Wang Xinxin, Xiao Xiangming, Zhang Xi, Wu Jihua, Li Bo
Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, Shanghai, China.
Department of Microbiology and Plant Biology, Center for Earth Observation and Modeling, University of Oklahoma, Norman, Oklahoma, USA.
Glob Chang Biol. 2023 Apr;29(8):2286-2300. doi: 10.1111/gcb.16583. Epub 2023 Jan 18.
Coastal wetlands provide essential ecosystem goods and services but are extremely vulnerable to sea-level rise, extreme climate, and human activities, especially the coastal wetlands in large river deltas, which are regarded as "natural recorders" of changes in estuarine environments. In addition to the area (loss or gain) and quality (degradation or improvement) of coastal wetlands, the information on coastal wetland structure (e.g., patch size and number) are also major metrics for coastal restoration and biodiversity protection, but remain very limited in China's four major river deltas. In this study, we quantified the spatial-temporal dynamics of total area (TA) and patch number (PN) of coastal wetlands with different sizes in the four deltas and the protected areas (PAs) and assessed the effects of major driving factors during 1984-2020. We also investigated the effectiveness of PAs through the comparison of TA and PN of coastal wetlands before and after the years in which PAs were listed as Ramsar Sites. We found both TA and PN experienced substantial losses in the Liaohe River Delta and Yellow River Delta but recent recoveries in the Yangtze River Delta. The coastal wetlands had a relatively stable and variable trend in TA but had a continually increasing trend in PN in the Pearl River Delta. Furthermore, reduced coastal reclamation, ecological restoration projects, and rapid expansion of invasive plants had great impacts on the coastal wetland structure in various ways. We also found that PAs were effective in halting the decreasing trends in coastal wetland areas and slowing the expansion of reclamation, but the success of PAs is being counteracted by soaring exotic plant invasions. Our findings provide vital information for the government and the public to address increasing challenges of coastal restoration, management, and sustainability in large river deltas.
沿海湿地提供重要的生态系统产品和服务，但极易受到海平面上升、极端气候和人类活动的影响，尤其是大型河流三角洲的沿海湿地，它们被视为河口环境变化的“天然记录者”。除了沿海湿地的面积（损失或增加）和质量（退化或改善）外，沿海湿地结构信息（如斑块大小和数量）也是沿海生态恢复和生物多样性保护的主要指标，但在中国四大河流三角洲地区仍然非常有限。在本研究中，我们量化了四大三角洲和保护区内不同规模沿海湿地的总面积（TA）和斑块数量（PN）的时空动态，并评估了1984 - 2020年期间主要驱动因素的影响。我们还通过比较沿海湿地在被列为拉姆萨尔湿地前后的TA和PN，研究了保护区的有效性。我们发现，辽河三角洲和黄河三角洲的TA和PN都经历了大幅损失，但长江三角洲最近有所恢复。珠江三角洲的沿海湿地TA呈相对稳定且有变化的趋势，而PN呈持续增加的趋势。此外，减少围垦、生态恢复项目以及入侵植物的快速扩张对沿海湿地结构产生了多方面的重大影响。我们还发现，保护区有效地遏制了沿海湿地面积的下降趋势，并减缓了围垦的扩张，但保护区的成效正被外来植物入侵的激增所抵消。我们的研究结果为政府和公众应对大型河流三角洲地区沿海生态恢复、管理和可持续发展日益增加的挑战提供了重要信息。
