Write short note on Acid Rain.

Acid Rain

Acid rain is a matter of great global concern and has become one of the major environmental problems. The term ‘acid rain’ used first by Robert Angus Smith, the Chief Alkali Inspector of UK in 1872, described the acidic
nature of rain falling around Manchester. Acid rain is commonly defined as “a condition in which acidic after reacting chemically with pollutants the air”.

Among air pollutants sulphur and nitrogen are significant compounds. In particular, sulphur dioxide (S02) and oxides of nitrogen (NO and N02) are released from a variety of sources sulphur dioxide reacts in air to form sulphur trioxide. In turn sulphur trioxde reacts rapidly with atmospheric moisture to produce sulfuric acid.
Sulphur trioxide + Water sulfuric acid.

Similarly, the oxides of nitrogen react in air to produce nitric acid. Both these acids are very strong acids. These materials, when present in the atmosphere, dissolve in water droplets and fall to earth as acid rain.
Under normal conditions, rain water is slightly acidic because carbon dioxide dissolves in it and reacts to form a weak acid, which is not harmful. But main’s contribution through fossil fuel , power plants, industries, automobiles has disturbed this natural acidic balance and inverted natural rain into precipitated acid rain with several environmental implications.

The ill effects of acid rain can be found on vegetation, soil, marine resources, monuments as well as on man. Air pollutants and acids generated by industrial activities are now entering forests at an unprecedented scale. Many forests in Europe and North America now receive as much as 30 times more acidity than they would if rain and snow fell without pollutants. Its reaction includes change in colour of leaves, premature drops of leaves and flowers, tree crowns progressively thin, and ultimately, trees die. Marine resources can be totally devastated with loss of aquatic life, fishes can die and entire lakes and streams can be destroyed. The affected fishes, if consumed by humans and birds, cause dangerous effects. In soil, the rate of decomposition of organic matter and formation of nitrogen fixing organisms is reduced by acids. Human health may also be affected increasing respiratory and skin problems.

Acid rain is an increasing problem in industrial areas of America, Europe and Asia. Where large amount of fossil fuels are burned. The ill effects of acid rains have no national limits as nature knows no geographical boundaries. Only developed technology can save the world from ill effects
of acid rain.

Discuss the main kinds of Ecological Succession? Describe the general process of succession?

Types of Ecological Succession

Ecological Succession may be of the following two types:

1. Primary succession : When succession begins on an area which has not been previously occupied by a community (e.g. a new exposed rock area, sand dunes, new islands, deltas, shore or recent lava flow) it is known primary succession. The first group of organisms (plants or animals) which become established in such an area is termed the pioneer community.

2. Secondary Succession : When community development is proceeding  in an area from which a community was removed and where nutrients and conditions for existence are already favourable e.g. cut over bandoned cropland and ploughed field, it is termed secondary sucession.

Secondary succession is usually more rapid because some s are already present. Moreover, previously occupied territory is receptive to community development than the sterile areas.

Depending upon the predominance of green plants or heterotrophic organisms in the initial serval stage, succession is distinguished into autotrophic succession and heterotrophic succession.

  1. Autotrophic succession: it is wide spread in nature and begins in predominantly inorganic environment. It is characterized by early and continued dominance by autotrophic organisms (e.g. green plants).
  2. Heterotrophic succession: It is characterized by early dominance heterotrophs such as fungi, bacteria and animals. It occurs in predominantly lanic environment such as in a stream heavily polluted with sausage, in len log or in small pools receiving leaf bitters in heavy quantities. Energy maximum at the beginning and declines as succession occurs unless .Additional organic matter is imported or an autotrophic community takes place. But in autotrophic succession, energy flow does not usually decline is maintained or increased.

General process of succession

Following steps are found in ground Succession

1. Nudation : Due to human or other natural activities the greenless of rd is called nudation. After nudation the real activity of succession start.

2. Invasion : The seeds collected near the nudation area. The seeds or plants collect first called pioneer. The following steps of invasion are —

(a) Migration: Plant community start at that time when the part of Jamules plants invasion in open area. And the jamules migrate through air, later or animals. Mostly Jamules destroy and those Jamules find according tuation, they raise up and migrate for other places.

(b) Ecesis : After migrate the transfer of new species called Ecesis.

