Do you want to to create an amazing science fair project for your next exhibition? You are in the right place. Read the below given article to get a complete idea on ecosystem: 1. Meaning of Ecosystem 2. Components of Ecosystem 3. Structure 4. Food Chain 5. Energy Flow 6. Functions.
Contents:
- Science Fair Project on the Meaning of Ecosystem
- Science Fair Project on the Components of Ecosystem
- Science Fair Project on the Structure of Ecosystem
- Science Fair Project on the Food Chain in Ecosystem
- Science Fair Project on the Energy Flow in Ecosystem
- Science Fair Project on the Functions of Ecosystem
Science Fair Project # 1. Meaning of Ecosystem:
The populations of organisms interact with each other in biological communities, and no biotic community can live in isolation. It lives in an environment which supplies its material and energy requirements and provides other living conditions. A biological community interacting with the non-living environment is called an ecosystem. An ecosystem can be natural or artificial, temporary or permanent.
A pond, a lake, a tract of forest, a coral reef, a large grassland, a village, an aquarium, a field of sugarcane, a manned spaceship, or a laboratory culture can all be regarded as ecosystems. Thus, an ecosystem may be defined as a dynamic system which includes both organisms (biotic component) and abiotic environment influencing the properties of each other and both necessary for the maintenance of life.
The concept of ecosystem was first put forth by Sir Arthur Tansley in 1935. Ecosystems can be recognised as self-regulating and self-sustaining units of landscape. Ecosystem is the major ecological unit.
In nature, two major categories of ecosystems may be distinguished:
(i) Terrestrial, and
(ii) Aquatic.
Forests, grasslands and deserts are main examples of terrestrial ecosystems, while ponds, lakes, streams or salt water (marine estuaries) represent aquatic ecosystems.
Ecosystem has both structure and function. The structure is related to species diversity. The more complex is the structure the greater is the diversity of the species in the ecosystem. The function of ecosystem is related to flow of energy and cycling of materials through structural components of the ecosystem.
According to E.P. Odum, the ecosystem is the basic fundamental unit of organisms and their environmental interacting with each other and with their own components. All the ecosystems of the earth are connected to one another, e.g., river ecosystem is connected with the ecosystem of oceans, and a small ecosystem of dead logs is a part of large ecosystem of a forest.
However, human activities may modify natural ecosystems into man -made or anthropogenic ecosystems. For example, natural forests have been cut and the land converted to tree plantations or agricultural systems. Sometimes dam construction involves submergence of forests and conversion to water reservoirs.
Science Fair Project # 2. Components of Ecosystem:
Organisation of the Ecosystem:
The living parts (biotic component) and the non-living parts (abiotic component) of ecosystems are very closely interconnected. As we have studied that the energy flows in the form of food from one organism to another organism within a community. This is being done through feeding relationships such as grazing, predation and parasitism.
The biotic community is only one part of ecosystem. Another important part of ecosystem is the abiotic portion. The abiotic part of the ecosystem includes chemical elements such as oxygen, carbon and nitrogen.
It also includes physical elements such as oxygen, carbon and nitrogen. It also includes physical elements such as wind, fire and climate. Together, the biotic and abiotic parts determine the characteristics of the ecosystem.
The study of the functional aspect of an ecosystem consists of the volume and the rate at which various materials circulate and the rate at which energy flows through it. Energy moves through the food chain in one direction only.
The movement of matter is cyclic or circular. Energy flows through the ecosystem and is finally lost to space in the form of heat. Matter may be changed from one form to another, but it always remains in the ecosystem.
The study of the functional aspect of an ecosystem also includes the processes by which living organisms change the non-living or abiotic environment. The processes by which abiotic environment affects living organisms and the events by which population levels of organisms are regulated.
Biotic Components:
All organisms require energy for their life processes, and this energy enters the world of living things through the process of photosynthesis carried on by green plants. Green plants produce carbohydrates by photosynthesis and also synthesise proteins and fats. The green plants are called primary producers. Producers are autotrophic, i.e., self-nourishing.
