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Anthropogenic nitrogen deposition enhances carbon sequestration in boreal soils
Author(s) -
Maaroufi Nadia I.,
Nordin Annika,
Hasselquist Niles J.,
Bach Lisbet H.,
Palmqvist Kristin,
Gundale Michael J.
Publication year - 2015
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.12904
Subject(s) - carbon sequestration , environmental science , soil respiration , taiga , ecosystem , deposition (geology) , soil water , soil carbon , boreal , biomass (ecology) , terrestrial ecosystem , environmental chemistry , soil organic matter , agronomy , soil science , nitrogen , ecology , chemistry , biology , paleontology , sediment , organic chemistry
It is proposed that carbon (C) sequestration in response to reactive nitrogen (N r ) deposition in boreal forests accounts for a large portion of the terrestrial sink for anthropogenic CO 2 emissions. While studies have helped clarify the magnitude by which N r deposition enhances C sequestration by forest vegetation, there remains a paucity of long‐term experimental studies evaluating how soil C pools respond. We conducted a long‐term experiment, maintained since 1996, consisting of three N addition levels (0, 12.5, and 50 kg N ha −1 yr −1 ) in the boreal zone of northern Sweden to understand how atmospheric N r deposition affects soil C accumulation, soil microbial communities, and soil respiration. We hypothesized that soil C sequestration will increase, and soil microbial biomass and soil respiration will decrease, with disproportionately large changes expected compared to low levels of N addition. Our data showed that the low N addition treatment caused a non‐significant increase in the organic horizon C pool of ~15% and a significant increase of ~30% in response to the high N treatment relative to the control. The relationship between C sequestration and N addition in the organic horizon was linear, with a slope of 10 kg C kg −1 N. We also found a concomitant decrease in total microbial and fungal biomasses and a ~11% reduction in soil respiration in response to the high N treatment. Our data complement previous data from the same study system describing aboveground C sequestration, indicating a total ecosystem sequestration rate of 26 kg C kg −1 N. These estimates are far lower than suggested by some previous modeling studies, and thus will help improve and validate current modeling efforts aimed at separating the effect of multiple global change factors on the C balance of the boreal region.