Environmental Studies

Chapter : 2 :- Ecology and Ecosystem

The word Ecology is derived from two Greek words oikos = house or place of living & logos = Study

Ecology is the study of the interrelationship between living organisms and their physical and biological environment

ECOLOGY & ECOSYSTEMS

ECOLOGY: It is the study of the structure and function of the nature. Ecology is the study of life, concerned with energy flows and

material cycles in the air (atmosphere), land (lithosphere), in the

oceans & fresh waters (hydrosphere) and thus the BIOSPHERE in

totality.

ECOSYSTEM: An ecosystem is defined as a natural functional ecological unit

comprising of living organisms and their non-living environment

that interact to form a stable self-supporting system.

For example - pond, lake, desert ecosystem etc

Objective of study

To study Interrelationship between Biotic and Abiotic component.

To study the changes in environment like – season etc. Behavior (action- reaction) under natural conditions. Development in the course of evolution or say growth To understand Biological productivity and Energy flow. The development of mathematical models to predict the effects For the knowledge to safeguard against interfering with

natural population- unchecked felling of trees – environmental pollution

Help to tackle the environmental problems –Pollution – Floods –variation in seasonal patterns – Global problems like Green house effects, Ozone depletion, Acid rains, Deforestations etc.

Necessary in maintaining ecological balance and understanding different biochemical cycles (Like, CO2, O2, H2O, NH2 cycle)

Helps in protecting flora and fauna By study of ecology we can maintain balance in nature and can

prevent many ecological disasters. Important role in human benefit, agriculture, pest control,

management of grass land, forestry, and conservation of wild life.

Scope of Ecology:

TYPES OF ECOSYSTEMS:

ECOSYSTEM

NATURAL ECOSYSTEM ARTIFICIAL ECOSYSTEM

AQUATIC TERRESTRIAL [Man made ecosystem, ECOSYSTEM ECOSYSTEM viz..Crop, Urban, Industrial,

[Forest, grassland, laboratory, space etc……...] desert] FRESH MARINE WATER ECOSYSYEM ECOSYSTEM [ocean, sea]

LOTIC LENTIC (Runn- (Standinging water) water)ECO- ECO-SYTSTEM SYSTEM

STRUCTURE AND COMPONENTS OF ECOSYSTEM:

(Organization of an Ecosystem)

Each ecosystem has two main components-

1) Biotic Components:

The living organisms including plants, animals and

micro-organisms (ie…. Bacteria & Fungi) that are present in an

ecosystem form the biotic component of the ecosystem. On the

basis of their role in the ecosystem, the biotic components are

further classified into-

- Producers

- Consumers – Primary, Secondary, Tertiary

- Decomposers or Reducers.

2) Abiotic Components:

The non living factors or the physical environmental prevailing in

an ecosystem form the biotic component of the ecosystem. They have

a strong influence on the structure, distribution, behaviour and

interrelationship of organisms and are further classified into-

Climatic Factors – Includes Rain, Temperature, Light, Wind,

Air, Humidity etc…. Edaphic Factors – Includes Soil, pH, Topography, Minerals etc….

AQUATIC ECOSYSTEM:

CHARACTERISTICS OF AQUATIC ECOSYSTEM:

1. It is the major structural and functional unit of ecology.

2. The aquatic ecosystems are of various types, depending on wide

variations of salinity, depth, area and temperature fluctuations.

3. Depending on their type, there is a wide variation of FLORA and

FAUNA.

[FLORA – all the plant species found in a country, area or region.

FAUNA – all the animal species inhibiting in a country, area or

region.]

4. Its structure is related to its species diversity; the higher the

diversity of the species the more the complex the ecosystem is.

TYPES OF AQUATIC ECOSYSTEMS:

AQUATIC ECOSYSTEM

FRESH WATER MARINE WATER ECOSYSTEM ECOSYSTEM (Ocean & Sea)

LOTIC LENTICECOSYSTEM ECOSYSTEM(Running Water (Standing WaterEcosystem) Ecosystem)Ex-Rivers, Streams etc…. Ex-Lakes, Ponds etc….

ECOSYSTEM FUNCTIONING or IMPORTANT:

Food Chain and Food Web.

Ecological Pyramids

Energy Flow

Nutrient Cycles

Development and Evolution

Homeostatis and Stability of Ecosystems.

FOOD CHAIN AND FOOD-WEB:

Food Chain:

In a food chain, each organism eats the smaller organism which in

turn is eaten by the larger one. All those organisms which are

interlinked with each other through food constitute a food chain. “The transfer of food energy from the source and through a

series of organisms with repeated stages of eating and being eaten

is known as the food chain”.

