4/6 - ICH - Succession & samping Flashcards
Define Species richness
Species richness = number of species in an ecosystem
What results in a stable ecosystem?
- What is the diversity like
- What are the food webs
In less extreme environemnts:
- Diversity of organisms is usually high
- Biotic factors dominate and abiotic factors are not extreme
- Food webs are complex - many inter-connected food chains
- Results in a STABLE ECOSYSTEM - if population of one species declines, there’s alternative food sources
What results in a unstable ecosystem?
- What is the diversity like
- What are the food webs
In extreme environments:
- Diversity of organisms is generally low
- Abiotic factors are extreme & few species have adaptations allowing them to survive ∴ abiotic factors dominate
- Food webs are relatively simple - few food chainss or connections as few producers can survive
- Results in UNSTABLE ECOSYSTEM - change in population of 1 species can cause really big problems for other species
What is succession?
Succession = Th way different species which amke up a community change over time
Define primary succession
Primary succession = New area of land has been newly fomed for exposed to bare rock. No soil/ organic material to begin with
Define secondary succession
Secondary succession = Land where soil is present but there’s NO animal or plant species
Define deflected succession
Deflected succession = Human activity that halts the natural succession process
Define pioneer species and climax community
Pioneer species = First organisms to colonise a area
Climax community = Final stage of succession where the community is in a stable stage
How is the diversity of a community expressed?
Simpsons index of biodiversity
N = Total no’ of organisms of all species in the habitat
n = Total no’ of organisms of each species
What is ecological succesion? What is a sere?
Ecological succesion = The changes to an ecosystem over time
Sere = Each stage of succession
What does each sere of succession result in?
A less hostile environment to increase the diversity
5 adaptations of pioneer species
- Produce large quantities of seeds/ spores which travel by wint to be deposited on new land
- Seeds that germinate rapidly
- Photosynthesise to produce their own energy
- Tolerence to extreme envionments
- Can fix N2 from the atmosphere so increase mineral content of soil
Define plagioclimax
Plagioclimax = Stages in succession where artificial or natural factors prevent the natural climax community from forming
What is a keystone species?
Keystone species = Species which a ecosystem depends upon. Loss of this species can lead to very large affects on the ecosystem
Why must succession happen?
Environment is constantly changing, without adaptations the organisms would become extinct
Why do pioneer species disappear quickly after succession beging to occur?
They highly specialised and are unable to compete well for resources
2 ways to ensure that samples reflect the true population when investigating the numbers and distribution of a habitat
- Take a relatively large sample
- Ensure there;s no personal bias. Must be an random to avoid observer bias
Explain what is happening in the graph to abiotic conditions, plants and the animals in the sand dune
What can be used to represent the abundance of a plant when sampling a habitat?
The % cover
Name 2 forms of random sampling
Quadrats and transects
- What type of quadrats can you get?
- What is each type used for?
- How are they used?
Frame quadrat:
- Placed on the ground at random points. Count the number of the squared that have the plant to find population density, freq or % cover
- Used to study distribution of plants in a fairly uniform area
Point quadrat:
- Quadrat with a reduced size to a single point
- Used to study the distribution of plants. Point quadrats are often used with transects
- Point frame is usually used of approx 10 pins 5cm apart. By lowering the pins in turn and recording the no’ of hits on a particular species of plant, freq or % cover can be estimated
What are the different types of transects that can be used in sampling?
Line transects:
- Tape measure is placed along the transect and the species that touch the tae measure are recorded
Belt transects:
- Data is collected along the transect using frame quadrats placed next to each other
Iterrupted transects:
- Instead of investigating the whole transect of either a line or a belt, you can take measurements at intervals e.g. by placing point quadrats at right angles to the direction of the transect at set intervals along its length e.g. every 2m
How do you ensure there is no observer bias during sampling?
In short:
- Make a grid
- Give the grid coordinates
- Use some form to randomly generate the numbers for the coordinates
What are the 3 measures to describe the distribution fo plants?
Population density = No’ of individual plants of a particular species in a given area
Frequency = Based on no’ of quadrats (ordinary or point) in which the species occur in e.g. 3 out of 10 pins hits a dandelion plants, freq = 30%
% cover = Measures proportions of the ground in a quadrat occupied by a species
Give 3 methods to sample animals that are moving
Aquatic animals = net
Flying insects = Sweepnet
Ground insects = Pitfall trap
Decribe another method used in sampling by which allows the estimate population size to be made of active animals
Mark, release, recapture:
- Use a trapping method to capture a no’ of animals fom the population begin investigated
- Mark these animals in a way that causes no hard + is inconspicious
- Release them + allow sufficient time for them to disperse back into the population which they have been taken from
- Useing precisely the same trapping method at the start, capture a second sample. Count the no’ of the animals that are marked and the no’ that are not marked
Estimated pop = (no’ of animals released x total no’ of animals in 2nd sample) / no’ of marked in second sample
Formula for estimated population size = ?
What are the 3 types of non-random sampling?
Opportunistic
- Weakest form of sampling as it may not be represntative of the popultion
- Uses organisms that are conveniently available
Stratified
- Some populations can be divided into a number of strata (sub-groups) based on a partcular characteristic
- A random sample is then taken from each of these strata proportional to its size
Syetematic
- Sampling different areas within an overall habitat
- Using a line or belt transect
Formula for species index of biodiversity
What does the answer indicate?
N = total no’ of organisms of all species in the habitat
n = total no’ of organisms of each species
The closer to 1 the answer is, the more diverse the habitat
Define genetic diversity
Genetic diversity = Variation of alleles within a species
Define species diversity
species diversity = The number of different species (species richness) and the abundance of each species (species eveness) in an area
Define Habitat diversity
Habitat diversity = The number of different habitats in an area
