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J Soils Sediments (2008) 8:398405 DOI 10.1007/s11368-008-0037-x
SOILS, SEC 1 SOIL ORGANIC MATTER DYNAMICS & NUTRIENT CYCLING RES. ARTICLE
In situ mineral 15N dynamics and fate of added 15NH4+ in hoop pine plantation and adjacent nativeforest in subtropical Australia
Kaiwen Pan & Zhihong Xu & Tim Blumfield &
Shane Totua & Manxin Lu
Received: 8 May 2008 /Accepted: 20 September 2008 / Published online: 11 October 2008 # Springer-Verlag 2008
AbstractBackground, aim, and scope Hoop pine (Araucaria cunninghamii) is a nitrogen (N) demanding indigenous Australia softwood species with plantations in Southeast Queensland, Australia. Soil fertility has declined with increasing rotations and comparison study of N cycling between hoop pine plantations, and adjacent native forest (NF) is required to develop effective forest management for enhancing sustainable forest production and promoting environmental benefits. Field in situ mineral 15N trans
formations in these two forest ecosystems have not been studied. Hence, the present study was to compare the differences in soil nutrients, N transformations, 15N fluxes, and fate between the hoop pine plantation and the adjacent native forest.
Materials and methods The study sites were in Yarraman State Forest (2652 S, 15151 E), Southeastern Queensland, Australia. The in situ core incubation method was used in the field experiments. Mineral N was determined using a LACHAT Quickchem Automated Ion Analyzer.
15N were performed using an isotope ratio mass spectrometer with a Eurovector elemental analyzer. All statistical tests were carried out by the SPSS 11.0 for Windows statistical software package.
Results Soil total C and N were significantly higher in the NF than in the 53-year-old hoop pine plantation. Concentrations of NO3 were significantly higher in the NF soil than in the plantation soil. The plantation soil had significantly higher 15N and 13C natural abundances than the NF soil. The NF soil had significantly lower C/N ratios than the plantation soil. NO3N was dominated in mineral
N pools in both NF and plantation soils, accounting for91.6% and 70.3% of the total mineral N pools, respectively. Rates of net nitrification and net N mineralization were, respectively, four and three times higher in the NF soil than in the plantation soil. The 15NO3N and mineral 15N were significantly higher in the NF soil than in the plantation soil. Significant difference in 15NH4+N...