Rapid population growth and inappropriate government policies in the past encouraged cultivation in unsuitable areas, and use of poor agricultural methods to produce sufficient food. Recent policies, international conventions, and community-based initiatives being carried out are aimed at improved conservation and more sustainable use of natural resources in future. This high level of diversity is due to the broad range of climatic, geological, soil and landscape forms found in South Africa. However, many species are threatened, and extinction rates in South Africa are high by global standards. South Africa is a semi-arid country, and drought and desertification are real threats to food security.
Terrestrial ecosystems are very complex, and research has only been able to cover a few aspects.
For more background information about terrestrial ecosystems, read this section . These processes impact terrestrial ecosystems, through degradation, alteration of processes, or transformation. In some cases these species have become invasive, i.e. they have dominated the natural vegetation, and place an additional burden on already scarce resources, such as water. Government policies cause changes to terrestrial ecosystems, in both positive and negative ways. For example, nature conservation laws have contributed to protection of species and habitats, preserving populations of species, the wilderness experience, enhancing quality of life, and slowing the rate of extinctions.