• The word Environment is derived from the French word
“Environner” that means to encircle or surround.
• All the biological and nonbiological things surrounding an orga
nism are thus included in environment.
• Environment can be defined as: “External surroundings and c
onditions which directly
or indirectly affects the living organisms.”
• “Environment is sum total of water, air and land,
interrelationshp amongthemselvesand also with human beings
, other living organisms and property.”
3. • Environment is usually divided in to two parts:
• 1. Biotic
Biotic environment is made up of all living organisms(Plants, anials
µorganisms) including their reactions, interactions and
• These biotic and biotic components are in a dynamic state i.e. th
ey constantly affecteach other and cannot be isolated from each
4. • 2. Abiotic
• Abiotic and environment or physical environment. It is composed of ext
• physical factors like temperature, humidity, water, soil, minerals, gases
etc.It provides both habitation and raw materials for the synthesis of or
• Any constituents of the environments of the environment which directy
orindirectlyaffects are growth and development of an organism is called
environmental or ecological factor.
• Examples of environmental factors are climatic factor, topographic fact
or, bioticfactors, and fire.
• The word ecology is derived from two Greek word “oikos” m
eaning house,habitation or place of living and “logos” meanin
• Ecology is the study of the interrelationship between living or
ganisms and their physical and biological environment.
• Division of ecology :
• There are two important division of Ecology namely.
6. • Autecology :
• Autecology or spices Ecology is the study of individuals spices, th
eir behaviorand adaption (adjustto be suitable for anew use or c
ondition) to the environmental conditions.
• Synecology :
• Synecology or community Ecology refers to the study of differen
t communities(group of organisms that are associated to gather
as a unit) their composition, theirbehavior and relation to the e
nvironment. E.g. study of a tree in forests.
• Ecosystem is made up two words “eco” and “system” eco m
eans environment andsystem means an interacting and inter
• The organisms of any community besides interacting among
themselves, alwayshave functional relationship with the envir
onment. This structural and functional
• system of communities and environment is called ecological s
ystem or ecosystem.
• It is a community of interdependent organisms together wit
h the environment.
8. • Ecosystems have no particular size ;
• Ecosystem can change with time.
• It is a system where matter and energy flows.
• It is a system where biotic and abiotic factors work together.
• Ecosystems can be natural and artificial.
• All ecosystem in nature work the same way.
• The foundation on which ecosystems rests is the production of the o
rganic matter byphotosynthesis.
• All ecosystems are open systems in the sense that energy and matte
r are transferred in and out.
9. • The components of the ecosystems:
• An ecosystems comprises of two basic components namely
• I The structural components:
• The biotic and abiotic parts, of an ecosystem are known as struc
tural components ofecosystems. The examples of each are given
ABIOTIC COMPONENTS BIOTIC COMPONENTS
Sunlight, Temperature, Precipitation, wat
eror moisture, soil or water chemistry.
Primary producers, Herbivores, Carnivore
s,Omnivores, Detritivores (Decom
10. • The functional component of ecosystems
• The functional component of ecosystem comprise of:
• I. Food chain
• II. Food web
• III. Biogeochemical cycle
• The sequence of food utilization starting with biomass produce by
photosynthetic producers is called the food chain. In a food chain each o
rganisms eatssmaller organism and is eaten by the larger one.
• At the base of the chain there are always green plants or other autotr
ophic (the producersor first tropic level
11. • Food web: An ecosystem consists of many food chains which are interco
nnected. The foodweb is complex network of interconnected food chain
s (each starting from the same point)as shown in.
• The detritus food chain: The detritus means dead organic matter.
• The detritus food chain starts from dead organic matter which is eaten
by other organismsfeeding on them detritivores.
• In fact, such food chains are less dependent upon the direct solar energ
y and mainly depend
on the supply of organic matter produced in the ecosystems.
• For examples woodlouse is depended on the dead leaves and woodlouse
is eaten by ablackbird.
12. • Biogeochemical cycle:
• All organisms are made up of basic elements such as carbon, nitrogen
,phosphorus,sulfur,oxygen and hydrogen. These elements are continuou
sly cycled between air, water, soil,rockand living organisms. I.e. the fo
ur spheres (atmosphere, biosphere, hydrosphere,andlithosphere) biogeo
chemical cyclesare the pathways describingthe movement of these
basic elements through the four spheres of the environment.