untertitel: produzenten, lagen, jahrgänge

burgund ist für den laien - und manchmal nicht nur für den - ein Sammelsurium was bezeichnungen...qualitäten....winzer....anbetrifft, um nur einiges zu nennen. oft  ist man mehr verwirrt nach dem lesen einer lektüre als vorher. das ist genau was dieses buch nicht tut ! selten habe ich ein klarer strukturiertes buch  gelesen als dieses. es dient mir als schnelles & kompetentes nachschlagewerk. mit nur wenig grundwissen über wein kann man sich in das burgund einlesen. es werden die gesetzlichen bestimmungen erklärt und passend dazu die reale qualitätspyramide. denn die grand-cru lage, um ein beispiel zu nennen,  als solche garantiert noch keinen  spitzenwein. etwas was man nach dem französischen ac gesetz, sehr wohl annehmen könnte. will heißen es wird einem vermittelt wer wo welche qualitäten zustande bringt.

ein buch sowohl für den experten als auch für den laien !

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hier der originaltext der anfrage in sachen weinhandelsabkommen eu - usa.

Angehängte Dateien: ka_wein.pdf (294 kb)

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Klimaveränderung - denkbare Folgen für den Weinbau

Dr. D.Rupp
LVWO Weinsberg
E-Mail: dietmar.rupp@lvwo.bwl.de

Nach Pressemitteilungen des IPCC, der Internationalen Stabstelle der Vereinten Nationen zur Beobachtung und Erforschung des Treibhauseffekts, war das Jahr 2001 das zweitwärmste seit Beginn der weltweiten Temperaturaufzeichnungen. Demnach nimmt die globale Erwärmung weiterhin zu.

Gilt diese Beobachtung auch für die Weinbauregion Württemberg? Wie sehen örtliche Messwerte aus und gibt es bereits Beobachtungen an den Reben?

Wetter und Klima ist nicht dasselbe

Nach einem feuchten, sonnenarmen September lagen die Messungen der Weinsberger Station für den Oktober 2001 mit einer Monatsdurchschnittstemperatur von 13,8 °C um 3,9 °C über dem langjährigen Mittel. Damit ist dies der wärmste Oktober seit Beginn der Weinsberger Wetteraufzeichnungen.

Im Kontrast dazu bestand in weiten Teilen des Landes von Beginn der Weihnachstage bis weit in den Januar 2002 eine geschlossene Schneedecke. Die Freude über diese selten gewordene, weiße Pracht wurde aber jäh getrübt. In der Nacht auf den 24.12. fiel das Quecksilber der Weinsberger Wetterstation auf eisige -18,5 °C. Direkt über dem Schnee wurden sogar -20,5 °C gemessen. Frostschäden bis hin zu Totalausfällen, vor allem im nordöstlichen Teil des Anbaugebiets, waren die Folge.

Trotz dieses Kälteeinbruchs lag die Jahresmitteltemperatur des Jahres 2001 um 0,7 °C über dem aktuellen 30-jährigen Mittel von 10,0 °C.

Der langjährige Temperaturtrend zeigt nach oben

Gerade die Daten der alle zehn Jahre fortgeschriebenen Normwerte ("Normalperiode") zeigen auch in Weinsberg eine kontinuierliche Entwicklung nach oben. Nicht nur die 30jährige Jahresmitteltemperatur hat sich seit den 1960er Jahren erhöht. Auffallend ist die stetige Zunahme bei den Monatsmittelwerten für die Monate Dezember, Januar, Februar sowie Juli und August. In der Tendenz sind damit die Wintermonate wärmer und die Sommermonate heißer geworden. Bei weitgehend unveränderten Niederschlagswerten hat dies nässere, d.h. schneeärmere Winter und ein vermehrtes Risiko von sommerlichen Trockenphasen zur Folge.

Rebaustrieb und Traubenreife setzen früher ein

Bereits zwanzigjährige Zeitreihen zeigen bei phänologischen Basisterminen eindeutige Verschiebungen nach vorne. So beginnt der Austrieb bei der Sorte Riesling am Standort Weinsberg im Vergleich zum Beginn der 1980er Jahre heute im Mittel eine Woche früher. Die Hauptblüte setzt durchschnittlich 8 Tage früher ein und der Reifebeginn ist in der Mehrzahl der Jahre um 6 Tage nach vorne gerückt.

Falls diese Beobachtungen keinem vorübergehenden Phänomen zuzurechnen, sondern Teil einer tiefgreifenden Veränderung sind, muss der Weinbau mit folgenden Auswirkungen rechnen:

Die Aussicht auf warme und gute Weinjahre oder gar die Vorfreude auf die weitere Verbreitung von Cabernet sauvignon oder Syrah am Neckar könnten aber auch trügerisch sein.

