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Soil Nitrogen Five Years after Bark Beetle Infestation in Lodgepole Pine Forests
Author(s) -
Norton Urszula,
Ewers Brent E.,
Borkhuu Bujidmaa,
Brown Nicholas R.,
Pendall Elise
Publication year - 2014
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2014.05.0223
Subject(s) - pinus contorta , infestation , litter , mountain pine beetle , soil water , nitrogen cycle , plant litter , agronomy , ecosystem , environmental science , mineralization (soil science) , bark beetle , biology , ecology , nitrogen , bark (sound) , chemistry , organic chemistry
The unprecedented scale of recent mountain pine beetle ( Dendroctonus ponderosae , MPB) infestation in lodgepole pine ( Pinus contorta ex Loudon var. latifolia Engelm. ex S. Watson) forests of western North America may significantly impact the role of forest soils as important sinks for global C and N. The aim of this study was to explain soil and litter N responses in stands experiencing total mortality during the first 5 yr of MPB outbreak. Four‐year monitoring (2009–2012) of needlefall deposition, soil water‐filled pore space (WFPS), NH 4 , NO 3 , potentially mineralizable N (PMN), dissolved organic N (DON), N 2 O, and CH 4 was established in Medicine Bow National Forest in stands of different infestation histories (infested in 2007, 2008, and uninfested). Results suggest that total stand mortality demonstrated strong temporal dynamics. First‐year soil responses included increases in PMN and were followed by WFPS and NH 4 increases in the second year, NO 3 increase in the third year, and DON increase in in the fourth year of the infestation. Litter NH 4 increased within 1 yr, but litter PMN, NO 3 , and DON increased 3 yr after the infestation, suggesting enhanced litter decomposability. Soil N 2 O and CH 4 fluxes also started to increase 4 yr after the infestation. These changes were indicative of ongoing disequilibrium for the period of at least 5 yr after MPB infestation. The magnitude of N mineralization and N 2 O and CH 4 fluxes may continue to increase beyond the initial 5 yr of monitoring because litter‐derived labile N will probably contribute to the second pulse of N mineralization.