How important is a rich soil ecology?

Intuitively for most people, a vineyard with grass and wild flowers between the vines is regarded as a Good Thing. It looks pretty, and is indicative of a healthy ecology that has not been destroyed by pesticides. A vineyard soil teeming with life can be an end in itself, and an important benefit of sustainable viticulture. But however good for the environment it may be, is a rich soil ecology critical for good wine?

By way of example, here are images of vineyards that have a lot in common, and yet are totally different. They are both on islands in Southern Europe, and both have volcanic soils. The first one is a vine on the island of Santorini, where the soil has been created by man tilling tuff (a rock of compacted volcanic ash) to a depth of half a metre or so. I only show a small area of the vineyard in the image, but it is typical of the island in that there is little or no vegetation, and the soil has very little organic matter. Lack of water, not over-use of pesticides, is the reason for this barren soil. The other image is from the Northern slopes of Mount Etna. Here there is more water, and nature has had more time to work after the most recent lava flow in the area. So there on Etna, the organic farming methods employed in the vineyard result in a much richer biodiversity – which would also be expected in most parts of Europe.

As for the wines from both these places, I think most people would agree that they are good if not excellent. I do not know where the grapes from that particular Santorini vine would finish up, but the soil is typical of the island and Santorini wine is generally of high quality, and the vineyard on the right is owned by Tenuta delle Terre Nere, one of the most highly regarded Etna producers.

So from these examples can we conclude that organic matter in vineyard soil is not necessarily so important? And that good wine can result from soils both rich and meagre? More contentiously, perhaps even soils poor from the over-use of pesticides can result in good wine? Or could, for example, Santorini wine be vastly improved by applying compost, most of the ingredients for which would need to be imported? These are not totally rhetorical questions – I would genuinely like to know, and I suspect the answers are not as clear-cut as some would have us believe.