(c) Aggregation : After the colony establish, the seeds become collected. And as a result of it there become start competition for light and place. During competition the strong plants keep alive.

3. Competition and Reaction: Inter specific competition start in plants for light and palace. Strong plants keep alive and start genesis. Plants do action through migration, it is called change in environment. This order is called reaction. Change situation become some little favour towards old plants and more towards new. Thus the new species comes in place of old. Thus the vegetarian plants convert into small and small change into tree.

Explain food-chain and food web with suitable examples.

Although biotic and abiotic components are separate by their complex relationship is balanced and functional, which can be explained by following points:

(1) Energy flow, (2) Food chains, (3) Food web

(1) Energy Flow: Existence of organisms depend on energy and main source of energy on the earth is the sunlight. Energy is required by the organisms for their various al activities. We know that two biotic components in the system are autotrophs and heterotrophs. Only green plants are capable to use sun-light r energy source and this energy is transferred from producers to consumers.
During transfer of energy there is loss of some part of energy and energy loss also occurred during respiration.It indicates that energy flow is unidirectional.

In any ecosystem only 1 percent solar energy can be used by green  plants for synthesis of food and such traped energy is responsible for an ecosystem, herbivore obtain energy – from green plants and secondary consumers obtain only 10% energy of a primary consumer (herbivore). At every level energy is lost in similar way. Energy flow and its distribution in the ecosystem is according to the Laws of Themodynamics which are as follows:

(1) First Law: Amount of energy is constant in the world and hence neither energy can be synthesized nor can be destroyed. Energy can be converted from one state to another state. Green plants convert light energy into chemical energy.

(2) Second Law: During energy transfer, some part of energy is lost. This energy loss is diffused in the environment mostly in the form of temperature and remaining is stored in the form of tissues.

Food Chains : The transfer of food energy from the producers through various organisms as they depend for food on one another (herbivore to carnivore to decomposers) with repeated eating and being eaten is known as food chain. In any food chain producers constitute the first trophic level. The energy stored in green plants is used by the herbivores (primary consumers) which constitute the second trophic level. Carnivores (secondary consumers) eat the herbivores and constitute the third trophic level As much, as longer chain, the highest consumer will get less energy because 90% energy is lost during each transfer in the form of temperature etc. are known as food web. Energy flow in a food chain is although unidirectional but through various path in a food web.

As much as complex food web in a ecosystems, the system will be more stable because consumers can obtain their food by various organisms. If there is scarcity of a particular kind of organisms then other organisms may be used as a food in a complex type of a food web. Terrestrial animals have following adaptations

  1. Cursorial adaptations: These adaptations provide ability for fast running. The body is streamlined and digitigrade so they can move through digits. Some are unguligrade for example horse.
  2. Fossorial adaptations : Many animals live in burrows. Body of these animals is Cylindrical e.g. snakes. Tail absent or reduced. Eyes are small and head is blunt.
  3. Desert adaptations : Lives of desert animals depend on water conservation. Some lizards for example moloch has skin capable to absorb moisture and a special structure in the alimentary canal is found in the camel for water storage. Sweat glands are absent in camel.

In Burrowing animals nostrils are on upper side of head to prevent from dust and large scales are present on the head indicate desert adaptation. Colour of desert animals is usually somewhat similar with soil.

  1. Scansorial adaptations : Many animals climb for obtaining food and defense. Lizards have adhesive glands for climbing on the walls. Similarly squirrels, tree frog, monkey etc. are able to run on the trees. These animals have prehensile tail, strong pectoral girdle, semicircular thorax, proximal part of forelimb is long and nailed digits, which are main adaptations.

Food chain : Any one sequence of species through which material and y passes is known as Food-chain. Food chain is a nutritional sequence in an Ecosystem.

Food-web: When number of food-chains are interlocked with each other, they make a very complex structure known as food-web. Food-web exhibits a complex inter-relationship of the populations of plan animals which exists in a particular system.

In other words, “The net work of inter-connected food chains in an ecosystem is called Food-web.”

Food-web exhibits a complex inter-relationship of the populations of plants and animals which exists in a particular ecosystem. In a Food-web each species is dependent upon other and the number of each link species must be sufficient for their continued existence.