After reading this article you will learn about:- 1. Meaning of Biodiversity 2. Varieties of Ecological Diversity 3. Conservation 4. Biodiversity Scenario in India.
Varieties of Ecological Diversity:
The following varieties of ecological diversity are recognized:
1. Species Diversity:
Species diversity is the effective number of different species that are represented in a collection of individuals (a dataset). The effective number of species refers to the number of equally abundant species needed to obtain the same mean proportional species abundance as that observed in the dataset of interest (where all species may not be equally abundant).
Species diversity consists of two components: species richness and species even ness. Species richness is a simple count of species, whereas species even ness quantifies how equal the abundances of the species are. Each natural habitat has a variety of species, some of which are rare, others are common and still others are abundant. Thus no community consists of species of equal abundance.
The following types of species diversity are described:
(a) Point diversity:
This type of diversity, on the smallest scale, is the diversity of a micro habitat or sample taken from within a homogeneous habitat. It is natural to expect differences in point diversity of any two sites.
(b) Alpha diversity:
This is the second category of species diversity. It is defined as within habitat diversity.
(c) Gamma diversity:
It is defined as the diversity of a larger unit such as an island or landscape. It is considered to be the overall diversity of a group of areas of alpha diversity
Gamma diversity = alpha diversity × β diversity
(d) Epsilon diversity:
The Epsilon or regional diversity is defined as the total diversity of a group of areas of gamma diversity.
According to Magurron (1988), a single plant may be considered as a unit of alpha diversity, a leaf as an area of point diversity, a group of plants occuring together as an area of gamma diversity and a forest within which the plants are located as an area of epsilon diversity.
(e) Beta diversity:
The term β diversity was coined by Whittaker (1960). It is the measure of how different or similar a range of habitats are in terms of the variety of species found in them. It tells us how species diversity changes along gradient.
Another way to view beta diversity is to compare the species composition of different communities. Beta diversity is also known as differentiation diversity.
(f) Delta diversity:
It is defined as the change in species composition and abundance between areas of gamma diversity, which occurs within an area of epsilon diversity. It represents differentiation diversity over wide geographical areas.
Calculation of diversity:
Species diversity in a dataset can be calculated by first taking the weighted average of species proportional abundance in the dataset, and then taking the inverse of this. The equation is:
2. Genetic Diversity:
Genetic diversity is the combination of different genes found within a population of a single species, and the pattern of variation found within different populations of the same species. Coastal populations of Douglas fir are genetically different from Sierran populations.
Genetic adaptations to local conditions such as the summer fog along the coast or hot summer days in the Sierra result in genetic differences between the two populations of the same species.
3. Ecosystem Diversity:
Ecosystem diversity encompasses the variety of habitats that occur within a region, or the mosaic of patches found within a landscape. A familiar example is the variety of habitats and environmental parameters that constitute the San Francisco Bay-Delta ecosystem: grasslands, wetlands, rivers, estuaries, fresh and salt water.
Agricultural diversity can be divided into two categories: intraspecific diversity, which includes the genetic variety within a single species, like the potato (Solanum tuberosum) that is composed of many different forms and types (e.g.: in the U.S. we might compare russet potatoes with new potatoes or purple potatoes, all different, but all part of the same species, S. tuberosum’).
The other category of agricultural diversity is called interspecific diversity and refers to the number and types of different species. Thinking about this diversity we might note that many small vegetable farmers grow many different crops like potatoes, and also carrots, peppers, lettuce etc.
A.R. Wallace had suggested that diversity in the tropics was greater than in temperate regions, because tropical regions have enjoyed longer periods of stability and thus, have more time for species differentiation. This idea is now sometimes referred to as the time hypothesis of species diversity. A number of evidences are available to support the time hypothesis.
The diversity-stability hypothesis proposes that ecological communities will decrease in ability to recover from disturbance and in productivity if there is reduction in species richness. The idiosyncratic response hypothesis proposed that with changes in biodiversity ecosystem processes also change, but the magnitude and direction of change is not predictable because each individual species has complex and varied roles.
The reductant species hypothesis predicts that a minimum diversity is necessary for ecosystem processes, but beyond this most species are reductant in their roles.
Conservation of Biodiversity:
The urgent need for conservation of biodiversity was felt in Rio conference (1972). The world summit on sustainable development held in Johannesburg in Aug. 2002 reiterated that the conservation of biodiversity was necessary for the survival of human race on this earth. In the conservation of biodiversity which has 42 Articles, Articles 8 and 9 are about in-situ conservation and ex-situ conservation respectively.
In-situ conservation is possible through protected area systems or networks. Nearly 10,000 protected areas in different countries of the world are recognised by IUCN Commission of Parks and protected areas.
Ex-situ conservation measures include blood banks, sperm, and ova banks, plant tissue cultures, and artificial propagation of plants. The conservation of biodiversity is presently one or our ‘best hopes7 and a number of countries have begun to develop and follow action in accordance with the articles of the convention.
Action Plan for India to clean-up and for conservation of environment:
1. Minimize deforestation and maintain the bio-reserves.
2. Reduce livestock population (source of methane, greenhouse gas emission)
3. Introduce E-vehicles and CNG vehicles and impose heavy penalties for motors exceeding emission level.
4. Use more and more solar energy.
5. Introduce CFL and LEDs for lighting.
6. Introduce CFG substitutes (such as butane and propane) in all air conditioners and refrigerators.
7. Shift from coal-fired thermal power stations to more efficient gas fired ones.
Biodiversity Scenario in India:
In India, several Bills and Action plans have been passed by the Parliament for the conservation of biodiversity. Some policies and legal frameworks recently developed to protect the biodiversity are The Forest (conservation) Act 1980, The World life protection Act 1972 and Biological Diversity Bill 2002.
In India commendable efforts have been made for in situ conservation of biodiversity. Under protected area network. Now we have 12 Biosphere Reserves setup in different biologeographic regions of the country, besides 485 wildlife Sanctuaries and 89 National Parks.