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Effects of nitrogen deposition on soil organic carbon fractions in the subtropical forest ecosystems of S China
Author(s) -
Chen Xiaomei,
Li Yuelin,
Mo Jiangming,
Otieno Dennis,
Tenhunen John,
Yan Junhua,
Liu Juxiu,
Zhang Deqiang
Publication year - 2012
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.201100059
Subject(s) - topsoil , total organic carbon , tropical and subtropical moist broadleaf forests , soil carbon , nitrogen , evergreen , agronomy , pinus massoniana , soil organic matter , chemistry , environmental chemistry , subtropics , environmental science , soil water , soil science , botany , ecology , biology , organic chemistry
Abstract Experiments were conducted between 2003 and 2008 to examine how N additions influence soil organic C (SOC) and its fractions in forests at different succession stages in the subtropical China. The succession stages included pine forest, pine and broadleaf mixed forest, and old‐growth monsoon evergreen broadleaf forest. Three levels of N (NH 4 NO 3 )‐addition treatments comprising control, low‐N (50 kg N ha –1 y –1 ), and medium‐N (100 kg N ha –1 y –1 ) were established. An additional treatment of high‐N (150 kg N ha –1 y –1 ) was established in the broadleaf mixed forest. Soil samples were obtained in July 2008 for analysis. Total organic C (TOC), particulate organic C (POC, > 53 μm), readily oxidizable organic C (ROC), nonreadily oxidizable organic C (NROC), microbial biomass C (MBC), and soil properties were analyzed. Nitrogen addition affected the TOC and its fractions significantly. Labile organic‐C fractions (POC and ROC) in the topsoil (0–10 cm) increased in all the three forests in response to the N‐addition treatments. NROC within the topsoil was higher in the medium‐N and high‐N treatments than in the controls. In the topsoil profiles of the broadleaf forest, N addition decreased MBC and increased TOC, while no significant effect on MBC and TOC occurred in the pine and mixed forests. Overall, elevated N deposition increased the availability of labile organic C (POC and ROC) and the accumulation of NROC within the topsoil irrespective of the forest succession stage, and might enhance the C‐storage capacity of the forest soils.