title: Physiological responses of bryophytes Thuidium tamariscinum and Hylocomium splendens to increased nitrogen deposition.
abstract: OBJECTIVE
  Increased levels of nitrogen (N) deposition lead to enhanced N contents and reduced productivity of many bryophyte species. This study aimed at elucidating the mechanisms by which enhanced N uptake may cause growth reduction of bryophytes, focusing on the effects of N addition on carbon (C) metabolism of bryophytes.
  
  
  METHODS
  Plantlets of Thuidium tamariscinum and Hylocomium splendens were fertilized with NH(4)NO(3) (N load equalling 30 kg ha(-1) year(-1)) for 80 d, including a pulse labelling experiment with (13)CO(2) to dissect the partitioning of carbon in response to N addition.
  
  
  RESULTS
  Growth of T. tamariscinum was not affected by N addition, while H. splendens showed a trend towards growth reduction. Total N concentration was significantly increased by N addition in H. splendens, a significant increase in amino acid-N was found in T. tamariscinum only. In both bryophyte species, a reduction in concentration of lipids, the greatest C storage pool, as well as markedly enhanced turnover rates of C storage pools in fertilized plants were observed.
  
  
  CONCLUSIONS
  The results suggest that growth reduction of H. splendens under high levels of N deposition may be caused by enhanced synthesis of N-containing organic compounds, most probably of cell wall proteins. Disturbance of cellular C metabolism, as indicated by enhanced C pool turnover, may further contribute to the decline in productivity of H. splendens.
authors.affiliation: Department of Chemical Ecology and Ecosystem Research, University of Vienna, Althanstr. 14, 1090 Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Koranda
authors.forename: S
authors.initials: S
authors.lastname: Kerschbaum
authors.forename: W
authors.initials: W
authors.lastname: Wanek
authors.forename: H
authors.initials: H
authors.lastname: Zechmeister
authors.forename: A
authors.initials: A
authors.lastname: Richter
mesh_terms: D019068:Bryopsida / Q000254:growth & development / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism; D002247:Carbon Isotopes; D005308:Fertilizers; D009584:Nitrogen / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D005308:Fertilizers; D002244:Carbon; D009584:Nitrogen