Slides in this set
Define the terms Species, Habitat and
· Species: A group of individual organisms very similar in appearance,
genetics and biochemistry, whose members are able to interbreed
freely to produce fertile offspring.
· Habitat: The place where an organism lives.
· Biodiversity: The variety of life the range of living organisms to be
Explain how biodiversity may be considered at
different levels: habitat, species and genetic
· The range of habitats in which different species live.
· The difference between species
· Genetic variation between individuals of a species.
- This is the variation found within any species that ensures we do not all
look alike.…read more
Explain the importance of sampling in
measuring the biodiversity of a habitat
· Human activities affect the environment in a variety of ways.
· Unless we study these affects, we cannot assess the impact that we
· Environmental Impact Assessments are very important parts of
planning processes, and they are used to estimate the effects of a
planned development on the environment.
· Sampling tries to provide an representative data of species that
should be able to be applied to the whole habitat.…read more
Explain how random samples can be taken when measuring
· To measure the biodiversity of a habitat, you need to observe all the species present, identify them and count how many of each species there are this is impractical as
there are thousands of fungi, bacteria etc. And this is impossible to count.
· Instead, you can randomly sample a habitat this is where random portions of the habitat is selected and then studied in detail, the findings are then generalised to the
· There are three ways of selecting an area:
· Take samples at regular distances across the habitat
· Use random numbers, generated by a computer or a random number table, to plot coordinates within the habitat
· Select coordinates from a map of the area and use a GPS system to find the exact position inside the habitat.
There are two main ways to measure the biodiversity of plants:
· The quadrat is placed at random on the habitat and the plants found within the quadrat are identified.
· Their abundance is then measured in one the three ways:
· Abundance scale: You observe the contents of the quadrat and apply an abundance score to each species. The commonest scale used is known as the ACFOR scale
(Abundance, Common, Frequent, Occasional, Rare).
· Percentage cover: The percentage cover of each plant in the quadrat is estimated. Sometimes the quadrat is divided into 100 squares to make the estimation easier.
· Point frame: A frame holding a number of long needles, usually 10, is used to measure percentage cover. You lower the frame into the quadrat and record any plant
touching the needles. If the frame has 10 needles, and is used 10 times in each quadrat, you will have 100 readings, each plant recorded as touching the needle will have a
· A transect is a line taken across the habitat. You stretch a long rope or tape measure across the habitat and take samples along the line.
· Line Transect: Record the plants touching the line at set intervals.
· Interrupted Belt Transect: A quadrat is used at set intervals along the line
· Continuous Belt Transect: A quadrat is used continuously along the transect.…read more
Explain how random samples can be taken
when measuring biodiversity
Measuring the biodiversity of animals:
· Smaller animals can be trapped, their numbers observed, and the total population estimated.
· Larger animals cannot be trapped They must be carefully observed and their numbers estimated.
· Sweep netting
· Sweeping a net through vegetation. Any organisms caught are released onto a white sheet and counted.
· Collecting from trees
· A white sheet is held under a branch, the branch is knocked, so any small animals drop onto the sheet.
· Pitfall trap
· A container is buried in the soil so that it is just below the surface. Any animals moving through the plants or leaf litter will fall into
· Tullgren funnel
· Leaf litter is placed in a funnel. A light above the leaves drives the animals downwards as the litter dries out and warms up. They
fall through the mesh screen into the jar below.
· Light trap
- An UV light attracts the insects, which eventually fall into the vessel of alcohol below.…read more