an archetypal methodology that can be applied to other winemaking regions worldwide.