Feather moss nitrogen acquisition across natural fertility gradients in boreal forests

Kathrin Rousk, Johannes Rousk, Davey L. Jones, Olle Zackrisson, Thomas H. DeLuca

35 Citations (Scopus)

Abstract

Feather mosses utilize various sources of nitrogen (N): they absorb N deposited on leaf tissue, they host N2 fixing cyanobacteria, and they are able to take up N directly from soil. In addition to their importance as primary producers in boreal ecosystems, feather mosses play a significant role in N cycling. However, estimates of their ability to take up N from soil in situ are scarce. Further, connecting uptake of N from soil with N2 fixation could significantly improve our understanding of their role in ecosystem N cycling, but to date this issue has not been addressed. We report results from an uptake experiment in which we tracked 13C-carbon (C), 15N-alanine and 15N-ammonium chloride (NH4Cl) into feather moss (Pleurozium schreberi (Brid.) Mitt.)-soil cores taken along natural fertility gradients in Northern Sweden. The varying fertility conditions coincided with a N2 fixation gradient in the feather moss. We found that P. schreberi takes up C and N directly from soil. However, the moss did not show a preference for inorganic or organic N sources and only 1.4% of the added amino acid appeared to be taken up from soil in an intact form. No differences in uptake of C or N from soil along the fertility gradients were detected. Nitrogen fixation rates in the moss were thus not correlated with C or N-uptake from soil. Nitrogen fixation as well as uptake of C and N from soil seem to be unaffected by C or N availability in the soil, suggesting that the moss can cover its nutrient demand by absorption of throughfall N and via associated N2-fixing cyanobacteria without soil-N supplementation. We suggest further, that the moss can represent a (temporary) N-sink in the boreal forest, and that the moss' mechanism of uptake and release thereby will characterize the ecosystem N cycle.

Original languageEnglish
JournalSoil Biology & Biochemistry
Volume61
Pages (from-to)86-95
Number of pages10
ISSN0038-0717
DOIs
Publication statusPublished - Jun 2013
Externally publishedYes

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