[ENVI] MOD 3: Population

Population Ecology

The study of populations in relation to environment, including environmental influences on density and distribution, age structure, and population size

Population

A group of organisms of the same species that live in the same area

Population size

The number of individuals in a population

Births, immigration, deaths, and emigration

Population size is primarily influenced by:

Population density

The average number of individuals in a population per unit of area or volume

Population distribution

Describes how the individuals are distributed or spread throughout their habitat

Carrying capacity

The maximum population size of the species the environment can sustain

Carrying capacity

Determined by the amount of available resources

Population growth

Change in the size of the population over time

Population growth rate

How fast a population changes in size over time

Increasing

A positive growth rate means a population is _________

Decreasing

A negative growth rate means it is ________

Birth rate and death rate

Two main factors affecting population growth

population growth rate = (birth rate + immigration rate) - (death rate + emigration rate)

Formula for population growth

Demography

Statistical study of human populations

Demographers

Use census data, surveys, and statistical models to analyze the size, movement, and structure of populations

Demography

Useful for government and private businesses as a means of analyzing and predicting social, cultural, and economic trends related to population

Ecological footprint

A measurement of the amount of resources a person consumes in his/her day to day living, including the energy required to dispose the waste

Ecological footprint

Measured in terms of the Earth area

Sir David Attenborough

Who quoted, “Instead of controlling the environment for the benefit of the population, perhaps it’s time we controlled the population to allow the survival of the environment.”

2.3 hectares

The average ecological footprint of each human is currently _______ of land

1.7 hectares

According to the World Commission on Environment and Development, there are only _________ of productive land available to every human

Unregulated construction and land development

A large influx of people can lead to unreguated construction and pressure for development in disaster-prone areas, leaving people vulnerable to flooding, sea level rise, earthquakes, and resulting destruction to life and property

Overcrowding and the proliferation of poverty

Urban migration to cities without proper infrastructure can lead to the proliferation of impoverished neighborhoods and unsanitary conditions. People residing in these areas are more susceptible to disease outbreaks, which can impede their ability to work productively. Further, inequality can lead to social instability, driving companies near these areas to transfer their operations. Closing businesses exacerbates unemployment and poverty, creating a cycle that leads to further instability in the society and economy

Inadequate infrastructure

With an increase in employment, rising incomes can lead to a greater number of households owning cars, However, this growth typically exceeds the city’s ability to expand the roadway infrastructure, causing traffic congestion, which takes a toll on businesses through higher fuel costs and delays in the delivery of goods and services. Heavy traffic congestion can also be detrimental to workers. Enduring long hours of heavy traffic while commuting can leave employees tired and unproductive once they reach their workplaces. And, in extending the workday with a lengthy commute, workers may have to cut back on their sleeping hours, which can also have negative effects on their health and productivity.

Impact on ecosystems

Cities have extreme effects on the lives and relationships of plants and animals, both directly within the urban space and indirectly elsewhere through their ecological footprint. Poor air quality is estimated to cause over 1 million premature deaths each year. Through GHG emissions and other factors, cities make a great contribution to global warming than any other source, increasing the likelihood of extreme weather events such as floods and droughts, which can have massive impacts on urban life.

Water and waste management

Water, the world’s most threatened essential resource, is a major challenge for cities, where the risk of pollution is high, and urbanization can affect rainfall patterns. Improper disposal of municipal waste can have adverse effects on everything from soil fertility and the health of plant life to the safety of drinking water.