Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Sci Total Environ. 2022 Sep 10;838(Pt 3):156060. doi: 10.1016/j.scitotenv.2022.156060. Epub 2022 May 23.
Increased nitrogen (N) deposition is known to reduce the ecosystem stability, while the underlying mechanisms are still controversial. We conducted an 8-year multi-level N addition experiment in a temperate semi-arid grassland to identify the mechanisms (biodiversity, species asynchrony, population stability and dominant species stability) driving the N-induced loss of temporal stability of aboveground net primary productivity (ANPP). We found that N addition decreased ecosystem, population, and dominant species stability; decreased species richness and phylogenetic diversity; increased species dominance; but had nonsignificant effects on community-wide species asynchrony. Structural equation model revealed that N-induced loss of ecosystem stability was mainly driven by the loss of dominant species stability and the reduction in population stability. Moreover, species relative instability was negatively related with species relative production and the slopes increase with N addition, indicating that N addition weakened the stabilizing effect of dominant species on ecosystem function. Overall, our results highlight that the dominant species control the temporal stability of ANPP in grassland ecosystem under N addition, and support 'dominance management' as an effective strategy for conserving ecosystem functioning in grassland under N deposition.
氮（N）沉降增加已知会降低生态系统稳定性，但其潜在机制仍存在争议。我们在温带半干旱草原进行了为期 8 年的多层次 N 添加实验，以确定导致地上净初级生产力（ANPP）时间稳定性丧失的机制（生物多样性、物种不同步、种群稳定性和优势种稳定性）。我们发现，N 添加降低了生态系统、种群和优势种的稳定性；降低了物种丰富度和系统发育多样性；增加了物种优势度；但对群落范围内的物种不同步没有显著影响。结构方程模型表明，N 诱导的生态系统稳定性丧失主要是由优势种稳定性丧失和种群稳定性降低驱动的。此外，物种相对不稳定性与物种相对生产力呈负相关，且斜率随 N 添加而增加，这表明 N 添加削弱了优势种对生态系统功能的稳定作用。总体而言，我们的结果强调了在 N 添加下，优势种控制着草原生态系统 ANPP 的时间稳定性，并支持“优势种管理”作为保护 N 沉降下草原生态系统功能的有效策略。
