8.4

Question 1

What is Carrying Capacity?

Answer 1

Carrying capacity is the maximum number of species that can be sustainably supported by a given area.

It is possible to estimate the carrying capacity of an environment for a given species by examining carefully its requirements and the resources available; however, this is problematic in the case of human populations.

Question 2

Reasons why human carrying capacity is difficult to quantify:

Answer 2

1. Humans are able to substitute one material for another. If a resource runs out, we can use another. We may burn coal instead of wood, use solar energy instead of oil, or eat mangoes instead of apples.
2. The resource requirements of local human populations vary significantly because of different lifestyles and levels of development. The more money there is available the more demand there tends to be for resources.
3. EVSs are an important influence on resource use. Some societies are more materialistic than others, even when there is not much difference in the degree of economic status.
4. Technological development can impact considerably on resource requirements and availability. For example, very few railway systems in the world now use coal, when at one time they all did. Modern railways are powered by electricity or diesel.
5. We can import resources from outside our immediate environment. While importing resources increases the carrying capacity of local populations, it has no impact on global carrying capacity.

Question 3

Signs of stress

Answer 3

However, we can estimate the carrying capacity through signs of stress. Signs of stress will show that our environment is reaching its limits.

Examples of signs of stress:
Loss of biodiversity
Declining water quality
Soil erosion and degradation
Coral bleaching
Increased pollution

Question 4

How can we identify signs of stress?

Answer 4

Signs of stress can be identified through the ecological footprint. The EF is a model used to estimate the demands that human populations place on the environment.

Instead of focusing on a given environment and trying to calculate the carrying capacity it provides, the Ecological Footprint focuses on a given population and estimates the area of environment necessary to sustainably support that particular population.

If the EF is greater than the area available to the population, this is an indication of unsustainability + exceeds the carrying capacity

Question 5

LEDCs vs MEDCs Carrying Capacity

Answer 5

Given the different standards of living between LEDCs and MEDCs, differences in resource consumption, energy use and waste production, disparities should be expected between
their ecological footprints.

LEDCs have smaller EFs
MEDCs have greater rates of consumption
LEDCs have a lower consumption because they have less to spend
A meat-eating diet, prevalent in MEDCs (where 30% of diet may be based on animal protein) requires the use of much more land than a vegetarian diet. LEDCs have a much lower percentage of meat in their diets (about 12%).