A procedure for the zoning of grapevine in a hilly area (Collio, North-Eastern Italy) using simulation models and GIS

The zoning of grapevine in a hilly area should consider the variability of the environmental characteristics due to topography. Since soil and climate data are usually available as point data, reliable spatialization procedures need to be developed, mainly based on topography.
For a hilly area of about 7000 ha (including 5000 ha of the Registered Origin Denomination “Collio”) in Friuli-Venezia Giulia region, North-Eastern Italy, information was integrated from meteo stations, soil survey, geology and topography (coded in a Digital Elevation Model), using a GIS (Idrisi 2.0), a deterministic model of the cropping system (CSS, Cropping System Simulator) and a stochastic weather generator (Climak). CSS and Climak were developed at the University of Udine.
A procedure was developed for the spatialization of soil and climate parameters, starting from point data and using ancillary information mainly about topography. The area was then divided in homogeneous units (given by a unique combination of soil and climate conditions) on which the CSS model was run, obtaining data on potential yield for each unit and yield shortage due to possible water stress.
A field survey was carried out, focusing on the relationship between grape characteristics (yield, sugar concentration at harvest) and soil, climate, topography, cultivation management techniques and crop features.
The evaluation of land suitability for grapevine cultivation was based on 1) expected quality of production, as a function of aspect, Huglin’s heliothermal index and yield reduction in non irrigated vineyards due to water stress (the most limiting factor); 2) potential suitability for grapevine, depending on quality and yield productivity in non irrigated vines; 3) actual suitability for grapevine, obtained combining potential vocation and ease of cultivation (as a function of slope).
A multi-criteria procedure allowed to define 4 classes of land suitability for grapevine cultivation, described as ‘not suitable’, ‘poorly suitable because of high transformation costs’, ‘suitable’ and ‘very suitable’.