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N2-fixing red alder indirectly accelerates ecosystem nitrogen cycling

Ecosystems

By:
, , and
DOI: 10.1007/s10021-012-9579-2

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Abstract

Symbiotic N2-fixing tree species can accelerate ecosystem N dynamics through decomposition via direct pathways by producing readily decomposed leaf litter and increasing N supply to decomposers, as well as via indirect pathways by increasing tissue and detrital N in non-fixing vegetation. To evaluate the relative importance of these pathways, we compared three-year decomposition and N dynamics of N2-fixing red alder leaf litter (2.34 %N) to both low-N (0.68 %N) and high-N (1.21 %N) litter of non-fixing Douglas-fir, and decomposed each litter source in four forests dominated by either red alder or Douglas-fir. We also used experimental N fertilization of decomposition plots to assess elevated N availability as a potential mechanism of N2-fixer effects on litter mass loss and N dynamics. Direct effects of N2-fixing red alder on decomposition occurred primarily as faster N release from red alder than Douglas-fir litter, but direct increases in N supply to decomposers via fertilization did not stimulate decomposition of any litter. Fixed N indirectly influenced detrital dynamics by increasing Douglas-fir tissue and litter N concentrations, which accelerated litter N release without accelerating mass loss. By increasing soil N, tissue N, and the rate of N release from litter of non-fixers, we conclude that N2-fixing vegetation can indirectly foster plant-soil feedbacks that contribute to the persistence of elevated N availability in terrestrial ecosystems.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
N2-fixing red alder indirectly accelerates ecosystem nitrogen cycling
Series title:
Ecosystems
DOI:
10.1007/s10021-012-9579-2
Volume
15
Issue:
7
Year Published:
2012
Language:
English
Publisher:
Springer
Publisher location:
Amsterdam, Netherlands
Contributing office(s):
Forest and Rangeland Ecosystem Science Center
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Ecosystems
First page:
1182
Last page:
1193
Country:
United States