Long-term effects of PO₄ fertilization on the distribution of bryophytes in an arctic river

Each year since 1983, H₃PO₄ has been added continuously during the ice-free season to a P-limited tundra river (Kuparuk River, North Slope, Alaska). In 1990 there was extensive coverage by bryophytes within the fertilized reach of the river, where very little had been noted before. Bryophyte biomass in 1990 and 1991 yielded 17 ± 9 (SE) g dry mass m^-2 in control reaches and 322 ± 96 g dry mass m^-2 in fertilized reaches. The moss Schistidium (Grimmia) agassizii was distributed in both control and fertilized reaches of the river. Hygrohypnum alpestre and H. ochraceum were found almost exclusively in the fertilized reach indicated that increased cover and biomass of Hygrohypnum spp. were confined to the fertilized reach of the river. Fontinalis neomexicana also occurred almost exclusively in the fertilized reach, but was much less abundant than Hygrohypnum. Analysis of total N and P in the tissues of the Hygrohypnum spp., and estimates of average coverage (c15%) and biomass (c150 g dry weight m^-2) over an 8 km fertilized reach, suggest that these species alone may have removed two-thirds of the P added in the fertilizer experiment. -from Authors