氮素添加对内蒙古退化草原生产力的短期影响  

Influence of nitrogen addition on the primary production in Nei Mongol degraded grassland

作　　者：王晶[1,2] 王珊珊[1,2] 乔鲜果 李昂[1] 薛建国[1] 哈斯木其尔[1,2] 张学耀[1,2] 黄建辉[1] 

机构地区：[1]中国科学院植物研究所植被与环境变化国家重点实验室,北京100093 [2]中国科学院大学生命科学学院,北京100049

出　　处：《植物生态学报》2016年第10期980-990,共11页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31670483和31430016);中国科学院战略性先导科技专项(XDB15010401)

摘　　要：不合理的土地利用方式以及气候变化导致我国草原生态系统普遍退化,主要表现在土壤养分降低、植被覆盖度减少、生产力下降。外源氮素添加是促进退化草原尽快恢复的一项重要措施,尤其是对那些退化较为严重的草原。该研究选取内蒙古东乌珠穆沁旗不同退化程度(轻度、中度和重度)的草原群落,于2014–2015年开展连续两年的氮素添加实验,设置对照(不添加)、低水平(5.0 g N·m^(–2)·a^(–1))、中水平(10.0 g N·m^(–2)·a^(–1))和高水平(20.0 g N·m^(–2)·a^(–1))4种氮素添加处理,探讨退化草原群落生产力在恢复过程中对不同水平氮素添加的响应。结果显示:(1)高、中水平氮素添加显著提高了轻度退化群落的地上生物量,分别比对照增加了53.1%、51.6%,氮素各水平添加对中度、重度群落地上生物量无显著影响;(2)高、中水平氮素添加显著提高了轻度退化群落中多年生根茎型禾草地上生物量,分别比对照增加了45.1%、47.7%,而多年生杂类草地上生物量分别比对照减少了37.4%、42.1%,但中度和重度退化群落各功能群生物量的响应不显著;(3)三种水平氮素添加对轻、中、重度退化群落物种丰富度在试验期间均没有显著影响。研究结果表明氮素添加有助于提高轻度退化草原中多年生根茎型禾草的生物量,进而提高群落的生物量,但多年生杂类草会被逐渐替代,导致生物量降低,可见施氮对草原恢复的影响取决于草原退化程度。Aims Irrational utilization and global climate change have caused degradation of grassland ecosystems in north- ern China with low soil fertility, decreased vegetation coverage and productivity. Nitrogen addition has been sug- gested an effective way to enhance restoration of those degraded grasslands. In this study, we selected a typical steppe with three different degrading levels, including lightly, moderately and heavily degraded communities, in East Ujimqin, Nei Mongol. Our objectives of this study are to examine if and how nitrogen （N） addition can en- hance restoration of those degraded grasslands. Methods Treatments with four levels of N addition （0, 5.0, 10.0 and 20.0 gN·m^-2·a^-1） were conducted to each of the three degraded communities from 2014 to 2015. Nitrogen was applied as urea in June of both years. Aboveground biomass was collected at the species level in 1 m × 1 m plot in August each year, all species bio- mass was summed as net primary production, and biomass of plant functional groups was calculated by perennial rhizome grasses, perennial bunchgrasses, perennial forbs, shrubs and semi-shrubs, annuals and biennials. Important findings Our results showed that the high （20.0 gN·m^-2·a^-1） and medium level N addition （10.0 gN·m^-2·a^-1） significantly increased the aboveground biomass of the slightly degraded community by 53.1% and 51.6% compared with no N addition. N addition had no significant effects on the moderately and heavily degraded communities. N addition with high and medium levels increased aboveground biomass of perennial rhizome grasses by 45.1% and 47.7%, but decreased that of perennial forbs by 37.4% and 42.1% at the slightly degradedcommunity. Our results indicated that N addition could increase the growth of perennial rhizome grasses, and the growth of perennial forbs was suppressed consequently. Our results suggest that even the application of N fertiliz- ers can only be helpful to restoration of those slightly degraded grasslands. Besides, N addition had

关 键 词：退化草原 氮添加 地上生物量 植物功能群 物种丰富度 

分 类 号：S812[农业科学—草业科学]