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2287308 
Journal Article 
Nitrogen:phosphorus ratio as the main ecological determinant of the differences in the species composition of brown-moss rich fens in north-eastern Poland 
Pawlikowski, P; Abramczyk, K; Szczepaniuk, A; Kozub, L 
2013 
1 
Preslia
ISSN: 0032-7786 
85 
3 
349-367 
WOS:000325118300008 
The species composition of 22 mires (brown-moss rich fens) was surveyed in north-eastern Poland, located in continental boreo-nemoral Europe. Detailed analyses of the water chemistry, biomass N, P, and K content, productivity and water level were made. Two floristically different types of rich-fen vegetation occur in this area, one with numerous Caricetalia davallianae (calcicole) species such as Scorpidium cossonii, Campylium stellatum, Carex lepidocarpa and Eriophorum latifolium (Cd fens) and the other with a few Caricetalia davallianae species and mainly Hamatocaulis vernicosus, Marchantia polymorpha, Plagiomnium ellipticum, Carex diandra and C. rostrata (non-Cd fens). In these two rich-fen types surface water chemistry and water levels were similar, but the Cd fens characteristically had higher pHs and lower PO43- concentrations. N and P availability revealed by the N:P ratio is the ecological factor that best accounts for the differences in species composition of the two rich-fen types: the non-Cd fens are N-limited while the Cd-fens are usually P-limited. Moreover, the Cd fens differ from the non-Cd fens in a higher productivity of the bryophyte layer. In the case of P and K concentrations, there is a correlation between that in vascular plants and bryophytes, while N concentrations are not correlated. We believe that in the case of low productive ecosystems the use of the broad "nutrient availability gradient" should be replaced by a (from) N-(to) P-limitation gradient with N:P ratio as a useful measure. Natural N-limited, low-productive rich fens and their ecological conditions can be a phenomenon typical of continentaleastern temperate European areas, which have been poorly surveyed and need further research. 
bryophytes; calcicole species; Caricetalia davallianae; continental fens; extremely rich fens; N:P ratio; nutrient availability; productivity; surface water chemistry