The Demarcated Region of Dão wine occupies, almost entirely, the southern half of the province of Beira Alta. It is extended over an area of 3760 km2. About 5% of this area is occupied by vineyards, that represents an area of 20,000 h. The Dão region area with Denomination of Origin holds sixteen municipalities in the district of Viseu, Guarda and Coimbra. From the district of Viseu: Municipalities of Sátão, Penalva do Castelo, Viseu (with the exception of the vilages of Bodiosa, Calde, Campo, Lordosa and Ribafeita), Mangualde, Nelas, Carregal do Sal, Tondela, Mortágua and Santa Comba Dão. From the district of Coimbra: Municipalities of Oliveira do Hospital, Tábua and Arganil. From Guarda district: Municipalities of Aguiar da Beira, Fornos de Algodres, Gouveia and Seia. Much has been said and written about the wine-growing heterogeneity of the Dão, defending the possibility of creating and separating more sub-regions due to their own character. Traditionally, the region is divided into three large areas that give rise to three types of wine, although with similar characteristics: North Central Zone (with rugged relief, it is influenced by the Dão River, and partially embraces the municipalities of Viseu and Tondela and entirely the municipalities of Nelas, Carregal do Sal, Mangualde and Penalva do Castelo); Central South Zone (with a flat topography, or less accentuated and uniform relief, it is dominated by the Mondego River, and includes the municipalities of Gouveia and Seia); Peripheral Zone (dominated by the mountains as Serra da Estrela, Açor, Lousã, Buçaco, Caramulo, Nave da Lapa).
The Beira highland is surrounded by a set of large mountains that protect it from outsider’s influences. The geographical limits are in southwest, with the mountains Serra da Estrela and Açor, in the northwest Caramulo mountain, which defend it from continental and maritime climatic agents, in the northeast the Serra da Nave mountain, in the south Lousã moutain, and in the southwest Buçaco mountain, that protect it from the humid winds coming from the south. The individuality of the Dão region is, in some point, due to the rugged nature of its relief, which origin manifest microclimatic variations, of great importance for the culture of the wine and of great significance for the quality of wines. The interior of the orographic border has its very own characteristics, with granitic soil dominating, where can be observed the existence of many valleys, often sinuous and deep, through which the rainwater flows from the mountains. The average altitudes of the Beirão highland decreases starting at 700 meters in the municipalities of Aguiar da Beira, Penalva do Castelo and Fornos de Algodres, to less than 200 meters in the municipalities of Santa Comba Dão, Tábua, Arganil and Mortágua. About 70 to 75% of the Dão area is located between the 400 and 700 meters. The region’s hydrographic network is characterized by a rigid line, indicating a clear adjustment to the relief structure. The two main rivers in the region are the Dão and the Mondego, whose courses are very parallel, running through the granite massif land. The network of tributaries and Sub-tributaries Rivers ensure the flow of water in the region. The region’s hydrographic network, as well as the reliefs that are on its origin, generate a great diversity of microclimates with substantial wine production significance.
The Dão region does not present major climatic differences, given its small geographic dimension. The climate is moderate, with hot, dry summers, and rainy, moderately cold winters. The monthly medium temperatures oscillate between 18 and 20ºC in the months of July and August, and the maximum temperatures in the order of 28 and 30ºC respectively. Minimum temperatures reach their lowest value in December and January, with averages around 2ºC in the Viseu region and 3 to 4ºC in the rest of the region. The rainfall is reduced in the summer months, not reaching an average of 20 liters per m2 in the months of July and August. The maximum is registered in the months of December, and from January to March, with average values in the order of 1000 per m2. The occurrence of frosts in the months of March, April and May, can cause considerable damage to the development of the wine influencing the crop yield in the following year. However, given the orographic characteristics of the region, that is surrounded by mountains, a great variety of microclimate can be expected. To this source of climatic variation, we must add the relative exposure and the angle of the slopes cultivated with vineyards, which, like other factors, may induce differences in the typicality of the wines and generate different “terroirs”, using a French expression that seeks to integrate the factors that, in some way, can contribute to the typicality of a wine.
Most of the region belongs to the denominated Iberian massif, formed by eruptive and metamorphic rocks. Granites appear in about 70% of the region and schists, from the Schist-Grauvach (Paleozoic) complex, occupies about 20 to 25% of the region’s surface. They also have some representation, the schist formations of the Crystallophilic complex (Paleozoic).
About 90% of the Dão vineyards are located on granitic terrain, generally with low fertility capacity, and the rest is located in schist spots. Porphyroid granite is made up of milky quartz (large pink or gray felspar crystals and usually black mica) constituting the substrate of the soils where about 97% of the region’s vineyards are located. The chemical fertility of these soils is very low, but we are not in the believe that this is a limiting factor for wine, except in conditions of extreme poverty in nutrients or marked imbalances that are difficult to correct through the use of chemical and/or organic fertilizers. The influence of factors, such as climate and soil, on the greater or lesser quality of the wine masses, should be attributed mainly to the hydrography of the soils. The agriculture practiced in the region is based on polyculture systems, which are related with an accentuated smallholder structure.