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Turnover of labile and recalcitrant soil carbon differ in response to nitrate and ammonium deposition in an ombrotrophic peatland
Author(s) -
CURREY PAULINE M.,
JOHNSON DAVID,
SHEPPARD LUCY J.,
LEITH IAN D.,
TOBERMAN HANNAH,
Van Der WAL RENÉ,
DAWSON LORNA A.,
ARTZ REBEKKA R. E.
Publication year - 2010
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/j.1365-2486.2009.02082.x
Subject(s) - ombrotrophic , chemistry , environmental chemistry , mineralization (soil science) , ammonium , peat , nitrate , soil carbon , carbon fibers , nitrogen , soil water , ecology , bog , organic chemistry , biology , materials science , composite number , composite material
The effects of 4 years of simulated nitrogen deposition, as nitrate (NO 3 − ) and ammonium (NH 4 + ), on microbial carbon turnover were studied in an ombrotrophic peatland. We investigated the mineralization of simple forms of carbon using MicroResp ™ measurements (a multiple substrate induced respiration technique) and the activities of four soil enzymes involved in the decomposition of more complex forms of carbon or in nutrient acquisition: N ‐acetyl‐glucosaminidase (NAG), cellobiohydrolase (CBH), acid phosphatase (AP), and phenol oxidase (PO). The potential mineralization of labile forms of carbon was significantly enhanced at the higher N additions, especially with NH 4 + amendments, while potential enzyme activities involved in breakdown of more complex forms of carbon or nutrient acquisition decreased slightly (NAG and CBH) or remained unchanged (AP and PO) with N amendments. This study also showed the importance of distinguishing between NO 3 − and NH 4 + amendments, as their impact often differed. It is possible that the limited response on potential extracellular enzyme activity is due to other factors, such as limited exposure to the added N in the deeper soil or continued suboptimal functioning of the enzymes due to the low pH, possibly via the inhibitory effect of low phenol oxidase activity.