Dealing with the lack of surface water and rainfall within the Kalahari area is a real challenge. The camel thorn (Vachellia erioloba) deals with this challenge by putting a lot of time and effort into its very large tap root structure. The roots of large camel thorn trees extend down to nearly 40 metres below the surface of the sand. This allows the tree to tap into subterranean water sources and thrive within Tswalu’s arid environment.
Most trees in these harsh areas also have small leaves. This means there is a smaller surface area for water to be lost through the process of transpiration. Herbivores, particularly those that thrive off shrubs, find the leaves very palatable. With a protein content of 17% and a digestibility of 35%, its one of the Kalahari`s most significant foraging trees. Being stationary life forms, trees are easy targets for over-utilisation by browsers. To help prevent this, trees can sense when they are being attacked and respond with the release of tannins (a bitter-tasting organic substance found in plant tissue). High amounts of this substance, if consumed by ruminants, could lead to complications. Another efficient way to avoid being over browsed is modified vegetative parts such as thorns and spines.
Most vascular plants (plants with specialised tissues for water and nutrient transportation) are seed-bearing, a highly effective adaptation for surviving hostile conditions such as droughts, freezing cold and even fire. Seeds also provide an effective means of dispersal with the assistance of insects, mammals, water and wind. Historically, the earliest known seeds were produced by seed-ferns that occurred more than 350 million years ago during the Devonian period.
Apart from providing us with oxygen through photosynthesis, trees are also an essential part of the food web, providing food for countless organisms, in various ways.
Trees are amazing organisms and one should take the time to appreciate their significance within all environments.