Mountain viticulture, hot climate and the art of blending the port wine triad

Abstract

The Douro Demarcated Region (DDR) is an extraordinary, living example of Mountain Viticulture in Hot Climates.

Even though the analysis of climate data for the three 30-year periods prior to 1990 is not predicative of the terrible climatic changes that the IPPC expects the Iberian Peninsula to suffer by the end of this century, our concern with this worst-case scenario led us to reflect on the climate of the Region.  The foremost result of our evaluation is that although it is the physical landscape of the DDR that sets it apart from other hot climate winemaking regions, it is the climate of this region and its inimitable product Port Wine that singles the DDR out from other mountain regions and gives it is unique identity.

In our reflection, we examined the heat-rainfall aridity indicators (AI) which ranged from 1.6 (non-arid, tending towards semi-arid, AI ≃ 2) and 2.8 (semi-arid, 2 < AI < 3), confirming that the higher values are characteristic of the vineyards located at lower altitudes, best classified for Port Wine.

Three main features that in mountain viticulture are essential to the nature of the wine they produce, must be associated to the vineyards of the Douro Demarcated Region:  a) location; b) altitude – the temperature drops 0.6ºC and rainfall increases 45mm every 100 metres; and c) aspect – daytime temperatures during the Summer vary by about 2ºC between northern and southern exposures; temperatures in west-facing vineyards are about halfway between the extremes in these two, and temperatures in vineyards facing east represent the arithmetic mean between northern and western exposures. In 1844, Francisco Rubião, has theorized the influence of altitude on air temperature, having determined that for every 200 meyers (100 toesas) rise in altitude the temperature down 1ºC.

At a time when, in excessively hot regions, scientists are studying and experimenting with the artificial cooling of the vineyards or, in extreme cases, accept that they will inevitably have to be relocated, we in the Douro Demarcated Region are comforted by the fact that we shall always be able to apply those three, primordial mountain viticulture features to ensure the natural cooling of our vineyards.

In this context, the centuries-old blending practices of Port Wine are an added advantage when it comes to resolving the impact of climate changes from one year to another on the wines from a particular vineyard.