Human population and the environment

HUMAN POPULATION AND THE

ENVIRONMENTBy

IJAS AHAMMED C.KS5 EEE Roll No. 30

GEC WAYANAD

POPULATION GROWTHThe term population was derived from the lattin

word populous meaning of peopleIn 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

Population size densityTotal size of population is expressed as the no. of individuals in a

populationThe 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 environmentEg. for larger trees 600 trees per hector where as smaller ones such

as phytoplanktons as 2 million cells per cubic meter of water surface

Density may by numerical density or biomass densityWhen size of individuals in the population is relatively uniform, as

mammels, birds, insects expressed in no. of individualsBut size of individuals is variable, as fishes, trees expressed in

biomassBiomass 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 patchesBiological /specific /ecological desity- density per unit of

habitual spaceEg.density value for only shady area

cassia tora

oplismenus burmanni

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

WORLD POPULATION TRENDS1. 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.

Pie Diagrams

POPULATION CHARACTERISTICS1.NatalityBroader term covering production of new individuals by birth.Natality rate =no. of organisms born/ female /unit timeIn 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;

• 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 occation2.The time between one reproductive event and next &3.The age of 1st reprodction

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 constantb. 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 .

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

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 people2. 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 .

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 .

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.

6. Aging oThe world is aging at unprecedented rates due to decrease in both birth

and death rateso In 2000 the median age was 26.5 and it is expected to climb to 36.2 by 2050o In more developed regions ,the median age of 37.4 yrs is expected to grow

to 46.4 yrs by 2050o In less developed countries, median age will increase from 24.3 to 35 yearso In 2000 Japan, Italy, Switzerland, Germany and Sweden had median ages of

40 or moreoSpain is projected to have the oldest median age 54 years by 2050 .

7. Youth BulgeoIn 2001, 30% of human population was between the ages of 15 & 24oAlthough 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.

POPULATION EXPLOTION

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 .

Causes of population explosion1. Increase in food production and distribution2. Improvement in public health (water & sanitation)3. Improvement in medical services(vaccins & antibiotics) along with

gains in education and standard of living4. Drop in death rates .

Effects of population explosionI. Over stress on natural resourcesII. Over production of wastesIII. Food problemIV. Over stress on water resourcesV. Unemployment

•Effects Of Population Explosion

Air Pollution . Water Pollutions. Increase in Demand For Food

Resources Deforestation

•Air pollution How air pollution because

of Population Explosion ?• Given Below-:

•Increase in Industries Industries

•Increase in Vehicle

•Water Pollution How Water Pollution because of

Population Explosion?

• Given Below-:

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

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

• Increase in Demand For Food Resourcesdue to increase in population needs

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

For Agriculture For Urbanization

•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.

Thank you

[email protected]