title: Delta15N of soil N and plants in a N-saturated, subtropical forest of southern China.
abstract: We investigated the delta(15)N profile of N (extractable NH(4)(+), NO(3)(-), and organic N (EON)) in the soil of a N-saturated subtropical forest. The order of delta(15)N in the soil was EON > NH(4)(+) > NO(3)(-). Although the delta(15)N of EON had been expected to be similar to that of bulk soil N, it was higher than that of bulk soil N by 5 per thousand. The difference in delta(15)N between bulk soil N and EON (Delta(15)N(bulk-EON)) was correlated significantly with the soil C/N ratio. This correlation implies that carbon availability, which determines the balance between N assimilation and dissimilation of soil microbes, is responsible for the high delta(15)N of EON, as in the case of soil microbial biomass delta(15)N. A thorough delta(15)N survey of available N (NH(4)(+), NO(3)(-), and EON) in the soil profiles from the organic layer to 100 cm depth revealed that the delta(15)N of the available N forms did not fully overlap with the delta(15)N of plants. This mismatch in delta(15)N between that of available N and that of plants reflects apparent isotopic fractionation during N uptake by plants, emphasizing the high N availability in this N-saturated forest.
authors.affiliation: Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu 1838509, Japan. keikoba@cc.tuat.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Koba
authors.forename: K
authors.initials: K
authors.lastname: Isobe
authors.forename: Y
authors.initials: Y
authors.lastname: Takebayashi
authors.forename: Y T
authors.initials: YT
authors.lastname: Fang
authors.forename: Y
authors.initials: Y
authors.lastname: Sasaki
authors.forename: W
authors.initials: W
authors.lastname: Saito
authors.forename: M
authors.initials: M
authors.lastname: Yoh
authors.forename: J
authors.initials: J
authors.lastname: Mo
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.forename: X
authors.initials: X
authors.lastname: Lu
authors.forename: T
authors.initials: T
authors.lastname: Zhang
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: K
authors.initials: K
authors.lastname: Senoo
mesh_terms: D000704:Analysis of Variance; D018533:Biomass; D002244:Carbon / Q000737:chemistry; D002681:China; D016014:Linear Models; D013058:Mass Spectrometry; D009566:Nitrates / Q000737:chemistry; D017672:Nitrogen Compounds / Q000737:chemistry*; D009587:Nitrogen Isotopes / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry*; D010944:Plants / Q000378:metabolism; D011189:Potassium Chloride; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D014329:Tropical Climate
chemical_list: D009566:Nitrates; D017672:Nitrogen Compounds; D009587:Nitrogen Isotopes; D000644:Quaternary Ammonium Compounds; D012987:Soil; D011189:Potassium Chloride; D002244:Carbon