Earth and climate A vast variety of soil types and a typically-Mediterranean climate
Just as the grape type constitutes an important reference on a wine list, understanding the soil type and the climate is also interesting for the consumer, since it provides useful information on the taste and character of the wine.
An incredible variety of soil types
In the Languedoc region, we find a vast variety of soil types that vary according to the origin-controlled labels: vast pebble terraces, sandstone and calcareous clay, limestone and shale, clayey soils, pudding stone, sandy soils, molasse, etc., all assets of the Languedoc soils, constituting the individual characteristics of each label of origin.
A typically-Mediterranean climate, albeit slightly different to the East
In the Languedoc, the most Southern region of the country, the climate is essentially Mediterranean. Summers are hot and dry with spring and autumn being rather warm, despite a few possible frosty mornings in April. Winters are also quite mild and sunny with temperatures rarely falling below 0°C. Rainfall is slight (among the lowest in France in some areas) and the Tramontana strong winds help dry the grapes and prevent disease. This is the ideal climate for cultivating the vine. Further west, however, the Mediterranean touch diminishes, mingled with the characteristics of the oceanic climate and influencing the Cabardès and Malepère labels in particular. Here the mildness of the Atlantic meets up with the harshness of the Mediterranean giving rise to a climate of transition.Not only in France, but also in other former wine-growing countries, legislation pertaining to origin-controlled wines depends upon the determination of the wine-growing areas in accordance with the climate and soil type, i.e. the land characteristics. Such characteristics are essential for explaining the originality and quality of a wine.
The main factors
The vine requires bright conditions; nevertheless, it has been noted that excess light and heat in Mediterranean countries can deteriorate the quality of the fruit producing grapes that lack acidity and aroma.
Knowing the overall temperature that is beneficial to the vine in a particular area is of great importance. Indeed, such factor will influence the polyphenol content of the grape harvest. On the other hand, excess heat during the ripening period may deteriorate the delicate aromas in the wine. Beyond a certain threshold in northern regions, grapes no longer ripen, while in other areas, the overall average heat received per annum determines the choice of the grape type (early or late fruiting).
The vine prefers a dry climate, 400 to 600 mm of water per day/month/year, even though it is able to withstand high rainfall. It is crucial that the rain falls as evenly as possible across the vine’s growing cycle.
Other climate factors:
Other climate factors of local interest are mist, fog, spring frosts, wind, hail, etc...
This comprises a three-tier analysis:
- Regional level
- Local level (small region) = mesoclimate
- Vine stock level (land plot) = microclimate
Climate influence at regional level:
Three major wine-growing regions are defined in France
- Alsace, Champagne, Burgundy, western part of the Loire Valley, Jura, Savoy.
- Very contrasted winter and summer temperatures
- Vineyards located in the most favourable areas (importance of local climate)
- Single-grape wines
- Region suited to white wines
- Loire Valley, Bordeaux, South-West
- Insignificant temperature increase between summer and winter
- Regular rainfall
- Most favourable climate for a quality and varied production (white and sweet wines, red wines, etc.)
- The wines are elaborated using an unlimited number of grape types.
- Vineyards from in and around the Mediterranean and from the Rhône Valley
- Extreme weather conditions = summer heat, drought
- Ideal climate for cultivating the vine for a wide range of products, namely, fresh grapes for the table or grapes for bottling, i.e. table wines, controlled-origin wines, natural sweet wines
- Region especially suited to red-wine production
- The wines are elaborated using several grape types.
Climate influence at local or mesoblast level:
At local level, several geographical factors are likely to modify the typical regional climatic data.
- Altitude: the vine is generally cultivated below 300 m altitude [˜ 1,000 ft]. Having said that, vineyards can be found at 3,000 metres [˜ 10,000 ft] above sea level (e.g. in Bolivia)
- Influence due to relief: hillside vineyards enable to obtain the best vintages. The soil is less fertile than on the plains, making harvest less abundant with enhanced sugar content. Sunshine is usually better quality and for longer hours, since the morning mist disappears faster than down in the valleys. Finally, the hillsides are less sensitive to spring frosts and to autumn fog, and provide better drainage.
- Exposure: generally-speaking, the best exposures are SE or SW. However, for vineyards in the North, S and SE exposures are often recommended, while for vineyards in the South, all exposures are acceptable.
- Forests: these provide shelter against cold or damp winds, and water reserves when located at the top of the slopes.
- Proximity of Sea, Lakes or Rivers: the water role is threefold, whether beneficial or not, depending on the considered latitude: it reduces the average temperature in the summer and increases average winter temperatures, and also reduces excessive temperature gaps (thermal cushion effect).
Climate influence at plot or microclimate level:
at plot level, several factors may affect the local climate.
- Upkeep of the land: put down to grassland (damper, cooler) or tilled (dryer, warmer)
- Management of the vineyard: espaliered vine (for better sunshine) or vines pruned into a cup shape (warm or windy areas)...
- Close planting: affects the foliage surface and thus the photosynthetic production.
It is somewhat irrational to unquestionably determine the vine’s preferred soil type. Even though it is clear that a relationship exists between the mineral and chemical content of the soil and the originality of a wine, it is nevertheless difficult to decipher subtle rules. Indeed, it is more the physical characteristics that determine the quality of the wine, rather than the chemical composition of the ground. Regulating the vine’s water supply (i.e. the possibility of retention in the event of excess water and of release during periods of drought) is considered an essential element for land quality. Moreover, an ideal soil for guaranteeing a quality harvest should have low fertility (modest production), while a heterogeneous structure will enable good
drainage and rooting of the vine (plant fed accordingly, though sheltered from climatic hazards).
Natural factors giving rise to the overall diversity of wines