2010—2018碳收支的变化分析年海南东寨港红树林湿

红树林生态系统在全球气候变化和碳循环过程中发挥着很重要的作用,准确评估红树林湿地的碳收支,对于保护和恢复海洋蓝色碳汇以及全球气候治理工作具有重要的意义。本研究以海南东寨港国家级自然保护区的红树林湿地为研究对 象,采用 《对 2006 IPCC 国家温室气体清单指南的 2013 增补：湿地》 （简称 《湿地指南》） 中的计算方法,利用野外现场调查数据及已有的研究成果作为参数,评估和量化海南东寨港红树林湿地在 2010—2018 年期间的碳收支情况。研究表明：（1） 2010 年红树林面积为 1 627.21 hm2,全部为成熟红树林,碳储量为 5.85*105t C;2018 年红树林面积为 1 665.42 hm2,其中 1 625.84 hm2为成熟红树林,碳储量为 6.71*105t C,39.58 hm2为过渡期红树林,碳储量为 4.36*103t C,总碳储量为6.75*105t C。 （2） 2010—2018 年期间红树林碳储量增加了 9.0*104t C。另外,有 1.37 hm2的红树林湿地退化为水域,释放了81.36 t 的碳储量。因此,2010—2018 年期间东寨港红树林湿地碳收支为+8.99*104t C,整体上表现为净碳汇生态系统。本研究结果可为气候变化背景下海南红树林湿地的保护与恢复、风险评估以及气候治理提供科学参考。     

河口红树林湿地CH_4通量的日变化研究

１引言 甲烷（ＣＨ４）是大气中除 ＣＯ２外最为丰富的含碳组分,其浓度以每年 ０． ７％－ １． １％的速率递增［１,２］．尽管大气 ＣＨ４含量仅为 ＣＯ２的二百分之一,但却对预计的全球变暖约有 ２０％的贡献率,而ＣＯ２的贡献率约为５０％［３,４］,由这些数据推算得一个分子的ＣＨ４比一个分子的ＣＯ２（目前最重要的温室气体）的增暖潜值高约８０倍． 很多研究者对全球大气ＣＨ４的预算结果均表明,湿地是大气 ＣＨ４最重要的生物源［５,６］,约占全球 ＣＨ４源的 ４０％～５０％［７］．湿地 ＣＨ４通量的日变化研究是正确估…     

基于无人机航测的红树林潮滩地貌高程反演

红树林潮滩地貌高程的变化直接影响红树林生长发育。精确快速获取潮滩地貌高程动态变化过程,对实施红树林培育与造林意义重大。然而,受限于潮水涨落、潮滩易陷及红树林区难以深入等因素,红树林潮滩地貌的高程获取成为当前备受关注的难点。基于此,本文以广西北部湾北部北仑河口为例,利用DJI Phantom 4 RTK无人机对区域进行多高度、多架次航测,以Structure from Motion(SFM)算法为核心反演该区域的红树林潮滩地貌高程,探讨影响高程反演精度的因素,进而拟合出一套误差修正关系式,并以钦江与南流江河口红树林潮滩为应用对象验证该关系式的适用性。结果表明：(1)无人机飞行高度直接影响高程提取精度,其中飞行高度越高,提取的地貌高程误差越大,飞行高度约在110 m时更能兼顾航测用时和高程提取精度;(2)无人机航测提取的潮滩地貌高程值与RTK测量值存在较为显著的垂向平移偏差关系,提取值普遍高于RTK测量值,基于此提出了修正关系式,实现了对不同飞行高度的高程提取值的修正,显著提高了其精度,且关系式有较好的适用性和普适性;(3)植被覆盖度是无人机提取潮滩地貌高程的重要影响因子,植被覆盖度越高,...     

