Bioclimatic zoning of Argentinian Malbec grape productivity regions by means of a unique combined index

Climate conditions are the main factor controlling winegrape production worldwide. Establishing the impact of climatic conditions on grape production allows for evaluation of the suitability of a given region for winemaking. Given the relevance of Malbec wine production in Argentina, this study was devoted to deriving a unique combined index (UCI) for assessing the suitability of Malbec grape production (MGP) in the country. The index is a zoning tool that also quantifies the degree of suitability both in terms of temporal and spatial behavior. We used monthly mean temperature and precipitation data from a set of stations over the main wine making regions of Argentina together with MGP data from Mendoza for the period 1979-2014. First, the co-variability between a set of bioclimatic indices and MGP was explored in order to identify the climatic variables that most strongly impact year-to-year variability of MGP. Growing season temperature, cool night index, growing season thermal amplitude and growing season precipitation were found to be the bioclimatic indices significantly correlated with MGP. This analysis also identified the ranges of each climatic variable corresponding to upper, normal and lower than normal MGP, allowing the definition of categories for each individual climatic variable. The individual categorized indices were then combined into the UCI, which quantifies MGP suitability. Finally, the UCI index was evaluated in terms of both its spatial and temporal behavior, and its utility as a tool for characterizing the suitability for MGP was demonstrated.