Ecosystems and sustainability Flashcards
Define population
All of the organisms of one species that live in the same place at the same time and can interbreed
Define habitat
The place where an organism lives
Define community
All the populations of different species that live in the same place at the same time and can interact withal each other
Define ecosystem
Any group of living organisms and non living things occurring together that have interrelationships
What are the 3 components of an ecosystem?
A habitat, a population and a community
Define niche
The role that each species plays in an ecosystem
Why is it impossible to define a niche exactly?
Because every organism interacts with both non living and living things
Give 3 examples of thing that help define a niche
What the species feeds on, what it excretes, how it reproduces etc.
True or false
It’s impossible for two species to occupy the exact same niche
True
Define biotic factors and give 3 examples
The effect of living components in an ecosystem
Predation, disease and food supply
Define abiotic factors and give 3 examples
The effect of non living components in an organism
PH, soil type and temperature
Why do the population sizes in an ecosystem always slightly change?
Because all the organisms interact so the increase in death of one species will have a knock on effect on others
What happens to other population sizes if the predator population increases?
What about if there’s low levels of nitrogen in the soil but nitrogen fixing plants live there?
The population size of the prey will decrease as more will get eaten
The nitrogen fixing plants will add more nitrogen into the soil allowing other plants to grow their which increases population sizes
Give 2 examples of nutrient cycles where matter is recycled
Is energy recycled in an ecosystem?
The carbon cycle and the nitrogen cycle
No, it flows through the ecosystem
What is at the start of nearly all food chains?
Plants
What are producers? Consumers? Primary consumers? Secondary consumers? Tertiary consumers? Decomposes?
Plants and photosynthetic organisms (algae, bacteria) that supply chemical energy to other organisms
Animal and fungi that digest other organisms
Herbivores who eat plants
Carnivores
Carnivores who eat secondary consumers
Bacteria, fungi and some animals thy feed on waste material/dead organisms
Define trophic level
The level at which an organism feeds in a food chain
Define food web
Various different food chains thy interact with each other allowing us to see energy flows throughout an ecosystem
Is energy lost at each trophic level?
Yes
List two ways in which energy is lost between trophic levels
- Living organisms use energy in order to respire/carry out metabolic processes and the Betty is released as heat
- Energy remains in parts of dead organisms that consumers can’t digest, like bones, decomposes like fungi and bacteria then consume what’s left
What is a pyramid of numbers?
It’s a visual representation of population sizes at each trophic level (the populations decrease higher up the pyramid)
What is a pyramid of biomass?
Name 2 ways in which you can measure biomass
When the area of the bars in the pyramid is proportional to the dry mass of all the organisms a that trophic level
You can measure dry mass by collecting the organisms and putting them in an 80 degrees oven until all the water has evaporated from them. This is very destructive
You can also measure biomass via looking at the wet mass of organisms
List two ways in which you can measure the efficiency of energy transfer between organisms
By creating a pyramid of biomass or a pyramid of energy
How do you collect data in order to create a pyramid of energy?
You burn the organisms in a calorimeter and then work out how much heat energy is released per gram. It’s calculated via the rise in temperature of a known mass of water
List a limitation for pyramids of numbers
And 2 pyramids of biomass
And 4 for pyramids of energy
Counting the number of organisms doesn’t provide an accurate picture about how much living tissue exist sat each level
It’s very destructive and different species may release different amounts of energy per unit mass
It’s destructive, time consuming and only provides a snapshot of data. Also populations sizes fluctuate so this might create a distorted idea of energy transfer
What is the best method of discovering energy transfer in an ecosystem?
The best method is looking at the rate at which energy passes through each tropic level. This is an pyramid of energy flow.
What is the rate of energy flow called?
How is this measured?
Productivity
It’s measured by looking at how much energy is available at a particular tropic level per unit area in a set time. It’s measured via mega joules (1000 kj)
What is primary productivity?
What about gross primary productivity?
And net primary productivity?
The total amount of energy fixed by photosynthesis aka the net flux of carbon from the atmosphere to plants in a set time. It’s measured in MJ m-2 yr-1
The rate at which plants convert light energy into chemical energy
The remaining energy, not including the energy that’s lost when the plant respires/when the energy is less available to consumers. Aka the rate at which carbohydrate accumulates in plant tissue measured via dry mass in kg ha-1 yr-1
What is the formula for net primary productivity?
Primary productivity - respiratory heat loss
Why is knowing the net primary productivity (NPP) useful?
