The fate of ^(15)N-labeled nitrogen inputs to pot cultured beech seedlings

作     者：Ali Bagherzadeh Rainer Brumme Friedrich Beese Ali Bagherzadeh;Rainer Brumme;Friedrich Beese

作者机构：Department of Agriculture Islamic Azad University-Mashhad Branch Institute of Soil Science and Forest Nutrition Georg-August University of Goettingen 

出 版 物：《Journal of Forestry Research》 (林业研究（英文版）)

年 卷 期：2009年第20卷第4期

页      面：314-322,I0005页

核心收录：

学科分类：0907[农学-林学] 08[工学] 0829[工学-林业工程] 09[农学] 

基　　金：supported by ibw  Goet-tingen University  Germany 

主　　题：^15N tracer nitrogen retention and recovery beech seedling forest soil immobilization nitrogen budget 

摘      要：The partitioning of nitrogen deposition among forest soil （including forest floor）, leachate and above- and belowground biomass of pot cultured beech seedlings in comparison to non-cultured treatments were investigated by adding 1.92 g.m^-2 ^15N tracer in throughfall for two successive growing seasons at a greenhouse experiment. Ammonium and nitrate depositions were simulated on four treatments （cultured and non-cultured） and each treatment was labeled with either ^15N-NH4^＋ or ^15N-NO3^-. Total recovery rates of the applied ^15N in the whole system accounted for 74.9% to 67.3% after ^15N-NH4^＋ and 85.3% to 88.1% after ^15N-NO3^-in cultured and non-cultured treatments, respectively. The main sink for both ^15N tracers was the forest soil （including forest floor）, where 34.6% to 33.7% of ^15N-NH4^＋ and 13.1% to 9.0% of ^15N-NO3^-were found in cultured and non-cultured treatments, respectively, suggesting strong immobilization of both N forms by hetero- trophic microorganisms. Nitrogen immobilization by microorganisms in the forest soil （including forest floor） was three times higher when ^15N-NH4^＋ was applied compared to ^15N-NO3^-. The preferential heterotrophic use of ammonium resulted in a two times higher retention of deposited ^15N-NH4^＋ in the forest soil as compared to plants. In contrast, nitrate immobilization in the forest soil was lower compared to plants, although statistically it was not significantly different. In total the immobilization of ammonium in the plant-soil system was about 60% higher than nitrate, indicating the importance of the N-forms deposition for retention in forest ecosystems.