Unit – II

Ecosystems, Biodiversity, and its conservation

Question banks

1. Explain   Concept of an ecosystem?

Term ‘Ecosystem’ was tossed in the year 1935 by an English Botanist- A.G. Tansley.

An ecosystem is a geographic area which contains both Biotic as well as Abiotic factors and their interaction with each other.

There are various types of Ecosystems such as:

• Terrestrial
• Aquatic
• Desert
• Grassland
• Forests
• Marine
• Freshwater, etc.

2.    Explain Structure and function of an ecosystem with a neat sketch ?

Ecosystem has 02 major components:

1)     Biotic (Living)

2)     Abiotic (Non- Living)

These 02 components when interacts with each other in a system, then give rise to an ecosystem.

Biotic Components are of 03 further types:

1)     Producers

2)     Consumers

3)     Decomposers

Abiotic Components are of 03 sorts:

1)     Climatic Factors (Rain, Lightning, Humidity, Wind, Temperature, etc.)

2)     Edaphic Factors (Soil based factors such as pH, minerals, etc.)

Fig2.1 Classification of Ecosystem and its components

Functions:

Basic function of ecosystem is merely an exchange of energy and nutrients in the food chain which impacts the survival of existence of all life forms. This exchange is responsible for the setting up of equilibrium between biotic and abiotic components.

3.    Define Producers, consumers and decomposers?

1)     Producers: They prepare their own food and initiate the cycle.

Example: Plants prepare their own food with the help of photosynthesis.

2)     Consumers: These are primary (who feeds on producers) & secondary (who feed on both producers and primary consumers)

Example: Herbivores & Carnivores

3)     Decomposers: Feeds on dead of lifeless residues of producers and consumers.

Example: Bacteria, Fungi, etc.

4.    Explain Energy flow in the ecosystem?

The behaviour of energy in ecosystem can be conveniently termed as energy flow because of unidirectional energy transformations. Total energy flow that constitutes the energy environment has already been dealt in detail, and now we take up the study of that portion of the total energy flow that passes through the biotic components of the ecosystem. Entrance of energy, its retention within the ecosystem and dissipation into space, are governed by two laws of thermodynamics. According to the first law, the law of conservation of energy, in a closed system, no energy comes in or escapes out and not created or destroyed but may be altered from one form to another. The second law of thermodynamics, the law of entropy, states that there is always a tendency for increase in entropy or degradation from a concentrated (non-random) to a dispersed (random) form leading to dissipation of heat. All the energy entering the earth’s surface can be accounted for. Some energy is used in photosynthesis; the rest is used in converting the water into vapours or heating the soil and air. Ultimately the energy reflected back to outer space as heat. The light energy fixed by green plants in the process of photosynthesis may be represented by the following equation:

Out of the amount of energy so fixed by green plants, some is released again in respiration. The fixed energy, in the form of food, then passes from plant source through herbivores to carnivores. At each stage of food transfer, potential energy is released, resulting in further loss of a large part of energy. The energy flow, thus follows the second law of thermodynamics.

5.    What is Ecological succession?

Ecological succession is the phenomenon or process by which an ecological community undergoes more or less orderly and predictable changes following disturbance or initial colonization of new habitat. Succession was among the first theories advanced in ecology and the study of succession remains at the core of ecological science. Succession may be initiated either by formation of new, unoccupied habitat (e.g., a lava flow or a severe landslide) or by some form of disturbance (e.g. Fire, severe wind throw, logging) of an existing community.

1. Primary succession

Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary succession. In primary succession pioneer species like lichen, algae and fungus as well as other abiotic factors like wind and water start to "normalize" the habitat. This creating conditions nearer optimum for vascular plant growth; pedogenesis or the formation of soil is the most important process.

These pioneer plants are then dominated and often replaced by plants better adapted to less odd conditions, these plants include vascular plants like grasses and some shrubs that are able to live in thin soils that are often mineral based.

For example, spores of lichen or fungus, being the pioneer species, are spread onto a land of rocks. Then, the rocks are broken down into smaller pieces and organic matter gradually accumulates, favouring the growth of larger plants like grasses, ferns and herbs. These plants further improve the habitat and help the adaptation of larger vascular plants like shrubs, or even medium- or large-sized trees. More animals are then attracted to the place and finally a climax community is reached.

2.    Secondary succession

Succession that follows disruption of a pre-existing community is called secondary succession. (e.g. Forest fire, harvesting, hurricane) that reduces an already established ecosystem (e.g. a forest or a wheat field) to a smaller population of species, and as such secondary succession occurs on preexisting soil whereas primary succession usually occurs in a place lacking soil.

6.    Explain Food chains, food webs and ecological pyramids?

1)     Food Chains:

Food chains were first introduced by the African-Arabic scientist and philosopher Al-Jahiz in the 9th century but got popularized by Charles Elton in the year 1927.

It is defined as an order of living organisms in a community in which continuous consumption of one organism by other organism and so on takes place.

It can be stated as a chain of organisms in their natural surroundings, through which energy is transferred.

2)     Food Web:

A food web may be defined as a graphical representation depicting interconnection between various food chains.

As a food web contains a number of interconnected food chains, hence it results in a complex structure.

Whenever various food chains form such a structure by overlapping each other, it results in generation of a Food Web.

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7. Define Biodiversity ?

