@article {1704,
	title = {Bark pH and susceptibility to toxic air pollutants as independent causes of changes in epiphytic lichen composition in space and time},
	journal = {Lichenologist},
	volume = {33},
	year = {2001},
	pages = {419-441},
	keywords = {agriculture, england, netherlands, pollution, quercus-petraea, vegetation},
	author = {van Herk, C. M.}
}
