Mediterranean climate and viticulture By Maurizio Gily A cool climate is the best one to get top quality wines from vineyards: this is what most people believe, especially in English-speaking countries. From this viewpoint, the wines produced in Southern Italy, which is considered a warm climate land, may certainly aim at being included among the good wines, yet without reaching the world s wine excellence, except for rare exceptions. In this short paper I will try to explain why, in my humble opinion, based on my experience and some evidence and recent scientific findings, things aren t what they seem. The crucial matters are three: the first one refers to the relationship between indigenous varieties and the environment, the second one is related to the environment itself and some clichés about climate of Southern Italy, the third one covers the viticultural "mitigation" of excess heat through the canopy management. The theory of "cool climate" has solid foundation, based on both science and experience. My only remark is its generalization. Many wines produced in Southern Italy (but also in the South of France and Spain), particularly those made from indigenous grapes, don t respect this rule. A premise about wine making: the use of cooling systems in the cellar has been the key to their quality revolution: without them, in large masses, producing quality wines in a warm place would have been almost impossible. This practice dates back to few decades ago, thus quality wines of South Italy rely on a quite brief history and this still affects negatively their image. It's time to dispel these prejudices which still exist. Vine and environment With their work and writings, remarkable scientists like Emile Peynaud in France and David Jackson in New Zealand have explained how quality viticulture is mainly a "borderline" one since vines are sometimes even hardly grown. However Peynaud has also recognized that these are strongly influenced by the vintage, thus benefiting from the opportunity to produce a great wine just for few vintages, whereas warmer climates offer a more consistent quality, although (in Peynaud s opinion) the level is rather lower. The fact that both Peynaud and Jackson were grown in cool-temperate climate areas (Bordeaux for Peynaud and Christchurch for Jackson) may raise some doubts of impartiality. But this is not the point. The first objection focuses on the relationship between grape variety and environment. In a 1993 work published on the American Journal of Enology and Viticulture, and widely cited in the literature, Jackson and Lombard compare the climates of some world's wine-growing areas and the period of harvest of three common worldwide spread varieties. They observe that the best wines are obtained where the grapes ripen in the "alpha" area with average temperatures below 15 degrees (Celsius) during the ripening. The maturation at too hot temperatures- this is what Jackson and Lombard explain - causes a "misalignment" between the sugar upload (too early), the physiological ripening (sugar / acid ratio, with excessive fall of the latter), phenolic ripening (when sugars are already high, tannins aren t ripe) the aromatic ripening (with loss of aromatic precursors due to oxidation and respiration) and the color ripening (the same problem of aromatic precursors).
In Perth, Australia, all the three varieties taken into consideration mature too early (beta zone) to the detriment of quality, while in Christchurch, New Zealand, all the three varieties ripen in alpha zone. Jackson, who was a teacher in Christchurch, omits to say that the Cabernet Sauvignon in Christchurch hardly ripens in a cooler year! But the real question is: which are the varieties examined by Jackson and Lombard? Two varieties from cool climates, Pinot Noir and Riesling, as well as a grape from a temperate oceanic climate, the Cabernet Sauvignon. By Jackson and Lombard, 1993 B = budburst F = flowering V = veraison H = harvest
This choice is justified by the widespread use of these grapes in the New World: but can we apply these conclusions to those regions where completely different varieties have been mostly grown- due to the way they adapt to the local environment-? Definitely not. First of all, southern varieties are generally later ripening than Cabernet sauvignon, and much later than Pinot noir. They often approach the alpha area, especially at altitudes exceeding 400 meters (Irpinia, Vulture, Alta Murgia, Etna); secondly their response to high temperatures is different from that of the Central European grape varieties. They often have high fixed acidity, which makes these grapes unsuitable to cooler climates, where they would give too aggressive wines. Then there is a physiological mechanism to take into consideration. At extremely Summer high temperatures some varieties, more than others, stop the photosynthesis through the mechanism of stomatal closure, thus delaying the ripening cycle. The stomata are the openings of the leaf through which gaseous exchanges take place, as well as the loss of water vapor and oxygen and the input of carbon dioxide. For this reason the closure of the stomata involves the blocking of photosynthesis, which takes over when the temperature drops. In cooler climate vineyards this closure takes place to a limited extent (isohydric behavior), so the basal leaves dehydrate because of the excessive perspiration and may fall, exposing the bunches to the direct sunlight, which can burn them, and over-ripening phenomena may also occur. The climate: warm, but... Wladimir Köppen is the most famous among modern climatologists. He created a universally accepted classification of the world climates. In this classification, the Mediterranean climate is a subset (s) of the larger group of temperate climates (defined as those where the coldest month has an average temperature between -3 and +18 C) and its distinctive feature is a dry summer in the respective hemisphere (high sun position). The mitigating effect of the sea limits the continentality, that s to say the temperature difference between summer and winter, and prevents the temperature from rising too much in summer (except for the occasional presence of sirocco wind from Saharan Africa) while winters are mild. Beyond the general blandness, another feature belonging to the Mediterranean climate, as we have seen, consists in a dry season, with little or no rainfall, along with the warmer months, and a wetter winter season (the exact opposite of what occurs in tropical climates). In any case the annual rainfall is low (less than 600 mm) while the level of solar radiation in the growing season is very high, as the sky is almost always clear: with obvious consequences, among other things, on the health of the fruit and low impact of fungicide defense. Regions classified by Köppen as Mediterranean are shown in the following map.