In a food chain, there exists many trophic levels viz – Producers, Consumers, Decomposers etc…

Grazing Food Chains: The type of food chain is consisting of plants and animals that

consume each other to continue life This system, on which humans

are chiefly dependent.

Detritus-Based Food Chain: The other type of chain in which living organisms die and are

decomposed by microorganisms such as fungi and bacteria break

down and metabolize dead organic matter.

Food Web: Food web is a group of number of interconnecting food chains. The food chains normally do not operate individually, but are

interlocked with each other forming a network of group of

interconnecting food chains known as “food web”. The food webs are very important in maintaining the stability

of an ecosystem in the nature, which in turn maintains the total

ecological balance of the environment.

ECOLOGICAL PYRAMIDS:

Each time the energy stored in an organism and its movement is temporarily stopped until that organism serves an energy source for another organism. Each of these temporarily stopping points in the movements of energy is called a trophic level. The trophic structure of an ecosystem can be indicated by means of ecological pyramid.

There exists some sort of relationship between the number, biomass and energy content of the primary producers, consumers of the first and second orders and so on to top ‘carnivores’ in the ecosystem. This relationship is represented graphically by means of pyramids known as ‘Ecological Pyramids’, where the first or producer level forms the base of the pyramid and the successive levels (the tiers) approaching and forming the apex.

1) The Pyramid of Number: This Pyramid differentiate by the number of living organism Smaller animals are more number then larger ones Below graphs shows the Pyramids of number Each species is limited in its total biomass by its strophic level If the size of the individuals at a given trophic level is small,

their number can be larger & vice versa.

2) The Pyramid of energy: The Pyramid shows energy decapitates as it proceeds from one

trophic level to another. In the ecosystem producer one first receiving energy from Sun and

it is used by producer and conserved, then it moves from

producers to primary consumers and so on.

3) The Pyramid of Biomass: Biomass here would refer to the combined weight of all the

organisums in the trophic level. General principle that as a trophic level increases from its source,

the biomass it contains will be reduced.

CARBAN CYCLE:

Two Main processes:Carbohydrates

Respiration ======= Produce = CO2 , H2O, Energy.

Oxygen__________________________________________

___ CO2

Photosynathesis ===Produce = Carbohydrates and O2 (Oxygen)

H2O

The Out-Puts of respiration are the In-Put of the Photosynthesis.

The Out-Puts of Photosynthesis are the In-Put of Respiration.Animals and Plants carry respiration.Only plants can carry photosynthesis. Major reservoir for

Oceans CO2

Rocks ( Calcium carbonate)Precipitation on calcium carbonate and it dissolve.

The land and water Plants takes up CO2 and convert Carbohydrates through

Photosynthesis.

Three possible fates Liberated to the atmosphere by the plant through respiration. It can be eaten by an animals. It can be remained in the plant up to the plants died.

When Animals or Plants dies Respiration (by decomposers) Form Coal, Oil or Natural gas. Burned in Environment and releasing CO2 to Atmosphere.

Effect Green house Effect Acid Rain Global Warming.

NITROGEN CYCLE: The simple words the nitrogen cycle works this way: Plant and animal wastes are decomposed and thus adds nitrogen

to the soil. Bacteria in the soil convert those forms of nitrogen into forms

which plants can use. Plants use the nitrogen from the soil, to Grow. People and animals eat the plants;

and the residues are return in alternate

form of nitrogen to the soil again,

thus complete the cycle.

Nitrogen is present in air and soil. Nitrogen in the atmosphere or in the soil can go through many

complex chemical and biological changes. Nitrogen is primarily stored in living and dead organic matter.

Due to decomposer which convert organic matter in Ammonia ( NH3 )

to Ammonium salts ( NH4 + ) This process is known as mineralization carried out by bacteria.

Nitrification process and Oxidation NH4

+

NO3- NO2

-

Nitrates Nitrites.

This NO3- is soluble and it is easily lost from the soil by leaching

( Due to hydrologic Cycle) Plant use this NO3- convert in organic matter.

Denitrification: The process of denitrification involves the reduction of nitrate

NO3- into nitrogen ( N2 ) and Nitrous Oxide ( N2O) gas. Both gases then diffuse into the atmosphere. This process is important to bacteria because it supply them with

Oxygen for Respiration. This N2 & N2O enter in soil through rainfall or the effects of

lightning.

Prepared by, Dhruvesh Patel

Prepared by, Dhruvesh Patel

www.drdhruveshpatel.com

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