海南岛东北部中全新世以来红树林的演化

通过对海南岛东寨港,清澜港,福田三个剖面的孢粉研究,从红树植物花粉数量的变化,对海南岛东北部海滩自中全新世以来的红树林演化作了分析,这为恢复古环境及今后红树林的演变及开发提供了有价值的资料。     

河口红树林湿地CH4通量的日变化研究

甲烷(CH₄)是大气中除CO₂外最为丰富的含碳组分,其浓度以每年0.7%-1.1%的速率递增[1,2].尽管大气CH₄含量仅为CO₂的二百分之一,但却对预计的全球变暖约有20%的贡献率,而CO₂的贡献率约为50%[3,4],由这些数据推算得一个分子的CH₄比一个分子的CO₂(目前最重要的温室气体)的增暖潜值高约80倍.很多研究者对全球大气CH₄的预算结果均表明,湿地是大气CH₄最重要的生物源[5,6],约占全球CH₄源的40%～50%[7].湿地CH₄通量的日变化研究是正确估算大时间尺度下CH₄排放量(如平均年排放量和季节排放量)的基础,因而具有相当的重要性.     

气候变化背景下海南东寨港红树林生态系统的脆弱性评估

鉴于红树林生态系统对气候变化背景下海平面上升和极端台风事件有高度敏感性,应用1980—2018年的海洋大气观测资料和实地调查数据,分析了海口东寨港地区的海平面、温度和台风最大风速的变化特征,并基于IPCC气候变化综合风险的理论框架,构建了"暴露度-敏感性-适应性"的脆弱性评价指标体系和估算方法,评估了海平面上升和台风事件背景下东寨港红树林生态系统的脆弱性主要特征。结果显示:①东寨港红树林生态系统的致灾影响因子主要为该地区沿海海平面的快速上升,其上升速率可达4. 6 mm/a,远高于全球和中国沿海平均值;其次为1993年之前和2006年之后,在海口地区250 km范围内出现的热带气旋或台风事件;②东寨港红树林脆弱性指数的平均值为0. 31,属于中度脆弱等级,其中三江片区的红树林脆弱性相对最高,演丰片区最低。构建的评价指标体系可较好地反映出海平面快速上升和热带气旋或台风影响下红树林生态系统的脆弱性特征。     

全球气候变化对红树林生态系统的影响、挑战与机遇

红树林是以红树植物为主体的常绿灌木或乔木组成的潮滩湿地木本植物群落, 具有“四高”特性(高生产力、高归还率、高分解率和高抗逆性)的典型海洋生态系统; 目前, 全球约有红树林1700万公顷, 主要分布在南北半球25℃等温线内。红树林生态系统的净初级生产力高达2000gC·m^-2·a^-1, 具有高强度的物质循环、能量流动以及丰富的生物多样性, 对热带、亚热带海洋生态系统的维持与发展起到关键作用, 并在全球变化过程中扮演着十分重要的角色。近30年来, 全球气候变化已引起了国内外学者的极大关注。红树林生态系统位于热带、亚热带海岸潮间带, 是一个脆弱的、敏感的生态系统, 也是首先受全球气候变化影响的典型海洋生态系统之一。作为全球海岸带地区应对全球气候变化最为重要的生态屏障之一, 气候变化将严重影响着全球红树林的生存和分布方式。本文将从全球变暖、海平面上升、大气中CO₂浓度的增加和极端天气4个主要方面, 揭示全球气候变化对红树林生态系统的影响与变化特征, 阐述红树林对全球变暖、海平面上升、大气中CO₂浓度增加和极端天气响应与适应的生态学机制, 并简要概述了红树林在减缓全球气候变化危害中的重要作用。全球气候变化也将为红树林的研究、保护和发展带来机遇与挑战。     

