Anthropogenic nitrogen deposition in boreal forests has a minor impact on the global carbon cycle

• DOI: 10.1111/gcb.12422
• Publication Date: 2013-10-12T01:47:14Z
• Authors: Michael J. Gundale; Fredrik From; Lisbet H. Bach; Annika Nordin
• Keywords: Understory; Carbon sink

Abstract It is proposed that increases in anthropogenic reactive nitrogen (N r ) deposition may cause temperate and boreal forests to sequester a globally significant quantity of carbon (C); however, long‐term data from describing how C sequestration responds realistic levels chronic N are scarce. Using (14‐year) stand‐scale (0.1 ha) addition experiment (three levels: 0, 12.5, 50 kg ha −1 yr the zone northern Sweden, we evaluated additions altered uptake biomass understory communities, whether changes communities explained by trees. We hypothesized (i.e. mosses shrubs) serve as important sinks for low‐level additions, with strength these weakening rates increase, due shifts species composition. further trees would exhibit nonlinear acquisition, subsequent increased, sink. Our showed was reduced 50% response high treatment, mainly moss biomass. A 15 labeling feather acquired largest fraction applied label, this decreasing level increased. Contrary our hypothesis, proportion label taken up equal (ca. 8%) across all three treatments. The relationship between vegetation pools combined linear, had slope 16 N. While canopy retention be slightly different than estimate, suggest minor annual CO 2 emissions sequestered into result deposition.