For a large number of wild species, crop species and varieties and domestic animal breeds, the establishment of a system of protected areas alone is not sufficient or appropriate. Therefore, in-situ conservation requires that consideration be given, within relevant sectoral and horizontal policy areas, to the conservation and sustainable use of biodiversity across the rest of the territory outside protected areas. This aspect constitutes one of the major gaps in the existing conservation policies.
Ex-situ conservation concerns the conservation of genetic resources and of wild and domesticated animals, plants, fungi, and microorganisms off-site, or outside of their natural habitats. Many techniques and facilities are used for ex-situ conservation, including botanical and zoological gardens, nurseries, arboreta, aquaria, herbaria, genebanks, tissue and culture collections, and captive breeding units. Ex-situ conservation includes indigenous and domesticated livestock breeds, plant genetic resources and microorganisms suitable for agricultural, medicinal, industrial, horticultural, or other commercial purposes.
According to the Convention on Biological Diversity, in-situ conservation (on site conservation) means the conservation of ecosystems and natural habitats and the maintenance and recovery of viable populations of species in their natural surroundings and, in the case of domesticated or cultivated species, in the surroundings where they have developed their distinctive properties; ex-situ conservation means the conservation of components of biological diversity outside their natural habitats.
This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. Agenda 21 recommends improved and diversified methods for ex-situ conservation with a view to long-term conservation of genetic resources of importance for research and development.
The Convention on Biological Diversity recommends the following actions for ex-situ conservation of biological diversity (predominantly for the purpose of complementing in-situ measures): (a) Adopt measures for the ex-situ conservation of components of biological diversity, preferably in the country of origin of such components; (b) Establish and maintain facilities for ex-situ conservation of and research on plants, animals and micro-organisms, preferably in the country of origin of genetic resources; (c) Adopt measures for the recovery and rehabilitation of threatened species and for their reintroduction into their natural habitats under appropriate conditions; (d) Regulate and manage collection of biological resources from natural habitats for ex-situ conservation purposes so as not to threaten ecosystems and [in-situ] populations of species; and (e) Cooperate in providing financial and other support for ex-situ conservation and in the establishment and maintenance of ex-situ conservation facilities in developing countries.
The responsibility for ex-situ conservation in South Africa lies with a variety of government, parastatal and private concerns. Most gene and seedbanks are held by the Department of Agriculture, and by institutes of the Agricultural Research Council, whose collections comprise both indigenous and foreign material. A genebank is also maintained by the Department of Water Affairs and Forestry, and a small number of endangered fynbos species are held in collections by the University of Cape Town. Living plant collections are contained in 30-40 botanical gardens, managed by the National Botanical Institute and an assortment of universities and local authorities. About twenty zoological gardens exist, the majority of which are privately owned. The National Zoological Gardens, in addition to managing several zoological collections which contain both exotic and indigenous species, operates four captive breeding centres. Also located within the country are several aquaria.
Zoological and botanical gardens have a key role in maintaining ex-situ populations of animals and plants respectively. The Botanical Gardens Conservation Strategy, the Botanic Gardens Conservation Secretariat and the World Conservation Union (UICN) and the IUCN Species Survival Commission (SSC) Captive Breeding Specialist Group (CBSG) contribute to the above aim.
Botanic gardens - although historically of great importance in the introduction of exotic materials often linked to cash crop development - were part of the plant introduction systems out of which developed the genetic resources programmes in the past few decades. But they have been less than successful in conserving plant materials. With the rapid growth in the nature conservation movement and the economic recession limiting funds, many have realized they have changing roles. Much of this has been sparked by dramatic appeals from botanic gardens in developed countries to help in conservation of the rapidly eroding tropical rain forest. Current compartmentalized action needs to be coordinated, not from the viewpoint of assuming roles and responsibilities which will only exacerbate the inactivities of many organizations over the past couple of decades, but to produce fruitful liaison based on good science and not emotional or financial considerations.
Ex-situ and in-situ conservation are interdependent, but there has been a tendency for 'pure' botany to separate from its more applied branches such as horticulture and forestry. This sometimes results in field and research botanists, and horticulturists, being unaware of, or inadequately satisfying, each other's needs. An essential part of ex-situ conservation must be adequate documentation of accessions with respect to provenance and field data, and subsequent history of maintenance, propagation and distribution to other collections. Another requirement is a long-term commitment to maintenance of threatened species in cultivation with availability of material both for research and establishment in the wild. Problems can occur with disease and predators and the potential for their accidental introduction into the wild or into other ex-situ collections. It is necessary to maintain an adequate representation of genetic diversity in ex-situ collections and to minimize genetic erosion. There are limitations to the conservation role of gardens because of the need to satisfy a range of conflicting aims.