title: Bioindicators of enhanced nitrogen deposition.
abstract: Increased deposition of atmospheric N largely from intensive agriculture is affecting biodiversity and the composition of natural and semi-natural vegetation in Europe. The value of species based bioindicators such as the Ellenberg N index and measurements of total tissue N and free amino acids in key plant species, is described with reference to a mixed woodland downwind of a livestock farm in the Scottish Borders, operated for over 20 years with a measured spatial gradient of ammonia concentration (29-1.5 microg m(-3)). All the indicators examined showed a relationship with N deposition and provided some indication of vegetation change. Total tissue N and arginine concentrations were most closely linked with ammonia concentrations and N deposition, with r(2) values of >0.97 and >0.78 respectively.
authors.affiliation: Centre for Ecology and Hydrology, Edinburgh, Bush Estate, Penicuik, Midlothian EH26 0QB, UK.
authors.forename: C E R
authors.initials: CE
authors.lastname: Pitcairn
authors.forename: D
authors.initials: D
authors.lastname: Fowler
authors.forename: I D
authors.initials: ID
authors.lastname: Leith
authors.forename: L J
authors.initials: LJ
authors.lastname: Sheppard
authors.forename: M A
authors.initials: MA
authors.lastname: Sutton
authors.forename: V
authors.initials: V
authors.lastname: Kennedy
authors.forename: E
authors.initials: E
authors.lastname: Okello
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000596:Amino Acids / Q000032:analysis; D000641:Ammonia / Q000032:analysis; D000818:Animals; D000829:Animals, Domestic; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D009584:Nitrogen / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry*; D011200:Poultry; D013997:Time Factors; D014197:Trees
chemical_list: D000393:Air Pollutants; D000596:Amino Acids; D000641:Ammonia; D009584:Nitrogen