@article {1273,
	title = {Diversity and sensitivity of epiphytes to oxides of nitrogen in London},
	volume = {146},
	year = {2007},
	pages = {299-310},
	abstract = {This study investigated the distribution and diversity of epiphytes in London in relation to NO(x) using fine-scale atmospheric dispersion modelling. The survey recorded over 3000 epiphytes from 334 trees (Fraxinus excelsior) representing 74 lichen, 14 moss, 7 fungal and 3 algal species. There was a significant inverse relationship between diversity and NO(x). Diversity declined where NO(x) exceeded 70 microg m(-3) and NO2 exceeded 40 microg m(-3), suggesting a phytotoxic effect. However, there was a significant positive relationship between NO(x) and lichen abundance due to the ubiquitous distribution of pollution tolerant species, mainly associated with eutrophication. A scale of lichen sensitivity to NO(x) has been derived.},
	author = {Davies, L. and Bates, J.W. and Bell, J.N.B. and James, P.W. and Purvis, O.W.}
}
@book {727,
	title = {Lichen Flora of Great Britain and Ireland},
	year = {1992},
	pages = {710},
	publisher = {The Natural History Museum},
	organization = {The Natural History Museum},
	address = {London},
	author = {Purvis, O.W. and Coppins, B.J. and Hawksworth, D.L. and James, P. and Moore, D.M.}
}
