Shi Linlu, Wang Yuyu, Jia Yifei, Lu Cai, Lei Guangchun, Wen Li
School of Nature Conservation, Beijing Forestry University, Beijing, China.
Water, Wetlands and Coastal Science Branch, NSW Office of Environment and Heritage, Sydney, NSW, Australia.
Front Plant Sci. 2017 Dec 22;8:2196. doi: 10.3389/fpls.2017.02196. eCollection 2017.
Floodplain wetlands are valuable ecosystems for maintaining biodiversity, but are vulnerable to hydrological modification and climatic extremes. The floodplain wetlands in the middle Yangtze region are biodiversity hotspots, particularly important for wintering migratory waterbirds. In recent years, extremely low winter water level events frequently occurred in the middle Yangtze River. The hydrological droughts greatly impacted the development and distribution of the wet meadows, one of the most important ecological components in the floodplains, which is vital for the survival of many migratory waterbirds wintering in the Yangtze region. To effectively manage the wet meadows, it is critical to pinpoint the drivers for their deterioration. In this study, we assessed the effects of hydrological connectivity on the ecological stability of wet meadow in Poyang Lake for the period of 2000 to 2016. We used the time series of MODIS EVI (Enhanced Vegetation Index) as a proxy for productivity to infer the ecological stability of wet meadows in terms of resistance and resilience. Our results showed that (1) the wet meadows developed in freely connected lakes had significantly higher resilience; (2) wet meadows colonizing controlled lakes had higher resistance to water level anomalies; (3) there was no difference in the resistance to rainfall anomaly between the two types of lakes; (4) the wet meadow in freely connected lakes might approach a tipping point and a regime shift might be imminent. Our findings suggest that adaptive management at regional- (i.e., operation of Three Gorges Dam) and site-scale (e.g., regulating sand mining) are needed to safeguard the long-term ecological stability of the system, which in term has strong implications for local, regional and global biodiversity conservation.
洪泛平原湿地是维护生物多样性的重要生态系统，但易受水文变化和极端气候影响。长江中游地区的洪泛平原湿地是生物多样性热点地区，对越冬候鸟尤为重要。近年来，长江中游冬季水位极低的情况频繁发生。水文干旱对洪泛平原最重要的生态组成部分之一——湿草甸的发育和分布产生了极大影响，而湿草甸对许多在长江地区越冬的候鸟的生存至关重要。为了有效管理湿草甸，找出其退化的驱动因素至关重要。在本研究中，我们评估了2000年至2016年期间水文连通性对鄱阳湖湿草甸生态稳定性的影响。我们使用MODIS增强植被指数（EVI）的时间序列作为生产力的替代指标，从抵抗力和恢复力方面推断湿草甸的生态稳定性。我们的结果表明：（1）在自由连通湖泊中发育的湿草甸具有显著更高的恢复力；（2）在受控湖泊中形成的湿草甸对水位异常具有更高的抵抗力；（3）两种类型湖泊对降雨异常的抵抗力没有差异；（4）自由连通湖泊中的湿草甸可能接近临界点，即将发生状态转变。我们的研究结果表明，需要在区域尺度（即三峡大坝的运行）和场地尺度（例如规范采砂）上进行适应性管理，以保障该系统的长期生态稳定性，这对本地、区域和全球生物多样性保护具有重要意义。
