Biodiversity is the total variety of life on the earth. It encompasses the total number, variety and variability of life forms, levels and combinations existing within the living world. This includes diversity within species, between species and of ecosystems.
Biodiversity can also be defined as all the types of species of plants, animals and other living beings present on earth. It consists of three fundamental and hierarchical categories which are mentioned and described below:
1. Ecosystem diversity: It comprises a variety of habitats, dynamic complexity of plant, animal and micro-organism communities and their non-living environment which interact as a functional unit. Non-living components include sunlight, air, water, minerals and nutrients.
2. Species diversity: A species may be defined as a group of individuals or as a population of organisms which resemble each other very closely and can interbreed with each other successfully for reproducing their own kind.
Species diversity refers to the frequency and variety of species (wild or domesticated) within a geographical area. Species diversity is usually measured in terms of the total number of species within discrete geographical boundaries. The total number of species in the globe has been estimated by World Conservation Monitoring Center to range from five to thirty million and approximately 1.7 million living species of all kinds of organisms have been described till date (WCMC 1992).
3. Genetic diversity: Genetic diversity refers to variation of genes and or genomes within living organisms, that is the genetic differences among populations of a single species and among individuals within a population. In other words, this covers distinct populations of the same species such as hundreds of traditional rice varieties in Nepal.
Scope of Biodiversity
Biodiversity has its own scope and importance. Some of the scopes of biodiversity are given below in points:
1. Early humans learned much about plants and animals, because they had to depend upon them for food and other requirements.
2. Biodiversity (plants and animals) constitute the structural component of ecosystem.
3. Wild variety of plants, animals, birds and other living beings are the gene banks of nature. These are of extreme importance in breeding programmes in agriculture and animal husbandry.
4. Biodiversity is an integral part of nature. It provides beauty to nature.
5. Wildlife provides valuable information to naturalists and biologists in understanding the environment, ecology and behaviour. These animals and plants are also used to study the effects of pollution.
6. Several wild species of plants and animals are widely used in medicine. They are mostly used in curative and rehabilitative health care system.
7. Wild species of plants and animals are economically most important for human life as they are used in various ways. Animal products like feather, skin, horn etc, fetch good money in the international market.
8. Wildlife provides the best means of sports and recreation. The country can earn good amount of money by attracting tourists as wildlife is linked with tourism.
9. Forests maintain the water cycle and gaseous cycle of the environment, which regulate the climate and quality of the environment.
10. Forest reduces the greenhouse effect of the environment.