A variety of photosynthetic bacteria, chemosynthetic bacteria and photosynthetic protozoans also produce organic substances in terrestrial and aquatic habitats, in very small amounts.
In terrestrial ecosystems, the autotrophs are usually rooted plants, such as herbs, shrubs and trees, while in deep aquatic ecosystems, floating plants called phytoplankton are the major autotrophs. The dominant producers of shallow water are called macrophytes, which are generally rooted plants.
All other populations in a community are dependent upon green plants and are referred to as consumers. Under this category are included all different kinds of animals that are found in an ecosystem. Consumers are also known as phagotrophs (phago = to eat).
They are hetrotrophic organisms, mostly animals which generally ingest or swallow their food. There are different categories of consumers, such as primary, secondary, tertiary, and scavangers, etc.
Primary consumers are purely herbivorous animals that are dependent for their food on producers or green plants, e.g., insects, rodents, rabbit, deer, cow, buffalo, goat, etc. The herbivores serve as the chief food source for carnivores.
Secondary consumers are carnivores. Generally, they are flesh eating animals that are adapted to consume herbivores, e.g., fox, wolves, cats, snakes, etc.
Tertiary consumers are the top carnivores which prey upon other carnivores and herbivores, e.g., lion, tiger, hawk, vulture, etc.
Besides different categories of consumers, the parasites, scavangers and saprobes are also included among consumers. The parasitic plants and animals utilize the living tissues of different plants and animals. The scavangers and saprobes utilize dead remains of animals and plants as their food.
The non-green organisms like the fungi and some bacteria, which are incapable of producing their food, live on dead and decaying plants or animal parts, and are consumers of a special kind, called the decomposers. These simplify step by step the organic constituents of each dead body.
Their activities make chemical substances available for other living beings, the producers. Decomposers are also known as saprotrophs (sapro = to decompose). Generally, they are hetrotrophic organisms, consisting mostly of bacteria and fungi which live on dead organic matter.
However, decomposers or saprotrophs release different enzymes from their bodies into the dead and decaying plant and animal remains. The extracellular digestion of the dead remains leads to the release of simpler inorganic substances which are then used by the decomposers. The decomposers play an important role in maintaining the dynamic nature of ecosystems.
Food-getting interactions are made up of several feeding, or trophic levels. The first trophic level is made up of populations of green plants and other autotrophs which use energy from sunlight to make food through the process of photosynthesis. These organisms which are mostly green plants are called primary producers.
The organisms depending for their food on primary producers are consumers. The herbivores such as cattle, deer and goat are primary consumers or the first order consumers. Animal populations that feed upon other consumers are secondary consumers or second order consumers, such as lion, tiger, leopard, etc.
Secondary consumers that only eat other animals are carnivores. Within a food chain, primary and secondary carnivores can be found. Primary carnivores eat animals and are in turn eaten by other animals, secondary carnivores. Omnivores are consumers that eat both plants and animals. For example, humans are omnivores.
Abiotic Components:
The living parts and the non-living parts of ecosystems are very closely interconnected. The biotic community is only one part of the ecosystem. Another important part of the ecosystem is the abiotic portion.
The abiotic part of the ecosystem includes chemical elements such as oxygen, carbon and nitrogen. Among the abiotic factors the most important are climatic and edaphic factors. The climatic factors consist of temperature, humidity, rain and snowfall. The edaphic factors comprise the soil and substratum.
Temperature:
A certain temperature is essential for all the vital functions of the plant and for its growth. All living organisms can survive only in a narrow range of temperature which allows their metabolism. For instance, plants normally prefer a temperature varying from 20°C to 40°C. Most flowering plants are killed at a temperature below 0°C and above 45°C, while seeds remain injured at a temperature far beyond these limits.
