biology chapter 24 populations and sustainability

phase 1 - period of slow growth

phase 2 - rapid growth

phase 3 - stable state (happens due to limiting factors where BR = DR)

what does a population growth curve look like?

limiting factors prevent further growth and can cause decline

can be abiotic or biotic

what are limiting factors?

factors that have an effect on the whole population regardless of size

earthquakes, fires, volcanic reuptions and storms

what are density independent factors?

interspecific - between species

intraspecific - within the same species

what are the two types of competition?

when two or more different species compete for the same resource

for food or habitats

less well adapted species will be outcompeted and the less adapted species will decline in number and no longer exist

this is the competitive exclusion principle

how does interspecific competition happen?

for resources such as food or mates

not always stable as resources can vary

how does intraspecific competition happen?

predator and prey population sizes fluctuate and are dependent on each other

1. as prey increases, more food for predators so predators also rise

2. more predators means more prey are eaten so prey deacreases

3. reduced prey population can’t support predators so they decrease

4. less predators so prey population rises

predator prey relationships graph

explain each main stage

maintenance of biodiversity through human intervention

to maintain biodiversity for sustainable development

also includes reclamation, restoring damaged ecosystems

what does conservation mean?

Protection of an area by restricting or banning human interference

Aim to protect sensitive ecosystems

what is preservation?

Economic - provide resources for human survival like emdicine and clothes

Social - people enjoy natural beauty

Ethical - moral responsibility to future generations

importance of conservation?

a renewable resource that is being economically exploited so that it will not run out

what is a sustainable resource?

• preserve environment

• ensure resources for future generations

• balance consumption of resources

what are the aims of sustainability?

• coppicing: tree trunk is cut close to the ground and new shoots are cut

• shoots make even more leading to a tree with multiple trunks

• rotational coppicing is done so that newly coppiced trees have time to grow and maintain biodiversity

How is timber sustainably produced through coppicing?

• selective cutting removing only large trees

• replace by replanting

• plant at optimal distance to reduce competition

• manage pests

Major disadvantage is that habitats are destroyed and soil minerals reduced. Trees are needed for binding soil together.

how is large scale timber production done sustainably?

disadvantage?

overfishing has led to species of populations reducing drastically

• fishing quotas to avoid overfishing

• bigger net holes to allow younger fish to get through

• restrict fishing at times year

• fish farming prevent the loss of wild species

what is sustainable fishing?

• limit grazing to edges of the reserve and grazing in different areas to allow plants to recover

• ecotourism to support the local tribes and the environment

• conservation and research in reserves

• livestock can compete with wildebeest during migration

• sustainable forest management and agriculture

how ecosystems can be managed to balance the conflict between conservation/ preservation and human needs?