State Key Laboratory of Grassland Agro-ecosystems, Gannan Grassland Ecosystem National Observation and Research Station, College of Ecology, Lanzhou University, Lanzhou 730000, Gansu, China.
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstrasse 4, 04103 Leipzig, Germany.
Sci Total Environ. 2022 Aug 20;835:155419. doi: 10.1016/j.scitotenv.2022.155419. Epub 2022 Apr 26.
Terrestrial ecosystems are under threat by the co-occurring biodiversity loss and nitrogen (N) deposition. Awareness is growing that the stabilizing effects of plant diversity on productivity depend on environmental context, but it remains unknown about how the loss of plant functional groups and N deposition interactively influence species richness and community stability. Here we carried out an eight-year experiment of plant functional groups removal and N addition experiment in subalpine meadow. We found that the removal of plant functional groups and N addition interactively affected averaged plant species richness and community stability. Without N addition, the absence of forbs, but not other functional groups, significantly decreased average species richness and community stability through decreasing species asynchrony (i.e., asynchronous dynamics among species under fluctuating conditions). Under N addition, the absence of forbs, grasses and legumes all led to significant declines in average species richness, causing a decrease in community stability by decreasing species asynchrony, among which the absence of forbs had the greatest negative effects on community stability. Moreover, N addition reinforced the destabilizing effects caused by the loss of functional groups. Our findings show that the diverse forbs maintain plant community stability through asynchronous dynamics among species, especially under N deposition scenario. Therefore, we suggest that conservation and restoration of plant communities and their stability would benefit from a functional-group specific strategy by considering the largely ignored forb species, while helps guide conservation management efforts to reduce temporal variability for ecosystem service in the face of uncertain species extinction and N deposition scenarios.
陆地生态系统受到生物多样性丧失和氮（N）沉积的共同威胁。人们越来越意识到，植物多样性对生产力的稳定作用取决于环境背景，但仍不清楚植物功能群的丧失和 N 沉积如何相互影响物种丰富度和群落稳定性。在这里，我们进行了为期八年的亚高山草甸植物功能群去除和 N 添加实验。我们发现，植物功能群的去除和 N 添加相互作用，显著影响了平均植物物种丰富度和群落稳定性。在没有 N 添加的情况下，没有草本植物，但不是其他功能群，通过降低物种的异步性（即在波动条件下物种之间的异步动态）显著降低了平均物种丰富度和群落稳定性。在 N 添加的情况下，没有草本植物、禾本科植物和豆科植物都会导致平均物种丰富度显著下降，通过降低物种异步性导致群落稳定性下降，其中没有草本植物对群落稳定性的负面影响最大。此外，N 添加增强了功能群丧失引起的不稳定性。我们的研究结果表明，多样的草本植物通过物种之间的异步动态维持植物群落的稳定性，尤其是在 N 沉积情景下。因此，我们建议，通过考虑到被广泛忽视的草本物种，采用特定功能群的策略来保护和恢复植物群落及其稳定性，同时有助于指导保护管理工作，以减少在物种不确定灭绝和 N 沉积情景下对生态系统服务的时间变异性。