广西钦州湾晚全新世红树林演变及对海平面变化的响应

Mangroves, widely distributed along the coasts of tropical China, are influenced by Asia monsoon, relative sea level change and enhanced human activity. To predict the impacts of future climate change on mangrove ecosystems, it can be understood by reconstructing past mangrove dynamics using proxies preserved in coastal sediments. In this study, we quantitatively partitioned buried organic matter(OM) sources, collected from a vulnerable mangrove swamp in the Qinzhou Bay of northwestern South China Sea, using a ternary end-member mixing model of δ~(13)C and C:N values. Mangrove-derived OM(MOM) contribution was used as a tracer for mangrove development since 2.34 cal ka BP. This information, together with paleoclimate records(i.e.,speleothem δ~(18)O values, sea level change, grain size parameters) and human activity, was used to divide mangrove development into three stages during the late Holocene: relative flourish(2.34–1.13 cal ka BP), relative degradation(1.13–0.15 cal ka BP) and further degradation(0.15–0 cal ka BP). Before 1.13 cal ka BP, mangroves flourished with a high MOM contribution((88.9±10.6)%), corresponding to stable and high sea level under a warm and humid climate. After 1.13 cal ka BP, rapid fall in relative sea level coupled with the strengthening of the Asian winter monsoon, resulted in mangrove degradation and MOM reduction((62.4±18.9)%). Compared with air temperature and precipitation, the relative sea level fall was the main controlling factor in mangrove development before entering the Anthropocene(the time of the Industrial Revolution). After ～150 cal a BP, reclamation of mangrove swamps to shrimp ponds is the main factor causing mangrove degradation and MOM reduction.     

Mangrove forests: Resilience,protection from tsunamis,and responses to global climate change

This review assesses the degree of resilience of mangrove forests to large, infrequent disturbance (tsunamis) and their role in coastal protection, and to chronic disturbance events (climate change) and the future of mangroves in the face of global change. From a geological perspective, mangroves come and go at considerable speed with the current distribution of forests a legacy of the Holocene, having undergone almost chronic disturbance as a result of fluctuations in sea-level. Mangroves have demonstrated considerable resilience over timescales commensurate with shoreline evolution. This notion is supported by evidence that soil accretion rates in mangrove forests are currently keeping pace with mean sea-level rise. Further support for their resilience comes from patterns of recovery from natural disturbances (storms, hurricanes) which coupled with key life history traits, suggest pioneer-phase characteristics. Stand composition and forest structure are the result of a complex interplay of physiological tolerances and competitive interactions leading to a mosaic of interrupted or arrested succession sequences, in response to physical/chemical gradients and landform changes. The extent to which some or all of these factors come into play depends on the frequency, intensity, size, and duration of the disturbance. Mangroves may in certain circumstances offer limited protection from tsunamis; some models using realistic forest variables suggest significant reduction in tsunami wave flow pressure for forests at least 100 m in width. The magnitude of energy absorption strongly depends on tree density, stem and root diameter, shore slope, bathymetry, spectral characteristics of incident waves, and tidal stage upon entering the forest. The ultimate disturbance, climate change, may lead to a maximum global loss of 10–15% of mangrove forest, but must be considered of secondary importance compared with current average annual rates of 1–2% deforestation. A large reservoir of below-ground nutrients, rapid rates of nutrient flux and microbial decomposition, complex and highly efficient biotic controls, self-design and redundancy of keystone species, and numerous feedbacks, all contribute to mangrove resilience to various types of disturbance.     

Topographical Mapping of a Bare Tidal Flat Outside a Mangrove Area based on the Waterline Method and an Iterative Hydrodynamic Model: A Case Study of Yingluo Bay,South China

A change in the elevation of bare tidal flats outside a mangrove area is an indispensable factor for the sustainable development of mangroves. Waterline extraction, as an effective and economical tool used in reconstructing the terrain of an intertidal zone, has been widely applied to open-coast tidal flats by constructing a digital elevation model (DEM). However, mangrove wetlands are usually located in wave-sheltered sites, such as estuaries and bays that have narrow tidal channels flanked by tidal flats. Changes in water level are affected by the dry-wet processes of complex landforms caused by tides. This article takes as a study case the area of Yingluo Bay, which covers the core region of the Zhanjiang and Shankou National Mangrove National Nature Reserve in southwestern China. Waterline extraction based on seventeen multisource and multispectral satellite images obtained from December 2014 to April 2015, combining the finite-volume coastal ocean model (FVCOM) hydrodynamic model in an iterative process, was used to generate a topographical map of the bare tidal flat outside the mangrove area in Yingluo Bay. The quality of the iterative DEMs was evaluated via six transects of a ground-based survey using Real - time kinematic (RKT) GPS in May 2015. The mean absolute error (MAE) and root mean square error (RMSE) of the DEM decreased with an increase in the number of iterations. In this study, the DEM in the third iteration was used as the final output because the difference from the previous iterative DEM satisfied an inversion-stopping criterion. The MAE and RMSE of the final DEM with the measured data were 0.072 and 0.09?m, respectively, without considering small tidal creeks. The method used in this study can be an effective and highly precise approach for detecting and reconstructing the historical terrain of a bare tidal flat outside a mangrove area. This work also has great importance regarding intertidal resource management and the sustainable development of mangroves facing the vulnerable coastal ecological environment.     