Because it tells us the amount of energy available to heterotrophs and is therefore an important factor in determining the amount of biomass an ecosystem can support.
How much sunlight energy that reaches the earth is used for photosynthesis?
Less than 1%
List 5 reasons why some sunlight isn’t used for photosynthesis
Because it’s reflected by clouds, it’s reflected by the earth, it’s used to heat the earth, it’s used to evaporate water and it’s the wrong wavelength for chlorophyll to absorb it
List 7 ways in which NPP can be improved
- Plant the crops early to provide a longer growing season meaning they harvest more light
- Irrigate crops and breed drought resistant strains
- Greenhouses increase temperature and therefore increase the speed of chemical reactions
- Crop rotation to ensures the soil contains nutrients and nitrogen fixing crops can replenish the levels of nitrates
- Use pesticides to stop pests reducing the dry mass and energy. Breed pest resistant plants or modify them with bacillus thuringiensis which is resistant against bollworm to increase yield
- Use fungicide or breed plants to be resistant to fungal infections like rhizomania in sugar beet. Potatoes have been genetically modified to be resistant to potato blight
- Use herbicides to reduce competition against weeds
List 6 ways in which fungal infections can reduce the yield in plants
- They can cause root rot which reduces water absorption
- They can damage xylem vessels which can interfere with water transport
- They can damage phloem tubes which can interfere with translocation
- They can damage foliage via wilt
- They can cause blight which interferes directly with photosynthesis
- They can damage flowers and fruit interfering with reproduction
Is the transfer of energy between producers and consumers efficient?
No
List 5 reasons why the transfer of energy between producers and consumers is inefficient
- Some plants die
- Consumers don’t eat every part of the plant
- A lot of the plant is egested in faeces
- A lot of the stored energy in plants is used to keep the consumer alive
- Not everything consumers eat is digested
List 5 ways in which humans can manipulate energy transfer between producers and consumers
- Harvesting animals before adulthood minimises a loss of energy from the food chain (from plants)
- Treat animals with steroids so that they grow quicker
- Use selective breeding so that the high yield animals pass on their traits
- Treat animals with antibiotics to avoid energy loss from fighting off pathogens
- Minimise grazing and movement so that more energy is used to build muscle and keep the temperature constant
Define succession
A directional change in a community of organisms over time
What is primary succession and give an example of it
The development of a community from bare ground
Example: Algae and lichens can live on the bare rock, these are the pioneer community. As the rock erodes and dead and rotting organisms build up, enough soil is produced for plants like mosses and ferns to grow. These succeed the algae and lichens. Larger plants then succeed the smaller plants and a final stable climax community is produced. These are often woodlands
What is secondary succession?
When succession occurs on a previously colonised but disturbed/damaged habitat
What is unique about succession in sand dunes?
The fact that they display all the stages of succession at the same place at the same time
Because sand dunes display all the stages if succession at the same time, where is the first stage of succession found and where is the last stage found?
The first stage is found just above the high water mark
The last stage is found much further away from the sea
Describe the 4 stages of succession in sand dunes
- Pioneer plants like sea rocket are prickly sandwort colonise in the sand just above the high water mark. They are able to tolerate sea water spray, lack of water and unstable sand
- Wind blown sand builds up around the base of the plants forming embryo dunes. As the dune gets bigger, sea sandwort and sea crouch grass colonise it. Sea crouch grass have underground stems that stabilise the ground
- The increased stability allows more nutrients to accumulate which means sea spurge and marram grass can grow there. Marram grass traps sand as it grows, making the dune increase in size as it moves up the beach
- As nutrients build up, hare’s foot clover and other legumes colonise. The bacteria in their root nodules add nitrates to the soil, which allows sand fescue to grow there.
Define quadrat
A square frame that defines the sample area, it’s used for studying ecosystems
Why do ecologists study ecosystems?
To find out whether abundance and distribution of a species is related to abiotic or biotic factors
What 2 types of data can you collect from a quadrat?
The distribution (the presence or absence of each species) and the abundance (estimate/count the number of individuals in a quadrat)
Instead of counting all of the individuals, what can ecologists do to estimate the amount of individuals within a quadrat?
Calculate/estimate the percentage cover by just looking at it or via point frame which involves sticking a needle in the ground and record each species that touches the needle
How do you avoid biasing a quadrat sample to ensure that the sample is an accurate representation of the whole habitat? 2 ways
You randomly position the quadrats across the habitat by using random numbers to plot coordinates
You take samples at regular, set distances and sample each part to the same extent