Biodiversity Recall the definition of SPECIES from the topic Classification Write the key ideas in bullet points on white boards

OBJECTIVES To define key terms To explain how biodiversity can be considered at different levels To discuss current estimates of global biodiversity

HABITAT Write the definition of habitat onto one of your glossary cards from the last lesson

Which has a greater biodiversity?

Low diversity High diversity

Definition of biodiversity from an OCR mark scheme The existence of many different species – Interspecific variation with a wide range of different alleles – Genetic intraspecific variation that live in many different habitats/ ecosystems – Variation in habitats (in purple: different levels of biodiversity)

Tropical rainforests These ecosystems have the highest biodiversity of any ecosystem on the planet.

Estimating global biodiversity Catalogue of life by – Species 2000 – Integrated Taxonomic Information System – All Species Foundation

Not accurate because – May not have found all – New species being found all the time – Continuing evolution and speciation – Species becoming endangered & extinct – Habitats which are difficult to access Estimating global biodiversity

Sampling

OBJECTIVES Explain the importance of sampling Describe how random samples of plants and animals can be taken

Theory of sampling If we want to work out the biodiversity of an area then we need to find out how many of each type of organism there are present This can be a bit of a challenge if you bear in mind that there might be hundreds of thousands of mites per square metre, not to mention the millions of bacteria

In practice Obviously, it’s not practical to count everything so we take a sample to estimate the abundance of each organism present

Sampling Study a small section of the habitat Multiply the number of individuals of each species to estimate the number in the whole habitat gives us quantitative data to calculate biodiversity. more valuable than qualitative data, which merely tells us what is present

Randomness To remove any influence of bias Systematic: Taking samples at regular intervals Random Using random number tables to plot coordinates within a habitat. – with tape measures or, – if the area is large, GPS coordinates

How should your quadrat be placed in the study area? RANDOMSYSTEMATIC

For example Random sampling of plant populations can be done using a quadrat by marking out 2 axis with a tape measure then using random numbers to chose which coordinates to sample at. Disadvantage: could miss trends as only gives overall data

Using a random number table Click here to see a random number tablerandom number table

How many quadrats?

Running mean – gaining a representative sample Quadrat no.No. of different species Running mean no. sp/no. quadrats

The number of quadrats needed in this case = 7

Making notes Make BRIEF bullet point notes on how plants are sampled from page 195 And a spider diagram on sampling animals pages The next slides will be shown at the end of the session to confirm if your notes are accurate

Sampling plants Using random quadrats Using a transect

Using quadrats Usually 50 cm to 1m 2 Generate pairs of random numbers Identify the plants Measure abundance – AFCOR scale (not quantitative) (abundant, common, frequent, obvious, rare) – Estimate percentage cover with gridded quadrat Point frame

Measuring abundance AFCOR scale (not quantitative) – (abundant, common, frequent, obvious, rare) Estimate percentage cover with – gridded quadrat – Point frame with 10 needles Used 10x in each quadrat Each plant touching needle wil have 1% cover Can have several plants & bare ground touching needle

Using a transect A line of rope or tape measure across a habitat For a large habitat Methods: – Interrupted line transect Record plants touching line at set intervals – Interrupted line transect Use quadrat at set inervals – Continuous belt transect Move a quadrat along the line

Sampling animals Large animals – observe NOT trap – Look for signs Droppings Undigested food Burrows Smaller animals – Can be trapped

Trapping animals Sweep netting – for low vegetation – Use with pooters Tree beating Pitfall traps – With water or scrunched up paper – Sheltered from rain Tullgren funnel – Light drives animal downwards through different-sized meshes UV light trap at night – With collecting vessel containing alcohol

Homework Bullet point 2 methods Method 1) How you would use a square quadrat and random coordinates to sample 2 areas of the school field, 1 in light and 1 in shade, to see which had more daisies. You may be able to actually do this if the weather is OK! Method 2) How you would use a point quadrat and transect to see if the percentage cover of daisies increased or decreased, with distance from a hedge.

Alternative homework Answer Qs: – 3 to 5 on Activity Sheet 30 – 1 to 5 on Activity Sheet 31

Measuring Biodiversity

OBJECTIVES Describe how species richness and evenness can be measured Use Simpson’s Index of Diversity Outline the significance of this Index

Measuring biodiversity Species richness = the number of species present - qualitative survey Species evenness = a measure not just of the number of species present but of the relative abundance of each. - quantitative survey Look at Table 1 on page 198 Compare the species richness and species evenness

Surveying frequency of plants Counting number of plants per unit area – For larger plants Estimating percentage cover – For smaller plants like grasses and herbs

Recording percentage cover Look down on the quadrat from above and estimate the percentage cover occupied by each species (e.g. species A - D). Species often overlap and there may be several different vertical layers. Percentage cover may therefore add up to well over 100% for an individual quadrat.

Measuring density of small animals Large animals - observe Small animals – Using the Mark-Recapture technique Soil animals – Take soil sample and sift through Aquatic animals – Use net – Sift through mud

Mark-and-recapture Trap a sample of animals – Count = C 1 Mark them without causing harm, release Re- capture – Count = C 2 Those already marked in the re-capture – Count = C 3

Calculating the total population Can you think of how you can use these counts to estimate the total population? Total population = (C 1 x C 2 )/C 3

Simpson’s Diversity Index Takes into account species richness and evenness Copy the formula from page 199, indicating what each part of the formula means SDI = 1 – [∑ n 2 ] N

Significance of the Index High value – Diverse habitat – A small change may affect only one or a few species – the effect on habitat is likely to be small Low value – A habitat dominated by a few species – A small change affecting dominant species could damage or destroy the habitat