生物多样性 ›› 2024, Vol. 32 ›› Issue (12): 24255.  DOI: 10.17520/biods.2024255  cstr: 32101.14.biods.2024255

• 研究报告 • 上一篇    下一篇

氮添加对东北温带阔叶红松林幼苗动态的影响

徐智超1,2(), 朱美慧1,2, 毛子昆1,2(), 王绪高1,2,*()()   

  1. 1.中国科学院沈阳应用生态研究所森林生态与保育重点实验室, 沈阳 110016
    2.辽宁省陆地生态碳中和重点实验室, 沈阳 110016
  • 收稿日期:2024-06-23 接受日期:2024-09-27 出版日期:2024-12-20 发布日期:2024-12-17
  • 通讯作者: E-mail: wangxg@iae.ac.cn
  • 基金资助:
    国家重点研发计划(2022YFF1300501);国家自然科学基金青年项目(32301344);国家资助博士后研究人员计划(C)(GZC20232878)

Effects of nitrogen addition on seedling dynamics in a broad-leaved Korean pine forest in Northeast China

Zhichao Xu1,2(), Meihui Zhu1,2, Zikun Mao1,2(), Xugao Wang1,2,*()()   

  1. 1. CAS Key Laboratory of Forest Ecology and Silviculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
    2. Key Laboratory of Terrestrial Ecosystem Carbon Neutrality, Liaoning Province, Shenyang 110016, China
  • Received:2024-06-23 Accepted:2024-09-27 Online:2024-12-20 Published:2024-12-17
  • Contact: E-mail: wangxg@iae.ac.cn
  • Supported by:
    National Key Research and Development Program of China(2022YFF1300501);National Natural Science Foundation of China(32301344);Postdoctoral Fellowship Program of CPSF(GZC20232878)

摘要: 大气氮沉降是驱动森林生物多样性变化的重要因子。尽管已有大量研究证实氮添加能够显著改变森林生态系统林下层种群密度以及物种多样性, 但现有研究大多局限于草本植物。而乔木幼苗阶段作为森林更新的关键时期, 其物种组成及动态变化对氮添加的响应趋势和内在机理仍不清晰。本研究依托长白山温带阔叶红松林氮添加控制试验平台, 基于连续7年的乔木幼苗动态监测数据, 分析不同氮添加处理对幼苗数量动态及物种多样性的影响; 并以负密度制约效应为切入点, 探讨氮添加影响物种多样性的机制。结果表明, 氮添加显著降低了群落水平的幼苗总个体和增补数量, 但增强了幼苗年际动态相似性。低氮处理的物种丰富度和Shannon-Wiener指数均显著低于对照组, 而Shannon-Wiener指数在中氮处理下显著高于对照组。此外, 同种幼苗负密度制约效应随氮添加浓度的升高呈现加剧趋势, 且与物种丰富度、Shannon-Wiener指数和Pielou均匀度指数显著负相关, 这证明了氮沉降对同种负密度制约效应的影响是改变物种多样性的潜在机制。综上, 本研究明确了氮添加对长白山温带阔叶红松林乔木幼苗动态的影响, 以密度制约效应为视角揭示了氮添加对物种多样性的作用机理, 为研究氮沉降背景下温带森林幼苗动态及其响应机制提供了新思路。

关键词: 氮添加, 幼苗, 物种多样性, 负密度制约效应, 温带森林

Abstract

Aims: Nitrogen deposition, an important factor driving the biodiversity change of forest ecosystems, has been a major influence of change in the global environment. Although many studies have confirmed that nitrogen intervention can significantly alter understory population density and species diversity in the forest community, most of these studies are limited to herbaceous plants. The seedling stage of woody plants, as the key period of forest regeneration, is rarely discussed in terms of the dynamics of nitrogen addition and its response mechanisms. In this study, we aim to test the effects of nitrogen addition on seedling dynamics and explore the mechanism of nitrogen addition on species diversity with negative density dependence.

Methods: This study was based on a manipulative experiment of nitrogen addition in the Changbai Mountain broad- leaved Korean pine mixed forest. Four nitrogen addition levels were set: Control (unadded), low nitrogen (25 kg∙ha·yr‒1), medium nitrogen (50 kg∙ha·yr‒1), and high nitrogen (75 kg∙ha·yr‒1).

Results: Our results indicated that nitrogen addition promoted a similarity of interannual seedling dynamics, and significantly decreased the community-level seedling density and recruitment. Also, under low nitrogen level treatment, species richness and Shannon-Wiener index were significantly lower than those of the control group but increased significantly under medium and high nitrogen levels. In addition, the conspecific negative density dependence of the seedling was intensified with an increase in nitrogen concentration, and was simultaneously negatively correlated with species richness, Shannon-Wiener, and evenness index, verifying the potential pathway in which nitrogen deposition could change species diversity by influencing the conspecific negative density dependence.

Conclusions: This study demonstrated the effects of nitrogen addition on seedling dynamics in the temperate broad-leaved Korean pine mixed forest on Changbai Mountain and confirmed the mechanism of nitrogen addition on species diversity from the perspective of negative density dependence. These results reveal the dynamics and interconnectivities of temperate forest seedlings and nitrogen deposition.

Key words: nitrogen addition, seedling, species diversity, negative density dependence, temperate forest