植物生态学报

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前期氮添加对无梗花栎幼苗干旱响应中地上-地下碳氮分配动态的影响

冯梅1,欧阳胜男2,Matthias Saurer3,李迈和4,周晓倩5,铁烈华5,申卫军6,段洪浪2,Arthur Gessler7   

  1. 1. 贵州大学贵州省森林资源与环境研究中心/贵州大学林学院
    2. 贵州大学
    3. 瑞士联邦森林、雪和景观研究所
    4. 瑞士联邦森林,景观和雪研究院
    5. 贵州大学贵州省森林资源与环境研究中心/贵州省高原山地林木培育重点实验室/贵州大学林学院
    6. 广西大学林学院
    7. 地球生态系统研究所,苏黎世联邦理工学院
  • 收稿日期:2024-07-04 修回日期:2025-01-08 发布日期:2025-01-20
  • 通讯作者: 欧阳胜男

Effects of previous nitrogen addition on aboveground and belowground carbon and nitrogen allocation dynamics in drought-exposed sessile oak seedlings

Mei FENG1,Sheng-Nan OUYANG1,Matthias Saurer2,Mai-He LI1,Xiaoqian Zhou3,Liehua TIE4,Weijun Shen5,Honglang Duan1,Arthur Gessler6   

  1. 1.
    2. Swiss Federal Institute for Forest, Snow and Landscape Research
    3. Institute for Forest Resources and Environment of Guizhou, Key Laboratory of Forest Cultivation in Plateau Mountain of Guizhou Province
    4. Institute for Forest Resources and Environment of Guizhou, Key Laboratory of Forest Cultivation in Plateau Mountain of Guizhou Province, College of Forestry
    5. College of Forestry, Guangxi University
    6. Institute of Terrestrial Ecosystems, ETH Zurich
  • Received:2024-07-04 Revised:2025-01-08
  • Contact: Sheng-Nan OUYANG

摘要: 干旱打破树木的碳平衡过程是诱发树木干旱死亡的主要因素之一, 这一过程可能受到土壤养分(如氮)有效性的调控。然而, 氮添加对树木干旱响应过程中地上-地下部分碳和氮利用、各器官碳氮耦合关系的影响仍不清楚。该研究通过为期两年的微宇宙实验, 在第一个生长季对无梗花栎(Quercus petraea)进行氮添加处理, 随后在第二个生长季进行干旱处理, 并在干旱前进行15N标记、干旱中进行13C标记, 双标记后经过连续3次破坏性取样研究氮添加对无梗花栎响应持续干旱过程中碳氮分配动态的影响。主要研究结果: 1)前期氮添加促进了无梗花栎地上部分光合碳和氮分配, 也促进了根系氮吸收, 改变了植株地上-地下新吸收碳和氮的关系, 降低了各器官非结构性碳水化合物(NSC)含量; 2)干旱对无梗花栎地上-地下碳氮分配过程、各器官碳和氮关系的影响较小, 但降低了各器官NSC含量; 3)干旱第40–73天过程中, 前期氮添加下的无梗花栎表现出将吸收的氮素和光合碳逐渐往地下器官转移的趋势。综上, 无梗花栎通过调控自身对碳和氮的利用策略, 具有较好的干旱适应能力, 而前期氮添加很可能会增加无梗花栎的干旱敏感性。

关键词: 前期氮添加, 干旱, 碳氮分配, 13C同位素标记, 15N同位素标记

Abstract: Aims: Drought effects on the carbon balance are considered as the major factor of tree mortality and are as-sumed to be regulated by soil nutrient (e.g., nitrogen) availability. However, the effects of nitrogen addition on trees carbon and nitrogen utilization between aboveground and belowground and on coupling relationship of carbon and nitrogen in various organs in response to drought are still unclear in trees. Methods: A two-year full factorial microcosm experiment was set up with sessile oak (Quercus petraea). Nitrogen addition was performed in the first year, and drought was conducted in the second year. The isotope 15N labeling and 13C labeling were carried out before drought and during drought, respectively. Three consecutive samplings were conducted after dual labeling of 13C and 15N labelling in the second year, and the effects of ni-trogen addition on carbon and nitrogen allocation dynamics during progressive drought were tested. Important findings: Our results showed that previous nitrogen addition promoted aboveground photosyn-thetic carbon fixation and nitrogen allocation, increased root nitrogen uptake, reduced the non-structural carbo-hydrates (NSC) contents in all organs and changed the relationships of carbon and nitrogen in aboveground and belowground organs in sessile oak. However, drought had minor effects on nitrogen and carbon allocation be-tween aboveground and belowground, and had minor effects on the relationship of carbon with nitrogen in all organs (represented by the ratio of 13C to 15N in all organs). Drought only significantly reduced the content of NSC in sessile oak. During drought (from day 40 to 73), previous nitrogen addition led sessile oak to prioritize belowground carbon and nitrogen allocation. Our results indicate that sessile oak can change its carbon and ni-trogen allocation strategies to adapt to drought well, while previous nitrogen addition may increase its drought sensitivity.

Key words: Previous nitrogen addition, Drought, Carbon and nitrogen allocation, 13C isotope labelling, 15N isotope labelling