Module 6: Ecosystems Flashcards
Primary Succession:
Occurs on an area of land that has been newly formed or exposed. There is no soil or organic material. -> e.g eruption, sand dunes, silt deposition, glacial retreat
Secondary Succession:
This occurs where soil is present but no animal or plant species. -e.g after forest fire of controlled burning
What is succession?
Changes to the present species in an environment in response to changes in abiotic factors.
What is a pioneer species?
The first species to occupy “new land” during succession.
What are adaptations of a pioneer species?
The ability to produce large quantities of seeds or spores
Rapid germination of seeds
The ability to photosynthesise.
Tolerance to extreme conditions
The ability to fix nitrogen from the atmosphere
What is the name of the steps of succession?
Seral stages
What are the different colonisers present in an intermediate community?
Secondary coloniser, tertiary colonisers and scrubland.
How fast is primary succession?
Slow
How fast is secondary Succession?
Rapid
How do the conditions of an ecosystem change over the course of succession?
The conditions become less hostile, species diversity increases and-so the ecosystem becomes more stable.
What are organic products released into the soil known as?
Humus
Secondary colonisers:
Use the humus deposited into the ground to grow, they act as a food source for primary consumers, allowing animal species to colonise the area.
Tertiary colonisers:
As the conditions improve tertiary colonisers arrive, with waxy cuticles for water retention.
Why does the soil become more fertile as succession continues?
Organic products and matter from plants deposit into the soil and rocks are eroded releasing minerals into the soil.
What is the dominant species in each seral stage?
The species with the greatest biomass in the ecosystem in a given time.
What is the name of the final seral stage?
The climax community.
What is the climax community?
The final seral stage. The community is in a stable state and will show very little change over time. There is high biodiversity with a couple of dominant species. The species present is dependent on the climate.
When does biodiversity peak during succession?
Mid-succession.
Animal succession:
Similar to plant succession although much slower. The land must also not be geographically isolated to allow for the animal species to enter the area.
What is the name of the final stage of succession when it’s artificially stopped?
Plagioclimax.
What is one of the main reasons for succession being interrupted?
Agriculture:
- grazing and trampling of vegetation by domesticated animals - areas remain grassland
- Removing existing vegetation such-as shrubs and replaced with crops
- Burning down forests - Increases biodiversity due to secondary succession
What are two examples of dynamic ecosystems?
Cold and Aquatic environments.
What diagrams can be used to show the transfer of biomass?
Food chains and webs
How is biomass measured?
Measure the mass of fresh material, kill the organism and heat it to obtain “dry mass”. This is then multiplied by the number of organisms in that trophic level.
Why is water content removed from biomass?
Water content makes results less precise as water content varies daily and seasonally.
What is the issue with how biomass is measured?
It doesn’t take into account seasonal changes and only provides the biomass at a particular time.
How can the method to measure biomass be improved?
A larger sample could be taken over a longer period of time.
What is nitrogen used for in plants and animals?
To synthesise proteins and amino acids.
How is nitrogen transferred from plants to decomposers?
The plant will either be digested by animal or the plant will die and be directly digested by a decomposer
How do decomposers transfer nitrogen into the soil?
Ammonification
What is ammonification?
The dead matter is broken down into ammonia in the soil.
What process transfers ammonium into nitrates?
The process of nitrification: 2 step process
Nitromonas converts ammonia into nitrite ions
Nitrobacter convert nitrite ions into nitrates
In what form is nitrogen assimilated into plants?
Assimilation: Nitrate ions in the soil diffuse into the roots.
What do denitrifying bacteria do?
Convert nitrates in the soil into nitrogen gas which is released into the atmosphere.
What plants have nitrogen-fixing bacteria in their roots where nitrogen fixation occurs?
Legumes
What is nitrogen fixation?
Nitrogen from the atmosphere is converted into ammonia in the soil.
What is an abiotic process of nitrogen fixation?
Lightning.
What is a human impact on the nitrogen cycle?
Over-use of fertilisers increases the nitrate content of the soil.
Waste from livestock can also increase the nitrate content of the soil.
The increase nitrate content can lead to eutrophication
Detritivores:
Alternate name for saprophytes that speed up the decay process.
What are the 3 types of organisms in the carbon cycle?
Consumers, Produces and Decomposers.
How is carbon transferred from animals and plants to the atmosphere?
Respiration and decomposition
How is carbon removed from the atmosphere?
Dissolved into the ocean, or photosynthesis.
How is carbon transferred from decomposers to the atmosphere?
If decomposition is prevented, the dead material will become fossil fuels, which then undergo combustion releasing carbon into the atmosphere.
What is the carbon containing compound present in the atmosphere?
CO2
