 DIVERSITY  RELATIONSHIP OF DIVERSITY & STABILITY  DIVERSITY INDEX  MICROCLIMATES  USING QUADRANTS

 DIVERSITY is all about how many different species there are in an ecosystem.  Diversity is the number and variety of organisms found within a specified geographic region.  In total about 1.5 million species have been described  However, the total number of species on Earth may be as high as 10 million

 ECOSYSTEMS with a large diversity of species tend to be more stable than those that are less diverse  Stable ecosystem 1. Resistant to change 2. If disrupted, return to original state quickly 1.I.E. Climate extremes, pest and disease over a long period

 Predator species don’t have much choice of prey  Prey species is reduced or wiped out › Predator species will be at risk

 Agricultural areas where only one crop is grown › COTTON FIELDS  Artificially low diversities

 TUNDRA, DESERTS, SALT MARSHES, AND ESTUARIES › Low diversities

 Plant and animal populations are mainly affected by abiotic factors  ABIOTIC FACTORS: › Nonliving components that effect the living organisms › For examples:  Radiation  Temperature  Water

 Predator species will have a large selection of possible prey species  One of the prey species is wiped out › Still plenty of other species that predators can eat

 Old, oak woodlands  Environmental conditions aren’t too hostile  Affected by biotic factors  BIOTIC FACTORS: › Of or relating to life › For example:  Plants, animals, fungi, bacteria

 How diversity is measured  Could just count up the number of species › This takes no account of the population size of each species › Species that are in an ecosystem in very small numbers shouldn’t be treated the same as those with bigger populations

 AN equation for diversity that takes different population sizes into account.  To calculate the diversity index of an ecosystem › d = N(N-1) / ∑ n(n-1) › Where...  N= Total number of organisms of all species  n= Total number of one species  ∑= ‘Sum of’ (i.e. added together)

 Higher the number the more diverse the area is › If all the individuals are of the same species (i.e. no diversity) the diversity index 1

 Small areas where thee abiotic factor are different from the surrounding area. › The underneath of a rock  Different microclimate than the top surface  Cooler and more humid  Provides a slightly different habitat that will suit certain species  Variety of microclimates can support a high divesity

3 different species of flower 11 organisms altogether 3 red 5 yellow 3 purple Diversity index d=N(N-1) / ∑n(n- 1) d=11(11-1) / 3(3- 1) + 5(5-1) + 3(3-1) d=110/ =3.44 When calculating the bottom half of the equation you need to work out the n(n-1) bit for each different species then add them all together.

 BASICALLY › more microclimates = more species= higher diversity

 ECOLOGISTS look at three key factors when they’re working out diversities › Species frequency › Species richness › Percentage cover

 HOW ABUNDANT A SPECIES IS IN AN AREA

 TOTAL NUMBER OF DIFFERENT SPECIES IN AN AREA

 HOW MUCH OF THE SURFACE IS COVERED BY A PARTICULAR PLANT SPECIES › (NOT FOR ANIMALS THOUGH AS THEY MOVE AROUND TOO MUCH)

 Measuring the three key factors use a piece of equipment called a frame quadrant  FRAME QUADRANT › A square frame made from metal or wood  The area inside the square is the quadrant

 Laid on ground (or the river / sea/ pond bed if it’s an aquatic environment)  Total number of species in the quadrant is recorded  As well as the total number of individuals of each species

 Not practical to collect data for a whole area › Takes ages › Can be costly  Samples are taken instead  Data samples are used to calculate the figures for the entire area being studied  Random sampling avoids bias

 Measured by counting how many quadrants each species in and is given as a percentage  If a species was found in 5 out of 20 quadrant samples › The frequency would be 25%

 Measured by dividing the area inside the quadrant frame into a 10x10 grid and counting how many squares each species takes up  Sometimes plants overlap so the percentage cover ends up being more than 100%

 Measured by counting up the total number of species found in all the samples  Assume that the number of different species in your sample is the same as the number in the whole area that you are studying

 What is meant by a ‘stable’ ecosystem?  Give three examples of ecosystems that are likely to be unstable?  What is the difference between the diversity index and species richness?  Why do percentage cover measurements sometimes add up to more that 100%?

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