Developing a Wine Grape Site Evaluation Decision Support System for the Inland Pacific Northwestern United States

Abstract

Site selection is critical in wine grape (Vitis vinifera) production. The wine grape industry is expanding in the inland Pacific northwestern United States (IPNW) using traditional means of site evaluation including on physical examination of topography, geomorphology, soil characteristics, and analysis of long-term observations from weather stations. Through the use of modeled spatial data, we present a geographic information system (GIS) representing environmental features important for evaluating vineyard site suitability for the production of wine grapes. Elevation, slope, insolation, heat accumulation, growing season length, extreme minimum temperature and the soil parameters of drainage, available water-holding capacity (AWC), depth to restrictive layer, and pH combine to represent composite topographic, edaphic, and overall production suitability. Comparing modeled site suitability predictions with existing vineyards, we found modeled data on site properties aligned with vineyard manager perceptions of production quality in established vineyards. Although remote spatial evaluation will never replace physical site examination for addressing specific site conditions, it allows an efficient, spatially extensive, initial assessment of sites that can direct attention to potentially problematic or distinguishing environmental characteristics.