在发现氮沉降可能降低热带亚热带地区“富氮”森林植物多样性现象的基础上（详见Global Change Biology, 2010, 16: 2688–2700），中科院华南植物园生态系统管理研究组鲁显楷博士等在莫江明研究员的指导下，通过在鼎湖山国家级自然保护区6年多野外试验观察和分析比较，发现再造林（reforested forests）植物多样性对模拟氮沉降的响应格局因土地利用历史不同而异。该研究在国际上首次揭示了热带亚热带区域氮沉降与土地利用历史变化对森林植物多样性的影响具有“交互作用”。
该研究表明了土地利用历史变化是决定森林植物多样性对氮沉降响应的重要因素，研究结果对于评估当前人类活动和大气氮沉降不断加剧的背景下森林植物多样性的变化具有重要的意义。（生物谷Bioon.com）
生物谷推荐原文出处：
Environmental Pollution doi:10.1016/j.envpol.2010.10.037
Effects of experimental nitrogen additions on plant diversity in tropical forests of contrasting disturbance regimes in southern China
Xiankai Lua, Jiangming Moa, , , Frank S. Gilliamb, Guirui Yuc, Wei Zhanga, Yunting Fanga and Juan Huanga
a Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510160, China
b Department of Biological Sciences, Marshall University, Huntington, WV 25755-2510, USA
c Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
Abstract
Responses of understory plant diversity to nitrogen (N) additions were investigated in reforested forests of contrasting disturbance regimes in southern China from 2003 to 2008: disturbed forest (with harvesting of understory vegetation and litter) and rehabilitated forest (without harvesting). Experimental additions of N were administered as the following treatments: Control, 50 kg N ha?1 yr?1, and 100 kg N ha?1 yr?1. Nitrogen additions did not significantly affect understory plant richness, density, and cover in the disturbed forest. Similarly, no significant response was found for canopy closure in this forest. In the rehabilitated forest, species richness and density showed no significant response to N additions; however, understory cover decreased significantly in the N-treated plots, largely a function of a significant increase in canopy closure. Our results suggest that responses of plant diversity to N deposition may vary with different land-use history, and rehabilitated forests may be more sensitive to N deposition.
Research highlights
? Nitrogen addition had no significant effect on understory plant diversity in the disturbed forest. ? Nitrogen addition significantly decreased understory plant cover. ? Nitrogen addition had no effect on richness and density in the rehabilitated forest. ? The decrease is largely a function of a significant increase in canopy closure. ? Land-use practices may dominate the responses of plant diversity to N addition.
Research in disturbed forests of southeastern China demonstrates that land-use history can substantially alter effects of excess nitrogen deposition on plant diversity of tropical forest ecosystems.
Keywords: Nitrogen deposition; Biodiversity; Tropical reforestation; Land-use history; Light limitation
