Ecosystems 4 Flashcards
Define interspecific competition
Competition between organisms of different species
Define intraspecific competition
Competition between organisms of the same species
Define climax community
Final stage of succession, where the community is said to be in a stable state
Define hummus
The organic component of soil formed by the decomposition of leaves and other plant material by soil microorganisms
Define plagioclimax
The stage in succession where artificial or natural factors prevent the natural climax community from forming
Define carrying capacity
The maximum population size that an environment can support
Define seral stages
The stages of succession
What key features does a pioneer species usually have?
seeds or spores which can disperse long distances
low nutrient requirement
shallow roots
quick growing
What is a lichen? What makes it a good pioneer species?
Symbiotic mutualistic relationship between a fungi and an algae
The fungi is able to absorb mineral ions from rocks and provide them to the algae
The algae is able to photosynthesise, so creates its own organic molecules (which it can pass on to the fungus)
Why are new species able to colonise as succession progresses?
Because other species change the abiotic and biotic conditions so that new niches are created, allowing new species to colonise
Why are earlier successional species outcompeted by later successional species?
Early successional species are able to grow in hostile conditions. When the conditions become less hostile other species colonise. These new species might be able to grow/reproduce faster than the pioneer species, so the pioneer species are outcompeted.
Why is the same climax community not found everywhere?
Because the climax community will depend on the climatic conditions in the area.
Describe and explain how succession occurs, leading to the formation of an oak woodland from bare rock
Pioneer species colonise the bare rock
Some of the individuals die and are decomposed, this increases the amount of organic matter
New niches are created, allowing new species to colonies (e.g. mosses and grasses which help to increase the amount organic matter further
Then small plants and shrubs colonise the area. They grow bigger than the mosses and grasses, blocking light and outcompeting them.
The small plants and shrubs will provide more shelter, they will decrease fluctuations in surface temperature and there will be a further increase in the amount of organic matter. Their roots can aid the break up of rocks, so increasing mineral content of the soil
Biodiversity increases as succession progresses and the ecosystem becomes more stable
Eventually larger trees will colonise and they will outcompete the earlier successional species
The woodland climax community is created
Describe and explain how succession could occur in a pond ecosystem leading to the formation of woodland
Seeds from pioneer species land in the pond and germinate. These grow under water and on the bottom of the pond.
As some of the individuals die and decompose there is a build up of organic matter on the bottom of the pond
This allows some plants (emergent) to start growing at the edges of the ponds
More plants die and decompose so the layer of organic matter at the bottom of the pond builds up. This causes the water to become shallower, so emergents are able to grow all across the pond. (It becomes a marsh/wetlands)
More and more organic matter builds up, so trees are able to colonise and grow. (This is called a swamp)
If the swamp dries out, a forest is formed.
What is primary succession?
When succession starts from pioneer species colonizing an area that has never had anything growing there
