When we bought DeMorgenzon we used satellite and historical data, as well as an examination of physical factors, to thoroughly analyse our climate (including temperature data, solar radiation patterns, rainfall records, wind and sunlight hours). We further commissioned a detailed soil analysis (nutrient status, physical properties, depth, colour and hydrological properties) drilling a few hundred holes in the process; and undertook a topographical study (altitude, slope steepness, slope form, terrain unit, openness of the landscape and drainage patterns).
This enabled the demarcation of the best option block boundaries and the allocation of cultivars according to varietal preferences. It also helped to determine our choice of rootstock, our row and plant spacing and our row direction. We have, we believe, established our vine rows in harmony with the terroir, the sun and the elements.
Our enormously old and diverse soils primarily comprise well drained Oakleaf and Tukula types which originally developed from a granite base.
Approximately 10% of DeMorgenzon has been set aside for the restoration of Renosterveld. We have removed 15ha of pine forest and assorted invasive alien species and are still in the process of clearing the occasional Port Jackson and wattle.
The consequences are already visible. A long-dry spring in one of the kloofs has bubbled to the surface. In line with our belief that we must grow in harmony with nature, we are restoring the original vegetation in some areas and creating a bio-diverse habitat in the vineyard. We are also experimenting with indigenous cover crops.
WHAT IS RENOSTERVELD
Renosterveld is one of the most threatened habitats in the Cape Floral Kingdom, because so little remains. Less than 1% of Renosterveld habitat is currently formally protected. Along with Fynbos, Renosterveld is a dominant vegetation type in the Cape Floral Kingdom. While Fynbos grows on sandy nutrient-poor soils, Renosterveld tends to occur on more fertile and fine-grained shale, granite or silcrete derived soils where rainfall is a moderate 350 to 650 mm/year. At rainfall levels above about 800 mm/year soils are leached and Renosterveld vegetation becomes dominated by Fynbos elements. Generally, where the rainfall is less than 250 mm it is replaced by one of the Succulent Karoo vegetation types. Because it occurs on fertile soils, much of Renosterveld has been ploughed for agriculture, including the Cape’s best vineyards.
Both vegetation types are characterised by very high species diversity. When differentiating between Renosterveld and Fynbos, it is usually easiest to refer to habitat (which considers geology and rainfall) rather than species composition. A rule of thumb, however, is that the typical Fynbos families Ericaceae and Proteaceae tend to be uncommon in Renosterveld.
According to UNESCO’s World Heritage Committee the Cape Floral Region is of “outstanding universal significance to humanity”, and “one of the richest areas for plants in the world”. “Its plant species diversity, density and endemism are among the highest world-wide,” and it has been identified as one of the world’s 18 biodiversity hot-spots.
Although the smallest, the Cape floral kingdom, is the richest of the world’s six floral kingdoms – and the only one to be contained within one country. South Africa has the third-highest level of biodiversity in the world – the Table Mountain National Park alone has more plant species within its 22 000 hectares than the whole British Isles or New Zealand.
A stretch of land and sea spanning 90 000 square kilometres, or 0.05% of the earth’s land area, the Cape floral kingdom contains roughly 3% of the world’s plant species – about 456 species per 1 000km². Of the 9 600 species of vascular plants (plants with vessels for bearing sap) found in the Cape floral kingdom, about 70% are endemic, i.e. occur nowhere else on earth. This degree of endemism is among the highest in the world.
The Cape, consequently, has more potential for varietal diversity in a relatively small area than any wine-growing area in the world. The Fynbos Biome is considered by many to be synonymous with the Cape Floral Kingdom and refers to the two key vegetation groups within the region – Fynbos and Renosterveld.
The two major vegetation groupings in Fynbos are quite distinct and have contrasting ecological systems. Essentially, Renosterveld used to contain the large animals in the Cape Floristic Kingdom, but these are now extinct or else have been reintroduced into conservation areas. By contrast, Fynbos is much richer in plant species, but cannot support even low densities of big game.
Distressingly, some three-quarters of all plants in the South African Red Data Book occur in the Cape Floral Kingdom: 1 700 plant species are threatened to some extent with extinction. This is much more than one would expect based on either the area of the Kingdom (6%) or its plant numbers (36%). This again reflects the unique nature of Fynbos vegetation: many Fynbos species are extremely localised in their distribution, with sets of such localised species organised into “centres of endemism.” The city of Cape Town sits squarely on two such centres of endemism and several hundred species are threatened by urban expansion. However, a more serious threat is alien plants, which infest large tracts of otherwise undisturbed mountains and flats: their impact on these extremely localised species is severe.