Vitis 46 (2), 63–70 (2007) Spatial climate variability and viticulture in the Miño River Valley of Spain D. BLANCO-WARD1), J. M. GARCÍA QUEIJEIRO1) and G. V. JONES2) 1) Sciences Faculty, Vigo University, Ourense, Spain 2) Southern Oregon University, Oregon, USA Summary The Miño River is the most important drainage in NW Spain with a basin that extends over 17,757 km2 with Understanding spatial variations in climates that abundant viticultural areas distributed along its path to the are crucial for crop suitability form the basis of zona- Atlantic Ocean. Wine producing regions in Spain are giv- tion studies in viticulture. This research applies princi- en denominations of origin (D.O.) status, which provides pal components analysis and cluster analysis to 39 cli- the legal nomenclature used to recognize those areas fa- mate stations in the Galician region of northwest Spain vorable for production and to specify a high quality level to examine the applicability for zonation in the region for the wines produced. In this region there are more than and produce a better understanding of the spatial cli- 10,000 ha of vines that include six denominations of origin mate structure in Galicia. Roughly 90 % of the spatial (D.O.). Four of these growing regions (Bierzo, Valdeorras, variation in climate types is explained by three main Ribeira Sacra and Ribeiro) are each located in the Miño components, which are defined by precipitation, tem- Valley and a fifth (Rias Baixas) is located near the end and perature, and frost risk variations across the region. mouth of the river as it flows into the Atlantic (Figure). The climate variables or indices most important for the Vineyards in these regions produce an average of more Galician region include the three main indices (Huglin than 40 million kilograms of grapes a year, with nearly index, Dryness index, and Cool night index) used within 85 % being white varieties (Albarinho, Palomino, Treixa- the Multicriteria Climatic Classification System (Geo- dura, and Godello) and the remainder predominantly the viticulture MCC System). The results provide evidence red varieties Garnacha and Mencia. that the Geoviticulture MCC System, which was devel- The landscape of Galicia is dominated by the valleys oped at the global scale, has tremendous applicability at and relief created by the Miño River and its principal tribu- the mesoscale. The identification of six climate types of tary the Sil River. Along the roughly 380 km course of the the Geoviticulture MCC System, which are used quite Miño, the river runs through both deep gorges and valleys, extensively for wine growing in the region, depicts the some of which are true narrow canyons whose flanks are great spatial diversity of viticultural potential found almost vertical and other valleys with gentle hills includ- within the relatively small area of Galicia. ing even some almost flat hollows. At the macroscale, the climate of the Iberian Peninsula is influenced by the Atlan- K e y w o r d s : Climate variability, viticulture, wine, tic Ocean and the seasonality and position of the Icelandic climate indices. low and Azores high pressure regions, but also has Medi- terranean climate structure inland due to the relief of the Introduction landscape (KÖPPEN 1931). The spatial distribution of mesoclimates in a region Grape growing and wine production are largely weath- is very important for understanding viticultural suitability er and climate driven. Extreme weather events such as hard (CARBONNEAU 2003) and this is never more evident than in frosts, heavy rains, and hail can result in major losses in a the heterogeneous landscape of Galicia. Viticulture zonifi- given vintage, while variability in growing season temper- cation studies include the identification and characteriza- atures can result in major differences in ripening potential tion of the mesoclimates in an area, apart from the macro- and the quality of wine (GLADSTONES 1992, JONES 1997). scale variations that may affect the frequency and intensity The major wine producing regions in the world each expe- of certain climatic factors (temperature, rainfall, sunlight, rience climate variability, however, depending on location frost, drought, etc.) and how their variations impact the (i.e. coastal vs. continental) they are subjected to different vine’s development. These factors are not normally ex- types, frequencies, and magnitudes of climate and weather amined separately, but are more commonly integrated as events. One region of particular interest is Galicia, Spain mathematical expressions that permit the calculation of which is in the extreme NW portion of the Iberian Penin- a series of bioclimatic indices (FREGONI 2003), which are sula just north of Portugal. Regionally, Galicia and Portu- typically summed over a period of time important to the gal share a cool maritime climate, the production of simi- vine’s growth and production (usually the 6 or 7 months lar wine varieties (e.g. 