Seasonal variation in nitrogen fixation and effects of climate change in a subarctic heath
2014 (English)In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 379, no 1-2, 193-204 p.Article in journal (Refereed) Published
Nitrogen fixation associated with cryptogams is potentially very important in arctic and subarctic terrestrial ecosystems, as it is a source of new nitrogen (N) into these highly N limited systems. Moss-, lichen- and legume-associated N-2 fixation was studied with high frequency (every second week) during spring, summer, autumn and early winter to uncover the seasonal variation in input of atmospheric N-2 to a subarctic heath with an altered climate. We estimated N-2 fixation from ethylene production by acetylene reduction assay in situ in a field experiment with the treatments: long- vs. short-term summer warming using plastic tents and litter addition (simulating expansion of the birch forest). N-2 fixation activity was measured from late April to mid November and 33 % of all N-2 was fixed outside the vascular plant growing season (Jun-Aug). This substantial amount underlines the importance of N-2 fixation in the cold period. Warming increased N-2 fixation two- to fivefold during late spring. However, long-term summer warming tended to decrease N-2 fixation outside the treatment (tents present) period. Litter alone did not alter N-2 fixation but in combination with warming N-2 fixation increased, probably because N-2 fixation became phosphorus limited under higher temperatures, which was alleviated by the P supply from the litter. In subarctic heath, the current N-2 fixation period extends far beyond the vascular plant growing season. Climate warming and indirect effects such as vegetation changes affect the process of N-2 fixation in different directions and thereby complicate predictions of future N cycling.
Place, publisher, year, edition, pages
2014. Vol. 379, no 1-2, 193-204 p.
Bryophytes, Global change, Lichens, Litter addition, Long-vs. short-term warming, Nitrogen and phosphorus, Plant cover
Agricultural Sciences Soil Science
IdentifiersURN: urn:nbn:se:umu:diva-89455DOI: 10.1007/s11104-014-2031-yISI: 000335166300014OAI: oai:DiVA.org:umu-89455DiVA: diva2:732128