Climate is an important component or determinant of terroir, especially at the regional level. One can define three levels of terroir. These are the macro– or regional scale, which applies over tens of kilometres of the landscape. The second level is the meso- scale, which applies over kilometres or hundreds of meters, at the individual vineyard scale. The third level of terroir is at the micro- level, and it applies to individual vines, or parts of them. This is measured over a scale of meters to centimetres.
Over two thousand years of experience of observing terroir, and more recently by scientific studies, man has shown that the principal determinant of terroir at the regional scale is that of climate. At the meso-scale, the principal determinants of terroir are topographical features such as slope or aspect. At the micro level, where differences may be seen from vine to vine, the influences are primarily those of the soil.
One can therefore identify appropriate methods of study for terroir at these three levels. For the macro scale terroir the appropriate analysis is that of climate, in particular temperature and rainfall, and typically using long term average data. For the second two levels of terroir, that being meso- and micro-, modern research approaches use GIS (Geographic Information Systems). The use of GIS typically involves imagery showing soil or vine attributes.
Authors: Richard E. SMART and John GWALTER
Smart Viticulture, PO Box 350 Newstead, Tasmania 7250 Australia