Heathlands Designing Investigations © Amy Rogers.

HeathlandsDesigning Investigations

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• Heathlands are excellent habitats to use for designing and carrying out experiments. Plants are often relatively easy to identify when compared with other habitats and invertebrate communities are usually diverse.

• Investigations can be classroom based ‘thought’ experiments or could be designed to be carried out in the field.

• Pupils could come up with their own investigation topics after observing a site. Alternatively, the following slides provides activity ideas. Click on the investigation that interests you to find further suggestions.

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Key words for pupilsEncourage pupils to think about:

• Predictions, accuracy, reliability, dependent and independent variables, random and systematic errors, fair test/avoiding bias, validity;

• Presenting data, graphs, tables, continuous/discontinuous variables;

• Data and experimental design limitations;

• Drawing conclusions, and the implications of the findings.

Possible investigations – heathland plants• Effect of trampling

• Effect of grazing

• Effect of different management techniques

• Effect of abiotic factors e.g., slope, soil pH, soil temperature, light, soil water content

• Edge effects (the effect of distance from the heathland edge)

• Adaptations of heathland plants

• Competition between plant species

Click here for invertebrate activity suggestions

Possible investigations - invertebrates• Which plants support the highest diversity of invertebrates

• Herbivore damage to plants

• Distribution of spider webs

• Pollinator visits to plants

• Invertebrate distributions - sweep netting

• Invertebrate distributions - quadrats

Click here for plant activity suggestions

• Effect of trampling on the abundance and diversity of heathland plants

Procedure: Human trampling may effect vegetation. The intensity of trampling is expected to decrease with

distance from a footpath. If there is a suitable footpath at the site, a transect could be run away (perpendicular) from the footpath. Every metre along the transect a quadrat could be placed and the % ground cover and average height of different plant species recorded.

Equipment:Tape measure, quadrat (0.5 m x 0.5 m), plant identification key.

Notes:Trampling may make it difficult for plant seedlings to become established. Some species may

be more susceptible to trampling then others. If grazing is taking place at the site trampling by livestock may effect the results observed. The intermediate disturbance hypothesis states that local species diversity should be greatest at intermediate disturbance levels.

Click to return to plant activity list

• Effect of grazing on the abundance and diversity of heathland plants

Procedure: Livestock grazing is a common management technique on heathland sites. You may have a site that has some areas that have been grazed and others that have been fenced off from livestock and un-grazed. The vegetation of the two sites could be compared by sampling the same number of quadrats at each site. Quadrats would need to be randomly placed. The % ground cover and height of different plant species in each quadrat sample could be recorded. Equipment:Quadrat (0.5 m x 0.5 m), plant identification key, random number generator, tape measures.

NotesUsed appropriately, grazing is thought to increase species diversity and structural diversity of vegetation at heathland sites. However, overgrazing or inappropriate stocking could result in unexpected results.


• Effect of different management techniques on the abundance and diversity of heathland plants

Procedure: Heathlands need to be actively managed to prevent succession. Common management

techniques include: controlled burning, grazing, turf removal, bracken bruising, chemical control of bracken, mowing/cutting, tree removal. You may have a site, or nearby sites that have been subjected to different management techniques. The vegetation of the two sites could be compared by sampling the same number of quadrats at each site. Quadrats would need to be randomly placed. The % ground cover and height of different plant species in each quadrat sample could be recorded.

Equipment:Quadrat (0.5 m x 0.5 m), plant identification key, random number generator, tape measures.

Notes:Landowners should be able to inform you of current and past management practices at the site.


• Effect of abiotic factors e.g. slope, soil pH, soil temperature, light, soil water content on the abundance and diversity of heathland plants

Procedure: A transect could be run along a known gradient e.g. down a slope, away from a tree with shading

branches. Quadrats could be taken at regular intervals along the transect and % ground cover and height of vegetation recorded. Abiotic measurements could also be recorded for each quadrat location, or soil samples collected for later analysis.

Equipment:Ranging pole, optical clinometer, pH probe, thermometer, light meter, trowel for collecting soil sample

for later moisture analysis, tape measure, quadrat (0.5 m x 0.5 m), plant identification key.

Notes:Students should be aware that it could be very difficult to distinguish between cause and effects of

some abiotic factors. For example, a change in pH could result in a change in vegetation composition or, alternatively, some other factor may effect vegetation composition and the plants themselves may then effect the soil pH e.g. by altering the composition of the leaf litter.

If you are carrying out soil chemistry tests or are planning to remove soil samples for later testing you will need to obtain permission from the land owners.


• How abundance and diversity of heathland plants varies with distance from the edge of a heathland

Procedure: A transect could be run from the edge of the heathland site towards the centre of the site.

Quadrats could be collected at regular intervals along the transect and the % ground cover and height of vegetation recorded. Abiotic measures e.g. soil pH, soil nitrate level, light intensity, could also be taken for each quadrat location.

Equipment:Tape measure, quadrat (0.5 m x 0.5 m), plant identification key.

Notes:Heathlands often display significant edge effects, this is particularly true of smaller sites. For

more details see: http://www.biw.kuleuven.be/lbh/lbnl/ecology/pdf-files/pdf-art/katrien/AEEdef.pdf


http://www.biw.kuleuven.be/lbh/lbnl/ecology/pdf-files/pdf-art/katrien/AEEdef.pdf

• Adaptations of heathland plants

Procedure:Many plants inhabiting heathland sites are xerophytes and provide a good opportunity to investigate

adaptations to water loss. Sloping sites may provide a particularly interesting opportunity as at the top of a slope drainage is more efficient and the soil moisture content will be lower than at the bottom of the slope. The effect will be more pronounced on south facing slopes. Species composition and morphological characteristics e.g. leaf surface area could be compared along a moisture gradient.

