Introducing heterogeneity measurements in terroir studies. Application in the região demarcada do douro (n portugal)

Terroir zoning studies have to manage the heterogeneity and complexity of the landscape properties and processes. The varying geology is one of the main landscape properties conditioning the spatial variability of terroirs. An entropy-based index used to characterize the heterogeneity of soil particle size distribution has been recently recognized to be controlled by the lithological properties at landscape scale. This index, known as the Balanced Entropy Index (BEI), which has been identified as a very good predictor of soil water content, is a promising tool in geosciences because it provides a continuous parameterization of soil texture that enables establishing quantitative relationships between soil texture and all the hydropedological attributes related to it.

In this study, carried out in the Portuguese winegrowing region called Região Demarcada do Douro (RD Douro), we explored the BEI in the lithostratigraphic units, and its potential relationship with the vineyard distribution and characteristics at plot scale. The data set for this work was the soil map of RD Douro scale 1/25 000, the vineyard distribution, and the information of the soil map database, which includes analytical and morphological data of 1 217 soil profiles.

Results evidenced that, in areas with similar lithological properties, vineyard plant density is linearly related with the soil texture heterogeneity, being this relationship stronger in metamorphic lithologies than in granitic lithologies. In light of this and other remarkable results we concluded that the BEI is a useful new tool that might have multiple applications in terroir studies.