Mapping natural terroir units using a multivariate approach and legacy data

This work aimed at setting up a multivariate and geostatistical methodology to map natural terroir units of the viticultural areas at the province scale (1:125,000). 

The methodology was based upon the creation of a GIS storing all the viticultural and oenological legacy data of experimental vineyards (1989-2009), the long term climate data, the digital elevation model, the soilscapes (land systems) and the legacy data of the soil profiles. 

The environmental parameters related to viticulture, selected by an explorative PCA, were: elevation, mean annual temperature, mean soil temperature, annual precipitation, clay, sand and gravel content of soils, soil water availability, redoximorphic features and rooting depth. 

The selected variables, spatialized by means of geostatistical methods, were used for a k-means clustering aimed to map the Natural Terroir Units (NTU). The vineyard of the province of Siena was subdivided into 9 NTU. 

Both the historical DOCG (Chianti Classico, Brunello di Montalcino and Nobile di Montepulciano) and the others DOC were mainly characterized by three or four NTU, whereas the wider Chianti and Chianti Colli senesi DOCG was mainly constituted by seven NTU.