自然资源学报 ›› 2012, Vol. ›› Issue (10): 1696-1707.doi: 10.11849/zrzyxb.2012.10.008

• 资源生态 • 上一篇    下一篇

模拟放牧改变了氮添加作用下高寒草甸生物量的分配模式

宗宁1,4, 石培礼1, 宋明华2, 林琳3,4, 马维玲1,4, 蔣婧2,4, 付刚1,4, 何永涛1, 张宪洲1   

  1. 1. 中国科学院 地理科学与资源研究所 生态系统网络观测与模拟重点实验室拉萨高原生态试验站, 北京 100101;
    2. 中国科学院 地理科学与资源研究所 生态系统网络观测与模拟重点实验室, 北京 100101;
    3. 中国科学院 寒区旱区环境与工程研究所 冻土工程重点实验室, 兰州 730000;
    4. 中国科学院大学, 北京 100049
  • 收稿日期:2011-11-23 修回日期:2012-04-26 出版日期:2012-10-20 发布日期:2012-10-20
  • 通讯作者: 石培礼,E-mail:shipl@igsnrr.ac.cn E-mail:shipl@igsnrr.ac.cn
  • 基金资助:
    国家重点基础研究发展计划(2010CB833502);中国科学院战略性先导科技专项(XDA05060700);国家重点基础研究发展计划(2010CB951704)。

Clipping Alters the Response of Biomass Allocation Pattern under Nitrogen Addition in an Alpine Meadow on the Tibetan Plateau

ZONG Ning1,4, SHI Pei-li1, SONG Ming-hua2, LIN Lin3,4, MA Wei-ling1,4, JIANG Jing2,4, FU Gang1,4, HE Yong-tao1, ZHANG Xian-zhou1   

  1. 1. Lhasa National Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    3. Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, CAS, Lanzhou 730000, China;
    4. University of Chinese Academy of Sciences, Beijing100049, China
  • Received:2011-11-23 Revised:2012-04-26 Online:2012-10-20 Published:2012-10-20

摘要: 高寒草甸是氮素匮乏的生态系统,氮添加和放牧都会显著改变土壤养分的有效性及高寒植物对养分的利用方式,从而影响群落生产力。为了认识氮沉降和放牧干扰对青藏高原高寒草甸的影响,在西藏当雄县高山嵩草草甸开展了氮添加及模拟放牧实验。在模拟放牧样地(G+N)和不放牧样地(NG+N)分别设置4个氮添加处理:0、 10、 20和40 kg N·hm-2·a-1,在生长季采用原位封顶埋管法测定净氮矿化速率,同时分析群落生物量分配与植物氮利用的相互关系。研究表明:氮添加与模拟放牧对植物的分配模式有不同的影响。在无放牧压力下,氮添加主要刺激植物地上部分的生长;在放牧压力下,氮添加更倾向于促进植物地下部分的生长。虽然剪草移走了15%~20%的地上生物量,但由于氮添加促进了植物的补偿生长,模拟放牧与不放牧处理的总生物量无显著差异,甚至前者高于后者。高寒草甸植物生物量分配对氮添加和模拟放牧的响应也体现在土壤供氮潜力的作用模式上,土壤净氮矿化速率在NG+N样地与植物地上生物量呈显著负相关,而在G+N样地与植物地下生物量呈显著负相关。这表明高寒草甸植物可以通过改变自身光合产物的分配模式来响应土壤养分状况和放牧干扰,在有效养分匮乏的高寒草甸添加氮素能够促进植物的补偿性生长。

关键词: 氮添加, 模拟放牧, 地上、 地下生物量分配, 土壤供氮潜力, 高寒草甸

Abstract: Growth of alpine plants is primarily limited by low available nitrogen in the soil. Both nitrogen addition and grazing affect soil nutrient availability and uptake of alpine plants, and consequently influence community productivity. To understand the effects of nitrogen addition and grazing on the ecosystem function, nitrogen addition experiment in combination with simulated grazing (clipping) has been conducted in an alpine ecosystem on the northern Tibetan Plateau since 2010. The levels of nitrogen addition in stimulated grazed (G+N) and non-grazed plots (NG+N) were controlled at 0 (N0), 10 (N10), 20 (N20) and 40 (N40) kg N穐m-2-1, respectively. Net nitrogen mineralization was measured by in-situ close-top incubation during the growing season in 2011. Nitrogen addition and clipping had different effects on the biomass allocation of alpine plants. Nitrogen addition mainly stimulated the above-ground productivity in non-grazed plots, but enhanced below-ground productivity in grazed plots. Although about 15%-20% of the above-ground biomass was removed by clipping, there is no difference of total biomass between grazed and non-grazed plots or even higher in grazed than non-grazed plots, owing to stimulating effects of nitrogen enrichment on the compensatory growth of alpine plants. Moreover, the different responses of biomass allocation to nitrogen addition and clipping were also reflected in the pattern closely related to soil nitrogen supply potential. Net nitrogen mineralization was negatively correlative with the above-ground biomass in non-grazed plots, but with below-ground biomass in grazed plots. It is indicated that alpine plants responded to soil nutrient and grazing by altering the allocation pattern of photosynthetic assimilates. The present study also suggested that in alpine meadow limited by available nutrient, nitrogen addition may stimulate compensatory growth of plants.

Key words: nitrogen addition, clipping, biomass allocation, soil nitrogen supply potential, alpine meadow

中图分类号: 

  • S812