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| Titel |
Bryophyte-cyanobacteria associations contribute to ecosystem-N-budget of boreal forest |
| VerfasserIn |
Maija Salemaa, Antti-Jussi Lindroos, Päivi Merilä, Raisa Mäkipää, Aino Smolander |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097797
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| Publikation (Nr.) |
 EGU/EGU2014-13411.pdf |
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| Zusammenfassung |
| Bryophytes frequently dominate the ground vegetation on the forest floor in boreal region.
Northern ecosystems are often nitrogen limited, and therefore biological nitrogen
(N2) fixation of bryophyte-associated microbes is an important source of new N. In
this study we estimated the N stock of bryophyte layer and the N input rate by N2
fixation of bryophyte-cyanobacteria associations at the ecosystem level. We studied
12 intensively monitored forest ecosystem plots (ICP Forests Level II) along a
latitudinal gradient in Finland during 2009–2013. The total biomass and N stock of the
bryophytes varied 700–2000 kg ha-1 and 9–23 kg ha-1, respectively. N2 fixation rate
associated to bryophytes increased towards the north and was at highest 1–2 kg N
ha-1 year-1 (based on the bryophyte biomass in the monitoring plots). This N
input was at the same level as the N deposition in the northern Finland (1.5 kg N
ha-1 year-1). In comparison, via needle litterfall and other tree litter c.a. 5 kg N
ha-1 is annually returned to the nutrient cycle. In southern Finland, very low rates
of N2 fixation were found probably because of inhibition by the anthropogenic
N deposition. The upper parts of the bryophyte shoots showed 2–3 times higher
N2-fixing rate than the lower parts, but differences between Hylocomium splendens and
Pleurozium schreberi were minor. However, Dicranum species showed much lower N2
fixation rates compared to these two species. The moisture level of bryophytes and
light/temperature conditions regulated strongly the rate of N2-fixing activity. The
results showed that the bryophyte layer significantly contributes to the N input
and plays an important role in controlling the N and C balances of boreal forests. |
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