Impact Type: Deposition of pollutant
Key Concerns:
Lobaria spp., as with other lichen species, are affected by sulphur species (Hawksworth & Rose 1970a,b). Each species within the Lobarion may have a critical load and or a critical bark pH at which point its population will begin to decline (Farmer et al. 1991a). However, while acid deposition is an important factor in determining the occurrence of Lobaria spp., bark chemistry is determined by a wider range of factors which include trees species, atmospheric chemistry, soil nutrient and buffering capacity (Farmer et al. 1991b). Even in areas of low acid deposition, decline in Lobaria spp. can occur if the soil is poorly buffered.
Additional Comments:
In Norway Lobaria were restricted to drainage channels on trunks as these had a higher pH than normal bark and were more nutrient rich (Gauslaa 1995). Acid rain reduces the quantum yield of photosystem 2 and, therefore, will restrict growth in these species (Gauslaa et al 1996).
| Critical Load/ Level |
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No estimate available |