Populations, population characteristics,world population growth and variations, population explosion and effects

1. HUMAN POPULATION AND THE
ENVIRONMENT
By
IJAS AHAMMED C.K
S5 EEE Roll No. 30
GEC WAYANAD

2. POPULATION GROWTH
The term population was derived from the lattin word
populous meaning of people
In ecology population may be defined as a group of organism of
the same species occupying a particular space
Eg. Deer population of Kaaziranga wildlife sanctuary &
Corbett national park, human population of Delhi or India …
The ultimate constituents of population are individual
organisms that can potentially inbreed

3. Population size density
Total size of population is expressed as the no. of individuals in a
population
The change in population size between an interval of time
Nt+1=Nt +B- D+ I- E
Nt+1=Nt +B +I –(D+E)
Population density is defined as the numbers of individuals per unit
area or per unit volume of environment
Eg. for larger trees 600 trees per hector where as smaller ones such
as phytoplanktons as 2 million cells per cubic meter of water surface

4. Density may by numerical density or biomass density
When size of individuals in the population is relatively uniform, as
mammels, birds, insects expressed in no. of individuals
But size of individuals is variable, as fishes, trees expressed in
biomass
Biomass represents wet wt, dry wt, volume, carbon and nitrogen wt
Crude density- density (no. or biomass) per unit total space
Eg. Plant species –cassia tora & oplismenus burmanni found more
crouded in shady patches
Biological /specific /ecological desity- density per unit of habitual
space
Eg.density value for only shady area

5. cassia tora
oplismenus
burmanni

6. Human Population Growth
• At A.D 1 world population --- 30 crore( 300 billion)
• At 18th century (after beginning of industrial revolution) populn---76
crore & in1750 reached 100 core (1 billion)
• Majority of world populn(86%) resided in Asia (65%) and Europe
(21%)
• In 2000 world had 6.1 billion human inhabitants
• In next 50 years it will rise to more than 9 billions

7. WORLD POPULATION TRENDS
1. In 2001 world populn exceeded 6.1 billion –growing 1.3% annually
over 60% lives in Asia, 13% in Africa & 12% lives in Europe &
remaining 14% in America and oceania
2. Most of developed world will experience aging and popln declines,
while less developed countries will continue to have growing poplns
3. Acc; to UN worlds population will be 9.3 billion in 2050. Between
2000-50 less developed countries will account for almost 99% world
populn growth with populn increase of 61%.
4. U.S is the only industrialized country expected to rank among top
10 nations in the world in 2050. 17 countries will have 100 million
or more by mid century; India & China will have 1.6 and 1.5 billion
people respectively.

8. Pie Diagrams

10. POPULATION CHARACTERISTICS
1. Natality
Broader term covering production of new individuals by birth.
Natality rate =no. of organisms born/ female /unit time
In humans natality rate= birth rate
a. Maximum/absolute/potential natality;
The theoretical max. production of new individuals under ideal conditions –no ecological
limiting factors reproduction is only limited by physiological factors so is aconstant for a
species populn
b. Ecological natality or natality;
• Population increase under an actual existing specific condition
• Depend on possible existing environmental conditions & also called fertility rate
• It is expressed as;

11. • Specific natality rate (b)= ^Nn/NDt
where N= reproductive part (mature females) of the population or
initial no. of organisms
n = new individuals of the population
^Nn = production of new individuals
t = time
^Nn/Dt = the absolute natality rate
^ = delta ; the change
Further the rate atwhich females produce offsprings is determined by
1.Clutch size or no. of young produced in each occation
2.The time between one reproductive event and next &
3.The age of 1st reprodction

12. 2.Mortality
 The rate of death of individuals in the population
 Ie, the no. of individuals dying in a given period
a. Minimum/specific /potential mortality; theoretical min. loss under
ideal or non-limiting conditions& is a constant
b. Ecological / realised mortality; actual loss of individuals under a
given environmental condition & is not a constant but depend on
conditons such as production ,disease …
Oldage – physiological or potential longevity representing the age
upto which the organism can live under ideal conditions .