Apart from southern Italy, south French regions and the Iberian peninsula are involved, as well as Greece, the north coast of the Maghreb countries and much of the Mediterranean coast (hence the name), but also California, sub- coastal South Africa, much of Chile, South Australia (Adelaide) and the West (Margaret River). These are all traditionally wine-growing regions. This is a rough classification since there are climatic differences between these areas, especially in terms of temperatures, depending on the latitude and the relieving effect of the sea, which is stronger in islands and peninsular offshoots as Puglia and Calabria. South Italy and France represent, in this sense, the Northern Mediterranean. Mitigating factors heat: altitude and wind Most wine-growing areas in Southern Italy are located at altitude, thus avoiding the risk of excessive heat. Among the best known wines produced in these areas there are all the wines belonging to the Etna area, as well as Taurasi, Aglianico del Vulture, most of the Fiano, Greco and Falanghina from Campania, different wines of high ground of the Sicilian mountains and the Apulian Murgia. As far the coastal areas we have to take into consideration the relieving effect of the wind, as well as of the sea. As shown in the map below, the windiest areas of Italy are the Southern parts of Sicily and Sardinia, and Salento too. The effect of the wind consists in standardizing the temperature of the fruit to that of the air. At a temperature of 35 degrees Celsius (95 F), when it s not windy, a cluster of black grape hit by the sun reaches and exceeds the temperature of 50 degrees C. (122 F). If it s windy its temperature reaches the same level of that of the air (35 ). We've all experienced this phenomenon parking the car in the full sunlight of a summer windy day if compared to what happens when the air is still.
Canopy management to cope with climate: the bushvine The tradition of southern Italy, as well as of other Mediterranean countries, at least in the warmer areas, provides only for a partial exposure of the fruit to the direct sunlight. The traditional method to reach this goal is the bushvine. Where the soil is more fertile and fresh, as it is in some areas of Campania, Lazio and Abruzzo they use a overhead, horizontal canopy (pergola). The bushvine has been partly abandoned in recent decades as it hasn t proved to be suitable for mechanization and thus it has been turned into partial VSP (vertical shoot
positioning) trellis systems,yet keeping a form of umbrella in the highest part of the canopy, obtained by making the top of the shoots fall downward. The aromatic precursors A widespread notion is related to the negative effect of high temperatures on aroma precursors and the positive effect of the excursion temperature variation. To stress how inaccurate this dogma is, it would be enough to point out that one of the most prestigious wine-growing areas of the world, the Médoc, Atlantic peninsula, usually enjoys modest day/night temperature variations. Recent studies have confirmed how negative excessive heat peaks are on the bunches. However some aromatic precursors, in particular norisoprenoids (aromas of tropical fruit and candied) develop better during mild nights (not too cold), while other precursors (terpyneols, benzenoids) show the opposite behavior. Since it s a rather complex mechanism which is not fully understood, we d better be very careful before embracing easy simplifications. Take the Chardonnay as an example, the most adaptable to the climate among the cultivated varieties. Chablis and Chardonnay from Sicily can be both rich in aroma, but very different as far their flavor spectrum. I would conclude my paper mentioning a North Italian man s opinion (I live in Piedmont) given by his long lasting experience in Southern viticulture. In ancient times the wines belonging to the Mediterranean area dictated the paradigm of quality which was then acquired by the northernmost wine in the twentieth century. In the twenty-first century it s time to appreciate the character of quality wines produced in different territories and from different grapes (which have been grown for centuries in these lands) using flexibility. The Mediterranean wines aren t better, and aren t worse: they are different. In essence, this has been already understood by the market. Maurizio Gily viticulturist www.gily.it