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Ecology and environment
Ecological diversity: At the ecosystem level, India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.
HOW MANY SPECIES ARE THERE ON EARTH AND HOW MANY IN INDIA
Scientific study of human population is called demography. Population is defined as the total number of individual of a species present in a particular area at a given time. The population have specific character different from the character of individual.
1. Character of population:
A. Population density (Population size)
It is measured as total number of individual present in unit area or unit volume. The size of a population for any species is not a static parameter. It keeps changing in time depending on various factor including food availability, predation pressure and reduced weather. For human population density is officially counted in first four month of first year of each decade is called census.
B. Birth rate / Biotic potential / Fertility / Natality:
Birth rate is defined as total number of birth in a population with respect to total number of individual of the population in a year. Birth rate is represented as per capita birth rate
Eg. If in a pond there are 20 lotus plant last year and through reproduction 8 new plant are added, then the birth rate during the year is calculated as:
Birth rate varies from region to region
Death rate/ Mortality:
Death rate is defined as total number of death in a populations with respect to total number of individual of the population in a year.
Death rate is represented as per capita death rate
Eg.: If 4 individuals in a laboratory population of 40 fruit fly died during week. The death rate is calculated
D=d=0.1 individual per fruitfly per week
Intrinsic growth rate(r) = b-d
Note: Natality, Mortality, Immigration and Emigration are the basic process responsible for fluctuation in population size under normal conditions, Natality and Mortality are the most important factors influencing population
Size than other two factor i.e., Immigration and Emigration.
Age and Sex Structures:
The age structure of a given population refers to the proportion of individuals of different age. This is important aspect because many functional aspect of individuals are related to age. (Like Reproduction)
Age structure of a population can be depicted in the form of a pyramid diagram. Diagram is particularly important in understanding future growth.
Population has 3 age groups.
Representation of age pyramids for human population
Population Growth Models / Curve
There are two type of growth curve
Definition – Total living factor (biotic) and total non-living factor (abiotic) of the environment present in a particular area is called ecosystem.
A.G.Tansley – The term "ecosystem" first of all coined by A.G. Tansley.
According to Tansley – Ecosystem is symbol of structure and function of nature.
E.P. Odum – Father of ecosystem ecology.
According to E.P. Odum – Ecosystem is the smallest structural and functional unit of nature or environment.
Karl Mobius – Used term biocoenosis for ecosystem
TYPE OF ECOSYSTEM
A. Natural Ecosystem –
(i) Lentic ecosystem à stagnant fresh water, lake, pond, swamp.
(ii) Lotic – Running fresh water ecosystem e.g. - river.
B. Artificial Ecosystem Man made e.g. cropland, Gardens etc.
On the basis of size types of ecosystem
2. COMPONENTS OF ECOSYSTEM
Every ecosystem is composed of two components - BIOTIC COMPONENT
It involve all livings (plant, animal and microbes) of ecosystem. Biotic component are mainly of two type.
1. Producers –
All the autotrophs of ecosystem are called producers. They prepare their own food. The green plants are the main producers. In the process of photosynthesis, producers absorb solar energy and convert it into chemical energy so producers are also called transducers or converters.
Energy enters into the ecosystem through the producers. The solar energy is the only ultimate source of energy in ecosystem. This energy is available for the remaining living organisms.
2. Consumer –
All the heterotrophy of the ecosystem are known as consumers. They directly (herbivores) or indirectly (Carnivores) depend on the producers for food.
Types of consumer
i. Macro consumers (Photographs or holozoic) – They digest their food inside the body of organism i.e. first ingestion then digestion.
Macro consumers are of following type
ii. Micro Consumers/Decomposers or Saprotrophs /osmotrophs –
Those living organisms which decompose the dead body of producers and consumers are known as decomposers or reducers or transformers or osmotrophs.
Functional aspects of ecosystem:
Energy flow – The storage, expenditure, transformation of energy is based on two basic law of thermodynamics
First law of thermodynamics: - Energy is neither created nor destroyed but only transformed from one state to another state.
Second law of thermodynamics (the law of entropy) - The transfer of food energy from one to another organism leads to loss of energy as heat due to metabolic activity.
Introduction to pollution
"Any undesirable change in physical, chemical or biological characteristic of air, water and land which is harmful to the man directly or indirectly through his animals, plants, industrial units or raw materials is called pollution".
Pollutants: - "Any material or act on the part of man, or nature which leads to pollution is called pollutants."
USUALLY POLLUTANTS ARE DIVIDED INTO FOLLOWING CATEGORIES
Nondegradable Pollutants– Many of such pollutants are usually not degraded or degraded partially in environment. Such as aluminium pecks, Mercury compounds, Iron, Compounds of phenols, Glass, D.D.T. benzene, BHC pesticides, etc.
Biodegradable Pollutants– If much of domestic sewage papers, woods, garbage, livestock wastes, etc. are easily degraded completely by microorganisms, it becomes useful. But if these materials enter the environment in such large quantities, that they cannot be degraded completely then addition of these materials causes pollution in environment.
Other Type of Pollution
Main Sources of Pollution:
Different Kinds of Pollution AIR POLLUTION
The air pollution is caused due to addition of unwanted substances or gases. The atmospheric pollution is mainly caused by the activities of man and concentrated to the inhabited and the industrial complexes in cities.
There are two main categories of air pollutants
ORGANISM AND ENVIRONMENT
The study of interaction or inter-relationship of organisms with their environment is called ecology.
Organism and environment are always interdependent, inter related or mutually reactive.
BRANCHES OF ECOLOGY
It is based on organism level
An organism is the smallest unit of ecological hierarchy and basic unit of ecological study.
A group of Individuals (members) of same species living at one place (specific geographical area) constitute a population.
Definition - Species is a basic unit of classification, defined as the group of living organisms similar in structure, function and behaviour and produced by similar parents, have common gene pool, can inter breed under natural conditions and reproductively isolated from other group of organism.
Groups of organisms of different species that live in common area, which are interrelated and interdependent. It is a natural aggregation of plants and animals in the same environment.
Biotic Community = Animal community + Plant community + Microbial community
Characteristics of a community –
There are different types of population (species) found in community, this is called species diversity.
It depends on size of the area, type of area, type of soil, altitude and climate.
The highest number of organism of a species present in community, is called as the dominant species.
Whole community is known by the name of that particular dominant species. E.g. Prosopis community at Aravali hills, Pinus community at Himalaya
The different growth form (trees, shrubs, under shrubs, herbs) determines the structure of a plant community. Stratification is based on mode of arrangement of various growth forms.
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