title: Humic Acid Composition and Characteristics of Soil Organic Matter in Relation to the Elevation Gradient of Moso Bamboo Plantations.
abstract: Studying the influence of climatic and/or site-specific factors on soil organic matter (SOM) along an elevation gradient is important for understanding the response of SOM to global warming. We evaluated the composition of SOM and structure of humic acids along an altitudinal gradient from 600 to 1400 m in moso bamboo (Phyllostachys edulis) plantations in central Taiwan using NMR spectroscopy and photometric analysis. Total organic C and total nitrogen (N) content increased with increasing elevation. Aromaticity decreased and ΔlogK (the logarithm of the absorbance ratio of humic acids at 400 and 600 nm) increased with increasing elevation, which suggests that SOM humification decreased with increasing elevation. High temperature at low elevations seemed to enhance the decomposition (less accumulation of total organic C and N) and humification (high aromaticity and low ΔlogK). The alkyl-C/O-alkyl-C (A/O-A) ratio of humic acids increased with increasing elevation, which suggests that SOM humification increased with increasing elevation; this finding was contrary to the trend observed for ΔlogK and aromaticity. Such a discrepancy might be due to the relatively greater remaining of SOM derived from high alkyl-C broadleaf litter of previous forest at high elevations. The ratio of recalcitrant C to total organic C was low at low elevations, possibly because of enhanced decomposition of recalcitrant SOM from the previous broadleaf forest during long-term intensive cultivation and high temperature. Overall, the change in SOM pools and in the rate of humification with elevation was primarily affected by changes in climatic conditions along the elevation gradient in these bamboo plantations. However, when the composition of SOM, as assessed by NMR spectroscopy and photometric analysis was considered, site-specific factors such as residual SOM from previous forest and intensive cultivation history could also have an important effect on the humic acid composition and humification of SOM.
authors: Biodiversity Research Center, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors: Hsueh-Ching
authors: HC
authors: Wang
authors: Biodiversity Research Center, National Taiwan University, Taipei 10617, Taiwan.
authors: Chiao-Ying
authors: CY
authors: Chou
authors: School of Forestry and Resource Conservation, National Taiwan University, Taipei 10617, Taiwan.
authors: Chyi-Rong
authors: CR
authors: Chiou
authors: Environmental Monitoring and Research Division, Monitoring and Research Department, Metropolitan Water Reclamation District of Greater Chicago (MWRD), Lue-Hing R&D Laboratory, 6001 W. Pershing Road, Cicero, IL 60804, United States of America.
authors: Guanglong
authors: G
authors: Tian
authors: Biodiversity Research Center, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors: Chih-Yu
authors: http://orcid.org/0000-0002-6842-1253
authors: CY
authors: Chiu
mesh_terms: D031723:Bambusa; D006812:Humic Substances; D009682:Magnetic Resonance Spectroscopy; D012987:Soil / Q000737:chemistry*; D013624:Taiwan
chemical_list: D006812:Humic Substances; D012987:Soil