The leaves of bilberry plants show morphological differences depending on whether they occupy the shade or sunny side of heather bushes and could be a good topic of investigation if they are present at your site.

Notes:Drier soil will be dominated by heather and bell heather, gorse (with needle-like leaves) and invading

bracken. Wet heath at the bottom of slopes will be dominated by cross leaf heath (as opposed to bell heather) and mosses, particularly Spaghnum mosses, will be more abundant. NB: In addition to it being drier at the top of slopes, nutrient levels will be lower at the top of a slope as nutrients are leached away with draining water.


• Competition between plant species

Procedure: Some species that are characteristic of heathlands, e.g. heather, are relatively slow growing

and particularly susceptible to interspecific competition with faster growing species such as bracken. If the site has areas with different densities of bracken, pupils could see if there was a relationship between the average distance between bracken plants (i.e. bracken density) and the amount of heather present. Alternatively, students could see if there is a relationship between the size of heather bushes and the distance separating them from the nearest bracken plant.

Equipment:Tape measure, pegs/tape to mark out large quadrats.

Notes:Bracken is known to produce and release allelopathic chemicals which inhibit the growth of

other plants.


• Which plants support the highest diversity of invertebrates

Procedure: Students could investigate particular plants e.g. heather vs bracken to determine which plant

species supports a more diverse range of invertebrates. Plants could be searched for a similar amount of time and any invertebrates found identified and recorded in a table.

Equipment:Pooter, dustpan and brush, paintbrush, sweep net, collecting pots, stopwatch, invertebrate

identification guide.

Notes:Encourage students to control for as many variables as possible e.g. to choose plants of similar

size/surface area when making comparisons between species.

Click to return to invertebrate activity list

• Herbivore damage to plants

Procedure: Students could look for evidence of insect herbivory in order to compare the amount of damage to different

plant species or the amount of damage to the same species in different locations (e.g. damage to heather plants in the centre vs the edge of the site).

The following resource provides information about the different categories of invertebrate herbivores e.g. cutters, grazers, miners, skeletonisers, galls with examples of the type of invertebrate that were probably responsible for the damage observed:

http://australianmuseum.net.au/Uploads/Documents/16435/H2D%20field%20guide.pdf

This website provides a useful way to record the extent of herbivore damage to leaveshttp://australianmuseum.net.au/document/Herbivore2Damage Equipment:Hand lens, invertebrate guide, leaf damage score sheet.

Notes:The most important herbivores of heather, in terms of biomass, are the larvae of moths and butterflies. More

than 100 UK species of moth caterpillars have been recorded feeding on heather e.g. ling pug, common heath, and northern eggar. The most damaging invertebrate herbivore found on heather is the heather beetle. Outbreaks can lead to the death of large areas of heather.


• Distribution of spider webs

Procedure: Pupils can investigate the distribution of spider webs within and between different plant species.

They could investigate a single plant species (for example, heather) and try and correlate factors (e.g. height above ground, aspect, surrounding vegetation type) with the abundance of spiders webs. Alternatively they could compare different plant species to see if spiders favoured different species when constructing webs or whether different species of spider/types of web were associated with different plants.

Equipment:Fine misting water spray to see webs more clearly, plant identification guide, spider

identification guide, hand lens, tape measure.

Notes:More species of spiders are found living on lowland heathland than any other habitat, including

the ladybird spider, one of the rarest spiders in Britain.


• Pollinator visits to plants

Procedure: Students can investigate pollinator visits to heathland flowers (e.g. heather). In particular

students could compare different flower species, shapes, colours, sizes and/or arrangements (i.e., clumped flowers vs. isolated flowers) to see if there is a difference in the species of pollinator the flowers receive, how often the flowers are visited by likely pollinators, and how long the pollinators stay on different flowers.

Equipment:Stopwatch, invertebrate identification guide.

Notes:The most effective pollinators of heather are honey bees and bumblebees. Other insects such

as wasps, flies, butterflies and moths also act as pollinators.


• Invertebrate distributions - sweep netting

Procedure: Pupils could sample invertebrates using sweep nets. Comparisons could be made between

different areas within the same site or along transects e.g. from the centre to the edge of a site. Pupils will need to ensure they put the same amount of effort into sampling if they are comparing different sites e.g. same number of sweeps, same amount of time in different locations. Pupils should also measure abiotic factors for each sample. Abiotic factors, such as light intensity, could be an important factor in the abundance and diversity of invertebrates found.

Equipment:Sweep nets, invertebrate collecting pots, invertebrate guide, stop watch, tape measure, light

meter.

Notes:This sampling method is likely to favour collection of the invertebrate orders Homoptera (true

bugs), Orthoptera (grasshoppers and crickets) and Araneae (spiders).


• Invertebrate distributions – quadrats

Procedure: Pupils could sample invertebrates using quadrats. Quadrats could be randomly placed within a

site, used to compare two different areas within a site, or used to sample along a transect (e.g. from the centre to the edge of a site, along a slope, or away from a footpath).

Equipment:Quadrat, invertebrate collecting pots, invertebrate guide, random number generator, tape

measures, white tray for leaf litter sampling.

Notes:This method of sampling is likely to miss quicker flying invertebrate species.


Heathlands Designing Investigations © Amy Rogers.

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