Effects of six years of simulated N deposition on gross soil N transformation rates in an old-growth temperate forest |
| |
| Authors: | Peng Tian Jinbo Zhang Christoph Müller Zucong Cai Guangze Jin |
| |
| Institution: | 1.College of Forestry,Northeast Forestry University,Harbin,People’s Republic of China;2.School of Geography Sciences,Nanjing Normal University,Nanjing,People’s Republic of China;3.Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application,Nanjing,People’s Republic of China;4.Department of Plant Ecology (IFZ),Justus-Liebig University Giessen,Giessen,Germany;5.School of Biology and Environmental Science,University College Dublin,Dublin,Ireland |
| |
| Abstract: | Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition with four levels of N addition rate(N0, N30, N60, and N120) for6 years in an old-growth temperate forest in Xiaoxing'an Mountains in Northeastern China. We measured gross N transformation rates in the laboratory using ~(15)N tracing technology to explore the effects of N deposition on soil gross N transformations taking advantage of N deposition soils. No significant differences in gross soil N transformation rates were observed after 6 years of N deposition with various levels of N addition rate. For all N deposition soils, the gross NH_4~+ immobilization rates were consistently lower than the gross N mineralization rates,leading to net N mineralization. Nitrate(NO_3~-) was primarily produced via oxidation of NH_4~+(i.e., autotrophic nitrification), whereas oxidation of organic N(i.e., heterotrophic nitrification) was negligible. Differences between the quantity of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were not significant for any treatment, which likely explains the lack of a significant effect on gross nitrification rates. Gross nitrification rates were much higher than the total NO_3~- consumption rates,resulting in a build-up of NO_3~-, which highlights the high risk of N losses via NO_3~- leaching or gaseous N emissions from soils. This response is opposite that of typical N-limited temperate forests suffering from N deposition,suggesting that the investigated old-growth temperate forest ecosystem is likely to approach N saturation. |
| |
| Keywords: | |
| 本文献已被 CNKI SpringerLink 等数据库收录！ |
|