However, many living organisms develop physiological and behavioural adaptations to withstand extremes of temperature, such as the polar bear can live in very cold regions and hibernates during winter. Some birds and mammals migrate to warmer places in winter to avoid extreme cold. Some desert animals live inside burrows to avoid the intense heat of the desert.
Water:
Without water the life cannot exist. The unique chemical properties of water make it the supporter and carrier of life, and all biological activities depend on it. A given molecule of water does not necessarily stay in the same place forever. It may evaporate from a lake into the atmosphere or it may precipitate from the atmosphere as rain or snow.
It may be taken up by plant roots and become part of plant tissue. It may be frozen into a glacier or run off the land to meet the ocean. This movement of water throughout the biosphere is called the hydrologic cycle.
Plants, in relation to the factor of water are divided into three groups, i.e., hydrophytes, mesophytes and xerophytes. Hydrophytes are adapted to extremely wet situations. The leaves of such plants are fine and thin and possess little cutin.
Mesophytes are plants adapted to inhabit regions with a moderate water supply. Examples are cultivated crops, garden vegetables, trees, ferns and mosses. Xerophytes are plants adapted to inhabit in arid or semiarid regions, such as cactus, yucca, etc.
Whether an animal lives in the water, or on land, the water balance in its body must be maintained. The amphibians and earthworms always live in a moist environment. Most animals obtain water by drinking. Many animals get most of the water they need from their food. Some carnivorous animals obtain their water from the blood of their prey.
The termites live without the intake of water. They satisfy their water requirements from the water of metabolism. The camel can live for long periods without drinking water partly because it has a flexible water temperature.
The animals that cannot actively swim live under stones or in burrows and crevices, to avoid the strong water currents. The plants found in fast flowing water possess finely divided or thin ribbon-shaped leaves.
Sea anemones and limpets, living in the intertidal zone of sea have sessile habit whereas Neries and some tube worms live in the burrows in soil. The sea weeds such as Fucus, Laminaria, Macrocystis and Nereocystis are found in attached condition to face the waves and water currents.
Humidity:
The humidity of the atmosphere directly regulates the rate of transpiration and perspiration from the plants and animals respectively. Various plants and animals develop several adaptations to face dry conditions.
Light:
Light is an important ecological factor which is essential for photosynthetic organisms for the preparation of food, on which the whole living world depends. The reproductive cycle of many species of plants is affected by duration of light or length of day. The response of plants to day length is called photoperiodism. Light has been involved in the evolution of photoreceptors in the various animal groups.
These photoreceptors, such as the pigment spots of many invertebrates, play a prominent role in the procurement of food, the avoidance of enemies, and the recognition of mates during the breeding season.
Animals such as true frogs and chameleons have the ability to change their colour. They do so by photic stimulation through the eyes. Relative lengths of day and night make an important factor in periodical animal migration.
Some animals, such as the deer, mate in autumn when the days are short. Poultrymen have been able to increase egg production by exposing hens to longer light periods through the use of artificial light.
Light plays an important role in determining the periods of activity of animals. Some animals are active only at dawn, others are active through the morning hours, and still others are active only during brightest hours of the day.
At night diurnal forms withdraw from the scene and nocturnal animals become active. Many nocturnal animals have eyes specialized for nocturnal vision. The leaves of many leguminous plants fold up or droop at night.
Wind:
Air gusts or wind affect the plants in several ways. It enhances transpiration. In the forests it has been noticed that some plants can resist the action of wind far better than others.
On seashore the coconut-palms can withstand them well because their leaves are cut into narrow segments with stout mid-rib. Where the wind gusts are quite strong, only the plants with tough roots and stems can survive. Wind is useful in disseminating seeds and fruits, particularly those provided with some kind of appendages.
Soil pH:
The living organisms require an optimal pH range for their survival. Certain plants and animals thrive best in acidic conditions, other prefer neutral or alkaline conditions. pH of the soil and water is responsible to a great extent for the distribution of organisms.
