5B: Ecology Flashcards
5B.1 - 5B.7
Define Ecology
- the study of the interactions between organisms and their environment
- these interrelationships determine the distribution and abundance of organisms and their environment
What does the life-supporting environment of an ecosystem include:
- all the living organisms interacting with it
- the nutrients that cycle throughout the system
- the physical and chemical environment in which the organisms are living
What does an ecosystem consist of?
a network of habitats and the communities or organisms associated with them
What is a habitat and a microhabitat?
the place an organism lives
a small area of a habitat
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 a niche?
the role of an organism within the habitat in which it lives (its profession)
several organisms can share the same habitat, occupying different niches
What are abiotic factors + examples?
non-living elements of the habitat of an organism including those related to the climate and soil (edaphic):
- amount of sunlight
- temperature
- rainfall
- drainage (soil)
- pH (soil)
- oxygen availability (in aquatic environments)
What are biotic factors?
the living elements of a habitat that affect the ability of a group of organisms to survive there
What is the biosphere and biomes?
biosphere is all areas of the surface of the Earth where living organisms survive
they’re divided into smaller parts distinguished by similar climates and plant communities called biomes (major ecosystems of the world)
Define succession
the process by which the communities of organisms colonising an area change over time
When does primary succession occur?
after a volcanic eruption, landslide, or after emergence of new volcanic island
What does primary succession start with?
starts with empty inorganic surface such as bare rock or a sand dune
What is the first stage of succession?
colonisation: process by which new species spread to new areas
What organisms are the first to appear in succession and why?
opportunists / pioneer species like algae, mosses, fungi
as these organisms can penetrate the rock surface by:
- dissolving rock with acids they secrete
- penetrate tiny cracks with root hairs and hyphae
What is the start of soil formation?
- after pioneer organisms penetrate rock surface, this helps break rock into small grains, and trap organic material that breaks down to form humus
- inorganic rock grains and organic humus are the start of soil formation
What happens during succession after there is soil?
- species like grass and ferns can establish root systems
- the action of their roots and humus they form when they die and decay add to the soil
What happens as the soil layer continues to develop during succession?
- as soil layer develops, more water and nutrients are kept and become available for plant roots meaning less resistant species survive
- gradually, larger plants can be supported and species diversity increases resulting in an increase in diversity of animals that can be supported
When do we reach a climax community?
a climax community is reached in which the biodiversity and range of species are generally constant
it’s self sustaining and the most productive group of organisms the environment can support
What is a plagioclimax?
a sub-climax community where succession has been held back / deflected by human activity
climax community can develop when humans move away
What is secondary succession and when does it occur?
the development of an ecosystem from existing soil clear of vegetation
occurs after fires, floods, disturbances caused by humans
there are a higher number of plants from the start
What factors does the time taken to go from bare Earth to a climax community depend on?
- temperature
- rainfall
- soil fertility
What is a climatic climax community?
the only climax community possible in a given climate
What is the effect of light (abiotic factor) on populations?
amount of light in a habitat has a direct effect on no. of organisms found there