科尔沁沙质草地优势多年生植物氮素回收效率的分异特征  

Divergence of Nitrogen Resorption Efficiency of Dominant Perennial Plants in Horqin Sandy Grassland

作　　者：李玉霖[1] 崔夺[1] 陈静[1] 毛伟[1] 赵学勇[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所奈曼沙漠化试验研究站,甘肃兰州730000

出　　处：《中国沙漠》2013年第3期688-695,共8页Journal of Desert Research

基　　金：中国科学院战略性先导科技专项(XDA05050406-4);国家科技支撑计划课题(2011BAC07B02-04);国家重点基础研究发展计划项目(2009CB421102);国家自然科学基金项目(31270501;30970471)资助

摘　　要：养分回收是多年生植物重要的适应策略,通过这种方式可以使植物重新利用体内养分。尤其在养分贫瘠的环境中,养分条件的微小变化都会影响植物的生长、竞争和适合度。但是,不同物种和不同生活型植物的氮素回收效率具有较高的变异,这对理解不同物种或生活型植物在生态系统功能中的作用具有重要意义。本研究分析了科尔沁沙质草地生态系统中39种多年生植物成熟绿叶和枯叶的氮素含量和氮素回收效率,以揭示不同物种或生活型植物氮素回收效率的分异特征。结果表明:科尔沁沙质草地优势多年生植物成熟绿叶氮素含量的变化范围在12.2～33.4mg.g-1,平均值为23.3mg.g-1;与全国及全球尺度上的研究结果相比,科尔沁沙质草地成熟绿叶氮含量平均值偏高,说明干旱荒漠环境植物叶片平均氮含量相对较高;多年生植物枯叶的氮素含量明显小于成熟绿叶氮素含量,变化范围在6.2～18.8mg.g-1,平均值为11.3mg.g-1;多年生植物氮素回收效率的范围在29%至74%之间变化,平均值为50.3%。这说明氮素回收是科尔沁沙质草地生态系统多年生植物重要的养分保留策略之一。另外,沙质草地不同生活型植物的氮素回收效率存在显著的差异。固氮植物和禾本科植物的氮素回收效率显著低于灌木和杂类草植物。这一结果间接说明植物氮素保持能力的分异是半干旱沙质草地植物共存的机理之一。Foliar nitrogen resorption is an important strategy which allows leaf nutrients to be reused rather than lost with leaf fall, particularly in nutrient-poor ecosystems where even small nutrient losses can have significantly negative impacts on plant survival, competitive ability, and fitness. However, plants vary greatly in nitrogen resorption among plant species during leaf senescence, which may be vital to understand the role of plant species in ecosystem functioning. Green and senesced leaf N concentrations of 39 plant spe- cies in Horqin sandy grassland were analyzed to detect variations of nutrient resorption efficiency （NRE） among plant growth forms. The results showed that green leaf N concentration ranged from 12.2 rag.g-1 to 33.4 mg. g-1, with an average of 23.3 4- 5.4 mg. g -1. Compared with those on national or global scales, Green leaf N concentrations were higher, suggesting that green leaf N is relatively higher in arid environments. Correspondingly, senesced leaf N concentration, significantly lower than green leaf N concentra- tion, varied between 6.2 mg. g-1 and 18.8 rag. g-1. Nitrogen resorption efficiency ranged from 29 % to 74%, with an average of 50.3 %±11.0%, suggesting that nitrogen resorption is a vital nutrient conservation strategy in this ecosystem. In addition, NRE differed significantly among the dominant plant growth forms in this sandy grassland. NRE for N-fixing species and graminoids were significantly lower relative to NRE for shrubs and forbs. These data give indirect evidence that the differentiation of N conservation serve as an important mechanism permitting the co-existence of growth forms in arid systems.

关 键 词：氮素回收效率 荒漠草地 分类群 沙漠化 

分 类 号：Q945.79[生物学—植物学]