Biodiversity: Concept, Types and Other Details (With Diagram)

Biodiversity, besides its ecological significance provides a socio-economic and monetary asset to the nation.

Human society depends on biological resources, their diversity and the ecosystems that sustain them to provide essential goods and services.

Concept of Biodiversity:

It has been estimated that more than 50 million species of plants, animals and micro-organisms are existing in the world. Out of these, about 1.4 million species have been identified so far. Each species is adapted to live in specific environment, from mountain peaks to the depth of seas, from polar ice caps to tropical rain forests and deserts. All this diversity of life is confined to only about one kilometer thick layer of lithosphere hydrosphere and atmosphere which form biosphere.

Though the study of environment and ecology is quite old, the term biodiversity has been introduced by Walter Rosen in 1986. Biological diversity or Biodiversity is defined as the variety and variability among the living organisms and the ecological complexes in which they occur.

It refers to the variability’s among species of plants, animals and microorganisms; ecosystems; ecosystem including terrestrial, aerial, marine and other aquatic system and ecological complexes of which they are part. In simpler terms, biodiversity is the assemblage of different life forms (Fig. 19.1).

If reflects the number of different organisms and their relative frequencies in an ecological system. It includes the organisation of organisms at many levels ranging from complete ecosystems to the chemical components that form the molecular basis of heredity. Thus, biodiversity is sum of all the genes, varieties, species, populations in different ecosystems and their relative abundance.

Scientists are aware of the immense potentials of various life-forms existing on the earth. Our planet’s requirements and services depend mainly on the biological resources. Biological resources not only provide us nourishment, clothing, housing, fuel and medicine but also meet our several other requirements. Therefore the knowledge of biodiversity is of immense utility in planning sustainable livelihood and conserving the natural resources.

Significance of Biodiversity:

Biodiversity, besides its ecological significance provides a socio-economic and monetary asset to the nation. Human society depends on biological resources, their diversity and the ecosystems that sustain them to provide essential goods and services.

Values related to biodiversity can be grouped into three categories as below:

Productive use:

This is assigned to the products that are commercially harvested for exchange in formal markets and is, therefore, the only value of biological resources that is concerned in national income. Biodiversity provides us many products, such as fuel, timber, fish, fodder, skin, fruits, cereals and medicines. In 1994-95 the income from agriculture, forestry and fisheries in India was nearly 30 per cent or 736.88 billion rupees.

Consumptive use:

Consumption value is related to natural products that are consumed directly, i.e., the goods which do not come under normal circulation of trade. For example, a significant number of such non-timber forest products as soft broom grass and cane come under this category.

Indirect use:

Indirect use of biodiversity is of much significance because this value is related primarily with functions of ecosystem and is concerned with national accounting systems. They may provide us indirect benefits as non-consumptive values. Maintenance of ecological balance, conservation of natural resources and prevention of soil erosion may be considered as the examples of indirect use of biodiversity.

Types of Biodiversity:

Biodiversity is of three types:

1. Species diversity

2. Genetic diversity

3. Ecological diversity

1. Species Diversity:

According to Biological Species Concepts (BSC), species is a basic unit of classification and is defined as a group of similar organisms that interbreed with one another and produce offspring’s and share a common lineage. Species diversity refers to biodiversity at the most basic level and is the ‘variety and abundance of different types of individuals of a species in a given area’. It includes all the species on Earth, ranging from plants such as bacteria, viruses, fungi, algae, bryophytes, pteridophytes, gymnosperms, angiosperms and all the species of animals including unicellular protozoans to mammals.

Certain regions support a more diverse populations than others. Regions that are rich in nutrients and have well balanced climatic factors, such as moderate temperature, proper light and adequate rainfall, show high degree of diversity in their life forms. The tropical areas support more diverse plant and animal communities than the desert and polar areas, as for examples, tropical forest has a higher species diversity as compared to a timber plantation. The regions that are rich in species diversity are called hotspots of biodiversity.

2. Genetic Diversity:

‘Genetic diversity pertains to the range of diversity in the genetic resources of the organisms’. Every individual member of a plant or animal species differs from other individuals in its genetic constitution. Each individual has specific characters, which is due to the genetic makeup or code. The genes present in the organisms can form infinite number of combinations that causes genetic variability.

