The nature of ecosystems Flashcards
What is an ecosystem
A life supporting environment
What is a habitat
The place where an organism lives
What is a population
A group of organisms of the same species, living and breeding together in a habitat
What is a community
All the populations of all the different species or organisms living in a habitat at any one time
What is succession
The process by which the communities of organisms colonising an area change overtime
Primary succession
Occurs when a new patch of land is created or exposed for the first time e.g. when lava cools and creates new rocks.
The first organisms (pioneer species) break down rock and enter cracks to create soil, therefore plants and therefore animals
What is a climax community
A self sustaining community with relatively constant biodiversity and species range
What is a climatic climax community
The only climax community possible in a given climate (FE Clements)
What is a plagioclimax community
A climax community that is at least in part the result of human intervention
Secondary succession
When a climax community is impacted by a disturbance e.g. if a patch of land became bare due to a river changing its course, and trees taking over
Surtsey - succession case study
When a volcano was erupting off the coast of Iceland and created a new island. Primary succession occurred resulting in birds, trees, plants etc.
What are some abiotic factors that can affect populations
Light
Temperature
Wind and water currents
Water availability
Oxygen availability
Edaphic factors
Effect of light on populations
Plants are dependent on light for photosynthesis
Animals are then effected by this indirectly due to distribution of food plants
Effect of temperature on populations
Every organism has a specific temperature in which it can grow and reproduce
Effect of wind and water currents on populations
Wind has a direct effect on organisms in a habitat. It also increases water loss from the body and cooling so adds to environmental stress
In water currents, organisms have to flow with the current, be strong swimmers or be able to resist the force of water - currents are damaging to most populations
Effect of water availability on populations
Water is vital for living organisms so when it is limited it can cause death
Too much water can cause changes in habitats
Effect of oxygen availability on populations
Oxygen availability can be short in both water and soils affecting organisms within them or their habitats
Effect of edaphic factors on populations (soil structure and mineral content)
Sand has a loose shifting structure that allows very little to grow in it
Marram grows in sand binding it together making it more suited for colonisation
Soils that contain a lot of sand are light, easily worked and easily warmed, but also easily drained
Water passes through rapidly taking minerals with it - leaching
Clay particles make it hard for water to drain
Plants therefore will not survive
Biotic factors affecting populations
Predation
Finding a mate
Territory
Parasitism and disease
Effect of predation on populations
Populations will oscillate in a repeating cycle
When prey increase, there is more food so predators increase, which eat the prey so prey decrease, resulting in less food so predators decrease etc.
Effect of finding a mate on populations
One plant or animal on its own will not survive in a habitat as it needs a mate to reproduce (unless it can reproduce asexually)
Effect of territory on populations
A territory is an area held and defended by an animal or group of animals
Used to make sure a breeding pair has sufficient resources to raise young
Effect of parasitism and disease on populations
Diseased animals will be wakened and do not reproduce successfully , sick predators cannot hunt well and diseased prey are more likely to be caught
Parasites also usually weaken the hosts body and can wipe out whole populations
What is a density independent factor
A factor that affects all individuals in a population the same no matter its size e.g. extreme temperatures