Biodiversity: Bio = Diversity = Variety

The term Bio-Diversity was first coined by Walter G. Rosen in 1986. Biodiversity, refers to the variety of life on Earth. It includes diversity of ecosystems, species and genes, and the ecological processes that support them. Everything that lives in an ecosystem is part of the web of life, including humans. Each species of vegetation and each creature has a place on the earth and plays a vital role in the circle of life. Plant, animal, and insect species interact and depend upon one another for what each offers, such as food, shelter, oxygen, and soil enrichment. Maintaining a wide diversity of species in each ecosystem is necessary to preserve the web of life that sustains all living things.

There are three levels of Diversity

• Species diversity
• Genetic diversity
• Ecosystem or Habitat diversity

8.    Define   Genetic, species and ecosystem diversity?

Species diversity:  The species diversity peaks in the tropical forest and coral reefs. India has around 2,00,000 species of the total species described.It is defines as variety of different species of living forms in a given area.

Genetic diversity:   These variations help the individuals to have a variant that help it to be suite for the new environment. The more genetic diversity in a population, the more chances in variations.

Ecosystem or Habitat diversity: Ecosystem is the structural and functional unit of the biosphere. Ecosystem diversity is defined as „the aggregation of various habitats, community types and abiotic environment in a given area‟.  India has one of the richest ecosystem diversities, ranging from deserts, plains, hills, mangroves, rainforests to cold Himalayas. Out of the 18 hot spots of biodiversity recognized in the world, India has two of them, Eastern Himalaya and The Western Ghats. Eastern Himalayas is recognized as the “Cradle of Speciation” due to rich diversity of primitive flowering plants.

9.    What is Bio-geographical classification of India?

Bio-geography is the study of the origin of world biota, environmental relationship and distribution of organism, both past and present, over the face of earth.  India is mega diversity country with different types of climate and topography in different parts. Variations due to the variability in flora and fauna . It is important to study and know the distribution, evolution and environmental relationship of plants and animals.  To know about the relationship of flora and fauna, biogeographers classified India into ten biogeographic zones .  They are :

1. Trans-Himalayas
2. Himalayas
3. Dessert
4. Semi-arid
5. Western Ghats
6. Deccan Peninsula
7. Gangetic Plain
8. Northeast India
9. Islands
10. Coasts

10  . Explain the Value of biodiversity?

Environmental economics (or ecological economics) provides methods of assigning economic values to species, communities and ecosystem. These values include the harvest (or market place) value of resources, the value provided by un-harvested resources in their natural habitat, and the future value of resources. For example, the Asian wild guar could be valued for the meat could be harvested from its current populations, its value for eco-tourism, or its future potential in cattle breeding.

The values can be divided as:

1. Direct values

Direct values, also known as use values and commodity values, are assigned to the products harvested by people. Direct values can be readily estimated by observing the activities of representative groups of people, by monitoring collection points for normal products and by examining the export/ import statistics. These values can be further sub-divided as:

a) Consumptive use value

It can be assigned to goods such as fuel wood and goods that are consumed locally and do not figure in national and international market

b) Productive use value

It is assigned to products that are derived from the wild and sold in commercial markets, both national as well as international markets.

2.    Indirect values

Indirect values are assigned to benefits provided by biodiversity that do not involve harvesting or destroying the natural resource. Such benefits include ecological benefits such as soil formation, nutrient cycling, waste disposal, air and water purification, education, recreation, future options for human beings, etc. Indirect value can be further sub-divided as:

a) Non-consumptive use value

It is assigned to benefits such as soil formation/ protection, climate regulation, waste disposal, water and air purification, eco-tourism, medical research, etc.

b) Aesthetic, social and cultural value

The diversity of life on Earth brings us many aesthetic and cultural benefits. It adds to the quality of life, providing some of the most beautiful and appealing aspects of our existence.

Biodiversity is an important quality of landscape beauty. Many species of birds, large land mammals, sea animals and flowering plants are appreciated for their beauty. Millions of people enjoy hiking, camping, picnics, fishing, wildlife watching, and other recreational activities based on nature. These activities provide invigorating physical exercise and allow us to practice pioneer living skills. Contact with nature can also be psychologically and emotionally restorative. In many cultures, nature carries spiritual connotations, and a particular plant or animal species or landscape may be inextricably linked to a sense of identity and meaning.

Today we continue to imbue certain animals and plants with cultural significance; for instance, in India tiger and peacock, which are endangered, are especially valued because they have been adopted as national animal and bird respectively.

c) Option value

The option value of a species is its potential to provide our economic benefit to human society in the near future. For instance, there are several plant species which are edible and superior than those which are currently in use; e.g. Katemfe, a plant found in W. Africa, produces proteins that are 1,600 times sweeter than sucrose.

d) Existence value

It is assigned to protect wildlife. Since, for many people, the value of wildlife goes beyond the opportunity to photograph or even see a particular species. They argue that ‘existence value’, based on simply knowing that a species exist, is a sufficient reason to protect and preserve it. This right to exists was also stated in the U.N. General Assembly World Charter for Nature, 1982.

e) Ethical value

Moral justification for conservation of biodiversity is based on the belief that species have a moral right to exist, independent of our need for them. Consequently, the argument follows that in our role as the most intelligent species on Earth we have a responsibility to try as much as possible for the continuance of all forms of life.

Ethical values are deep rooted within human culture, a religion and society, but, those who look on cost benefit analysis, they overlook these ethical values. International boycotts of furs, teak and ivory are the good examples of moral justification.