And you can see where the delicate lichens have been disturbed by human feet.

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Ecologists have launched a campaign to protect internationally important lichens at a national park.

BBC: Campaign to protect rare lichens in Pembrokeshire

The slopes are abundant with wild flowers and lizard green ferns, with soft moss and lichens.

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The deer feed primarily on lichens in the winter, which they obtain by digging through the snow.

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She told BBC Wales the lichens would be lost unless action was taken as the mossy covering under the trees is out-competing it.

BBC: Campaign to protect rare lichens in Pembrokeshire

Lichens are sensitive to changes in their environment, and scientists use lichens as a way of finding out whether air is polluted or clean.

BBC: York & North Yorkshire - Can you help identify lichen?

For example, he mentions a scientific paper that suggests that lichens, bacteria and the like may have been a driving force behind prehistoric geology and the formation of continents.

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The softening of the soil and the consequent release of nutrients is likely to encourage the growth of shrubs on land that is now dominated by grass, moss and lichens.

ECONOMIST: Global warming and the permafrost

But I'll admit that I look more like a chimp than I look like my cousin the shrimp or my distant kin the lichens or the snowy egret or the moss.

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We want you to go and look at four trees in your local area, this could be a garden, park or stray, and tell us which lichens you find on them.

BBC: York & North Yorkshire - Can you help identify lichen?