Term Paper on Ecosystem: Top 7 Papers | Biology

Here is a compilation of term papers on ‘Ecosystem’. Find paragraphs, long and short term papers on ‘Ecosystem’ especially written for school and college students.

Term Paper on Ecosystem

Term Paper Contents:

1. Term Paper on the Introduction to Ecosystem
2. Term Paper on the Components of Ecosystem
3. Term Paper on the Kinds of Ecosystem
4. Term Paper on the Ecological or Eltonian Pyramids
5. Term Paper on the Ecological Succession
6. Term Paper on the Ecological Interdependence
7. Term Paper on the Ecosystem Services

Term Paper # 1. Introduction to Ecosystem:

Ecosystem (Greek Eco –  environment, system – interdependent and interacting complex) is said to be an integrated system resulting from interaction of living and non-living factors of the environment. An ecosystem can be defined as a dynamic system in which living organisms interact with themselves and with their physical environment, influencing the properties of each other. The term ecosystem was first coined by Arthur G. Tansley.

According to Odum (1963), the ecosystem is the basic functional unit of ecology in which both biotic community and abiotic environment influence each other. Ecosystem is self-regulatory and self-sustaining structural and functional unit of biosphere.

Ecosystem may be natural and manmade or anthropogenic. Natural ecosystems are further classified into terrestrial and aquatic. Terrestrial ecosystems are deserts, forests, meadows, grasslands, etc. Aquatic ecosystem can be fresh water as well as marine.

Fresh water ecosystems are streams, lake, ponds, and marine water ecosystems are seas, oceans, estuaries, etc. There are artificial or man-made or anthropogenic ecosystems as well. They are aquarium, artificial lakes, crop fields and space ships.

---

Term Paper # 2. Components of Ecosystem:

According to Odum, ecosystem comprises of two main components, biotic (living) compo­nent and abiotic (non-living) component. This can also be categorised as structural component. The components of ecosystem can also be categorised as functional components. These are energy flow and productivity, cycling of nutrients and development and stabilising of ecosystem.

Structural Components of an Ecosystem:

a. Biotic Components:

These are the living components of ecosystem. Depending on their nutritional relationship they can be categorised as autotrophic, heterotrophic and de­composers (Fig. 1).

i. Autotrophic Component (Greek Auto – Self; Trophos –  Feeders):

Autotrophic components are those components which are self-dependent and have the capacity to change the inorganic substances into organic forms. This category includes photosynthetic green plants, photosynthetic bacteria, cyanobacteria and chemosynthetic bacteria. Photosynthetic bacteria use energy from the Sun whereas chemo­synthetic bacteria utilise chemical energy.

Autotrophs are also known as producers. These can be herbs, shrubs, trees, free-floating microscopic phytoplankton and algae. With the help of sunlight and chlorophyll they undergo the process of photosynthesis which generates glucose. This glucose changes into complex organic compounds like starch, lipids, proteins, etc.

Producers are the primary basis of life and provide shelter, oxygen and food to the rest of the biotic world.

ii. Heterotrophic Component (Greek Hetero – Other; Trophos – Feeders):

They are also called as consumers as their requirement for food and energy is met by the producers directly or indirectly. These are mainly animals and depending on their feeding they can be categorised as herbivores, carnivores and omnivores.

Herbivores are those animals which directly feed on producers or plants and are known as primary consumers. Some examples of primary consumers are deer, rabbit, goat, sheep, etc. Carnivores feed on herbivores and are also known as secondary consumers.

A few examples of secondary consumers are snake, dog, cat, etc. These secondary consumers are further consumed by other animals which are categorised as tertiary consumers. Examples of tertiary consumers are lion, hawk, tiger, etc. Omnivores are the organisms which feed both on plants as well as animals, e.g. Humans, foxes, dog, cockroaches, etc.

iii. Decomposers:

These are also known as saprophytes. ‘Sapro’ means to decompose. These organisms feed on dead and decaying matter. Unlike other animals they digest the food outside the body and then take in the digested food. For this, they release the enzymes on the dead and decaying matter. They help in breaking down the nutrients and returning it back to nature.

b. Abiotic Components:

This comprises of non-living matter which can be divided into three categories. They are organic substances, inorganic substances and climatic factors. Organic substances include carbohydrates, proteins, fats, etc. Inorganic substances include carbon, nitrogen, sulphur, phosphorus, carbon dioxide and water. Sunlight, moisture, temperature and soil texture contribute to the climatic factors.

