Click here to Download Ecology for Millions PDF Book by H. L. Kundu English having PDF Size 2.9 MB and No of Pages 298.
Along with this exploitation of Nature, the growth of knowledge of modern medicine gave a spurt in the growth of human population. So since renaissance, human population of the world has grown very fast. Between 5000 B.C. and 1000 A.D. the growth in human population was quite slow. But from about 1500 A.D. or so (soon after renaissance) the rise in human population became spectacular and fearful (Fig. I.1.).
Ecology for Millions PDF Book by H. L. Kundu
|Name of Book||Ecology for Millions|
|Author||H. L. Kundu|
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|No of Pages||298|
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This explosive growth of human population however, is not due to any rise in human fertility (as is commonly believed ) but mostly owing to drop in child mortality as a result of modern medical care. 3.3. Gradually the native populations of North America, South America, Australia & New Zealand were almost decimated or withered away and replaced by more energetic and demanding people of European stock.
The Oregon Trail Francis Parkman; 1967. Bantam Books pp.298). Other European colonies in Asia and Africa could not however decimate the native populations but the control passed on to European hands. Only China and Japan in Asia remained free of European control. A glance at pages 244/5 of Harper Collins Atlas of World History edited by Geoffrey Barraclough (1998) will corroborate the above statement.
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Here is one sentence form the same. “The late 19th century saw a new imperial outburst of an intensely competitive kind. In the scramble for territory, resources, markets and outlets for capital investment, an immense part of the world’s total land area passed under European control”
After several such descriptions of self sustaining habitats by ecologists both in Europe and in America, the definition of Ecosystem offered by English Botanist A.G. Tansley (1935) seemed most appropriate. According to Tansley all the living beings of a place ( i.e. plants, animals and bacteria etc.
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Along with their habitat ( i.e. physical and chemical components of environment) when interact and produce a recognisable stable entity, the place may be called an ecosystem (1935). An Ecosystem contains adequate amount of Autotrophs* (green plants—trees, grasses, algae etc. which can produce their own food), Heterotrophs (animals-herbivores, carnivores etc.), bacteria etc.
Which feed upon the matter produced by the autotrophs), Saprotrophs (bacteria, fungi etc.) and the Abiotic Components of surrounding environment (soil, water, air, light and heat—ingredients used by autotrophs to produce food). The above four factors or features autotrophs, heterotrophs, saprotrophs and abiotic components.
Interact with each other in such a fashion as to create a more or less stable and self sustaining unit of environment. Such a self-sustaining unit of Nature is an ECOSYSTEM. A large forest, a lake, a coral reef, a mangrove forest or a desert, all , if left undisturbed and remain self sustaining, are ecosystems. Ecology for Millions PDF Book
So henceforth we shall call these components namely, autotrophs, heterotrophs saprotrophs and abiotic components as the four basic components of all ecosystems. 2.1. With a little imagination we can easily see that ecosystems can be of various types. For example, a lake or a large pond can be an ecosystem as these are self-sustaining; so is a forest and so on.
Human interference often robs ecosystems of their self-sustenance and thus kills them. A detailed examination of a simple ecosystem say, a large pond or a small lake, will help to understand the basic fetures of ecosystem. As early as 1927, T. Gaarder and H. H. Gran devised a very clever experiment for measuring – both gross and net productivities, of an aquatic ecosystem.
First the principle. During photosysthesis the plants produce biomaterials with the help of their green pigment i.e., chlorophyll, using carbon dioxide and water with energy from sunlight. During this process oxygen is released. So simply, photosynthesis can be shown as follows : CO2 + H2O + energy (from sunlight. Ecology for Millions PDF Book
And help of chlorophyll CH2O + O2 CH2O is a very simple biomolecule from which other complex biomolecules are made. So the net direct outcome of photosynthesis is the production of CH2O and O2 (oxygen) and removal of CO2. Therefore if we can measure how much CO2 is taken up or, how much O2 is released from the ecosystem we shall know how much biomaterial is produced.
Here we must not forget that oxygen is also used by plants themselves in their own respiration. Therefore whatever oxygen that comes out of the ecosystem is that which is surplus after providing for respiration. This information is what Gaarder and Gran used. They measured the amount of oxygen released during a fixed period of time by a fixed amount of photosynthetic plants.
And also determined the amount of oxygen that was used up during the same period by the same plants. By adding one with the other they got the total amount of oxygen produced during photosynthesis by the same plants. From this sum total of oxygen produced, Gaarder and Gran determined the amount of biomaterial that was synthesised by these plants during that period. Ecology for Millions PDF Book
Following is the technique. 3.3. Three empty bottles of equal size were filled up with water from the same depth and preferably near the surface of a pond/ lake which is welllighted and has normal phytoplankton flora, i.e., the water not crystal clear but rather somewhat greenish. The bottles are marked ‘A’, ‘B’ and ‘C’.
The O2 present in the bottle ‘A’ is immediately fixed with chemicals so that, both photosynthesis and respiration are stopped in this bottle. The bottle ‘B’ is thoroughly wrapped up in 3 layers of aluminium foil so that no light can penetrate into the bottle. This will stop photosynthesis but not respiration.
The bottle ‘C’ is left as such i.e., unwrapped; so, here both photosynthesis and respiration will go on as usual. 3.4. Now all the three bottles i.e. ‘A’, ‘B’ and ‘C’ are stoppered and tied with three strings are left hanging in the same depth but near the surface of water, so that these can receive enough sunlight, and then left there for 24 hours i.e. one full day and one full night (Fig. III.1.). Ecology for Millions PDF Book Download
After 24 hours the bottles are lifted and their respective oxygen contents are fixed and measured. First the solar energy is picked up by green plants. This energy locked into plants’ bodies is passed on from them into animals providing energy for all their biological activities. Again as wood, coal and petroleum.