Mineral elements:
Soil is defined ‘as mineral material that may exist in solid or unbroken form, such as boulders and gravels or as finely divided particles of mineral matter referred to as sands, silts or clays, depending upon the texture’. Often these finely divided soils will contain considerable amounts of organic matter that form a very rich productive humus.
A soil is described as ‘a complex physical and biological system providing support, water, nutrient and oxygen for the plant’. The major elements present in the soil are aluminium, silicon, calcium, magnesium, sodium, potassium and iron. The minor elements are -cobalt, boron, iodine, zinc, arsenic etc.
The concentration and availability of essential mineral elements control the distribution of all living organisms. Plants found in nitrogen deficient soil develop special adaptations to obtain it, such as harbouring nitrogen-fixing bacteria, and the insectivorous habit of plants.
The salinity of soil or water has great influence on the distribution of organisms. Special salt secreting glands develop in plants and animals to eliminate excessive salt. The fresh water species cannot survive in a marine habitat.
Animals living in the estuaries near the seashore have special physiological adaptations for facing fluctuations in salinity accompanying tidal rhythms. The pneumatophores and vivipary are special adaptations in the mangrove vegetation.
Topography:
The topography of an area is represented by physical features, such as hills, plains or slopes. It influences distribution of organisms in the direct way. Sometimes, it indirectly affects the factors, such as wind, water current, light or wave action. The centre and edge of a pond, top-side and under-side of a rock or boulder, north and south faces of a ridge are generally occupied by different species of organisms.
Background:
The background of the habitat is responsible for the distribution of animals by enabling them to paint against the colour, pattern and general texture, such as desert animals like lion and the camel are sand-coloured. The jelly fishes and sea cucumbers are glassy in appearance. The chameleon changes its colour according to its background.
Science Fair Project # 3. Structure of Ecosystem:
As described earlier, biotic and abiotic components are physically organised to provide a characteristic structure of the ecosystem.
Important structural features are:
(i) Species composition, and
(ii) Stratification.
For example, some ecosystems, such as tropical rain forests, show a canopy of tall plants and a large number of biological species. On the other hand, a desert ecosystem shows a low discontinuous layer of herbs or small shrubs which consist of less number of species and extensive bare patches of soil.
In the forest, tallest trees, influence the under storey plants and ground vegetation. The plants form more or less, distinct strata or storeys on vertical as well as in horizontal planes, which is characteristically known as stratification. The individuals of different layers represent different species of plants.
Trophic levels:
There is another way to depict the structure of ecosystem through food relationships of producers and consumers. Trophic or food structure of ecosystem is based on the existence of several trophic levels.
The energy in a community is passed from one organism to another in feeding patterns. These patterns of energy transference together form a food chain. Each step in the food chain represents a trophic level.
The plants represent the first trophic level, the herbivores make the second trophic level, the primary carnivores constitute the third trophic level, and the secondary carnivores, such as large fish, man, etc., constitute the fourth trophic level of an ecosystem. Thus energy from the sun enters the living world through photosynthetic organisms and passes open from one organism to another in the form of food.
Trophic structure may be described in terms of living material, called standing crop, found in different trophic levels at a given time. The standing crop is commonly expressed as the biomass of organisms per unit area. The biomass is defined as the total weight of dry matter (dry weight) present in the ecosystem at any one time.
Nutrients are required for the proper growth and development of living organisms. They flow from abiotic to biotic components and back to the non-living component again in a more or less cyclic manner. This is known as biogeochemical cycle or inorganic-organic cycle.
The amounts of nutrients, such as nitrogen, phosphorus and calcium present in the soil at any given time, are called the standing state. The standing states of nutrients differ from one ecosystem to another, or with seasons even in the same ecosystem.
Science Fair Project # 4. Food Chain in an Ecosystem:
In the ecosystem, green plants alone are able to trap in solar energy and convert it into chemical energy. The chemical energy is locked up in the various organic compounds, such as carbohydrates, fats and proteins present in the green plants. All trophic levels in ‘an ecosystem is connected by transfer of food or energy.
