Nitrogen utilization by <i>Hylocomium splendens</i> in a boreal forest fertilization experiment

Abstract

1 Nitrogen uptake in the terricolous bryophyte Hylocomium splendens (Hedw.) B.S.G. was studied in a boreal forest long-term N-treatment experiment including control plots, N-addition plots (50 kg N ha−1 year−1 for 8 years) and recovery plots (50 kg N ha−1 year−1 for 5 years and thereafter no N addition for 3 years). 2 A main objective was to explore whether the N treatments changed bryophyte uptake of different inorganic and organic N forms. In addition, we estimated the contribution of N from throughfall precipitation to the bryophyte N supply. 3 The results demonstrated that bryophyte N uptake was similar in all the long-term N-treatment plots. Hylocomium splendens took up more 15N labelled than or glycine when these N forms were applied in situ by the spraying of solutions with N concentrations similar to those in precipitation. 4 Analysis of the precipitation collected beneath the closed tree canopy from late May to early October revealed that it contributed 2·0 kg N ha−1 during the period studied, distributed between (78%), amino acid N (17%) and (5%). 5 The study highlights that, in addition to analyses of and (normally included in standard environmental monitoring of precipitation), analysis of amino acid N must be performed to account fully for the precipitation N input to bryophytes in boreal forest ecosystems.