Environmental Science: Unit 2C

Budd, 26-27

Exponential Growth (J-Curve)

Growth under ideal conditions with unlimited resources; accelerates continuously

(dN/dt = rN)

Logistic Growth (S-Curve)

Growth slows and stops as population size (N) approaches Carrying Capacity (K)

Carrying Capacity (K)

Maximum number of individuals an ecosystem can sustainable support over time

r-Selected Species

High biotic potential, quick maturation, many offspring, low parental investment (e.g. insects, dandelions; J-curve

K-selected species

low biotic potential, slow maturation, few offspring, high parental investment (e.g., humans, elephants; S-curve)

Abiotic limiting factors

non-living physical/chemical components limiting growth (e.g., water, sunlight, temperature, soil nutrients)

Biotic limiting factors

living interactions limiting growth (e.g., food supply, predation, competition, disease).

Density Dependent factors

Impact scales with population density 9e.g., competition, parasitism, infections disease).

density independent factors

impact occurs regardless of density (e.g., droughts, freezes, natural disasters)

Agriculture/green revolution

synthetic fertilizers, high-yield crop strains, and mechanization expanded food calories.

Industrial revolution

mass manufacturing, improved transportation, power generation, urban infrastructure

medical advances

mass production of antibiotics, vaccines, sterile surgery, and municipal clean water/sewage sanitation

21st century trend

global human population will not triple in the 21st century as it did in the 20th. According to the UN Population Division, growth is slowing rapidly as fertility rates drop worldwide, projecting a peak near 10-10.5 billion

Ecological footprint

measure of land/water area required to produce the resources an individual or nation consumes and absorb their waste. Calculated based on energy, housing, transportation, food, and goods/services

Affluence v population

high affluence nations can have a far larger footprint with small populations than heavily populated developing nations with low resource consumption

mitigation plan

reduce energy/water use, adopt low emissions transport, eat lower on the food chain, and practice source reduction

crude birth/death rate

number of live births (cbr) or deaths (cdr) per 1000 individuals in a population per year

total fertitily rate

average number of children born to a woman in her lifetime, affected by female education, female employment, age at first child, access to family planning, and child labor demand

replacement level fertility

TFR required to keep population stable;e (~2.1 in developed nations to offset infant mortality)

life expectancy

average age a person lives. driven by clean water, sanitation, healthcare, diet, hygiene, and crime rates

population momentum

continued growth after reaching replacement feritilitu because a large percentage of the population is under reproductive age

dependency ratio

ratio of non-working indivifuals (aged <15 and >65) to the working age population (15-64)

high stationary

high birth rate, high death rate, very low/stable population growth. pre-industrial, subsistence farming, high infant mortality

early expanding

high brith rate, death rate falls rapidly, population rapidly increases. improvements in sanitation, clean water, and basic medicine.

late expanding

birth rate falls rapidly, death rate low/levelling, population growth slows down. Increasing female education, urbanization, family planning.

low stationary

birth rate low, death rate low, population growth stable/gradual. Industrialized; e.g., US, South Korea, Australia, Brazil, Europe.

declining

birth rate below replacement, death rate low, population growth goes into negatives. Aging population; e.g., Japan, germany

biotic potential

max reproductive Capacity of a species under ideal conditions

fecundity

biological physical ability to reproduce offspring

family planning

educational/medical services enabling control over birth numbers and timing

zero population growth

birth +immigration = death + emigration

pronatalist pressures

curtural/economic factors encouraging higher birth rates

UN population division

UN body providing authoritative global demographic estimates

population change equation

N = (B+I) - (D+E)

[B=birth, I=immigration, D=death, E=emigration]