Yeast and terroir

An article in Decanter informs us that scientists in New Zealand "have proved for the first time that wine yeasts vary from region to region." This is a idea I have had since I was an MW student - if you check the people who have commented, one is Peter Vinding-Diers and he put on a tasting, in 1994, for a very small group of 2nd year MW students in Sete to highlight the importance of yeast in winemaking. This tasting is mentioned in Patrick Matthews' book, "The Wild Bunch".

Peter's tasting was simple. First, we tasted a wine made at his property in Bordeaux, Chateau Landiras, a decent white Graves. It was fresh, with soft fruit notes (primarily the green flavours of sauvignon blanc) and not overly strong aromatically. He then gave us four glasses, each made from the four separate strains of yeast he had identified as living in the winery. These were very different - two were fairly bland in style, being quite similar to the wine we had just tasted. Two were much fruitier, with one having a strong character of mango and tropical fruits. Peter explained that these latter wines were made from yeasts which made up less than 10% or so of the total yeast population.
After this, we then were given two glasses of wine which tasted very different to each other. These, fascinatingly, were made from grapes picked in one of his vineyards but vinified in two batches. The first batch was vinified at Landiras but, crucially, the second was vinified at Lynch-Bages in the Haut-Medoc! Although the absolute origin of the fruit was identical the flavours were vastly different.
The conclusion which I drew from this was that the so-called flavour of terroir was more likely down to differences in the local yeasts - remember that, in Europe, spontaneous fermentations are caused by yeasts which live in the winery (Ribereau-Gayon & Peynaud); this is different in the new world where most winemakers use cultured yeasts. This all suggests that the difference between wines from different sites is more likely due to the differences in yeast strains to be found in the relevant wineries - something borne out at a tasting in Oregon in 1999 where 3 producers showed 3 wines: each made 1 wine from their own fruit as well as 1 wine each from fruit from their neighbours, but with all the wines made at their own winery. When asked to find patterns in the 9 wines tasted I found it easier to identify who had made the wines, rather than where the wines originated - I assume because each winemaker had used a yeast of their own.
There are, undoubtedly, site-specific issues in relation to flavour pre-cursors (Nerida Abbott did her PhD on this very topic) but I firmly believe that yeast is an important contributor to regional identifiers in a wine.