基于结构方程模型的森林生态系统空气负离子影响机制分析

空气负离子(Negative air ion, NAI)是衡量空气质量的重要指标之一，受到植被和环境的共同影响。然而，森林生态系统作为NAI产生的重要来源，森林中的植被和环境之间的相互作用以及对NAI的影响机制和贡献潜力仍难以捉摸。以暖温带森林生态系统中广泛分布的栓皮栎(Quercus variabilis BI.)为对象，基于自动观测设备长期定位观测获取了气象、土壤性质、空气洁净度以及植被光合等数据，利用皮尔逊相关系数分析和偏最小二乘结构方程模型分析了森林植被和环境要素对NAI的影响机制和贡献潜力。结果表明，环境要素和植被光合对NAI的贡献差异显著，植被光合对NAI的贡献潜力为62.65%,环境要素对NAI的贡献率为37.35%。环境要素中太阳辐射和饱和水汽压差的影响程度最大，分别为68.94%和16.55%。植被光合和PM_2.5主要通过直接效应影响NAI,而光合有效辐射、紫外辐射、土壤温湿度和饱和水汽压差主要通过间接效应影响NAI。因此，利用结构方程模型可以阐明植被光合与环境要素的变化对NAI的影响趋势，从而全面揭示了森林生态系统中植被产生NAI的作用机制以及...

The influence mechanism of negative air ion in forest ecosystem based on structural equation

Negative air ion (NAI) is an important index for measuring air quality and is affected by vegetation and the environment in the forest. However, forest ecosystems are an essential source of NAI, and we know little about how the interactions are between forest vegetation and the environment, and its effects on NAI. In this paper, we selected Quercus variabilis as research subjects in warm temperate forest ecosystems and obtained meteorology, soil properties, air cleanliness, and vegetation photosynthesis data based on long-term positioning of automatic observation equipment. Finally, we analyzed the influence mechanism and contribution potential of forest vegetation and environmental elements on NAI using Pearson correlation analysis and partial least squares structural equation modeling (PLS-SEM). The results showed that the contribution of the environment elements and vegetation photosynthesis to NAI were significantly different, the contribution potential of vegetation photosynthesis was 62.65%, and the environment elements were 37.35%. The contribution of solar radiation and vapor pressure deficit (VPD) was the highest among the environment elements, with 68.94% and 16.55% contribution rates. Vegetation photosynthesis and PM_2.5 mainly affected NAI through direct effects, while photosynthetically active radiation, ultraviolet radiation, soil temperature, humidity, and VPD mainly affected NAI through indirect effects. Therefore, the structural equation model can be used to clarify the impact of vegetation and environment on NAI in the forest. This study can improve a comprehensively understanding of the influence mechanism of the environment elements and vegetation photosynthesis on NAI in forest ecosystems, and provide a theoretical basis for assessing the contribution potential of forest ecosystems to NAI.