Functional Components of an Ecosystem:

The functional components of ecosystem include producers, consumers and decomposers. Producers convert the inorganic matter into organic matter, consumers consume the producers directly or indirectly and decomposers break the complex organic matter into simpler inorganic forms and return it back as abiotic component. In these interactions there is a unidirectional flow of energy from lower to higher trophic level.

---

Term Paper # 3. Kinds of Ecosystem:

Arbitrarily, the various ecosystems in the world can be grouped under two kinds:

1. Natural Ecosystem:

These types of ecosystem operates under natural condi­tions without much interference of man and can be further divided into the following kinds:

(i) Terrestrial ecosystem:

It comprises of grassland, forest, desert and so on.

(ii) Aquatic ecosystem:

It can be further subdivided into —

(a) Fresh water:

Fresh water comprising of lentic (standing water system such as ponds, lakes, pools, ditches etc.) or lotic (running water system such as rivers, streams, springs etc.) water conditions.

(b) Salt water:

Salt water comprising of sea, deep sea, estuaries, salt water berries, and salt water lakes etc.

(iii) Wetland ecosystem:

It comprises of marsh, bog, fen, shrubcarr and swamp.

2. Artificial Ecosystem:

Here the natural balance of nature is frequently disturbed by manipulation and addition of energy.

Examples:

Intensive culture of prawns in an impoundment, artificially maintained pond, croplands like maize, wheat, rice-fields etc.

The study of an ecosystem:

Large, complex ecosystems can be approached in two ways:

1. Holological (holos, whole):

Here the inputs and outputs are measured collectively. The properties that emerges of the whole ecosystem are assessed and then the component parts are investigated as needed.

2. Merological (meros, part):

Here the major components of the ecosystems are studied first and then integrated into a whole system.

---

Term Paper # 4. Ecological or Eltonian Pyramids:

An ecological pyramid is a diagrammatic representation of an ecological parameter like number, biomass or energy at different trophic levels in a food chain in an ecosystem. The credit of creating these pyramids goes to Charles Elton (1927), so the name given as Eltonian pyramids. Depending on the parameter used there are three types of pyramids, pyramid of numbers, pyramid of biomass and pyramid of energy.

A pyramid can be upright depicting that the producers outnumber and outweigh the herbivores which in turn outweigh and outnumber the carnivores.

A food web gives alternate pathway for the availability of food. This helps the organism to survive even with the shortage of one or two organisms. The scarcity of food is taken care of as organisms can get energy from different sources. Food web also keeps a check on the population.

1. Pyramid of Numbers:

The most convenient way to understand the food web is to count the organisms of a given area and put them in different trophic levels. We find that the largest number is of producers and the number keeps on decreasing as we move forward in the food chain. When this information is transferred in the form of pyramid it gives rise to an upright pyramid (Fig. 8).

This shows that producers are more than the herbivores which in turn are more than the carnivores. However, in a tree dominated ecosystem the pyramid of numbers is inverted. Here the producer is a tree which will have numerous insects, hence the number at the base is small as compared to the leaf eating insects (Fig. 9).

2. Pyramid of Biomass:

This pyramid represents the dry weight or standing crop of every trophic level. In a terrestrial habitat it is an upright pyramid, but in an aquatic habitat it is inverted. In terrestrial ecosystem biomass is maximum at the producer level and it progressively decreases as we move up in the trophic level. In aquatic ecosystem the biomass of producers (phytoplankton) is less than the primary consumers (zooplanktons) which in turn is less than the secondary consumers (Fig. 10).

3. Pyramid of Energy:

This pyramid represents the number of calories transferred from one trophic level to the next. This pyramid is always upright as the energy that flows always decreases with every trophic level. It is maximum in producers and least in carnivores (Fig. 11).

---

Term Paper # 5. Ecological Succession:

Ecological or biotic succession means the occurrence of definite, gradual and predictable sequence of communities over a long period of time in the same area resulting in establishment of stable community. This occurs in a stepwise manner. The complete succession is called sere. Each sere has a number of seral stages. Final and last seral stage are called as climax community.

Ecological succession is a continuous change in the kind of plants and animals. As the succession proceeds there is an increase in the species diversity. This is associated with increase in organic matter and biomass. On barren ground biotic succession increases wetness, whereas in water bodies it increases dryness.

There are certain important definitions related to succession:

a. Hydrach succession – Succession occurring in water bodies

b. Xerach succession – Succession occurring on dry and hot terrestrial area

c. Primary succession — Succession occurring on a previously unoccupied area

d. Secondary succession — Succession occurring on areas where natural vegetation has been destroyed

e. Pioneer species – This is the first species that colonises the area

f. Pioneer community – Various pioneer species together form pioneer community

g. Seral stage – Intermediate stages from pioneer to climax stage

h. Climax community – Last and final stage of succession

i. Sere – Different seral stages of succession together constitute sere.

