POPULATION AND ENVIRONMENT

Age Structures and Poverty

ECOSYSTEM ORGANIZATION

GO FORTH AND MULTIPLY...

CHARACTERISTICS OF POPULATIONS

Population size: number of individuals in the gene pool

Population density: number of individuals in a given area

Population distribution: pattern of distribution (uniform, random, clumped)

Age structure: pre-reproductive, reproductive, post-reproductive

Reproductive base: those individuals in the pre-reproductive or reproductive stage

POPULATION SIZES

Births and immigration increase population size,

Deaths and emigration decrease population size

Zero Population Growth (ZPG) = no net increase or decrease

For a small population, as long as the birth rate is slightly above the death r a t e , a p o p u l a t i o n g r o w s exponentially with a characteristic J-curve

HUMAN POPULATION GROWTH

HONOR ROLL!

FERTILITY RATE

THE PHILIPPINE POPULATION

Average Annual Exponential Growth Rates, Philippines: 2000-2040

Year Growth Rate 2000-2005 2.05 2005-2010 1.95 2010-2015 1.82 2015-2020 1.64 2020-2025 1.46 2025-2030 1.27 2030-2035 1.09 2035-2040 0.92

Projected Total Fertility Rates, by Five-Year Interval, Philippines: 2000-2040 (Medium Assumption)

Year Rate 2000-2005 3.41 2005-2010 3.18 2010-2015 2.96 2015-2020 2.76 2020-2025 2.57 2025-2030 2.39 2030-2035 2.23 2035-2040 2.07

ISSUES RELATED TO POPULATION GROWTHPublic health: Unc lean wate r, a long w i th poor sanitation, kills over 12 million people each year, most in developing countries. Air pollution kills nearly 3 million more. Heavy metals and other contaminants also cause widespread health problems.

Food supply: Will there be enough food to go around? In 64 of 105 developing countries studied by the UN Food and Agriculture Organization, the population has been growing faster than food supplies. Population pressures have degraded some 2 billion hectares of arable land — an area the size of Canada and the U.S.

ISSUES RELATED TO POPULATION GROWTH

• Freshwater: The supply of freshwater is finite, b u t d e m a n d i s s o a r i n g a s population grows and use per capita rises. By 2025, when world population is projected to be 8 billion, 48 countries containing 3 billion people will face shortages.

• Coastlines and oceans: Half of all coastal ecosystems are pressured by h igh popu la t ion densities and urban development. A tide of pollution is rising in the world’s seas. Ocean fisheries are being overexploited, and fish catches are down.

ISSUES RELATED TO POPULATION GROWTH

• Forests: Nearly half of the world’s original forest cover has been lost, and each year another 16 million hectares are cut, bulldozed, or burned. Forests provide over US$400 billion to the world economy annually and are vital to maintaining healthy ecosystems. Yet, current demand for forest products may exceed the limit of sustainable consumption by 25%.

The demand for forest products exceeds sustainable consumption by 25%.

• Biodiversity:

The earth’s biological diversity is crucial to the continued vitality of agriculture and medicine — and perhaps even to life on earth itself. Yet human activities are pushing many thousands of plant and animal species into extinction. Two of every three species is estimated to be in decline.

ISSUES RELATED TO POPULATION GROWTH

• Global climate change: The earth’s surface is warming due to greenhouse gas emissions, largely from burning fossil fuels. If the global temperature rises as projected, sea levels would rise by s e v e r a l m e t e r s , c a u s i n g widespread f looding. Global wa rm ing a l s o cou l d cause droughts and disrupt agriculture.

10 POOREST PROVINCE IN RP (DATA AS OF 2006)

WHAT CAN BE DONE

Taking action: Many steps toward sustainability can be taken today. These include: using energy more efficiently, managing cities better, phasing out subsidies that encourage waste, [etc.]

The world must sustain 1 billion more people every 13 years

Stabilizing population: While population growth has slowed, the absolute number of people continues to increase — by about 1 billion every 13 years. Slowing population growth would help improve living standards and would buy time to protect natural resources. In the long run, to sustain higher living standards, world population size must stabilize.

