Portugal The Refuge: A Hot Spot For Diversity

Text and photographs by John Szabo MS

Most European countries are fiercely proud of their indigenous grapes. Unique local varieties provide a critical point of difference on the over-crowded shelves of wine shops and attract the attention of sommeliers. But the term “indigenous”, so frequently used in the world of wine, is, as it turns out, often incorrectly applied to grape varieties. Technically, an indigenous plant originates in the region in question, a true native as it were. Most European grapes are more correctly termed endemic varieties, that is, belonging exclusively to or confined to a certain place, even if they are not originally from there.

The true origins of most Vitis vinifera varieties is almost certainly somewhere in the Middle East. Over the course of millennia, vines moved from the East throughout continental Europe, each finding their ideal growing environment, first through Nature’s, and later man’s vast experiments of trial and error during domestication. Many varieties have since become confined to relatively small areas.

Although the line is purely arbitrary, most would consider a grape that has been growing somewhere for more than a few hundred years to be indigenous, even if it is really only endemic. Sure, it will have adapted to local conditions, but its origins are nonetheless elsewhere. The distinction may seem overly academic, and it surely is, though in a wine world increasingly hungry for diversity and originality, the discrepancy may one day take on some importance.

Truly Indigenous

And if such is the case, then recent research just might give Portuguese winegrowers a marketing leg up on their competitors, arming them with unassailable proof that the country’s 250-odd grapes can truly be called both unique and indigenous. The discovery of wild grape vines growing in southern Portugal has led researchers to hypothesize that this corner of the Iberian Peninsula was a so-called refuge for Vitis vinifera during the last ice age.

Until some 12,000 years ago, Europe and Central Asia (and North America) were covered under a vast ice sheet, and had been for over 100,000 years. During this period, it’s believed early man built underground refuges to survive and escape the cold. Grapevines, of course, had no such recourse, and many of the wild European grapevine species known as Vitis vinifera sylvestris would have perished during the endless cold like merlot on a frigid Niagara night.

It had long been speculated that only the area around the Middle East and the Caucasus Mountains was spared the worst of the Ice Age, enabling plants such as grapevines to survive. The scientists call these areas “refuges”, and many of today’s popular grapes can trace their DNA breadcrumbs back to this Middle Eastern refuge. Yet there’s increasing evidence that the grapevine found refuge elsewhere in Europe. Southern Italy, for example, displays genetic diversity not found in the Middle East. But the scientific jury is still out.

But a refuge on which the scientists do seem to have recently agreed is the southwest corner of the Iberian Peninsula. The proof? “Most native Portuguese varieties are not found in the Middle East, or anywhere in between the two presumed refuges”, says António Graça, the technical director for the Sogrape Wine Group, one of Portugal’s largest wine companies.

Growing Wild

What’s more, several populations of wild grapevines have been discovered in the southern half of Portugal, covering more territory than any other population found so far in Western Europe. The vines were found growing up trees in woods near riverbanks that regularly overflow. The repeated flooding is believed to have kept phylloxera out, the louse that may otherwise have killed the wild vines, as it did virtually all of Europe’s commercial vineyards around the turn of the 20th century.

And according to Graça, “recent advancements in DNA studies have confirmed that many of Portugal’s unique native varieties are more closely related to these wild Iberian plants than to anything found in Eastern Europe or the Middle East”. This leads to the tempting suggestion that the vines must have originated there, otherwise they would show more genetic similarities to other common European grape varieties.

This evidence is corroborated by Swiss researcher Dr. José Vouillamoz, co-author with Jancis Robinson MW and Julia Harding MW of the monumental tome Wine Grapes, published in 2012. Vouillamoz quotes via email that “According to Arroyo-García et al. (2006), over 70% of the grape varieties of the Iberian Peninsula display chlorotypes (i.e. categories of chloroplastic DNA) that are only compatible with their having derived from western Vitis vinifera subsp. silvestris populations of wild grapevines, thus suggesting a secondary domestication centre. This is backed up by Cunha et al. (2009) who found a predominance of chlorotype A both in wild populations and cultivars in Portugal, and by Lopes et al. (2009) who have found evidence for a gene flow between local wild grapevine populations and domesticated vines in Portugal, suggesting that this region was a possible refuge during the last glaciation, giving rise to many of the Western European cultivars.”

