中文摘要：

CO2浓度升高与氮沉降增加对陆地生态系统的耦合作用已成为全球变化的研究热点。应用大型开顶箱（OTC）人工控制手段研究了人工生态系统在1）高CO2（700±20μmol·mol^-1）＋高氮沉降（100kg N·hm^-2·a^-1）（CN）;2）高CO2（700±20μmol·mol^-1）＋背景氮沉降（C＋）;3）高氮沉降（100kg N·hm^-2·a^-1）＋背景CO2（N＋）;4）背景CO2＋背景氮沉降处理（CK）4种处理条件下荷木（Schima superba）、红锥（Castanopsis hystrix）、海南红豆（Ormosia pinnata）、肖蒲桃（Acmena acuminatissima）、红鳞蒲桃（Syzygium hancei）等主要南亚热带森林植物的生物量积累模式及其分配格局。连续近3年的实验结果表明：不同处理条件下,各参试植物生物量积累具有不同的响应特征,N＋处理显著促进荷木、肖蒲桃及红鳞蒲桃生物量的积累;C＋处理显著促进肖蒲桃、海南红豆生物量的积累;CN处理显著促进除红锥外其他物种生物量的积累,并且具有两者单独处理的叠加效应。不同处理改变物种生物量的分配模式,N＋处理降低植物的根冠比,促进地上部分生物量的积累;C＋处理增加红锥和红鳞蒲桃地下部分生物量的分配,却促进荷木和海南红豆地上部分的积累;CN处理仅促进红磷蒲桃地下部分的积累。群落生物量的积累与分配格局取决于优势物种的生物量及其分配格局在群落中所占的权重。

英文摘要：

Aims Interactive effects of elevated atmospheric CO2 concentration [CO2] and nitrogen （N） deposition on terrestrial ecosystems play an important role in global carbon cycling. Ecosystems in subtropical and tropical areas occupy a large percent of the global biomass, but few studies have been done in these areas. Therefore, our objective was to conduct an experiment to improve our understand-ing of atmospheric [CO2] enrichment and N deposition effects on biomass accumulation and allocation in subtropical and tropical forests. Methods A model forest ecosystem was constructed of five tree species native to South China： Schima superba, Castanopsis hystrix, Ormosia pinnata, Acmena acuminatissima and Syzygium hancei. The species were exposed to a factorial combination of elevated CO2 and high N deposition in open-top chambers beginning March 2005. There are four experimental treatments, including CN （elevated [CO2] of （700±20） μmol·mol–1 and high N of 100 kg N·hm–2·a–1）, C＋ （elevated [CO2] of （700±20） μmol·mol–1 and ambient N）, N＋ （ambient [CO2] and high N of 100 kg N·hm^-2·a^-1） and CK （ambient [CO2] and am-bient N）. Each treatment was replicated two to three times. Important findings The first 3 years of study indicated that responses of biomass accumulation to different treatments varied among species. Total biomass of S. superba, A. acuminatissima and S. hanceiexhibited significant positive responses to N＋ treatment, while biomass of A. acuminatissima and O. pinnata were significantly enhanced under C＋ treatment. Biomass accumulation of all species except C. hystrix differed significantly between CN and CK treatments. Furthermore, responses of biomass allocation to treatments differed among species. N＋ treatment stimulated aboveground biomass accumulation, with decreasing root：shoot ratio. C＋ treatment significantly increased biomass allocation to below-ground biomass in C. hystrix and S. hancei, but enhanced biomass allocation to aboveground biomass in