摘要
海草床是近岸高生产力的生态系统之一,具有巨大的碳储潜力,是“蓝碳”的重要组成.海草床生态系统中的有机碳大部分存储于沉积物,其沉积物有机碳(sediment organic carbon,SOC)存储是“蓝碳”功能的重要体现.受多重压力的影响,全球海草床急剧衰退,导致其SOC储存潜力下降.近年来,通过海草床修复来恢复其碳存储或扩增其碳汇能力逐渐受到重视,对于延缓气候变化具有重要意义.本文综述了海草床退化与修复对其SOC的影响过程.研究表明,海草床退化会导致海草源碳的贡献减少,捕获颗粒有机物和阻止颗粒物再悬浮的能力下降,进而直接降低海草床SOC储量;此外,海草床退化通过改变沉积物中的微环境,加快SOC的转化,间接减少已存储SOC的量.海草床修复是提升碳储存潜力的有效手段,可以增加海草植株碳对SOC的贡献,其海草群落形成的复杂冠层结构可以减缓水流速度,从而捕获更多细粒径的悬浮颗粒物.同时,海草床修复还可改变微生物群落,从而抑制SOC的再矿化,最终恢复甚至提高海草床的储碳功能.在此基础之上,本文提出未来的研究重点:(1)研究人类活动和气候变化多因子联合作用对海草床SOC储存的影响过程;(2)阐释海草床退化对SOC稳定性的影响机制;(3)探索海草床SOC的组分和转化过程对修复的响应;(4)构建基于SOC储量提升的海草床修复技术体系.
Seagrass meadows are important coastal ecosystems with high levels of productivity.They generally have significant carbon storage potential and are important components of“blue carbon”.Seagrass ecosystems can store up to 19.9 Pg organic carbon,more than 90%of which is stored in sediments.Protecting the organic carbon stored in seagrass meadows sediments is therefore considered an important means of mitigating climate change.Unfortunately,approximately 29%of seagrass meadows have disappeared due to the influence of human activities and global climate change.They have been declining at a rate of 7%per year since 1990,resulting in the release of up to 299 Tg of carbon per year.The restoration of seagrass meadows has become one of the most important means for mitigating the continuing loss of seagrass habitat and preventing them from being a significant carbon source.A systematic review of relevant national and international research was conducted to summarize the response processes and mechanisms of sediment organic carbon(SOC)during seagrass meadow degradation and restoration.Seagrass biomass carbon is an important source of SOC.However,eutrophication and ocean warming have important negative impacts on seagrass biomass carbon,thereby reducing its contribution to SOC.Suspended particulate matter contributes approximately 70%to SOC,but the increasing patchiness and fragmentation of seagrass meadows significantly reduces its capture by the seagrass canopy.This significantly decreases the sedimentation of suspended particulate matter.Furthermore,the degradation of seagrass meadows could lead to the exposure of bare sediments and deep sediments to human activities and wind waves,which would alter the microbial environment of sediments and induce the remineralization of SOC.All of these directly or indirectly reduce the carbon storage and carbon sequestration capacity of seagrass meadows.Recently,the response of SOC to a single disturbance factor has been estimated,but the uncertainties of multiple factors remain.In the future,the comprehensive interference of human activities and global climate change will drive SOC trends.Approximately 68%of the global seagrass restoration experiments have been concentrated on the temperate and subtropical coasts of the Northern Hemisphere.The main restoration methods are habitat restoration,seeding,and plant transplantation,all of which can effectively increase the carbon storage potential of seagrass meadow sediments.Seagrass shoot density is the key driver of seagrass primary productivity and the most significant indicator of changes in the restoration process.It is closely related to the aboveground biomass of seagrass.Rapid plant recovery after disturbance is the key to minimizing blue carbon net loss in seagrass meadows.Increasing the density of seagrass shoots would increase the complexity of the seagrass canopy.On the one hand,this is beneficial for trapping suspended particulate matter.On the other hand,it can effectively reduce the flow of seawater,thus promoting the sedimentation of suspended solids and increasing their contribution to SOC.The microbial environment of the sediment changes during the restoration process,which can weaken the remineralization of organic carbon and enable the storage of SOC for a long time.As the most widespread area seagrass area in China,the seagrass meadows in South China are severely degraded and SOC has not yet been systematically studied.Several key points of research on the response mechanisms of seagrass meadow SOC to degradation and restoration were proposed.(1)To determine the comprehensive contributions of human activities and climate change to SOC storage in seagrass meadows.(2)To elucidate the mechanism of seagrass meadow degradation influence on SOC stability.(3)To investigate the effects of seagrass restoration on the composition(labile organic carbon and recalcitrant organic carbon)and transformation process of SOC.(4)To develop a technical system for seagrass restoration based on the enhancement of SOC storage.Such studies based on local seagrass ecosystems will contribute to improving research on the global seagrass carbon storage system.
作者
任玉正
刘松林
罗红雪
江志坚
吴云超
黄小平
Yuzheng Ren;Songlin Liu;Hongxue Luo;Zhijian Jiang;Yunchao Wu;Xiaoping Huang(Key Laboratory of Tropical Marine Bio-resources and Ecology,South China Sea Institute of Oceanology,Chinese Academy of Sciences,Guangzhou 510301,China;Sanya Institute of Ocean Eco-Environmental Engineering,Sanya 572100,China;Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences,Guangzhou 510301,China;Guangdong Provincial Key Laboratory of Applied Marine Biology,Guangzhou 510301,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2023年第22期2961-2972,共12页
Chinese Science Bulletin
基金
国家自然科学基金(U1901221,42176155)
中国科学院青年创新促进会项目(2023359)、中国科学院南海生态环境工程创新研究院自主部署项目(ISEE2021PY06,ISEE2021ZD03)资助
海南省科技专项(ZDYF2020180,ZDYF2021SHFZ254)
广东省应用海洋生物学重点实验室运行经费(2020B1212060058)。
关键词
海草床退化
海草床修复
蓝碳
沉积物有机碳
碳汇
seagrass degradation
seagrass restoration
blue carbon
sediment organic carbon
carbon sinks