Plants provide energy for all other activities responsible for sprouting up and spread of human civilisation in its breath-taking splendour of today. This phenomenon has been beautifully described by the Indian poet Rabindra Nath Tagore in the second poem quoted in the beginning of this chapter.
He said “Oh trees, by lending the power which you have drunk from the Sun, to men, you have made them so strong that they have conquered the Earth and now they are trying to challenge God himself”. (The preceeding lines within italics are author’s own translation of a part of this poem in an attempt to depict the spirit of this superb poem). Ecology for Millions PDF Book Download
This forms part of the 2nd poem in the begening of this chapter. 2.2. The properties of energy can be understood by following the basic laws of thermodynamics. 2.3. The First Law of Thermodynamics states that energy can neither be created nor destroyed; it can only change from one state to another. For example, from light to heat etc.
When sunlight falls upon a surface it warms up the surface, which means light is converted to heat. There are many such examples. 2.4. The Second Law states that at every step of conversion i.e. change from one state to another some energy will be invariably lost (or dissipated) into the environment. Consequently energy will always flows from a higher level to a lower level (Fig. IV. 2.).
The Third Law states that Nature if left to herself tends to lose energy and thus gradually sink to more and more disorder. In thermodynamics this is known as entropy. Ample sunlight is a positive factor. Reasonable amount of wind current or water current are positive factors as currents help the supply of oxygen and remove unwanted metabolic products. Also up to a point, temperature is helpful for growth. Ecology for Millions PDF Book Download
On the other hand too much of heat or, too much or cold or too high winds all are negative factors for productivity. 6.2. Agriculture is essentially creation of an artificial ecosystem where, for certain selected species such as, rice, wheat , maize or cows, sheep and poultry etc. the specific positive factors for productivity are boosted such as, fodder and minerals for cows, sheep etc.
And nutrients and water for crops and also the elimination of competitive species such as weeds, pests etc. in order to ensure a very high productivity of grains or standing crop as the case may be, from the point of view of the requirements of humanity. Still it would be well-worth to remind ourselves of the fact that the world average of utilisation of solar energy for primary production (P1) is only 2%.
A look at the following table (Table IV. 1.) will give us an idea about the net annual primary productivities and biomass of all major ecosystems of the world. This compilation by R. H. Whittaker (1975) is a very useful one. For example it can help planners to focus on such ecosystems where investments to augment primary production to yield maximum output vis a vis capital invested. Ecology for Millions PDF Book Free
It would also help to do the opposite i.e. help to decide for which ecosystems paying attention may wait. Also it should be noted that the net annual world primary production is 170 billion tons from which all our and the requirements of other consumers such as fishes, deers, tigers, elephants, birds etc. etc. are met. And all this 170 billion tons come from only 1% of solar energy that reaches the ecosystem.
Rest 99% of solar energy absorbed by plants goes for other things such as weather regulation, creating ocean currents, rains etc. all of which collectively keep the biosphere alive. 6.4. It seems it would be an interesting mathematical speculation to work out a computer model and estimate what would be the likely fall-out if, say, through genetically enginered plants we succeed to utilise instead of present 1%.
1.25% or even 1.5% of solar energy that reaches the earth surface. Would the meteorological ripple that would result may, through butterfly effect (Chaos Theory), bring havoc in our earth through changes in weather? Would this lead to serious tampering with Nature? Off course tampering with Nature in small ways have already started long ago.Ecology for Millions PDF Book Free
When we became herdsmen instead of food gathers (Paleolithic Age) we tampered with ecosystem. Again when we became agriculturists instead of herdsmen (Mesolithic Age) we once again tampered with Nature. Electricity, damming of rivers, deforestation, atom bombs, genetic engineering etc. all are forms of tampering with Nature’s Ways.
Unrestricted breeding inevitably leads to catastrophe. Here are some examples, some estimated, some actual. Carl Linnaeus has calculated that if, an annual plant produce only two seeds each year, even then in twenty years it will leave a million plants! Charles Darwin estimated that an elephant, one of the slowest breeder amongst animals, will leave in five hundred years.
From one initial pair, a population of fifteen million elephants (pl. see Table VI.1, as well). Following table gives how houseflies would multiply in one year, if unchecked (Tab. VI. 4). Eggs layed by houseflies Musca domestica in just one year starting from one pair of housefly and assuming it will lay 120 eggs in one generation of which 50% will be females. Ecology for Millions PDF Book Free
And it will have seven generation in a year and all will live only for one year then one pair will lead to the production of nearly 5000 billion eggs of houseflies in just one year, (E. J. Kormondy- P. 76. Concepts of Ecology 1978. Printice Hall. New Delhi). Here is our estimation for human beings Homo sapiens (Table VI.1).
Normally one healthy human female can produce ten children in her reproductive life of twentyfive years of these half may be females. If they can breed unrestricted, in a short span of 325 years, one pair of human beings will lead to a human population of 2.44 billion human beings-double of today’s population of China (Table VI. 6).
Obviously Nature can never permit such unrestricted breeding to any species. When Nature is prevented from acting freely then conscientious human intervention is the next best thing. Today human beings are the most powerful manipulator of Nature. But limited human intervention is not enough. Human population has never grown as fast as its physiology permits (i.e. ‘r’). There was always some pressure on it to grow slowly. Ecology for Millions PDF Book Free