Dynamics of soil inorganic nitrogen and their responses to nitrogen additions in three subtropical forests, south China  

作　　者：FANG Yun-ting ZHU Wei-xing MO Jiang-ming ZHOU Guo-yi GUNDERSEN Per 

机构地区：[1]Dinghushan Forest Ecosystem Research Station, South China Botanical Garden, Chinese Academy of Sciences, Zhaoqing 526070, China [2]Biological Sciences, Binghamton University-SUNY, Binghamton, NY 13902-6000, USA [3]Forest and Landscape Denmark,Hoersholm Kongevej 11, 2970, Denmark [4]The Graduate School of the Chinese Academy of Sciences, Beijing 100039, China

出　　处：《Journal of Environmental Sciences》2006年第4期752-759,共8页环境科学学报（英文版）

基　　金：TheNationalNaturalScienceFoundationofChina(No.30270283);theFieldFrontiersProjectofChineseAcademyofSciencesKnowledgeInnovationProgram(KSCX2-SW-133);theDirectorFoundationofSouthChinaInstituteofBotany,ChineseAcademyofSciencesandtheProvincialNaturalScienceFoundationofGuangdong,China(No.021524)

摘　　要：Three forests with different historical land-use, forest age, and species assemblages in subtropical China were selected to evaluate current soil N status and investigate the responses of soil inorganic N dynamics to monthly ammonium nitrate additions. Results showed that the mature monsoon evergreen broadleaved forest that has been protected for more than 400 years exhibited an advanced soil N status than the pine （Pinus massoniana） and pine-broadleaf mixed forests, both originated from the 1930＇s clear-cut and pine plantation. Mature forests had greater extractable inorganic N pool, lower N retention capacity, higher inorganic N leaching, and higher soil C/N ratios. Mineral soil extractable NH4^＋-N and NO3-N concentrations were significantly increased by experimental N additions on several sampling dates, but repeated ANOVA showed that the effect was not significant over the whole year except NH4^＋-N in the mature forest. In contrast, inorganic N （both NH4^＋-N and NO3^--N） in soil 20-cm below the surface was significantly elevated by the N additions. From 42% to 74% of N added was retained by the upper 20 cm soils in the pine and mixed forests, while 0%-70% was retained in the mature forest. Our results suggest that land-use history, forest age and species composition were likely to be some of the important factors that determine differing forest N retention responses to elevated N deposition in the study region.Three forests with different historical land-use, forest age, and species assemblages in subtropical China were selected to evaluate current soil N status and investigate the responses of soil inorganic N dynamics to monthly ammonium nitrate additions. Results showed that the mature monsoon evergreen broadleaved forest that has been protected for more than 400 years exhibited an advanced soil N status than the pine （Pinus massoniana） and pine-broadleaf mixed forests, both originated from the 1930＇s clear-cut and pine plantation. Mature forests had greater extractable inorganic N pool, lower N retention capacity, higher inorganic N leaching, and higher soil C/N ratios. Mineral soil extractable NH4^＋-N and NO3-N concentrations were significantly increased by experimental N additions on several sampling dates, but repeated ANOVA showed that the effect was not significant over the whole year except NH4^＋-N in the mature forest. In contrast, inorganic N （both NH4^＋-N and NO3^--N） in soil 20-cm below the surface was significantly elevated by the N additions. From 42% to 74% of N added was retained by the upper 20 cm soils in the pine and mixed forests, while 0%-70% was retained in the mature forest. Our results suggest that land-use history, forest age and species composition were likely to be some of the important factors that determine differing forest N retention responses to elevated N deposition in the study region.

关 键 词：N deposition N saturation extractable inorganic N soil solution inorganic N subtropical China 

分 类 号：X131.3[环境科学与工程—环境科学]