This article throws light on the three major priorities for conservation of species in an ecosystem.
The three major priorities are: (1) Aims for Conservation, (2) Giving Priority to Particular Species, and (3) In Situ and Ex Situ Conservation.
(1) Aims for Conservation:
(a) To preserve ecosystem processes e.g. primary productivity, water balance, energy balance, nutrient cycling, slow soil erosion.
(b) To maintain all the genetic diversity within living things.
(c) To prevent extinction of any species.
(d) To preserve particular species.
High priority is given to preserve ecosystem processes. For example, destruction of forest and converting it to other vegetation can bring around climatic changes and increase soil erosion. However, the ecosystem processes are likely to be primarily influenced by characteristics of the most abundant plant species and much less by plants and animals of sporadic occurrence.
Maintenance of genetic diversity is also highly desirable. Various populations within each species and each individual within a population may exhibit genetic diversity. This enables the species to overcome future environmental change (e.g. climatic change) and against sudden catastrophes (e.g. disease epidemic). A gene may carry a useful character that we can later insert into a farm crop or animal, or the ability to produce a useful chemical such as an antibiotic.
There should always-be efforts to prevent any species from becoming extinct. The preservation of any species is an absolute, which must take priority over anything else. Every species is unique, and once it is extinct it is lost for ever.
(2) Giving Priority to Particular Species:
Some species must be given priority in conservation. We should first concentrate on conserving species that have strong and widespread public appeal called flagship species. As there will be widespread support for conserving areas where they live, many other wild species will also be saved. Examples of flagship species are the Florida panther, the giant panda, the African elephant and in New Zealand the takahe (a flightless bird).
A serious limitation of using flagship species as the centre of conservation planning is that there is no guarantee that preserving them will preserve many other species. An example of this is the northern spotted owl in the forests of us Pacific Northwest. The plan for preserving forest patches was specifically geared to the needs of the owl and was clearly not suited to other species, for example some fish and amphibians.
This has led to the suggestion of giving priority to the preservation of umbrella species, which are chosen because in order to preserve them we shall also preserve suitable habitat for many other species. The difficulty is that we know too little about the ecology of most of the species in any community to have a sound basis for choosing umbrella species.
A third suggestion is to identify and conserve a keystone species which remains at the top of an arch. If it is removed the whole arch will fall down. The keystone species is defined as a species whose impacts on its community or ecosystems are large and much larger than would be expected from its abundance (Power and Mills 1995).
If a keystone species disappears many other species will be affected and will perhaps disappear too. The converse is redundant species, whose disappearance has little or no effect on the remaining species. It has been suggested that keystone species should have high priority in conservation and redundant species low priority.
This distinguishes between keystones and dominants. The elephant is an example of a species that is sometimes endangered and which can have a major effect on savanna vegetation. By destroying trees elephants can influence the balance between trees and grassland. Elephant could certainly be classed as a keystone species, and a flagship species too.
Another approach to setting priorities for conservation is to decide which species are in danger of becoming extinct soon and to concentrate our conservation activities on these. Lists of species at risk have been drawn up, notably the Red Lists and Red Data Books of IUCN (now called the World Conservation Union).
(3) In Situ and Ex Situ Conservation:
In situ conservation is conservation of biodiversity in its natural habitat. The strategy of in situ conservation involves the establishment of protected areas (an area of land and/or sea specially dedicated to the protection and maintenance of biodiversity). There are many types of protected areas with different degrees of protection, permanency and purpose.
The range of protected areas can be classified broadly into the following: National Park, Sanctuary, Protected landscapes, and seascapes, biosphere reserves, World Heritage Sites etc. Today, there are approximately 9,832 protected areas (IUCN-1995), including 1,508 national parks of 9.25 million km2 or about 8.2% of the Earth’s land surface.
A further 40,000 smaller protected areas cover another 5% of the land area (UNEP 1995). The recommendation by IUCN is preservation of a cross-section of all major ecosystems to the extent of 13 million km2 or about 10-12% of the Earth’s surface. In India, 4.2% of the total land area earmarked for in situ conservation includes 448 wildlife sanctuaries, 85 national parks, 5 world heritage sites, 10 biosphere reserves, 6 Ramsar sites, 15 mangrove areas, 23 tiger reserves and 17 wetland areas.
Ex-situ conservation is the maintenance of species away from their natural habitat. It is considered a means of static conservation (opposite to dynamic in situ conservation). Ex-situ conservation can be applied to both wild and domesticated species. A botanic garden is the most important form of ex-situ conservation.
There are more than 1,500 botanic gardens in the world (UNEP 1995) of which 582 have a seed bank facility. In India, there are 33 botanic gardens. Zoos of the world contributed significantly to ex situ conservation of endangered wild life. Many species maintained in zoos have already become rare and some even extinct in the wild.
A seed bank is one of the most efficient methods of ex situ conservation for angiosperms. Dried seeds (5-8% moisture content) can be stored for 5-25 years at 0°C to 5°C or for up to 100 years if stored at -10°C to -20°C.
The total number PGRFA (Plant Genetic Resources for Food and Agriculture) stored in seed banks worldwide is 3,610,428 (FAO 1996). In vitro methods are applied throughout the world for conservation of plant germplasm. Around 1,500 wild taxa have been stored in vitro in various institutions of the world.