Insbesondere die Kosten oder die denkbaren weltpolitischen Folgen einer Klimaverschiebung dürften auch der Weinwirtschaft Probleme bereiten.

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As more new world producers start to take an interest in terroir, scientists are turning their attention to defining it and explaining how it affects a wine. Jamie Goode investigates. (This feature was originally published in Harpers Weekly, September 12th 2003)

‘Terroir’ is currently an in vogue concept. Once almost exclusively the preserve of the old world, it’s now a talking point in the new world, too. The traditional, old world definition of terroir is quite a tricky one to tie down, but it can probably best be summed-up as the possession by a wine of a sense of place, or ‘somewhereness’. That is, a wine from a particular patch of ground expresses characteristics related to the physical environment in which the grapes are grown. But why the sea-change in the new world, where for so longer the job of grape growing was seen merely as a mundane prelude to the work of the all powerful winemaker?

Even fairly recently, the new world response to ‘terroir’ was that it was a last ditch marketing ploy by European winegrowers who were panicking about their increasing loss of market share. This turn-around is because new world wine growers have realized that one of the keys to wine quality is starting with grapes that show homogeneous (even) levels of ripeness, and the recognition of the role that natural variation within and between their vineyards plays. With the increasing adoption of technique known as precision viticulture, vineyards are commonly broken up into sub-plots sharing similar characteristics (known as natural or basic terroir units) so that vineyard interventions can be precisely targeted to where they are needed. But you don’t have to look too far below the surface to see that there are subtle but important differences between old world and new world notions of terroir. Speaking generally, in the old world terroirists aim to make wines that express the typicity of the specific vineyard site, whereas in the more pragmatic new world, understanding terroir is seen as a route to improved quality.   

A taste of the soil?
The notion of terroir is fundamental to the wine industries of old world countries such as France, Italy and Germany. It’s a philosophical framework within which wine growers work. Local wine laws are built around the concepts of appellations, which lend official sanction to the idea that a combination of certain vineyard sites and grape varieties creates unique wines that faithfully express their geographical origins. 

Correspondingly, many old world growers feel they have a duty to make wines faithful to the vineyard sites they are working with. These growers will commonly make associations between properties of the wines and the soil types the grapes are grown on. In some cases these putative associations are quite specific: people will talk about mineral characters in wines and associate them with the minerals in the vineyard, taken up by the roots of the vines.

There’s even a French expression, goût de terroir, that is used to describe this. Do chalk, flint or slate soils impart chalky, flinty or slate-like characters to wine? As a scientist who has a working knowledge of plant physiology, I find this notion, which I call the ‘literalist’ theory of terroir, implausible. Yet I can’t get away from the fact that an overwhelming majority of the world’s most compelling and complex wines are made by people who hold the notion of terroir as being critical to wine quality. 

Thus the goal of this feature is to explore the mechanisms of terroir, focusing specifically on soils. Just how do soils affect wine quality? Is it a direct or indirect relationship? What are the scientific explanations for terroir effects?

Randall’s Rocks
In fact, the inspiration for this article came from a characteristically wacky experiment conducted by Randall Grahm, of California’s Bonny Doon. Even though he’s from California, Grahm is actually one of the most eloquent proponents of terroir, and he had the unusual idea of bypassing the vine and adding rocks directly to wine, to investigate their influence on flavour. 

‘Our experiments were incredibly simplistic and gross in comparison to the very subtle chemistry that occurs in mineral extraction in real soils,’ explains Grahm. ‘We simply took interesting rocks, washed them very well, smashed them up and immersed them in a barrel of wine for a certain period of time, until we felt that the wine had extracted some interesting flavours and we were able to discern significant differences between the various types.’ 

Surely, this is taking the literalist notion of terroir – that flavour compounds are translocated from the soil to the developing grapes through the vine roots – to its extreme. Grahm continues, ‘We initially screened a number of different rocks with bench trials and ultimate decided on a few for larger scale experimentation - rip rap (granite), Noyo cobble stone, black slate and Pami pebbles.  We certainly took the extraction way too far as we ended up seeing pH rises of 0.5–0.7 units, i.e. from 3.5 to 4.1 or 4.2, which is clearly beyond the pale for most wines.  Obviously the big pH shift and the lowering of the acidity caused major changes in the texture and mouthfeel of the wine, but we also observed dramatic differences in aromatics, length and persistence of flavour.’ 

Grahm is convinced of the importance of mineral flavours in wine. ‘In every case, low doses of minerals (before we really overdid it), added far more complexity and greater persistence on the palate.’ His view is that minerality in wines has important implications for wine quality. ‘It is my personal belief that wines that are richer in minerals just present way differently. I believe that in general mineral-rich wines there is a suppression of obvious fruit. What is most striking to me though about wines that have higher levels of minerals is that they seem to have a certain sort of nucleus or density around their centre, they are gathered, focused, cohered the way a laser coheres light. It is a different kind of density relative to tannic density, somehow deeper in the wine than the tannins.  In any event, I am utterly convinced that minerality is the one true key to ageability in wines and that everything else—tannin, acidity, sulphur dioxide—plays a far more secondary role.’ 

