-Module 6.3.1 Ecosystems Flashcards
What is the definition of a habitiat?
The place where an organism lives.
What is the definition of population?
Members of the same species living in the same place and at the same time, that can interbreed.
What is the definition of a community?
Populations of different species living in the same area at the same time, they can interact with each other.
What is the difference between a habitat vs an environment?
The environment is the conditions of the area due to biotic or abiotic factors.
Habitat is a defined place or area of the environment according to the life requirements of a particular life form.
-A habitat has life in it whereas an environment doesn’t ALWAYS.
-A habitat is always a preference of ONE species but an environment can be for multiple.
-Usually the environment governs the properties of the habitat and not vice versa.
What is an ecosystem?
A community of animals, plants and bacteria interrelated with the physical and chemical envrionment.
How big are ecosystems?
They can range in size from a tiny bacterial colony to the whole biosphere of the earth.
The size is determined by the person or team carrying out the study.
Ecosystems don’t have a clear edges.
What is an ecological niche?
A species’ niche is his ecological role, it is defined by the set of conditions, resources and interactions that it needs (or can make use of)
A description of it’s niche could include what it feeds on, what it excretes and how it reproduces.
What are the two groups of factors that affect an ecosystem?
Biotic and abotic factors.
What are examples of biotic factors?
Living organisms that can affect each other, it can involve competition.
What are examples of abiotic factors?
Light
Temp
Water availability
O2 availability
Edaphic (soil) factors
pH
Relative humidity
Concentration of pollutants
What are the 3 main soil types?
Clay, loam (retains water wothout getting water logged, fine particles) and sandy.
What is meant by ‘ecosystems are dynamic’? Why are they dynamic?
It means that ecosystems change.
Non-living elements change, living elements grow and die, populations of species rise and fall (mostly very small/not noticable)
Living things can interact with each other and with their physical environment and any small changes in one thing can affect another.
What are the 3 types of changes that affect population size?
Cyclic - repeat in a rhythm,
eg predator-prey cycles.
Directional - long lasting in one direction, eg erosion of coastline
Unpredictable/erratic - no rhythm/no constant direction, eg hurricane or effects of lightning.
What is a food web?
An interlinked system of food chains.
How is a food chain represented on a diagram?
Each level of the food chain is a trophic level.
Arrows show the flow of energy.
The first trophic level is always a producer - an organism that converts light energy into chemical energy by photosynthesis.
Subsequent trophic levels are all consumers - organisms that obtain energy by feeding on other organisms.
What are pyramids of numbers?
They represent food chains, each level represents the number of organisms at each trophic level.
Producers are always at the bottom.
It can look like a regular or irregular pyramid.
What is biomass?
The mass of living material present in a particular place or in a particular organism.
It can be equated to energy content and represented in a pyramid of biomass.
What are the units for energy available at each trophic level?
As biomass is transferred between trophic levels the energy contained is transferred.
Energy available at each trophic level is measured in kilojoules per metre squared per year (kJm-2 yr-1) to allow for changes in photosynthetic production and consumer feeding throughout the year.
What is the easiest way to measure biomass?
The easiest way is to measure the mass of fresh material present.
Why is it best to measure the dry mass of an organism?
Variable amounts of water in different organisms makes it unreliable unless very large samples are used.
How is dry mass created?
Organisms have to be killed, they are placed in an oven at 80 degrees until all water is evaporated.
They are periodically checked and measured until the mass stops reducing.
Why is biomass lost?
Only a small proportion of food ingested is actually converted into new tissue. Only this part of biomass available for the next trophic level to eat.
What is ecological efficiency?
Efficiency with which biomass or energy is transferred from one trophic level to the next.
What is primary production? How much sunlight is actually converted into chemical energy?
Generation of biomass in a producer.
Only 1-3% of sunlight is converted into chemical energy and hence biomass, 90% reflected, some transmitted through the leaf and some unusable wavelength.
Other factors limit photosynthesis, such as water availability.
What is gross production?
Total solar energy that plants convert to organic matter.
What is the equation for net production?
Net production = gross production - respiratory losses
How much biomass is converted into an organisms new organic tissue?
10% at most.
Why can trophic levels only convert small amounts of biomass into new tissue?
Not all biomass can be digested.
Living organisms have to carry out life processes.
Some material is lost from excretory materials like urine.
What are the units for net biomass?
Grams/Kg per square meter (g-1m-2) for areas of land.
Grams/kg per cubic meter (g-1m-3) for areas of water.
What is secondary production?
The generation of biomass in a consumer.
What are the 3 word equations for ecological efficiency?
Ecological efficiency = (biomass at the higher trophic level / biomass at the lower trophic level) x 100
Ecological efficiency = (biomass available after the transfer / biomass available before the transfer) x 100
Ecological efficiency = (biomass of the primary consumer / biomass of the producer) x 100
What are the 7 ways of increasing primary productivity?
1- Light levels
2- Water availability
3- Temperature
4- Nutrient availability
5- Pest control
6- Fungal disease
7- Competition from weeds for light, water and nutrients
How can light levels be used to increase primary productivity?
Light levels limit the rate of photosynthesis and hence production of biomass, some plants are planted early to provide a longer growing season to harvest more light.
How can water availability be used to increase primary productivity?
Water is a reactant in photosynthesis and irrigation systems ensure that plants/ crops have enough water.
How can temperature be used to increase primary productivity?
It affects rate of photosynthesis and therefore growth.
An optimum temperature is required for maximum production of biomass.
How can nutrient availability be used to increase primary productivity?
A lack of nutrients is a limiting factor of photosynthesis.
Crop rotation can be used, including nitrogen fixing crops like peas or beans which replenish nitrogen levels.
Many crops have been bred to respond to high levels of fertiliser which provide ammonium, nitrate, potassium and phosphorus.
How can pest control be used to increase primary productivity?
Pests remove biomass and create a lower yield by eating crop plants.
Pesticides, pest resistant plants can be used.
How can control of fungal disease be used to increase primary productivity?
Fungal disease causes a loss in biomass.
It can cause root rot (reduces water absorption), damage xylem, damage foliage through wilt/blight/spotting, damage phloem, damage flowers and fruit.
Fungicides can be used and crops can be bred to be resistant to fungal infections, potatoes have been GM to resist potato blight.
How can controlling competition from weeds for light, nutrients and water be used to increase primary productivity?
Herbicides are used to kill weeds.
Herbicide usually binds to an enzyme, stopping it from working, and frequently leading to a toxic build up of the enzyme’s substrate.
What are the 4 ways to increase secondary productivity?
1- Harvesting animals just before adulthood
2- Selective breeding
3- Prophylactic antibiotics
3- Intensive indoor farming
How can harvesting animals just before adulthood improve secondary productivity?
It minimises energy losses from the food chain.
A young animal invests a larger proportion of it’s energy into growth than an adult.