LANDSCAPE AND VEGETATION

Being a global biodiversity hotspot, the Little Karoo has almost 3 200 plant species, of which over 400 are endemic. These grow on both nutrient-rich clay soil and nutrient-poor sandstone and receive rain year round. This, because Sanbona lies in a transition zone between summer and winter rainfall regions and receives frontal rain in winter and thunderstorms in summer. While sporadic droughts are common here, prolonged droughts luckily are not.

However, within the reserve rainfall also varies dramatically. With the Warmwaterberg mountain range bisecting Sanbona, a rain shadow is created on the northern side. Here rainfall is very low, averaging 160 but no more than 300 mm a year during spring and summer. To the south of the Warmwaterberg, rainfall is mainly in winter and can be between 265 to 400mm.

With different rainfall across different soil times also comes different vegetation. So because of this variation, the reserve straddles two important biomes: Fynbos and Succulent Karoo. Across the reserve are also river and floodplain habitats zig zagging through the landscape. They are easily recognised by the trees, reeds and bulrushes that grow there, along with grasses after good rains. Vegetation in the upper drainage areas can also be quite different to that along the main river channel. Historically, the river and floodplain habitats provided important corridors for elephant, rhino and hippo, but they’re also vital for the grazers on the reserve.

It is climatic conditions that have forced these plants to evolve a number of strategies to survive, either by developing water-storage capabilities like vygies, or by being able to bury themselves in soil to minimise water loss, absorbing sunlight for photosynthesis through transparent windows at soil level; or by adopting extremely short life cycles completed within one growing season. In arid regions, you need to adapt or you will die.

Winter rain is important for the survival of succulents. Though less than 300mm per year falls, rain increases overall air moisture and prevents black frost – when a plant’s internal moisture freezes and kills it. Occasionally winter frost does occur, but frozen condensation on the surface of plant leaves does it no harm.

The Succulent Karoo also includes all the quartz gravel patches, which create unique habitats with very distinct flora. Most dominant are succulent, compact, dwarf plants that are highly endemic to the area. Covering about 35 000 ha, Succulent Karoo covers the largest area on Sanbona, and provides sustenance for mammal species large and small.