It is unlikely that adding rocks to wines will ever become a common winemaking manipulation, though. Grahm’s rock-infused wines ran into some trouble with the regulatory body in California who were finding elevated levels of nickel and antimony, among other things, so it looks like this experiment won’t be repeated.

Scientific views of terroir
While in some circles it is quite common to hear such literalist explanations of terroir, they are treated with a degree of incredulity by many new world viticulturalists. I asked viticultural guru Dr Richard Smart what he thought of popular notions of terroir which propose direct translocation of flavour molecules from the soil to the grapes, and hence the wine. ‘This is an absolute nonsense’, he replied. ‘I have never heard this, yet you say it is popular. Who on earth postulated this?’ 

Dawid Saayman, a South African viticultural expert known for his work on terroir, adds that, ‘I don’t believe that the minerals taken up by the vine can register as minerality in the wines. Minerality appears to me to be more the result of absence of fruitiness.’ But it’s pretty much a given that wines that made from grapes differing only in the soil in which they were grown taste different. 

So just what is the scientific explanation for these terroir effects? It is an important question, because providing a sound scientific footing for terroir is a worthy cause. Not only will it lend credibility to the concept in the eyes of sceptics, but it will also help the already converted understand and therefore better utlilize terroir effects.

If we are going to frame terroir in scientific language, then we’ll need to start with some plant physiology. The miracle of the plant kingdom is that these complex organisms build themselves from virtually nothing: all a plant needs to grow is some water, sunlight, air and a mix of trace elements and nutrients. All the complex structure and chemistry of an oak tree, a daffodil or a grapevine is fashioned from these very basic starting ingredients. What do vine roots take up from the soil? Primarily water, along with dissolved mineral ions. 

It seems implausible that such a complex structure as a vine is created from virtually nothing by photosynthesis – the capture of light by specialized organelles called chloroplasts, which turn light energy into chemical energy that the plant can use—but that’s the way it is. As Richard Smart emphasizes, ‘All flavour compounds are synthesized in the vine, made from organic molecules derived from photosynthesis ultimately, and inorganic ions taken up from the soil.’ 

Professor Jean-Claude Davidian of the Ecole Nationale Supérieure Agronomique in Montpellier, echoes these sentiments. ‘Nobody has been objectively able to show any links between the soil mineral composition and the flavour or fragrance of the wines’, he says. Davidian adds that ‘those who claim to have shown these links are not scientifically reliable’.  

Mechanisms of terroir, part 2

Treating vines mean to keep them keen  

It is helpful to think about plants as sophisticated environmental computers. Just as we sense the world around us and then use this information to guide our actions, so do plants. It’s just that whereas we respond quickly – for example, if it is too hot in one place we move somewhere cooler – plants respond over a much longer timescale. Literally rooted to the spot, they adapt their growth form to best suit the local conditions. 

This extends to their reproductive strategies. Generally (and simplistically) speaking, if conditions are good, then plants opt for vegetative growth; if they are bad, they choose to reproduce sexually (the ‘I’m outta here’ option), which means fruit production. So viticulturalists want to treat their vines mean enough that they focus on fruit production, while giving them just enough of what they need so that they don’t suffer from water or mineral deficit, which would hamper their efforts at producing ripe fruit. Thus many viticultural interventions aim at encouraging the vine to partition nutrients to the grapes so that they ripen properly, rather than concentrating on growing more leaves and stems (vegetative growth or ‘vigour’). 

An example of this ‘environmental computing’ is seen in the growth of plant roots. Root growth is determined by interplay between the developmental program of the plant and the distribution of mineral nutrients in the soil. The roots grow to seek out the water and nutrients in the soil: to do this it appears that they sense where the various nutrients are and then preferentially send out lateral shoots into these areas. Low levels of nutrients in the upper layers of the soil results in the roots growing down to a greater depth, which is likely to improve the regularity of water supply to the vine. 

‘Vines have roots which can reach up to 3 metres in depth’, reports Davidian. ‘These deep roots can actively take up water and minerals, even though most mineral ions are more abundant at the root surface.’

A popular notion is that very old vines with deep roots express terroir better. ‘The claims often made regarding the importance of deep rooted vines are based on the assumption that the roots are then able to better exploit the underlying geology’, says Dawid Saayman. ‘In turn, this is considered by some to contribute certain minerals and thus impart a certain character to the wine. There is no scientific proof for this.’ It’s also worth mentioning here the existence of mycorrhizae. Many plant roots form an association with specific soil fungi, where the fungi hitch a ride on the roots, gaining energy from the plant, while the plant root gains an enhanced absorptive area and ability to extract mineral nutrients from the soil – this is termed a ‘mutalistic symbiosis’, because both partners benefit. 

