title: Quantifying nitrogen-fixation in feather moss carpets of boreal forests.
abstract: Biological nitrogen (N) fixation is the primary source of N within natural ecosystems, yet the origin of boreal forest N has remained elusive. The boreal forests of Eurasia and North America lack any significant, widespread symbiotic N-fixing plants. With the exception of scattered stands of alder in early primary successional forests, N-fixation in boreal forests is considered to be extremely limited. Nitrogen-fixation in northern European boreal forests has been estimated at only 0.5 kg N ha(-1) yr(-1); however, organic N is accumulated in these ecosystems at a rate of 3 kg N ha(-1) yr(-1) (ref. 8). Our limited understanding of the origin of boreal N is unacceptable given the extent of the boreal forest region, but predictable given our imperfect knowledge of N-fixation. Herein we report on a N-fixing symbiosis between a cyanobacterium (Nostoc sp.) and the ubiquitous feather moss, Pleurozium schreberi (Bird) Mitt. that alone fixes between 1.5 and 2.0 kg N ha(-1) yr(-1) in mid- to late-successional forests of northern Scandinavia and Finland. Previous efforts have probably underestimated N-fixation potential in boreal forests.
authors.affiliation: School of Forestry, The University of Montana, Missoula, Montana 59812, USA. thd@forestry.umt.edu
authors.forename: Thomas H
authors.initials: TH
authors.lastname: DeLuca
authors.forename: Olle
authors.initials: O
authors.lastname: Zackrisson
authors.forename: Marie-Charlotte
authors.initials: MC
authors.lastname: Nilsson
authors.forename: Anita
authors.initials: A
authors.lastname: Sellstedt
mesh_terms: D000114:Acetylene / Q000378:metabolism; D019068:Bryopsida / Q000378:metabolism* / Q000382:microbiology*; D000458:Cyanobacteria / Q000378:metabolism*; D005387:Finland; D007700:Kinetics; D009586:Nitrogen Fixation; D009664:Norway; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology; D013548:Sweden; D013559:Symbiosis; D014197:Trees
chemical_list: D000114:Acetylene