Continued Research To Preserve Diversity

Although Graça and others have already spent years studying the native grapes of Portugal, the research is set to continue with the establishment of a far-reaching program called PORVID, whose aim is to preserve, protect and evaluate the commercial potential of Portugal’s rich vine biodiversity.

PORVID, founded in 2009, is a public-private funded association composed of universities, technical groups, wine companies, municipalities and the Ministry of Agriculture. 110 hectares of public property have been set aside outside of Lisbon to establish a vine conservation park for a 50-year term. 50,000 clones of 250 native varieties have been planted in the park, with vine cuttings taken from Portugal’s enviable collection of old, and in some cases abandoned, vineyards. “About a quarter of native Portuguese varieties have already been studied extensively”, says Graça, “but there’s still a lot of work to be done”.

Over the next 50 years each of the varieties and their clones will be grown and observed, and made into wine, and the results of the research will be shared with the industry.

I consider this critically important work, especially considering the erosion of vine diversity that has occurred across Europe since the era of phylloxera, and the predominance of a small handful of grapes transplanted outside of Europe. In the end, the world can only benefit from preserving vine, and thus wine, diversity.

Biodiversity in a Glass and the Benefits of Government Non-Intervention

Origins aside, most would agree that Portugal has a marvelous collection of unique varieties. And one reason why such a deep repertoire of vine diversity was retained is the fact that up until the 1970s, virtually all of Portugal’s vineyards were planted to field blends, rather than the monovarietal plantations that came to dominate in the rest of Europe. The persistence of these valuable field blends was the unanticipated benefit of Portugal pretty much missing the industrial revolution, as well as other international developments during the 20th century under the Luso-centric dictatorship of António de Oliveira Salazar, whose introverted right-wing government ruled Portugal until 1974.

It was during the period of post war growth that many of Europe’s vineyards were “rationalized” and mechanized for industrial agriculture, and converted to monocultures. Portugal (and Spain) followed a different path, and even today there are many old vineyards in the Douro Valley, for example, that still contain over 50 different grapes co-planted. By comparison, the top 20 most planted grapes in France in the 1950s represented just over 50% of vineyard area. Today, that figure is over 90%, as local specialties have been replaced with more “popular” grapes.

Back to the Future

But now the benefits of interplanted cultivars are (re)gaining recognition. Among other advantages, mixed plantings confer greater resistance to disease, thanks to genetic diversity. In monocultures, a single pathogen can wipe out an entire vineyard. But with mixed plantings, usually only some, but not all plants succumb. Mixed plantings could lead to a reduction in pesticide use.

Many also claim that field blends make for better, more complex wines, which is logical enough – more instruments make for a richer sounding orchestra.

The most common disadvantage cited is that the ripening times between varieties differ, leading to complicated harvests and an inevitable mix of under and overripe grapes. But Cristiano Van Zeller, a leading figure in the Douro Valley at his Quinta Vale Dona Maria, points to empirical evidence that the ripening cycles of grapes harmonize over time, leading to more uniform ripeness (Jean-Michel Deiss, another proponent of mixed plantings, has observed the same phenomenon in Alsace). Van Zeller has vowed only to plant field blends in the traditional style in the future. “The results are far superior”, he says, and he’s far from alone in his belief.

Alvaro Martinho Dias Lopes, the man responsible for viticulture at the Quinta das Carvalhas – the jewel in the crown of the Real Companhia Velha in the Douro – is also a believer. “The best parcel we have every year is the old vine field blend”, he tells me. The site, a north-facing slope down towards the river produces the exceptional Quinta des Carvalhas Vinhas Velhas [old vines], one of the Douro’s top red table wines, so the evidence is compelling. All future plantings at Carvalhas will be field blends of at least a dozen varieties, Martinho reveals, pointing to a recently re-planted parcel to prove the point.

There are many more great wines from field blends yet to come it seems, something I look forward to seeing.

John Szabo MS

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