Environmentalists and economists increasingly agree that efforts to protect the environment and to achieve better living standards can be closely linked and are mutually reinforcing. Slowing the increase in population, especially in the face of rising per capita demand for natural resources, can take pressure off the environment and buy time to improve living standards on a sustainable basis

CARRYING CAPACITY

The resources in any given habitat can support only a certain quantity of wildlife

As seasons change, food, water, or cover may be in short supply.

Carrying capacity is the number of animals the habitat can support all year long

The carrying capacity of a certain tract of land can vary from year to year. It can be changed by nature or humans

The number of animals the habitat can support throughout the year without damage to the animals or to the habitat.

CARRYING CAPACITY

Factors that limit the potential production of wildlife include:

Disease/parasites

Starvation

Predators

Pollution

Accidents

Old age

Hunting

If the conditions are balanced, game animals will produce a surplus, which can be harvested on an annual, sustainable basis.

WORLD POPULATION MOVIE

ANALYSIS OF AGE STRUCTURE PYRAMIDS

Age structure diagrams show how a population is distributed

It divides the population into pre-reproductive, reproductive and post-reproductive phases

The shape of the diagram can show you if a country is growing rapidly, slowly, or negatively

It can also show is there is zero growth

The wider the base of the diagram the more individuals below the age of fifteen

The more individuals under fifteen the more individuals poised to reproduce increases

The left hand side is always the males.

AGE STRUCTURES

RELATIVE PROPORTION OF INDIVIDUALS BELONGING TO DIFFERENT AGE CLASSES IN A POPULATION

CATEGORIES: PRE-REPRODUCTIVE; REPRODUCTIVE; POST-REPRODUCTIVE

DEPENDING ON ITS AGE STRUCTURE:

PYRAMIDLESS INDUSTRIALIZEDHIGH PRE-REPRODUCTIVEMAY CONTINUE TO GROW : 2 CHILDRENHIGH WOMEN ENTERING REPRODUCTIVE THAN LEAVING

BULLETSTABLESAME NUMBER PER GROUP

COMMUNITY AND SUCCESSION

EARLY SUCCESSION SPECIES

HIGH GROWTH RATE, WIDE DISPERSAL, SMALL, FAST POPULATION GROWTH

LATE SUCCESSION SPECIES

LOWER RATES OF DISPERSAL, SLOWER GROWTH RATE, LONGER LIVES, LARGER

PRIMARY SUCCESSSION vs SECONDAY SUCCESSION

DISTURBANCE: SMALL SCALE or LARGE SCALE

IMPORTANT TERMS IN SUCCESSION

Succession is a directional non-seasonal cumulative change in the types of plant species that occupy a given area through time.

I t involves the processes of colonizat ion, establishment, and extinction which act on the participating plant species.

Succession begin when an area is made partially or completely devoid of vegetation because of a disturbance.

Some common mechanisms of disturbance are fires, wind storms, volcanic eruptions, logging, climate change, severe flooding, disease, and pest infestation

Succession stops when species composition changes no longer occur with time, and this community is said to be a climax community.

TYPES OF SUCCESSION

Primary succession - is the establishment of plants on land that has not been previously vegetated - Mount Saint Helens. Begins with colonization and establishment of pioneer species

Secondary succession - is the invasion of a habitat by plants on l a n d t h a t w a s p r e v i o u s l y vegetated. Removal of past vegetation may be caused by natural or human disturbances such as fire, logging, cultivation, or hurricanes.

TYPES OF SUCCESSIONAllogenic succession - a succession where the stimulus for change is an external one.

An allogenic succession can be brought about in a number of ways which can include: Volcanic eruptions; Grazing animals; Human in ter ference ; F lood ing ; Non-anthropogenic climate change

Autogenic succession - a succession where the stimulus for change is an internal one.

F o r e x a m p l e g r a d u a l s o i l improvement could allow a new species to develop

TYPES OF SUCCESSION

Progressive succession - is a succession where the community becomes complex and contains more species and biomass over time

Retrogressive succession - is a succession where the community becomes simplistic and contains fewer species and less biomass over t i m e . S o m e r e t r o g r e s s i v e successions are allogenic in nature.

For example, the introduction of g raz ing an ima l s resu l t i n degenerated rangeland.