Population Ecology: Population Growth

Geometric Growth Pattern
Exponential Growth Pattern
Logistics Growth Pattern

3 Population Growth Patterns

Geometric Growth Pattern

Finite rate of increase, λ

Geometric Growth Pattern

• Factor by which a population increases during a single unit interval (e.g. hours, months or years)
• Useful measure of population changes when the growth is seasonal
• Growth in populations with discrete generations

2

A population that increases twice every hour has λ =

Exponential Growth Pattern

Growth of population occurs continuously at a fixed rate rather than intermittently regardless of population size

Exponential Growth Pattern

• Chosen time interval is not restricted to a particular life cycle

• Typical for r- strategists

• J-shaped growth curve

• relaxation-oscillation (boom-and-bust) pattern

• conforms to the exponential equation

r strategists

J-shaped pattern

there is relaxation and oscillation pattern

carrying Capacity / Resisting Factor

When population in the exponential growth pattern , the carrying capacity set in the population would abruptly stop/decrease in growth

Exponential Growth Pattern

growth pattern typical for r-strategists

J-shaped curve

Type of curve for exponential growth pattern

Logistic Growth Pattern

Predicts that population growth slows and eventually stops as it reaches the carrying capacity (K)

Logistic Growth Pattern

growth pattern typical for k-strategists

S-shaped curve

type of curve for logistic growth pattern

Verhulst-Pearl Equation

equation for logistic growth pattern

lag phase
log phase
negative acceleration phase

phases of S-shaped curve

raw materials
energy
space
means of disposal
Interactions

5 environmental resistance factors that set the carrying capacity, K:

1. Availability of _____
2. Availability of _______
3. Availability of ______
4. Accumulation of waste products and their _________
5. _________among organisms

Global Carrying Capacity

• Just how many humans can the biosphere support?

• …no agreement in the scientific community on a number.
• But, estimates of global population in 2050 are between 8 and 11 billion (currently about 7.9 billion)
• Will technological advances continue to increase the Earth’s capacity for humans?

Ecological Footprint

with the knowledge of carrying capacity we become aware or the resources in all forms in the environment. Consumption of such resources could be measured using _____________

Ecological Footprint

The aggregate land and water area needed to sustain the people of a nation. What area is needed to produce the resources consumed and absorb wastes generated.

Ecological capacity

the actual resource base of a country

carrying capacity

Looking at the ecological footprint is one measure of how close we are to the ____________ of Earth

Ecological Footprint

• MEASURES how fast we consume the resources/energy , settlement, timberapaper, food& Fiber , seafood) and generate waste

• COMPARED to how fast nature can absorb our waste and generate new resources w/ is the ecological capacity (include: Carbon footprint , buildup land , forest , cropland and pasture, fisheries)--provide resources for consumptions and waste generation

Human Development Index

measure of average achievement in key dimensions of development including long healthy life, being knowledgeable and having decent standard of living