The transfer of energy from one trophic level, e.g., producers, to the next trophic level, e.g., consumers, is called food chain. Thus, a food chain may be defined as the transfer of energy and nutrients through a succession of organisms through repeated process of eating and being eaten.
Mainly, food chains are of two types:
(i) Grazing food chain and
(ii) Detritus food chain.
i. Grazing Food Chain:
The grazing food chain starts from green plants and goes from herbivores (primary consumers) to primary carnivores (secondary consumers) and then to secondary carnivores (tertiary consumers) and so on. Cattle grazing in grasslands, deer grazing in forest, and insects feeding on crops and trees, are most common biotic constituents of the grazing food chain.
Autotroph → Herbivore → Primary carnivore → Secondary carnivore, etc..
ii. Detritus Food Chain:
The dead organic remains including metabolic wastes and exudates derived from grazing food chain are generally called detritus. The energy contained in detritus is not lost in ecosystem as a whole; rather it serves as a source of energy for a group of organisms called detrivores that are separate from the grazing food chain.
The food chain so formed is called detritus food chain. This begins with dead organic matter and passes through detritus feeding organisms (detrivores) in soil to organisms feeding on detritus-feeders.
In some ecosystems more energy flows through the detritus food chain than through grazing food chain. In detritus food chain the energy flow remains as a continuous passage rather than as a step wise flow between discrete entities.
In detritus food chain, there are many organisms which include algae, fungi, bacteria, slime molds, actinomycetes, protozoa, etc. Detritus organisms ingest pieces of partially decomposed organic matter, digest them partially and after extracting some of the chemical energy in the food to run their metabolism excrete the remainder in the form of slightly simpler organic molecules.
The waste from one organism can be immediately utilised by a second which repeats the process. Gradually the complex organic molecules present in the organic wastes or dead tissues are broken down to much simpler compounds, sometimes to carbon dioxide and water, and whatever is left that is humus. In a normal environment the humus is quite stable and forms an essential part of the soil.
Links between Grazing and Detritus Food Chains:
Just as energy enters the detritus food chain from the grazing food chain as leaf litter, or dead organisms, energy can re-enter the grazing food chain from the detritus food chain if organism from the latter are consumed by grazers. Considering the diversity of the detritus community, it is not surprising that many of these serve as prey for carnivores in the grazing food chain.
A common example is robin eating earthworms. In addition, many insects, among them beetles and flies, spend their larval period in the detritus food chain and their adulthood in the grazing food chain.
But through such links through which energy passes from detritus food chain basic into grazing food chain, very little amount of energy is passed in comparison to the amount of energy which flows from grazing food chain to detritus food chain.
Science Fair Project # 5. Energy Flow in an Ecosystem:
Energy has been defined as the capacity to do work.
Energy exists in two forms:
(i) Potential, and
(ii) Kinetic.
Potential energy is the energy at rest, i.e., stored energy, capable of performing work Kinetic energy is the energy of motion, i.e., free energy. It results in work performance at the expense of potential energy. Conversion of potential energy into kinetic energy involves the imparting of motion.
The source of energy required by all living organisms is the chemical energy of their food. The chemical energy is obtained by the conversion of the radiant energy of sun.
The radiant energy is in the form of electromagnetic waves which are released from the sun during the transmutation of hydrogen to helium. The chemical energy stored in the food of living organisms is converted into potential energy by the arrangement of the constituent atoms of food in a particular manner.
In any ecosystem there should be unidirectional flow of energy.
This energy flow is based on two important laws of thermodynamics, which are as follows:
a. First Law of Thermodynamics:
It states that the amount of energy in the universe is constant. It may change from one form to another, but it can neither be created nor destroyed. Light energy can be neither created nor destroyed as it passes through the atmosphere. It may, however, be transformed into another type of energy, such as chemical energy or heat energy. There forms of energy can be transformed into electro-magnetic radiation.
b. Second Law of Thermodynamics:
It states that non-random energy, i.e., mechanical, chemical and radiant energy, cannot be changed, without some degradation into heat energy. The change of energy from one form to another takes place in such a way that a part of energy assumes waste form, i.e., heat energy. Thus, after transformation the capacity of energy to perform work is decreased, and energy flows from higher to lower level.
