This document provides an introduction to environmental science and ecology. It defines key terms like environment, environmental science, and ecology. It explains that environmental science is interdisciplinary and involves subjects like biology, geology, and economics. It also describes different types of ecosystems like natural, artificial, terrestrial and aquatic. Finally, it discusses the structure and functions of ecosystems, including species composition, trophic levels, nutrient cycling, and energy flow.

1. UNIT - 1
INTRODUCTION AND
ECOLOGY
IV SEMESTER ENVIROMENTAL SCIENCE

2. INTRODUCTION
 Environment means surroundings.
 Environmental Science is an interdisciplinary subject and involves the study of
various subjects in relation to environment.
 The Environment Protection Act, approved by the Government Of India in 1986,
defines the environment as the sum total of water, air, land, the
interrelationships among themselves, with human beings and with other
organisms and property.
 Environmental study is a broad subject having the components from biology,
geology, chemistry ,physics, engineering, sociology, health, anthropology,
economics, statistics, computer and philosophy.

3. INTRODUCTION
 Our dependence on nature is so great that we cannot continue to live without
the protecting the earth’s environmental resources.
 Thus most traditions refer to our environment as “MOTHER NATURE” and most
traditional societies have learned that respecting nature is vital for their
survival.
 Proper understanding of the subject is seriously important in view of the
enormous population increase and its related higher increase in demand of
natural resources.
 Our natural resources are in need of careful maintenance, and the use should be
according to the need that the environment can continuously supply. This is
called sustainable utilization or development.

4. INTRODUCTION
 our country is one of the very few countries that have provided constitutional
safeguards for the preservation and protection of the environment. Article 48 A
and 51 A (g) in the section on directive principles of state policies in the Indian
Constitution, approved in the year 1976 states that the "State shall endeavour to
protect and improve the environment and to safeguard the forests and wildlife
in the country and to protect and improve the natural environment including
the forests, lakes, rivers and wildlife and to have compassion for the living
creatures.“
 Despite this the importance of environmental studies was not recognized in the
Indian curriculum. Hence, the Honorable Supreme Court of India in 1991, on a
public litigation interest file by M.C. Mehta in 1988, made it mandatory to
include the subject environmental studies in all the universities and colleges

5. ECOLOGY
 Ecology deals with the various principles that govern the relationships between the
organisms and environment.
 The term ecology was derived from two Greek words, oikos (meaning 'house' or
'dwelling place) and logos (meaning 'the study of') to denote such relationships
between the organisms and the environment.
 The term ecology was first proposed by a German Biologist Ernst Haeckel (1866), and
defined it as the study of reciprocal relationships between organisms and their
environment.
 According to Woodbury (1954), "Ecology is a science which investigates organisms in
relation to their environment“
 Ecology is the branch of biology that deals with the study of interactions between
organisms and the environment.
 Prof. Ramdeo Misra is regarded as the "Father of Ecology in India" for his great
contribution in the field of ecology in India.

6.  It is also classified as autecology and synecology.
 Autecology deals with the ecological study of one species of organism.
 Synecology deals with the ecological studies of communities or entire
ecosystems.
However, we can classify ecology into following branches.
 Habitat Ecology: It deals with ecological study of different habitats on
earth and their effects on the organisms living there.
 Community Ecology: It deals with the study of the local distribution of
in various habitats. Also, it is related with the recognition and
community units, and succession.
CLASSIFICATION OF ECOLOGY

7.  Population Ecology: This is also known as demonology. It deals with the
study of the pattern of growth, structure and regulation of population
organism. The population ecology also deals with interactions between
populations of different species in a community.
 Human Ecology: It is mainly related to population ecology. It studies the
relationship between man and man along-with the environment. Effects
human beings on the biosphere and the implications of these effects for
mankind is the subject matter of human ecology.
 Palaeo Ecology: It is the study of environmental conditions and life of the
ages.
CLASSIFICATION OF ECOLOGY

8. LEVELS OF ORGANISATION
Organization may be defined as 'the manner in which smaller components of any
structure, system or a situation are arranged in a hierarchy to co-ordinate with one
another towards a goal

