David’s work on Lichens

Lichens
A lichen is union between a fungus and an algae. The algae provides food for the fungal partner through photosynthesis .This same process is used by the higher plants from mosses through ferns to tree. This is why many lichen are epiphytic (growing on tree branches to make best use of available light).
Lichen are used as pollution indicators (Eg: more lichen in an area would mean less pollution)
There are three types of Lichen.
1 Crustose lichen
•These lichen are low growing and form crusts on surfaces such as stones or wood.
2 Foliose lichen
•These form more leafy lobes that spread over a surface and are raised above the surface.
3 Fruticose lichen
•These are raised above the surfaces the are attached to and look like bunches of twigs growing from the surfaces.
In Sussex there are as many as 500 to 600 Lichens. Ancient woodlands, sandstone outcrops and churchyards have good selections.
Lichens in the East Grinstead area.
In the East Grinstead area there are many different lichens. In St Swithun’s Church yard crustose lichen seem to dominate.
They are rather low in number which suggests that there is quite considerable air pollution in the area.
In other parts of East Grinstead there seems to be a certain amount of Nitrogen pollution. This is because there appear to be Nitrogen loving lichens on many house roofs. These. are on my roof as well as buildings erected 20 years ago. Prominent among them is the orange lichen called Xanthoriria
In Ashplatts Wood on the East side of East Grinstead fruticose lichen are scarce This is probably because there are low light levels in the wood. .The few lichen in the wood itself tend to be mainly crustose. On the margins of the wood there area few fruticose lichens high up on tree branches.
Lichens at the Briars Field Study Centre
The Briars Field Study centre is some eight miles from East Grinstead at Hartfield in East Sussex on the Northern edge of Ashdown Forest
Here pollution is not as severe and lichen sensitive to nitrogen pollution seem to be more common such as Usnea, Evernia and Hypogymnia.
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Fruticose Lichen on pine
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Crustose Lichen
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Long bushy lichen - clean air
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Mixed lichens on apple tree
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