Andersen, H.V., Nielsen, K.E., Degn, H.J., Geels, C., Løfstrøm, P., Damgaard, C. & Christensen, J.H. 2009. Lokal kvælstofdeposition og kvælstofindhold i lav. Danmarks Miljøundersøgelser, Aarhus Universitet. 46 s.- Faglig rapport fra DMU nr. 732.
For a one year period, lasting from April 2006 to April 2007, the geographical and seasonal variation in nitrogen content in lichen (Cladonia portentosa) and ammonia concentrations in air were measured at several locations. The region covered a triangle with approximately 50 km between the locations, two inland heaths and one dune heath. At one of the heaths and on the dune heath samples were taken to investigate the local variation within at distance of a few kilometers. The seasonal variation in the nitrogen content of the lichen was small and a local variation was detectable, even at the few kilometer scale. Nitrogen content in the lichen is a parameter monitored in the surveillance program and these data compared well to the data obtained in this investigation. The seasonal variation of the concentration of ammonia in air is very similar at the different locations, though with a clear difference in absolute values. The nitrogen content in the lichen shows a good correlation to the yearly mean value of the measured ammonia concentration in air at the different locations. The total nitrogen deposition was calculated by use of models and apart from ammonia these results show very similar deposition loads at the investigated locations. Considering uncertainties in modeling, only the modeled deposition of ammonia has a good correlation to the nitrogen content in the lichens. At locations with similar background deposition of nitrogen compounds the nitrogen content in the lichen (Cladonia portentosa) seems to be a good indicator to detect local differences in ammonia concentrations and ammonia depositions. It is not unambiguous whether the nitrogen content of the lichens also relates to the nitrogen deposition as a hole. Vegetation analysis has been performed and showed relatively high cover of grass species at the inland heaths. The vegetation analysis is not regarded as a suitable indicator for nitrogen deposition, since other factors have an influence on the diversity of species.
Full report in danish in PDF-format (9.3 MB).