Some people have claimed that mycorrhizae are important for terroir expression, but this is not clear from the scientific literature. Dawid Saayman points out, however, that grape vine mycorrhizae mainly assist in phosphorus uptake, an element that vines usually don’t have problems getting enough of. ‘It is highly unlikely that mycorrhizal associations are prominent enough to contribute to a terroir effect’, he concludes.

How soils have their effect  
Soils differ in their chemical and physical properties. According to Victoria Carey, a lecturer in viticulture at Stellenbosch University who specializes in terroir, the latter are more important for terroir effects. ‘The most convincing indications in the scientific literature are that the effect of soil type is through its physical properties, and more specifically, through the water supply to the grapevine,’ she suggests. 

This is a position that Richard Smart agrees with: he cites the pioneering work of French scientist Gérard Seguin, who conducted a survey of the properties of the soils in the Bordeaux region. Seguin couldn’t find any reliable link between the chemical composition of the soil and wine character or quality, and maintained that it was the drainage properties of the soil affecting the availability of water that mattered. He concluded that it is ‘impossible to establish any correlation between the quality of the wine and the soil content of any nutritive element, be it potassium, phosphorus or any other oligoelement.’ 

The verdict was that it was the physical properties of the soils, regulating the water supply to the vine, that were all important in determining wine quality. The best terroirs were the ones where the soils are free draining, with the water tables high enough to ensure a regular supply of water to the vine roots which then recedes on veraison (when the berries change colour) so that vegetative growth stops and the vine concentrates its energies on fruit ripening.

The consensus among the viticulture experts I consulted seems to be that the chemical composition of the soil – that is, nutrient availability – is only important when there is excess nitrogen, leading to excess vigour, or when there is a serious deficiency. ‘Nutrition can be instrumental to the specific growth pattern of the vine and thus can cause a specific canopy architecture and therefore ripening pattern,’ says Dawid Saayman. ‘The plant performance therefore modifies the vineyard climate creating a specific microclimate in the bunch zone, and in this way it can greatly determine the character of the wine’, he adds. ‘Overall, nutrient effects are minimal’, adds Smart.

Soil chemistry effects
But before we give up on soil chemistry as an important factor in terroir, it’s worth taking a look at recent research on the effects of mineral nutrition on plant physiology. I spoke to a number of researchers who are actively working on plant mineral nutrition, so see whether their work might shed some light on the mechanisms of terroir transduction. 

‘I wouldn't be at all surprised if soil chemistry had an effect on the expression of genes that are involved in the production of the compounds that determine flavour,’ says Professor Brian Forde of Lancaster University (UK). ‘There is certainly plenty of evidence that plants are tuned to detect and respond to soil nutrients’, he adds. ‘The balance between the nutrients (nitrogen, phosphorus, potassium, sulphur and calcium, and even the micronutrients) is likely to be important and the plant stress responses elicited by limiting amounts of one nutrient would probably be subtly different from the stress responses elicited if another nutrient is limiting.' 

Forde referred me to some publications showing that the levels of various plant metabolites were significantly altered under different nutrient regimes. At a more detailed level, it is now clear that patterns of gene expression in plants are altered by the presence and absence of various nutrients.

I spoke to Professor Malcolm Bennett and Dr Martin Broadley of Nottingham University, who recently published a paper showing the effects of phosphate deficiency on plant gene expression. Broadley feels that it won’t be too long before we have a much better idea about the influence of soils on wine flavour. ‘There is a large amount of work underway to understand the molecular biology of grapes, and scientists are identifying genes that influence wine flavour’, he explained. ‘As more grape molecular biology is known, the easier it will be to understand mechanisms of terroir on wine taste. When genes encoding for proteins that influence wine taste are identified, then the effects of different components of terroir (e.g. the availability of different minerals, soil pH, soil water content) on specific biochemical pathways can be identified and tested. This research may allow current agronomical practices to be improved to enable better-tasting grapes to be produced, or it might even allow varieties of grapes to be selected or bred more effectively.’

Concluding remarks  
Even if science leaves us with what currently looks like rather an emasculated version of terroir, I don’t think that this necessarily diminishes the importance of this cherished concept. Wine growers who use terroir as their guiding philosophical framework and focus on the importance of the soil are responsible for a disproportionately large share of the world’s most interesting wines. Perhaps Randall Grahm’s wacky rock experiments aren’t so misguided after all: although it seems clear that there is no direct link between soils and wine flavour, by framing their activities within the context of a soil-focused worldview and trying to get a bit of somewhereness and minerality into their wines, winegrowers might be vastly increasing their chances of making interesting wine. And that’s something the world needs more of.  

quelle: harpers

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