Succession and Conservation Flashcards
Succession
The process by which an ecosystem changes over time (the biotic conditions change as the abiotic conditions change)
Primary succession
Occurs on bare rock, with no soil, ie. land that’s been newly formed or exposed (volcano, falling sea levels etc)
Secondary succession
Occurs on bare soil, ie. land that has been cleared of plants (from a forest fire, deforestation etc)
What are stages of succession called?
Seral stages
Seral stages of primary succession:
1 - the abiotic conditions are hostile, as there is no soil to retain water.
2 - the pioneer species change the abiotic conditions; they die and decompose humus to form basic soil, making conditions less hostile.
Humus
Dead organic material.
How does secondary succession differ from primary succession in terms of rate of succession?
The pioneer species starts at a later seral stage (i.e. shrubs rather than lichens)
Why do biotic conditions change at each seral stage?
Different plants and animals that are better adapted for the improved conditions enter, out-compete the species that are already there and become the dominant species in the ecosystem.
What is the final seral stage called, and why is it the final stage?
The climax community.
The ecosystem is supporting the largest and most complex community of plants and animals it can. It won’t change much more and is said to be in a steady state.
What does conservation often involve, and how?
Managing succession, or sometimes preventing it by removing growing points (such as shrub shoots).
Can be by grazing or by manages fires, which conserve the pioneer species.
Briefly outline the main reasons for conservation:
- to conserve resources for human need
- it is the right thing to do
- to bring joy to future generations
- to prevent climate change (burning trees)
- to prevent disruption to food chains (which could mean loss of resources)
How do we conserve plants, and give an advantage and disadvantage of this method:
Seedbanks.
+ It doesn’t take up much space therefore many seeds can be stored, for a long time.
- Requires regular viability testing, which is expensive.
How do we conserve fish, and give an advantage and two potential disadvantage of this method:
Fishing quotas.
+ They involve international agreements, removing extinction risks.
- There can be disagreements between fishermen and scientists on the actual numbers.
- Arguably job losses.
How do we conserve animals, and give an advantage and two potential disadvantage of this method:
Captive breeding programs, i.e. breeding endangered animals in controlled environments them reintroducing them to the wild.
+ leads to increased numbers in the wild, bringing the species back from the brink of extinction.
- animals have problems breeding successfully outside their natural habitat, eg. pandas.
- reintroducing the animals can cause problems, eg. they can bring with them new diseases, harming the other species there.
What can we do to conserve any species, explain how this can be done and give a potential disadvantage of this method:
Relocation. By moving it to an area where it is not in risk (eg. by poaching, rising sea levels etc), making it more likely to survive and reproduce.
However, native species may be out-competed themselves and in turn endangered by the relocated species.