9. CONCEPTS OF ECOSYSTEM
 The biotic community together with the physical environment forms an
interacting system called ecosystem.
 The term ecosystem was introduced by Sir Arthur Tansely (1935).
 An ecosystem can be defined "as a structural and functional unit of
biosphere or segment of nature consisting of community of living
beings the physical environment both interacting and exchanging
materials between them.‘
 An 'Ecosystem' is a region with a specific and recognizable landscape
form such as forest, grassland, desert, wetland or coastal area
 . The nature of the ecosystem is based on its geographical features such
as hills, mountains, plains, rivers, lakes, coastal areas or islands.
 It is also controlled by climatic conditions such as the amount of
sunlight, the temperature and the rainfall in the region

10. Ecology and Ecosystem

11. TYPES OF ECOSYSTEM
NATURAL ECOSYSTEMS
These operate by themselves under natural conditions without any major
interference by man. Based upon the particular kind of habitat, these are
further divided as:
Terrestrial, e.g. forest, grassland, desert.
Aquatic which is further distinguished as:
1) freshwater which may be lotic (spring, stream or river) or lentic (lake,
pond, pools, ditch, swamp, etc.)
2) Marine, e.g. sea or ocean (deep bodies) and estuary (shallow bodies).

12. TYPES OF ECOSYSTEM
ARTIFICIAL ECOSYSTEMS
They are also called man-made or man-engineered ecosystems.
They are maintained artificially by man where, by addition of energy
and planned manipulation, natural balance is disturbed regularly, e.g.
croplands such as sugarcane, maize, wheat, rice-fields; orchards,
gardens, villages, cities, dams, aquarium etc.

13. STRUCTURE AND FUNCTION OF AN
ECOSYSTEM
STRUCTURE
The structure of an ecosystem is characterized by the physical organization
of biotic and abiotic components. The major structural features of
ecosystem are species composition, stratification, trophic organization and
nutrients.
 Species composition: Each ecosystem has its own type of species
composition. Different ecosystems have different species composition. A
great variety of species is found in forest ecosystem whereas a few
species occurs in a desert ecosystem.

14. STRUCTURE AND FUNCTION OF AN
ECOSYSTEM
 Stratification: The organisms in each ecosystem form one or more layers or
strata, each comprising the population of particular kind of species. In some
ecosystems, such as tropical rainforests, the crown of trees, bushes and ground
vegetation form different strata and are occupied by different species. On the
other hand, the desert ecosystem shows a low discontinuous herbs layer
consisting of fewer and extensive bare patches of soil.
 Trophic organization: Food relationships of producers and consumers is another
way to depict ecosystem structure. Trophic (food) structure of ecosystem is
based on the existence of several trophic levels in the ecosystem. The producers
(autotrophs) form the first trophic level or T1 herbivores the second or T2 and
carnivores constitute the third or T3.

15. STRUCTURE AND FUNCTION OF AN
ECOSYSTEM
 Nutrients: In each ecosystem, the nutrients necessary for the growth of
living organisms are accumulated in the biomass and the abiotic
components like soil.
The amount of nutrients such as nitrogen, phosphorus and calcium present
in the soil at any given time is termed as standing state.
Different ecosystems have different standing state of nutrients. The
standing state of nutrients may vary at different time even in the same
ecosystem.

16. FUNCTION OF AN ECOSYSTEM
 Ecosystems have some functional attributes which keep the component parts
running together. Each ecosystem possesses a natural tendency to persist. Various
functions performed by the structural components of the ecosystem ensure
persistence of the system. For instance, green leaves prepare food and roots
absorb nutrients from the soil. Herbivores feed on part of the plant production
and in turn serve as food for carnivores. Decomposers carry out the function of
breaking down complex organic materials into simpler inorganic products which
can be used by the producers. All these function in the ecosystem occur through
delicately balanced and controlled processes. For example, food production in
plants is carried out by the process of photosynthesis, nutrients contained in the
organic matter are released through the process of decomposition. A knowledge
of the rates of different processes at which they occur in the ecosystem is
necessary to understand the interrelations, structure and functions of the
ecosystem. Its function can be summarized as

17. FUNCTION OF AN ECOSYSTEM
 Rates of biological energy flow, i.e. the production and respiration rates
of the community.
 Rates of materials or nutrient cycles.
 Biological or ecological regulation including both regulation of
organisms by environment and regulation of environment by the
organisms and vice versa. Thus in any ecosystem, structure and function
are studied together.