Population and the environment - Principles of population ecology and their application to human populations Flashcards
What is an ecological footprint
A measure of the human demands we place on ecosystems that support
us, expressed in global hectares (100m x 100m = 10 000 square metres): the amount of biologically
productive land needed to
produce the resources we
consume and absorb the waste we
generate.
what happens if a populations ecological footprint exceeds the regions bio capacity
region runs an ecological deficit
demand for the goods and services that its land and seas can provide—fruits and vegetables, meat, fish, wood, cotton for clothing, carbon dioxide absorption— exceeds what the region’s ecosystems can renew
what happens to a region in an ecological deficit
has to meet demands by importing, liquidating its own ecological assets (overfishing) and/or emitting carbon dioxide into the atmosphere
what is an ecological reserve
if a regions biocapacity exceeds its ecological footprint
What is the carrying capacity of a population
the idea of a population
ceiling, beyond which an
environment cannot
support people at a high
standard of living (or
worse a subsistence level),
for a sustained period of
time without
environmental
degradation
What is optimum population
ideal balance between population and resources
population size in an area which working with all resources will give the highest standard of living for the people of that area
Maximises the income per capita
a balance that most nations will try to achieve through direct or indirect population or resource management
constantly changing e.g. the development of new technology may increase resources available
what is under population
there are too few people to use the resources efficiently for a given level of technology
suggests an increase in population would mean more effective use of resources and increased living standards for all
Developed countries with access to resources and advanced technology but with relatively small populations such as Canada (38 million pop) which may be regarded as underpopulated (has potential to double) and with potential to support larger populations
What is overpopulation
too many people in area relative available resources puts pressure on resources
Continued increase in population will reduce the average standard of living for all
Conversely it implies that with no advances in technology and no increase in resources only a fall in population would increase living standards. Measure applies only to the relationship between population size and available resources. Thus a densely populated country such as the Netherlands (448 people per km^2) can enjoy a relatively high standard of living while less densely populated Mali (12 people per km^2) struggles to provide the basic needs for its population because of a poor resource base
What is easter island
UNESCO world heritage site
163km^2 island in the pacific ocean
Next inhabited island 1600 km away
1000 years ago polynesians settled
Over next 600 years society grew and thrived
Population peak at several thousand
16 million trees removed - could be slash and farm burning
Quarries stones used to build houses and statues - 900
1774 james cook visited island - only 700 people
What happened to easter island according to pessimists
there are finite limits on our environment
If exist beyond our means we will go down together
what do anthropologists suggest happened to easter island
unlikely story of success
Rats, stowaways in the canoes of the first settlers colonised the island
They ate the trees
Islanders could have adapted their diet to eat rat and also vegetables from newly created rock gardens
Although island was tripped of resources the ecosystem was under sever pressure - the islanders adapted to survive
As a global society need to learn to adapt to our environment or we will face the consequences
What can we learn from easter island
Basic physical level - food water energy, need more as we grow
Produce waste and pollution
Planets ecosystems many becoming gradually depleted
To survive need to understand ecological footprint and the constraints that the environment places activities and population growth
In 1970 we overlooked earth’s rate of replenishment of natural resources
Since then we have been living unsustainably
How is food productivity constraining population growth
20% more food per person is produced today than 40 years ago
1 billion people who go hungry
grow enough food but many don’t have sufficient land to grow enough food or income to purchase
How is water consumption constraining population growth
2.5% of earth’s water is freshwater - reducing because of climate change and greater pressure from population growth
Around 1.1 billion people do not have access to freshwater - mainly LICs
Major failure of irrigation and water distribution schemes in future may lead to prolonged drought within regions not used to environmental hardships e.g. southeastern and south western Australia, the southern Mediterranean and Florida
How is climate change constraining population growth
Greenhouse gases created faster than they can be absorbed by shrinking forests and oceans
Around 10% of world population live less than 10m above sea level - rise in sea level will put homes, crops and livelihoods at risk
Knock on effect on the productivity of natural and manmade ecosystems will be severe
