What am I ?????

1. What am I ?????

2. My name is “Golden Shields”, or “Xanthoria parietinar” in Latin • I am a lichen • I am found growing on rocks, walls and trees • I am one of the most common lichens found today in our towns and cities • I am even found in London

3. What are lichens? • Unlike trees, grasses and flowers, lichens are not a single plant • They are actually composed of two organisms living together in a symbiotic relationship… • A blue-green algae which photosynthesises to make food, and a fungus which creates a “body” in which both partners live

4. Types There are about 30,000 species of lichen worldwide, covering 8% of the land surface. There are 3 main types… Crusty (crustose) Leafy (foliose) Shrubby (fruticose)

5. Why study lichens? • They grow just about everywhere • They tell us about the health of our environment • They are very useful; - as recyclers of nutrients, providing homes for insects, humans extract dyes from them, eat them, use them as ingredients in drugs and cosmetics

6. Lichens and air quality • Lichens are very sensitive to sulphur dioxide (SO2) pollution in the air – from industry and burning fossil fuels, especially coal • They absorb it dissolved in water • It destroys the chlorophyll in the algae preventing it from photosynthesising and killing the lichen. • Levels have fallen since the 1970’s

7. Nitrogen pollutants • Nitrogen compounds from traffic on roads and from intensive farming (fertilisers) have become major pollutants • Town and country areas can be affected

8. Bio-indicators • Lichens are widely used as environmental or bio-indicators • If the air is clean, shrubby, hairy and leafy lichens become abundant • If the air is polluted more tolerant crusty lichens are present • In extreme cases of high pollution, there may be no lichens at all (lichen deserts)

9. Fieldwork aims • To survey and identify species of lichen on the trunk and twigs of selected trees • Assess levels of pollution by examining the pollution tolerance of lichen species found • Compare and contrast different areas

10. How? • You are going to survey both trunks and twigs of tree species with acid bark • Choose from; Oak, Birch, Cherry, Alder, Sweet Chestnut, Rowan, Hornbeam. • Use the “Which tree?” resource to help you identify these species

11. Trunk • Tree trunks are the oldest part of the tree • Some lichens grow very slowly and tree trunks may carry a long-established colony of lichens, as long as environmental conditions have not been altered • You will choose three trees (with accessible trunks) of the same species at each site to survey

12. Twigs • Every spring new twigs are produced – this is the youngest part of a tree. • In good conditions lichens rapidly colonise new twigs • You will sample non-shaded twigs of about 3-4cm thick at the base, in on one or more trees of the same species • You will sample 10 twigs in total at each site

13. Identification You will need to identify… • The tree species (using the ‘which tree’ resource) • The lichen species (using the key / chart provided by your teacher)

14. Recording • Your teacher will go through the recording sheets with you • You must fill in the recording sheets… • Fully • Clearly • Accurately

15. Follow-up • You must use the data you collected at each site and recorded in the field work booklet • Complete the ‘follow-up resource’ to summarise your main findings and make judgements about the environmental conditions at each site

16. Extension • Your field work can be written up formally, as a proper investigation • You must use the ‘investigation write-up resource’ to help you to plan, structure and write it