'Alvarinho', 'Loureira'), viticultural of the vine’s growth and development cycle). Among these areas (e.g. the Tamega and Miño river valleys), as well as indices some of the most utilized in viticultural zonifica- various aspects of traditional viticultural practices (e.g. ter- tion studies are the WINKLER index (1962), the Heliother- racing, pergolas, etc). mic index (HUGLIN 1978), BRANAS index (1974) and the Correspondence to: G. V. JONES, Department of Geography, Southern Oregon University, 1250 Siskiyou Blvd, Ashland, OR 97520, USA. Fax: +1-541-552-6439. E-mail: [email protected] 64 D. BLANCO-WARD et al. Figure: Miño basin areas where vines are grown more extensively and their respective viticultural climates classified according to the Geoviticulture MCC System. Solid dots denote the locations of the temperature and precipitation only meteorological stations used in this study and flags show the locations of the complete meteorological stations. The map in the upper right hand corner depicts the location of the Miño-Sil river drainage and the Galician Denominations of Origin (D.O.). quality index of FREGONI (1985). However, each of these mesoclimates present in wine-producing areas of the Miño indices have been criticized in one way or another (i.e. too Valley. The overall aim is to provide a comprehensive and simplistic or appropriate for one region only) (GLADSTONES climatically appropriate zonation of viticultural potential 1992, JONES et al. 2005). in the region. More recent research (CARBONNEAU and TONIETTO 1998, TONIETTO 1999, CARBONNEAU 2003, TONIETTO and CARBON- NEAU 2004) has combined a reduced number of climatic Data and Methods indices that account for solar, frost, and drought variabil- ity and provide a classification of viticulture climates that To carry out this study, data were obtained from a are arguably more universally valid. The Multicriteria network of weather stations maintained by six organiza- Climatic Classification System (Geoviticulture MCC Sys- tions i.e. The National Meteorological Institute of the tem) results in 36 different climatic types from a summa- Ministry of Environment (IMN), the Geographical Infor- tion of three indices; the Huglin index (HI), a cool night mation System of the Ministry of Agriculture, Fishing and index (CI), and a dryness index (DI). The classification Food (SIGA), the Environmental Information System of has been successfully tested to differentiate the climate of the Council of Environment for the Galician government 97 viticulture zones worldwide (TONIETTO and CARBONNEAU (SIAM), the Station of Areeiro of Pontevedra, the hydro- 2004). However, there are many regions such as Galicia logic services of the western electrical company FENOSA, where the Geoviticulture MCC System has not been ap- and the Institute of the Higher Agronomic Studies of the plied. Therefore, the main purpose of this research is to use Technical University of Lisbon (ISAUL). In addition, to the Geoviticulture MCC System to investigate the poten- account for a lack of data in the Sil Canyon, three stations tial to provide a more comprehensive viticultural zonation were collected from a 1945-1974 database published by of the region. In addition, the Geoviticulture MCC System CARBALLEIRA et al. (1983). will be compared to other commonly used climatic indices Variables available for the analysis include: monthly in viticultural zonation studies to investigate which meth- mean maximum temperature, monthly mean minimum ods/variables provide the most suitable description of the temperature, monthly average temperature, absolute mini- Spatial climate variability and viticulture in the Miño River Valley 65 mum temperature per month, and monthly total precipita- After normalizing the station data, 14 climate vari- tion. Five of the stations also collected data on solar radia- ables or indices commonly used in viticultural zoning were tion, surface wind speed, and relative humidity (complete summarized or calculated (AMERINE and WINKLER 1944, stations), and were used to compute the potential monthly BRANAS et al. 1946, HIDALGO 2002, HUGLIN 1978, GLAD- evapotranspiration by the Penman-Monteith method (AL- STONES 1992, GÓMEZ-MIGUEL and SOTÉS 2003, TONIETTO and LEN et al. 1988). Evapotranspiration for the stations with CARBONNEAU 2004, YGLESIAS 1983). The first processing only temperature and precipitation variables were comput- included calculating normalized values of six main climate ed by the hybrid method of BLANEY and CRIDDLE (1950). variables: The data were combined into a geographic information - Annual