13. 3.Doubling time
 Time needed for a population to double its size at a constant annual
rate
 Expressed as;
Td = 70/ r
where Td = doubling time in years &
r = annual growth rate

14. 4. Total Fertility Rate (T.F.R)
• It is the avg no. of children that would be born to a woman in her life
time if the age specific birth rates remains constant
• The TFR values lie between 1.9 in developed nations to 4.7in
developing nations
• Some trends in global TFR are ;
1.In 2000 , 44% of world populn lived in countries with fertility
rates at or below replacement level. In the next 50 yrs these nations is
projected to increase by 7% , from 2.7 to 2.9 billion people
2. Nations with high fertility rates have extremely low contraceptive
rates. In 2001 about 4% of married women in Chad has a TFR of 6.3
birts /woman in contrast about 91% of married women in Italy , has a
TFR of only 1.3 .

15. 5. Age Structure
 Represented by age pyramids
 Age classes :
a. Pre-reproductive (0- 14 years)
b. Reproductive (15-44)
c. Post reproductive (45 years and above)
 3 types of populns or pyramids :
1. Expanding population- birth rate is high & population growth is
exponential eg. House fly, yeast, paramecium, algae…
Age structures in India , Bangladesh, Nigeria …
2. Stable/ stationary population- as rate of growth slows and stabilizes pre-
reproductive and reproductive groups become more or less equal in size.
(Bell shaped structure ) eg. France, USA and Canada .

17. 3. Diminishing / declined population :
• Dying off population
• If birth rate is drastically reduced, pre-reproductive reduces in
response to the reproductive & post reproductive groups resulting an
urn-shaped structure
• Low percentage of young individuals
• Eg. Germany, Italy, Hungary, Sweden & Japan.

18. 6. Aging
oThe world is aging at unprecedented rates due to decrease in both birth
and death rates
oIn 2000 the median age was 26.5 and it is expected to climb to 36.2 by
2050
oIn more developed regions ,the median age of 37.4 yrs is expected to grow
to 46.4 yrs by 2050
oIn less developed countries, median age will increase from 24.3 to 35 years
oIn 2000 Japan, Italy, Switzerland, Germany and Sweden had median ages of
40 or more
oSpain is projected to have the oldest median age 54 years by 2050 .

19. 7. Youth Bulge
oIn 2001, 30% of human population was between the ages of 15 & 24
oAlthough the propotion of this group is expected to decline , the net
of young adults will grow from 914 million to 1.13 billion in 2025.

20. POPULATION
EXPLOTION

21.  Population of an species increases suddenly is called population explosion
 Population of an organism decreases suddenly is called poplation crash
 Most populations are in a state of dynamic equilibrium
 Either cause serious problems for their-own populns as well as the
populations of depending organisms
 Eg. Population crash in snakes and population explosion in rats will be in
equilibrium with populns of other organisms including humans
 In 2000 ,world populn was 6.1 million & is predicted to grow 4 times in the
next 100 yrs
 This unprecedented growth of human population at an alarming rate is
known as population explosion
 It doent mean over popln or populn density-the problem arises when
economic development fails to maintain pace with populn growth .

22. Causes of population explosion
1. Increase in food production and distribution
2. Improvement in public health (water & sanitation)
3. Improvement in medical services(vaccins & antibiotics) along with
gains in education and standard of living
4. Drop in death rates .

23. Effects of population explosion
I. Over stress on natural resources
II. Over production of wastes
III. Food problem
IV. Over stress on water resources
V. Unemployment

24. •Effects Of Population Explosion
 Air Pollution .
 Water Pollutions.
 Increase in Demand For Food Resources
 Deforestation

25. •Air pollution
 How air pollution because of
Population Explosion ?
• Given Below-:

26. •Increase in Industries
 Industries

27. •Increase in Vehicle

28. •Water Pollution
 How Water Pollution because of Population
Explosion?
• Given Below-:

29. •Raw sewage and industrial waste flows
directed to main River or Sea

30. •Bathroom and Garbage sewage flow Directed to
the River or Sea.

31. •Increase in Demand For Food Resources
due to increase in population needs

32. •Increase in Deforestation For occupying land for
day by day increase in population .
For Agriculture For Urbanization

33. •Use of population in positive a ways-:
 For intense Labor for Private Sector which leads to
development of countries Economy.
 For Increase in Defence Sector of countries which lead
strong position of countries.
 For intense Labor for Government Sector which leads to
smooth running of Administration of Governess.

34. Thank you

35. ijasahmedck@gmail.com