Response and correlation of above- and below-ground functional traits of Leymus chinensis to nitrogen and phosphorus additions
Response and correlation of above- and below-ground functional traits of Leymus chinensis to nitrogen and phosphorus additions
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DOI：
10.17521/cjpe.2015.0164
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发表时间：
2016-01-01
影响因子：
--
通讯作者：
Bai Yong-Fei
中科院分区：
文献类型：
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作者：
Zhan Shu-Xia;Zheng Shu-Xia;Bai Yong-Fei
羊草（Leymus chinensis）是我国北方典型草原的建群种和优势种。本文对L.近几十年来，由于长期的过度放牧，中国草原生态系统退化严重。作为恢复退化草地的有效措施，养分添加对植物生长和生态系统结构与功能的影响一直是人工草地研究的热点。研究了不同营养添加（特别是磷添加）对L.特别是其支撑机制尚不清楚。本研究的目的是探讨L.方法在温室条件下，采用盆栽试验，研究了不同氮、磷水平（N：50、100、250 mg·Kg-1）和不同磷水平（P：5、10、25 mg·P.kg-1）对中华绒螯蟹生长发育的影响。地上和地下生物量、叶片性状（例如，比叶面积，叶片N和P含量）和根系性状（例如，比根长、根系N、P含量）。结果表明：1）不同海拔高度的羊草地上部分生物量和总生物量分别为：1.施N对羊草地上部生物量的影响最大，施P对羊草地下部生物量的影响最大。施氮显著提高了羊草地上部生物量。而施磷则降低了中、高氮水平下的地下生物量。根冠比为0。根冠比随N、P水平的增加而降低。N、P的添加促进了生物量的增加，促进了N、P向地上部和叶片生物量的分配。2)在低N和高N水平，羊草对P添加的响应与适应机制不同。在低氮水平下，L.结果表明，羊草具有较高的光合速率和比根长（SRL），提高了光合能力和根系对氮的吸收，促进了地上部生物量的增加。根系磷含量高有利于地下生物量的增加。在高氮水平下，施磷对黑麦草生长无显著影响。甚至降低了其地下生物量。羊草具有较高的比叶面积（SLA）和SRL，有利于提高光能截获和氮素吸收，维持地上部生物量的稳定。3)施磷对地上部功能性状的影响大于地下部。SLA与SRL呈弱正相关，表明L.结果表明，中国春小麦叶片和根系功能性状在资源获取和利用上表现出相对独立性。
Aims Leymus chinensis is a constructive and dominant species in typical steppe of northern China. The structure and functions of L. chinensis grassland ecosystem has been degenerated seriously due to long-term overgrazing in recent decades. As an effective measure to restore the degraded grasslands, the effects of nutrient addition on plant growth and ecosystem structure and functioning have been paid more attention in manipulation experimental research. The effects of nutrient addition, especially P addition on the above- and below-ground functional traits of L. chinensis have rarely been studied; particularly the underpinning mechanisms remain unclear. Our objective is to examine the responses and adaptive mechanisms of L. chinensis to different levels of N and P additions.Methods We conducted a culture experiment in the greenhouse, with three levels of N (50, 100 and 250 mg N.Kg(-1)) and P (5, 10 and 25 mg P.kg(-1)) addition treatments. The above- and below-ground biomass, leaf traits (e.g., specific leaf area, leaf N and P contents) and root traits (e.g., specific root length, root N and P contents) of L. chinensis were determined in this study.Important findings Our results showed that: 1) the aboveground biomass and total biomass of L. chinensis were mostly affected by N addition, while the belowground biomass was mainly affected by P addition. N addition greatly enhanced the aboveground biomass of L. chinensis, while P addition reduced the belowground biomass at the moderate and high N levels. The root-shoot ratio of L. chinensis was influenced by both N and P additions, and root-shoot ratio decreased with increasing N and P levels. N and P additions promoted more biomass and N and P allocations to aboveground and leaf biomass. 2) Leymus chinensis showed different responses and adaptive mechanisms to P addition at low and high N levels. At low N level, L. chinensis exhibited high photosynthetic rate and specific root length (SRL) to improve photosynthetic capacity and root N acquisition, which promoted aboveground biomass. High root P content was favorable for belowground biomass. At high N level, P addition did not significantly affect plant growth of L. chinensis, even reduced its belowground biomass. Leymus chinensis showed high specific leaf area (SLA) and SRL to improve light interception and N acquisition in order to maintain stable aboveground biomass. 3) P addition greatly impacted below-ground than above-ground functional traits. SLA exhibited a weakly positive correlation with SRL, indicating L. chinensis exhibited relatively independence of resource acquirement and utilization between leaf and root functional traits.