Thus, in ecosystem, the transfer of food energy from one organism to another leads to degradation and loss of a major fraction of food energy as heat due to metabolic activities, with only a small fraction being stored in living tissues or biomass. Energy in food is in concentrated form, while heat energy is highly dispersed. All changes in energy forms can be accounted for in any system.
Main source of energy is sun. Approximately 57 percent of sun energy is absorbed in the atmosphere and scattered in the space.
Some 35 per cent is expanded to heat, water and land areas and to evaporate water of the approximately 88 per cent of light energy striking plant surface, 10 percent to 15 per cent is reflected, 5 per cent is transmitted and 80 per cent to 85 per cent is absorbed, and an average of only 2 per cent (0.5 to 3.5 per cent) of the total light energy striking on a leaf is used in photosynthesis and rest is transformed into heat energy.
However, only the visible light, i.e., the photosynthetically active radiation (PAR), which carries about 50 per cent of the energy of total incident solar radiation, is available to primary producers for absorption.
By multiplying the estimated productivity with the calorific value, i.e., energy content per unit weight, of biomass, the energy captured can be determined. The calorific value is determined by burning known weight of dry biomass in a bomb calorimeter in the presence of oxygen, and measuring the heat evolved.
Energy Flow in Ecosystems:
Living organisms can use energy in several forms: radiant and fixed energy. Radiant energy is in the form of electromagnetic waves such as light. Fixed energy is potential chemical energy bound in various organic substances which can be broken down in order to release their energy content.
Organisms that can fix energy from inorganic sources into organic molecules are called autotrophs. Organisms that cannot obtain energy from abiotic source but depend on energy-rich organic molecules synthesised by autotrophy are called heterotrophs. Those which obtain energy from living organisms are called consumers and those which obtain energy from dead organisms are called decomposers.
When the light energy falls on the green surfaces of plants, a part of it is transformed into chemical energy which is stored in various organic products in the plants. When the herbivores consume plants as food and convert chemical energy accumulated in plant products into kinetic energy, degradation of energy will occur through its conversion into heat.
When herbivores are consumed by carnivores of the first order, i.e., secondary consumers, further degradation will occur. Similarly, when primary carnivores are consumed by top carnivores, again energy will be degraded.
However, under favourable environmental conditions, only about 1-5 per cent energy of incident radiation, or 2-10 per cent of photosynthetically active radiation, as actually captured by the photosynthetic process, i.e., gross primary productivity, and the remaining portion is dispersed.
As the simultaneously occurring respiratory processes are energy consuming and use up the part of photosynthetic gain, the net capture of energy, i.e., net primary productivity is reduced to only 0.8 – 4 per cent of the incident total radiation, or 1.6 to 8 per cent of photosynthetically active process (PAR). Only the energy captured in net productivity is used by other trophic levels.
Trophic Level:
The producers and consumers in ecosystem can be arranged into several feeding groups each known as trophic level or feeding level. In any ecosystem, producers represent the first trophic level, herbivores represent the second trophic level, primary carnivores represent the third trophic level and top carnivores represent the last trophic level.
There are two main aspects of energy flow in ecosystem:
The energy flows one way, i.e., from producers through herbivores to carnivores. This cannot be transferred in reverse direction.
The amount of energy flow decreases with successive trophic levels.
Producers capture only a small fraction of solar energy, i.e., only 1-5 per cent of total solar radiation, and the bulk of unutilised energy is dispersed mostly as heat.
However, part of energy captured in gross production of producers is used for maintenance of their standing crop (respiration) and for providing food to herbivores, i.e., herbivory.
The unutilised net primary production is ultimately converted to detritus, which serves as source of energy to decomposers.
