Biodiv Sci ›› 2024, Vol. 32 ›› Issue (12): 24255.  DOI: 10.17520/biods.2024255  cstr: 32101.14.biods.2024255

• Original Papers • Previous Articles     Next Articles

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)

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