Thus, we find that each human, who is representative of the same species, i.e. Homo sapiens, is distinct from another. Similarly, there are many varieties within the same species such as rice, wheat, apples, mangoes, etc. that differ from one another in shape, size, colour of flowers and taste of fruits and seeds due to the variations at the genetic level.

The term ‘gene pool’ has been used to indicate the genetic diversity in the different species (Fig. 19.2). This also includes the diversity in the wild species, which through intermixing in nature over millions of years have given rise to newer varieties. The domesticated varieties of agricultural crops and animals have also evolved from the wild gene pool.

The genetic variability is essential for healthy breeding population, the reduction in genetic variability among breeding individuals leads to inbreeding which in turns can lead to extinction of species. In the recent decades, a new science named ‘biotechnology’ has emerged. It manipulates the genetic materials of different species through various genetic re-combinations to evolve better varieties of crops and domestic animals.

3. Ecological/Ecosystem Diversity:

Each ecosystem consists of organisms from many different species, living together in a region connected by the flow of energy and nutrients. The Sun is the ultimate source of energy for all the ecosystems. The Sun’s radiant energy is converted to chemical energy by plants. This energy flows through the different systems when animals eat the plants and then are eaten, in turn, by other animals. Fungi and bacteria derive energy from the decomposing dead organisms, releasing nutrients back into the soil as they do so.

An ecosystem, therefore, is a collection of living components, like microbes, plants, animals, fungi, etc. and non-living components, like climate, matter and energy that are connected by energy flow. Ecological diversity refers to the ‘variability among the species of plants and animals living together and connected by flow of energy and cycling of nutrients in different ecosystems or ecological complexes’. It also includes variability within the same species and variability among the different species of plants, animals and microorganisms of an ecosystem. Thus, it pertains to the richness of flora, fauna and microorganisms with in an ecosystem or biotic community.

The richness of the biosphere in terms of varied life forms is due to the variations in the ecosystems. The earth has a number of ecosystems like grasslands, forests, semi arid deserts, marine, freshwater, wetland, swamp, marshlands (Fig. 19.3) etc. each one having its distinct floral, faunal and microbial assemblages. Ecological diversity represents an intricate network of different species present in local ecosystems and the dynamic interaction among them. The ecological diversity is of great significance that has developed and evolved over millions of years through interactions among the various species within an ecosystem.

Measuring Biodiversity:

There are various mathematical ways of measuring biodiversity, which calculate the number of species diversity in different regions. The measure of diversity of species is also known as species richness.

These are as follows:

Alpha diversity:

This is the diversity in species, i.e. the number of species within a community. This depends on the interaction between the biotic and abiotic factors and also takes into account immigration from other locations.

Beta diversity:

This is the change in the composition of the species with reference to the changes in the environment.

Gamma diversity:

This refers to the overall diversity and is applied to larger areas in which both alpha and beta diversity are measured.

Value of Biodiversity:

Biodiversity is the most precious gift of nature the mankind is blessed with. The uniqueness of our planet Earth is due to the presence of life manifested through the diversity in flora and fauna. As all the organisms in an ecosystem are interlinked and interdependent, the value of biodiversity in the life of all the organisms including humans is enormous. Besides its ecological and environmental value, biodiversity has significant socio-economic values as well.

The value of biodiversity can be grouped under the following heads:

Environmental Value:

The diverse group of organisms found in a particular environment together with the physical and biological factors that affect them, constitute an ecosystem. Healthy ecosystems are vital to life. The natural environment is responsible for the production of oxygen, maintenance of water-cycle and other biogeochemical cycles.

The more a region is rich in terms of biodiversity, the better are the different cycles regulated. For example, forests regulate the amount of carbon dioxide in the air by releasing oxygen as a by-product during photosynthesis, and control rainfall and soil erosion. As you are well aware, deforestation would further increase carbon dioxide in the earth’s atmosphere leading to greenhouse effect and global warming.

This will cause irreparable damage to all organisms including mankind. Ecosystems depend on the health and vitality of the individual organisms that compose them. As all the organisms in an ecosystem are interdependent, removing just one species can prevent the ecosystem from operating normally.

