Atmospheric Ammonia

pp 101-108

Macrolichens on Twigs and Trunks as Indicators of Ammonia Concentrations Across the UK — a Practical Method

  • Patricia A. WolseleyAffiliated withDepartment of Botany, NHM London
  • , Ian D. LeithAffiliated with
  • , Netty van DijkAffiliated with
  • , Mark A. SuttonAffiliated with

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Lichen community composition on acid-barked trees has been shown to respond to increasing atmospheric ammonia (NH3) concentrations by loss of acidophyte species and an increase in nitrophyte species. A simple method of sampling selected acidophyte and nitrophyte lichens on trunks and twigs of trees in the vicinity of ammonia monitoring sites across the UK allowed us to test the correlation of lichen communities with ammonia concentrations across the climatic and vegetation zones of the UK.

Sites were selected and field staff from the conservation and regulatory agencies introduced to standard lichen sampling and identification techniques at a workshop co-organised by NHM and CEH Edinburgh. LAN (Lichen Acidophyte Nitrophyte) values were calculated for all sites, based on the frequency of acidophyte and nitrophyte macrolichens on trunks and twigs. Bark samples from trunk and twig were collected and surface bark pH measured in the lab, to test the correlation of acidophyte and nitrophyte communities with bark pH.