Ecosystems, Populations And Sustainability Flashcards
Define ecosystems
All the living organisms found in one area and the non living aspects of their environment
Can range in size from rock pool to African savannah
Known as ‘dynamic’ as they depend on interactions between biotic and abiotic factors
Describe biotic factors with examples
The living features of an ecosystem
Any from
Predators
Disease
Symbiosis
Parasitism
Mutualism
Competition
Describe abiotic factors and give examples
Non living features of an ecosystem
Any from
Light
Soil
Water availability
Water movement
Oxygen concentration
pH
Wind
Salinity
Temperature
Humidity
What is biomass and how is it transferred?
Total weight of living matter in a certain area, transferred up trophic levels through consumption. Can be measured in terms of mass of carbon or dry mass of tissue
Give the formula for the efficiency for a biomass transfer
Efficiency = ( Biomass transferred / Biomass intake ) x100
How can human activities affect biomass transfer
• Light, water, temperature maximised
• Increased nutrients in soil
• Pests and weeds removed
• Growth rates boosted through steroids, selective breeding etc
Outline the role of microorganisms in the nitrogen cycle
Nitrogen-fixing bacteria e.g. Rhizobium in roots and Azotobacter in soil convert gaseous nitrogen into ammonia
Nitrifying bacteria e.g. Nitrosomonas convert ammonium compounds into nitrites
Nitrobacter then converts nitrites to nitrates
Outline the role of organisms in the carbon cycle
- Respiration of plants and animals add carbon dioxide into the atmosphere
- Photosynthesis of plants removes carbon dioxide from the atmosphere
- Decomposers (microorganisms) decay plant and animal material into carbon dioxide
What is meant by primary succession
Where an area previously devoid of life is colonised by a community of organisms
Summarise the process of primary succession
- Pioneer species, able to survive harsh conditions, colonise the area
- They die, decompose and add nutrients to the ground
- Over time, this allows more complex organisms to milestone
What is the climax community and how is it reached?
The final stage of succession, where the ecosystem is balanced and stable. It is reached when the 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
Allows us to measure the distribution and abundance of organisms
Give methods of sampling and explain how they are used
Quadrats = used in small areas. Randomly or regularly placed across habitat. Frequency or % cover calculated
Transects = used in larger areas. Sample taken along a line that crosses the habitat. Can be combined with quadrats in the form of a belt transect
Define carrying capacity
The maximum population size that a habitat can support, defined by the presence of limiting factors