Consumptive Value:

This is related to natural products that are used directly for food, fodder, timber, fuel wood, etc. Humans use at least 40,000 species of plants and animals on a daily basis. Many people around the world still depend on wild species for most of their needs like food, shelter and clothing (Fig. 19.4 and Table 19.1). The tribal people are completely dependent on the forests for their daily needs. Similarly, fishermen in the coastal areas are dependent on the marine resources. The wood derived from the forests has been used from the birth of civilization as fuel.

Productive Use Value:

This is assigned to products that are commercially harvested and marketed. Almost all the present day agricultural crops have originated from wild varieties. The biotechnologists continuously use the wild species of plants for developing new, better yielding and disease resistant varieties. Biodiversity represents the original stock from which new varieties are being developed. Similarly, all our domesticated animals came from wild-living ancestral species.

Through scientific breeding techniques animals giving better yield of milk, meat, etc. are being developed. The commonly used animal products used by the modem society come from the advances made in the fields of poultry farming, pisciculture, silviculture, dairy farming, etc. Even the fossil fuels like coal and petroleum are the products of biodiversity from the geological past. Most of the drugs and medicines used in the present times are extracted from different plant parts. The commonly used drugs derived from plants are given in Table 19.2 and Fig. 19.5.

Social Value:

The lifestyle of the ancient people was closely interwoven with their surroundings. The life of the indigenous people in many parts of the world still revolves around the forests and environment, even in the modem times. Many of them still live in the forests and meet their daily requirements from their surroundings. Due to modernisation, their habitats are being encroached upon and their very survival is at stake. It is ironic that the societies, whose whole life is intricately associated with the forests, are now not able to use the natural resources for their sustenance.

The biodiversity in different parts of the world has been largely preserved by the traditional societies. Since the indigenous people always protect the forests for their own benefit, the Government should formulate plans to involve such people for environmental protection.

In ancient times, especially in India, the environment in totality i.e. flora, fauna, etc. were held in high esteem. Trees like Peepal, Banyan and Tulsi are still worshipped. Ladies offering water to Tulsi daily is considered good and there are festivals when ladies tie sacred threads around Peepal and Banyan trees and pray for the welfare of their families. Similarly, certain animals and birds were represented as vehicles of Gods and were duly respected. Thus, the different facets of biodiversity were closely linked to the social values in many regions.

Ethical and Moral Values:

It is based on the principle of ‘live and let others live’. Morality and ethics teach us to preserve all forms of life and not to harm any organism unnecessarily. Some people take pleasure in the hunting of animals. People also sometimes degrade and pollute the environment by their unethical actions.

Through proper education and awareness, the people’s conscience against such practices must be raised. We may not be deriving direct benefits from many plants and animals, but should they be harmed because of this? Each species has its own utility in the world of biodiversity and has every right to live.

Aesthetic Value:

The beauty of our planet is because of biodiversity, which otherwise would have resembled other barren planets dotted around the universe. Biological diversity adds to the quality of life and provides some of the most beautiful aspects of our existence. Biodiversity is responsible for the beauty of a landscape. Humans are also attracted towards the biologically rich regions and nobody likes to live or visit a barren place. People go to far off places to enjoy the natural surroundings and wildlife.

This type of tourism is referred to as eco-tourism, which has now become a major source of income in many countries (Fig. 19.6). Eco-tourism includes visiting wildlife sanctuaries, national parks, coral reefs, exotic islands, safaris and trekking in the mountainous and forested areas. In some countries like Nepal, Bhutan, Kenya, Rwanda, eco-tourism has now become the major source of foreign currency income.

In many societies, the diversity of flora and fauna has become a part of the traditions and culture of the region and has added to the aesthetic values of the place. For example, in India, the richness of flora and fauna are depicted in many paintings; animals are represented as vehicles of Gods; the dances and festivals are intricately associated with nature.

Optional Value:

This refers to the value of biodiversity that is yet unknown, but needs to be explored for future possibilities and use. Scientists have discovered and named about 1.75 million species, which is of utmost importance. We should preserve all the world’s biodiversity that can be used by the future generations.