Chapter 7: Population Ecology

Population Ecology

The study of how populations change in size and composition over time and what factors affect them.

Population

A group of individuals of the same species living in a specific area at a given time.

Growth Rate Formula (Global)

r = (b - d); population growth rate equals birth rate minus death rate.

Growth Rate Formula (Local)

r = (b - d) + (i - e); includes immigration (i) and emigration (e).

Biotic Potential

The ability of a species to reproduce under ideal environmental conditions; also called intrinsic rate of increase.

Factors Affecting Biotic Potential

Age reproduction begins, duration of reproductive period, number of reproductive periods, and offspring per cycle.

Exponential Growth Curve (J-shaped)

When a population increases rapidly under ideal conditions, doubling faster over time.

Overpopulation

A situation where the number of people exceeds the environment's carrying capacity, leading to resource depletion and environmental degradation.

Causes of Overpopulation

Decline in death rate, agricultural advancement, better medical facilities, poverty, child labor, fertility treatments, immigration, lack of family planning, poor contraceptive use.

Effects of Overpopulation

Resource depletion, environmental degradation, unemployment, poverty, high cost of living, conflicts, pandemics, famine, water shortage, extinction, intensive farming, and faster climate change.

Depletion of Resources

Overuse of natural resources due to high population demand.

Environmental Degradation

Damage to the environment through pollution, deforestation, and resource overuse.

Conflicts and Wars (Overpopulation Impact)

Caused by competition over scarce resources like food and water.

High Cost of Living

Prices increase because of high demand and limited supply of goods and services.

Pandemics and Epidemics

Spread of infectious diseases due to overcrowding and poor sanitation.

Famine and Malnutrition

Occurs when food supply cannot meet population needs, causing hunger and poor health.

Water Shortage

A condition where demand for clean, usable water exceeds supply.

Lower Life Expectancy

Result of poor health care, poverty, and lack of resources due to overpopulation.

Extinction

Permanent loss of species due to habitat destruction and overuse of resources.

Intensive Farming

High-input, high-yield farming method that damages soil and increases pollution.

Solutions to Overpopulation

Better education, education for girls, family planning awareness, tax benefits for small families, sex education, and social marketing.

Population Change Impacts on Environment

Overpopulation leads to deforestation, pollution, global warming, and loss of freshwater.

Deforestation (from Farming)

80% of global deforestation caused by converting forests into farmland.

Eutrophication

Excess nutrients in water bodies cause algae overgrowth, oxygen depletion, and fish death.

Freshwater Availability

Only 2.5% of Earth's water is fresh; by 2025, 2/3 of people may face water scarcity.

Global Warming (Population Effect)

Rising temperature caused by excess greenhouse gases from energy use and deforestation.

Forests as Carbon Sinks

Forests store twice as much carbon dioxide as the atmosphere, reducing global warming.