Thus, energy actually used by the herbivore trophic level is only a small fraction of the energy captured at the producer level.
On an average, in different ecosystems, the herbivore assimilation or productivity approximately comes to 10 per cent of gross productivity of producers.
The energy assimilated by herbivores is used in respiration and a fraction of unassimilated energy is transferred to decomposers, e.g., faecal matter.
The remaining herbivore level energy is either utilised by the carnivores, or gets transferred to decomposers after the death of herbivores.
The energy available at carnivore trophic level is again partitioned, leaving a very small fraction to support the next trophic level.
The species which occupy each trophic level in the food chain form a link, called the food – link. The links of one food chain are a flower, a butterfly, a dragonfly, a frog, a snake and a hawk. Here the flower nectar is eaten by butterfly; the butterfly is eaten by dragon fly, and so on through each successive link of the food chain.
The chain ends with the hawk. When a hawk dies, its cells and tissues are digested and used as food by bacteria and other organisms of decay. In this way, the organic materials of the food chain are returned to the soil and recycled through another chain.
However, the organisms that traps solar energy and act as producers also use up some energy for their own life processes. Animals being more active than plants use much of the energy acquired before they are consumed by the next trophic level.
The studies have shown that only about ten per cent of the food energy in green plants is utilized by themselves at the primary consumer level. Much of the other 90 per cent of the energy goes to heat and movement. The actual percentages of energy from food at one level converted to energy from food at the next level are more than 10 per cent or less than 10 per cent.
This general pattern forms an energy pyramid as each successive trophic level has less energy available to it. So, at each stage of energy transfer, a considerable energy is lost from the food chain. The decomposition of dead organisms also releases chemical energy. The chemical energy is transferred to living world through food.
Food means “materials containing energy that organisms can use”. Since food is the means of transfer of both matter and energy in the living world hence the study of food relation becomes necessary to understand the community and environment.
Science Fair Project # 6. Functions of Ecosystem:
An ecosystem is a discrete structural, functional and life sustaining environmental system. The environmental system consists of biotic and abiotic components in a habitat. The synthesis and perpetuation processes involve energy exchange and this energy comes from the sun in the form of light or solar energy.
Thus, in any ecosystem, there are three functional components:
(i) Inorganic constituents (i.e., air, water and minerals)
(ii) Organisms (i.e., plants, animals and microbes), and
(iii) Energy input which enters from outside (i.e., sun).
These three interact and form an environmental system. Inorganic constituents are synthesized into organic structures by the green plants (primary producers) through photosynthesis and solar energy is utilized in the process. Green plants become the source of energy of renewals (herbivores) which, in turn become source of energy for the flesh eating animals (carnivores).
Animals, of all types grow and add organic matter to their body weight and their source of energy is complex organic compound taken as food. They are known as secondary producers. All the living organisms, whether plants or animals in an ecosystem have a definite life span after which they die.
The dead organic remains of plants and animals provide food for saprophytic microbes, such as bacteria, fungi, and many other animals. The saprobes ultimately decompose the organic structure and break the complex molecules and liberate the inorganic compounds into their environment. These organisms are known as decomposers.
During the process of decomposition of organic molecules the energy which kept the inorganic components bound together in the form of organic molecules gets liberated into the environment as heat energy. Thus, in an ecosystem energy from the sun, the input is fixed by the plants and transferred to animal components.
The ecosystems operating in different habitats, such as deserts, forests, grasslands and seas are interdependent on one another. The energy and nutrients of one way find their way into another, so that, ultimately all parts of the earth are interrelated, each comprising a part of the total system that keeps the biosphere functioning.
Thus, principal functions of ecosystems are as follows:
(i) Reception of radiant energy of sun.
(ii) Manufacture of organic materials from inorganic ones by producers.
(iii) Consumption of producers by consumers and further elaboration of consumed materials
(iv) After the death of producers and consumers, complex organic compounds are degraded and finally converted by decomposers and converters into such forms as are suitable for reutilization by producers.