Kinds of Ecological Successions:

There are two kinds of successions – primary and secondary. Primary succession

This succession occurs on community previously existed. The area is totally devoid of life. It can be on bare rock, volcanic islands, etc.

a. Primary Succession on Bare Rock/Xerach Succession:

The pioneer organisms on bare rocks are lichens. In this association, algae provide the food and fungal component holds on to the rock. Lichens form crust which starts the formation of soil from their organic remains. Lichens also stimulate the chemical break down of rocks. Lichens erode the rock surface which leads to formation of crevices and fissures (Fig. 14). All these provide sufficient soil for the larger plants to grow.

Lichens are followed by mosses. They speed up the process of soil formation. Along with lichens they form a mat like surface on the rock. This helps in further accumulation of soil particles. Due to increase in soil, ferns and grass start growing. Small animals and insects also start living along with vegetation.

This is later replaced by more complex plants like herbs, shrubs and trees and higher animals. The dead and decaying matter of plants and animals keep on enriching the soil. Later on large plants and tall grass start growing along with different kinds of animals. This final and stable self-contained community is known as climax community.

b. Primary Succession in Aquatic Environment/Hydrach Succession:

This succession can be divided into seven stages:

i. Pioneer Stage:

In hydrach succession phytoplanktons and zooplanktons form the pioneer stage. They include bacteria, algae and animals like amoeba, paramaecium, etc.

ii. Submerged Stage:

During this stage plants with root anchored in mud start growing in pond. Examples of such plants are Vallisneria, Hydrilla, etc. As they die their remains reach the bottom and decay to form humus. Along with soil it makes the pond shallow.

iii. Floating Plant Stage:

During this stage rooted plants like lily and free floating plants start growing. With their death and decay, the pond becomes shallower and becomes rich in nutrients.

iv. Reed Swamp Stage:

In this stage the pond shows growth of plants which have the roots at the bottom and aerial parts coming up above the surface of water. Plants growing at this stage are reed grass and arrow head, etc. Crusta­ceans, dragonflies and small animals also invade the pond. With the settling down of silt and formation of more humus the pond becomes more shallow.

v. Marsh Meadow Stage:

Soil in the pond is now marshy with very little water left. Marshy plants start appearing. At this stage there is so much of deposit by rooted plants and dead animals that there is hardly any water left. This pond now looks more like a terrestrial habitat.

vi. Scrub Stage:

Till the aquatic succession reaches this stage there is no water left in the pond and it is completely a terrestrial habitat. It harbours terrestrial species of plants and animals.

vii. Forest Stage:

This is the final or the climax community of hydrach succession. Now it has a large number of trees and land plants. It can also have forests of willow, oak or ash trees (Fig. 15).

Secondary Succession:

This succession is found in areas which have been destroyed by earthquakes, fire or floods. This succession is similar to that of primary succession but it takes lesser time. Destroyed grassland takes only 50-100 years to again reach climax community and a forest may take around 200 years.

---

Term Paper # 6. Ecological Interdependence:

In an environment or ecosystem individuals cannot survive alone. They are dependent on each other. A biotic community is only formed when there is an association of number of different interrelated populations of different species. There are a number of different kinds of interactions existing in nature between plants and animals.

A few of them are mentioned below:

a. There is interdependence of plants on insects for pollination and in turn insects are dependent on plants for nectar.

b. Plants depend on animals and birds for dispersal of seeds and in turn provide food to birds and animals.

c. Mimicry is a kind of protective measure by animals where they resemble other animals to avoid predation. Generally a weaker animal mimics a stronger animal e.g. viceroy butterfly mimics monarch butterfly which is avoided by birds because of its unpleasant taste (Fig. 16).

d. By camouflage animal blends with their surroundings to save themselves from predators. This can be done by changing the colour or the animal may have a body shape similar to surrounding e.g. stick insect (Carasius morosus) resembles a thin dry twig. Dead leaf butterfly resembles a dry leaf. Praying mantis resembles a green stem (Fig. 16), leaf insect resembles a leaf.

---

Term Paper # 7. Ecosystem Services:

Many services are provided by an ecosystem, the value of which is not measurable.

A healthy forest ecosystem provides the following life-supporting services:

a. It purifies the air and water.

b. It prevents droughts and floods.

c. It helps in recycling nutrients.

d. It helps in soil formation and enriches the soil.

e. It provides a habitat for a number of animals.

f. It maintains biodiversity and houses a number of animals which help in pollinating plants.