Spatial Analysis of Aridity during Grapevine Growth Stages in Extremadura (Southwest Spain)

Aridity is a key determinant of agriculture worldwide due to rising temperatures, rainfall variability, and drought frequency and intensity, amongst other factors. The De Martonne aridity index is particularly useful to evaluate the spatial and temporal variations in aridity in agricultural regions for characterising the climate of these areas and evaluating their susceptibility to climate change. From the mean precipitation and maximum–minimum daily temperature values recorded at 108 weather stations over 32 years (1989–2020) in Extremadura (southwest Spain), spatial analysis of aridity was performed at different grapevine growth stages. The present study aimed to (1) determine the mean aridity conditions in Extremadura according to year and growth stage and (2) assess aridity in six grapevine-growing areas of Ribera del Guadiana de Extremadura (Spain) protected designation of origin (PDO). To visualise aridity patterns, maps were generated using a geographic information system and a multivariate regression geostatistical algorithm (ordinary kriging). The climate of Extremadura is primarily Mediterranean at the annual scale, and aridity widely varies from extremely humid at the dormancy stage to arid at the berry development and ripening stages. This variation shapes the conditions of the studied grapevine-growing region. Furthermore, large differences were noted amongst the sub-areas of the Rivera del Guadiana PDO at the initial and final grapevine growth stages, requiring differential crop management. In addition, analysis according to growth stage allowed us to identify the most vulnerable areas and periods to climate change and potential grapevine-growing areas highly suitable for this climate.