Ecosystems Flashcards
Define ecosystem
All the living organisms in one area and the non-living aspects of their environments.
Can range in size
Dynamic and are influenced by biotic and abiotic factors
Define biotic and abiotic factors and give examples
Biotic - living features of an ecosystem e.g predators, disease
Abiotic - non-living features of an ecosystem e.g light, temperature
What is biomass and how is it transferred?
The total weight of living matter in a certain area
Biomass is transferred up trophic levels through consumption
How is biomass measured?
Mass of carbon
Dry mass of tissues
Give the formula for efficiency of biomass transfer
Biomass transferred
= —————————— x 100
Biomass intake
How can human activity affect biomass transfer?
Light, water, temperature maximised
Increased nutrients in soil
Pests and weeds removed
growth rates boosted through steroids and selective breeding
Outline the roles of microorganisms in the nitrogen cycle?
Nitrogen fixing bacteria e.g Rhizobium in the roots and Azotobacter in the soil - convert nitrogen to ammonia
Nitrifying bacteria e.g Nitrosomonas convert ammonium compounds to nitrites
Nitrobacter converts nitrites to nitrates
Outline the role of organisms in the carbon cycle
Respirarion adds CO2 to the atmosphere
Photosynthesis removes CO2 from the atmosphere
Decomposers decay plant and animal matter to release CO2
What is primary succession?
Where an area of newly exposed land is colonised by a community of organisms
What is the process of primary succession?
Pioneer plants colonise the area because they can survive harsh conditions.
They die, decompose and add nutrients to the ground
Overtime this allows more complex organisms to survive
What is the climax community?
The final stage of succession, where the ecosystem is balanced and stable
How is the climax community reached?
Soil is rich enough to support large trees or shrubs and the environment is no longer changing
What is deflected succession?
Where succession is interrupted, usually by human interference
What is sampling
Selecting a group of individuals that will represent the whole target population.
Give methods of sampling and explain how they are used?
Quadrats - used in small areas. Randomly or regularly placed across habitit. Frequency or % cover calculated
Transects - used in larger area. Sample taken along a line that crosses habitat. Can be combined with quadrats to form a belt tansect
