Germany's changing vineyards

In a recent post, I discussed Australia's changing vineyards, as an example of a New World wine-producing area that has changed considerably since 1960, in terms of both vineyard area and grape varietal composition. [Note: one late part of that post has since been modified, due to an error in calculations.] In this second part of the series, I look at Germany, as an example of an old-established vineyard area.

As before, the data come from the Global megafile, National 0920 spreadsheet file of:

Anderson, K. and S. Nelgen (2020) Which Winegrape Varieties are Grown Where? A Global Empirical Picture (revised edition). University of Adelaide Press: Adelaide.

These data consist of the estimated growing areas for each of 107 grape varieties, for each decade or so from 1960 to now — 1964, 1972, 1979, 1991, 2000, 2010, 2016. Sadly, some of the data are reported to be missing for the first four years. However, even more obvious is that there are no data for the Gewürztraminer variety in either 2000 or 2010, even though there are hundreds of hectares reported for the other years  — I had to mathematically interpolate the missing data, in order to do my calculations.

We can start to look at the time-series data by noting that there was a continual increase in total vineyard area in Germany until 1990, as shown in the first graph (click to enlarge). This coincided with the rise in global popularity of German wines, the whites in particular — if there are customers, then the producers will provide the required product. Since 1990 there has been no further increase, and even a slight (<10%) decrease in recent years.

As expected there has been a steady increase in the number of varieties reported, as well, although this may at least partly reflect better data collection in more recent years. In 2016, four times as many varieties were reported compared to 1964 (103 versus 24).

Of more interest, though is the varietal make-up of these grapes. As in my previous post on grape varieties, I have used a network as a convenient pictorial summary of the complex varietal data. As before, I first calculated the percent of each grape variety as a component of the viticultural area, and then calculated the similarity among pairs of years using the Bray-Curtis measure (important, because it ignores varieties that do not occur in either of the two years being compared). I then used these similarities to calculate a NeighborNet network, as shown next. Years that are closely connected in the network (along the edges) are more similar to each other, in terms of their grape varietal composition, than they are to years further apart.

The basic picture is pretty clear. There was a continual change in the varietal make-up of Germany's vineyards from 1964 (at the top-right of the graph) until recently (2010 and 2016, at the bottom). The years are not especially different from each other in the network, except 1964, and their similarities to the general pattern are most prominent. The biggest change in varietal composition occurred between 2000 and 2010, although this was not due to much of an increase in the actual number of varieties (67 and 75, respectively). Between 2010 and 2016 there was the addition of c. 20 new varieties, mostly at 1-2 ha, although Cabernet Carol and Cabernet Cortis had 34 and 59 ha, respectively. Obvious candidates like Grüner Veltliner (so abundant in neighboring Austria) also arrived (14 ha in 2016).

Since Germany is famous for its white wines, we might expect white-grape varieties to dominate; and this is indeed so, as shown in the second graph above. However, even more obvious is the rise of red-grape varieties since 1980. These particularly include Dornfelder (now 8,000 ha versus nothing in the 1960s) and Pinot Noir (11,500 ha versus 1,800), but also Blaufränkisch (1,700 ha versus 400) and Regent (2,000 vs 0).

Dornfelder is a complex hybrid developed in Germany in the 1950s, with both Pinot Noir and Blauer Portugieser in its ancestry (the latter of which has actually decreased in area by 40% since the 1960s). Pinot Noir is, of course, the world's most popular cool-climate red grape variety. Actually, other members of the Pinot family have also increased in area in Germany during the past half-century, including Pinot Blanc, Pinot Gris, Pinot Meunier, and Pinot Noir Précoce.

Note that the increasing prominence of red-grape varieties does not really coincide with the increase in total vineyard area, indicating that the red-grape vineyards were mostly not added, but instead white-grape vineyards were replaced. The most notable decrease occurred in Silvaner (now 5,000 ha versus 18,000 in the 1960s). Interestingly, several other white-grape varieties increased from the 1960s to 1990 and then decreased again, notably Müller-Thurgau (from 14,000 ha in the 1960s to 25,000 in the 1980s, and then back to 12,000 in the 2010s), but also Bacchus, Huxelrebe, Kerner, Morio-Muskat, Ortega, and Scheurebe. Note, also, that the recent decrease in vineyard area (graph 1) coincides with a plateau in the varietal composition (graph 2). This is presumably not actually a coincidence.

All of these changes have lead to an increase in varietal diversity in the German vineyard area, as shown in the third graph above. To illustrate this, I calculated Simpson's Diversity Index for each year, which is a formal measure of such things. Low index values indicate dominance by very few varieties, while higher values indicate much more equal abundances among the varieties. In this case, there has been a continual increase in diversity for 50 years. Notably, the varietal predominance of the triumvirate of Müller-Thurgau + Riesling + Silvaner decreased from 75% of the German vineyard area to 40%. This is still an awful lot of area for only three varieties, of course (but they do make very nice wine).

Presumably, things will continue to change in Germany, given the government's stated intention to be proactive about response to climate change (No wine left behind: how Germany wants to adapt to climate change).

Next time, I will look at France, as the most prominent of the Old World viticultural areas.