A species is a group of individual organisms very similar in apperance, anatomy, physiology, biochemsitry and genetics, whose members are able to interbreed freely to produce fertile offspring
A habitat is the place an organism lives
Biodiversity is the variety of life - the range of living organisms to be found. It can be characterised by:
- Habitat diversity- is the number of different habitats in an area e.g wild meadow vs lawn
- Species diversity- is the number of species and abundance of each species in an area (species richness and evenness)
- Genetic diversity- is the variation of allels within a species or a population of a species e.g Human Blood
Collecting data on biodiversity
Collecting data on biodiversity usually means finding out the number of different species in a habitat or the number of individuals in each species.
General Method of collecting data:
- Choose an area to sample. To avoid bias in results, the sample should be chosen at random. This makes the sample for likely to be representative.
- Record the number of different species or count the number of indivduals of each species. How you do this depends on the organisms. Make sure to use appropriate equipment for the organisms. If sampling mobile organisms make sure they can't escaple and that individuals are not counted more than once.
- Repeat the process- at least X3. Calculating the mean of the results will make estimated more reilable.
- The number of individuals for the whole are can then be estimated by taking an average of the data collected in each sample and multiplying itr by the size of the whole area
- When sampling different habitats and comparing them, alwayds use the same sampling technique.
Sampling is a randomly selected, representative group of individuals within a population (saves time and money than using the whole population).
methods depend on:
- The accuracy required
- Type of organisms being sampled
- The size of the area being sampled
- Time available for study
Reasons for sampling is often linked to a EIA (environmental impact assessment), which predicts impact of human intervention on the environment. All modern planning involves ETA.
Random walk - A quick method to discover the different populations in a habitat
Quadrats - Used to sample the population in a large, homogenous habitats
Line transect - A rough method to study the effect of a changing habitat on populations
Belt transect - A detailed method to study the effect of a changing habitat on populations
1.Choose appropriate number and size of quadrat (dependent on the organism to be sampled and size if the sampling are).
2. Place quadrats randomly within sampling area. This is done by random numbers to generate coordinates
I. Qualitative: Using ACFOR scale:
- A - Abundant
- C - common
- F - frequent
- O- Obvious
- R - Rare
II.a Quantitative: Interal grid to measure percentage cover, estimate the percentage cover using interal grid and areas for each species within quadrat.
IIb. Point Frame
Where points touch a species it is recorded and used to calculate percentage cover.
- Place survey tape perpendiculary across of the changing habitat
- Sample at regular intervals a long length of trasect
- Record species present at each point
- Place survey tape perpendiculary across the changing habitat
- Sample of regular intervals using a qudrat to measure percentage cover for all species.
Sweepnetting (long grass, trees and flying organisms): Sweeping a net through vegetation. Sweep for a set period of time in a number of random areas. Produce a mean of the number of organisms caught. Any organisms caught are released
- Sweep for a set number of times
- Use a pooter to collect animals
- Count and identify animals
Light trap (nocturnal flying insects) : An ultraviolet light attracts the insects, which eventually fall into the vessel of alcohol below
- Lay traps in a set area (random number used for coordinates)
- Leave traps for a set time (at same time of day/night)
- Collect using pooter
- count and identify
This could also be done by using a stick by wacking it in a tree with a sheet underneth to collect animals
Animal Sampling continued
Pitfall trap (surface animals) Sweep netting
A container buried in the soil so that it is just below the surface. Any animals moving though the plants or leaf litter will fall into the container.
- Set of traps to be the same size
- Postioning using random numbers coordinates
- Leave a set time/same time of day
- Collect, identify and count
Leaf litter is placed in a funnel. A light above the leaves drives the animals downwards as the leaf litter dries out and warms up. They fall through the mesh screen into the jar bellow