Impact Type: Direct exposure to pollutant
Key Concerns:
Xanthoria parietina is an orange-grey crustose lichen which can occur on acid substrates, trees (i.e. oaks and limes) which have acid bark or rocks (Bates & Farmer 1992), which are exposed to NH3 . This is probably due to the alkalising effect of the NH3 (van Dobben & ter Braak 1998).
Additional Comments:
X. parietina is one of a group of lichens which may together be used to indicate high nitrogen deposition. It is a species commonly found growing on farm buildings. The species is on the increase.
| Habitat/ Ecosystem Type | Critical Load/ Level | Status | Indication of exceedance | Reference |
|---|---|---|---|---|
| Higher plants |
3 µg NH3 m-3 annual mean (uncertainty of 2-4 µg NH3 m-3) |
UNECE, 2007 |
Direct visible injury; species composition changes. Ecosystems where sensitive lichens and bryophytes are an important part of the ecosystem integrity, the critical level is set at 1 µg NH3 m-3. |
860 |