College of Resources and Environmental Sciences, Key Laboratory of Plant-Soil Interactions of MOE and Beijing Key Laboratory of Farmland Pollution Prevention and Remediation, China Agricultural University, Beijing, 100193, China.
Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, Sichuan, 610041, China.
Ecol Appl. 2018 Jan;28(1):237-248. doi: 10.1002/eap.1647. Epub 2017 Dec 27.
Atmospheric nitrogen (N) deposition has been shown to decrease biodiversity and change nutrient cycles in terrestrial ecosystems. However, our understanding of ecological responses to chronic N addition and ecological recovery of grassland from N enrichment is limited. Here we present evidence from an 11-year grassland experiment with a range of N addition rates (0, 30, 60, 120, 240, and 480 kg N·ha ·yr ) in Inner Mongolia, China. Chronic N addition led to a reduction in species richness, Shannon diversity index, and soil pH and an increase in aboveground biomass, foliar N, and soil mineral N. High N addition rates (240 and 480 kg N·ha ·yr ) showed significant effects in the first and second years, which stabilized over time. Nitrogen addition at low rates (30 and 60 kg N·ha ·yr ) took longer (e.g., three years or more) to achieve significant effects. The negative impacts of high N addition (480 kg N·ha ·yr ) were reduced and species richness, Shannon diversity index, and soil pH showed a limited but rapid recovery with the cessation of N addition. Our findings suggest serious and cumulative impacts of N addition on plant and soil communities but the potential for partial system recovery over time if N inputs decline or cease.
大气氮（N）沉降已被证明会降低陆地生态系统的生物多样性并改变养分循环。然而，我们对长期氮添加的生态响应以及草原从富氮中恢复的生态理解是有限的。在这里，我们提供了来自中国内蒙古为期 11 年的草地实验的证据，该实验涉及一系列氮添加率（0、30、60、120、240 和 480 kg N·ha·yr）。慢性氮添加导致物种丰富度、香农多样性指数和土壤 pH 值降低，地上生物量、叶片 N 和土壤矿质 N 增加。高氮添加率（240 和 480 kg N·ha·yr）在第一和第二年表现出显著影响，随着时间的推移而稳定。低氮添加率（30 和 60 kg N·ha·yr）需要更长的时间（例如三年或更长时间）才能达到显著影响。高氮添加（480 kg N·ha·yr）的负面影响减少，随着氮添加的停止，物种丰富度、香农多样性指数和土壤 pH 值表现出有限但快速的恢复。我们的研究结果表明，氮添加对植物和土壤群落产生了严重且累积的影响，但如果氮输入减少或停止，系统可能会随着时间的推移而部分恢复。
