J. A. Santos (Portugal) 1,2; H. Fraga (Portugal) 1,2; R. Costa (Portugal) 1,2; A. Fonseca (Portugal) 1,2; M. Santos (Portugal) 1,2
1 - Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB; 2 - Universidade de Trás-os-Montes e Alto Douro, UTAD
Portugal comprises a large diversity of terroirs, owing to its multiple climates, soils, native varieties and cultural practices. The vineyard area in Portugal is roughly 190 000 ha, largely devoted to wine production (about 6 million hl annually), thus being the 11th wine producer and the 9th wine exporter worldwide. Therefore, vitiviniculture plays a key role on national economy, contributing to approximately 2% of total exports. However, owing to the strong sensitivity of the grapevine physiological development to weather and climate conditions, through a number of direct and indirect processes, grape berry quantity and quality reveal important inter-annual variability that can only be partially stabilized by oenological practices. Furthermore, grapevines are also vulnerable to climate change, as their responses will be necessarily different under future climates and may threaten wine typicity and wine balance of a given region, or even its viticultural suitability. Some examples of impact assessment and adaptation measures in Portugal will be given, based on downscaling approaches, climate model ensembles and crop models, which may be regarded as decision support tools for stakeholders from the winemaking sector.
The projected warming and drying trends will enhance water and heat stress, will anticipate the phenological timings (e.g. budburst, flowering and veraison) and may lead to decreases in yields, as well as decreases in wine acidity and increases in sugar content, thus challenging the production of high-quality wines (Port and Douro, specifically in Douro valley). A number of adaptation measures can be undertaken to mitigate climate change detrimental impacts, ranging from short to long-term measures, namely changes in agricultural practices (e.g. pruning, application of sun screens, cover crops, mulching and soil tillage), the implementation of smart irrigation strategies, changes in training and trellis systems, variety-clone-rootstock selection, vineyard design and shading, or even vineyard re-location. The effectiveness of all the measures will, nonetheless, strongly depend on the strength of the local climate change signal and on the current local conditions, such as financial capacity, water availability and environmental degradation. Along these lines, climate change impact assessments on viticulture and adaptation must be considered at a local scale, i.e. a global problem that requires local solutions. Further research in this field is also envisioned within the framework of the Clim4Vitis H2020 twinning project, which is coordinated by the Universidade de Trás-os-Montes e Alto Douro, Portugal, and is promoting several knowledge transfer and capacity building actions amongst partners and the Portuguese winemaking sector.