P2 Populations and Sustainability

Question 1

What is the ecosystem carrying capacity?

Answer 1

• The maximum population size that can be supported by an environment.
• It is determined by limiting factors (biotic or abiotic factors).

Question 2

What abiotic factors affect population size?

Answer 2

1. Temperature increases can cause populations to increase.
2. Light
3. pH
4. Water - limited water supplies can cause the population to decrease.

Question 3

What biotic factors affect population size?

Answer 3

1. Food - eg. improved access to food increases population size
2. Competition - as competition increases, food decreases, decreasing population size
3. Predation - as preys population increases, predators population increases which decreases prey population… etc.

Question 4

What are the two types of competition?

Answer 4

1. Intraspecific - competition between the same species
2. Interspecific - competition between different species

Question 5

What is conservation?

Answer 5

• The active management of an ecosystem to maintain it’s species and habitat.
• This often involves managing succession eg. if an ecosystem would normally progress from grasses to woodland, grazing animals can preserve grasses and prevent larger plants growing.

Question 6

What are the reasons for conservation?

Answer 6

1. Economic reasons - promoting ecotourism and drug development.
2. Social reasons - provides a variety of activities with others.
3. Ethical reasons - prevention extinction of endangered species, and conserve biodiversity for future generations.

Question 7

What is preservation?

Answer 7

The protection of an ecosystem by restricting or banning humans from it to maintain it’s original state.
- preventing agriculture and ecotourism

Question 8

What is ecosystem management?

Answer 8

When humans use/manage an ecosystems natural resources sustainably (give time to renew).

Question 9

How is timber production managed sustainably?

Answer 9

1. Coppicing (cutting a trees trunk close to ground level rather than removing the tree, this stimulates new shoots to grow, which can then be harvested). This can be repeated indefinitely. The benefits of coppicing are: increasing the life span of the tree, provides a variety of light levels, increasing biodiversity of other plant species. It grows new shoots more quickly than saplings, increasing timber production.
2. Clear felling (removes all trees from a forrest area chosen for harvesting). This can damage biodiversity, therefore:
   - the size of the area that is felled is limited
   - felled trees are replanted
   - this limits soil erosion
   - keep a minimum distance between replanted trees
   - let replanted trees fully regrow before the next cycle of clear felling

Question 10

How is fishing sustainably managed?

Answer 10

1. Fishing quotas limit the number of fish that can be caught.
2. There are regulations on mesh sizes to ensure that only adult fish are caught.
3. Certain fish are placed under species restrictions, protecting endangered species.
4. The size of trawlers are limited, to reduce the number of fish that can be caught.
5. Regular catch inspections by officials to enforce these measures.

Difficulties:
- however the area open for fishing is often too large
- false reporting of numbers of fish caught to avoid quotas
- catch inspections prove too expensive, threatening the measures to not be enforced at all