胶州湾大沽河口小型底栖动物分布的季节变动

Sediment samples were collected in the intertidal zone of the Dagu River Estuary, Jiaozhou Bay, China in April,July and October 2010 and February 2011 for examining seasonal dynamics of meiofaunal distribution and their relationship with environmental variables. A total of ten meiofaunal taxa were identified, including free-living marine nematodes, benthic copepods, polychaetes, oligochaetes, bivalves, ostracods, cnidarians, turbellarians,tardigrades and other animals. Free-living marine nematodes were the most dominant group in both abundance and biomass. The abundances of marine nematodes were higher in winter and spring than those in summer and autumn. Most of the meiofauna distributed in the 0–2 cm sediment layer. The abundance of meiofauna in hightidal zone was lower than those in low-tidal and mid-tidal zones. Results of correlation analysis showed that Chlorophyll a was the most important factor to influence the seasonal dynamics of the abundance, biomass of meiofauna and abundances of nematodes and copepods. CLUSTER analysis divided the meiofaunal assemblages into three groups and BIOENV results indicated that salinity, concentration of organic matter, sediment sorting coefficient and sediment median diameter were the main environmental factors influencing the meiofaunal assemblages.     

高分辨率风场对长江口海域波浪场模拟能力的影响研究——以台风“灿都”为例

长江口海域岛屿众多, 地形复杂多变, 对灾害性海浪模拟和预报能力的提升有迫切需求。本研究基于长江口高分辨率非结构网格海浪模式SWAN(Simulating WAve Nearshore), 结合“两洋一海”区域耦合预报系统模拟风场, 以2021年第14号台风“灿都”为例, 研究了台风轨迹、台风移速和台风风场分辨率等对长江口及邻近海域海浪模拟和预报的影响。结果表明: 风场模型水平分辨率增加有利于台风细结构和台风悬臂状结构的模拟。分辨率增加, 风速整体呈减弱趋势, 但在台风中心(小于两倍最大风速半径)和外围悬臂区域风速增加显著。风场分辨率从27 km提升至9 km和3 km, 波浪模拟精度增加显著, 3 km风场驱动的波浪模拟精度最高, 继续提升风场分辨率至1 km对波浪模拟无明显提升。改变风场模型分辨率同时会影响台风路径和移动速度。波浪场的差异反映了台风结构、路径和移动速度的共同影响, 由于波浪的波动传播属性, 台风浪的差异一般比风场差异的范围更大。     

滩涂水边线Landsat-5影像提取方法

快速获取遥感影像水边线时空变化信息具有重要意义,滩涂水边线提取一直是遥感技术应用的难点问题。水边线在遥感影像上具有独特的空间关系与光谱特征。本文综合使用颜色模型变换法、信息熵计算法、最大类间方差法及边缘检测方法。以长江口崇明东滩为研究区,研究了Landsat-5卫星影像海陆对比度增强及不同尺度下的边缘提取,重点给出了基于热红外波段的水边线空间特征与光谱特征的计算方法,在面向对象技术框架下提出了一种顾及空间关系和光谱特征的遥感影像水边线快速提取方法。实验结果表明:(1)基于最大类间方差法的局部阈值分割法能够自动提取band 6的水边线,水边线连续、完整,空间信息丰富;(2)综合使用最佳指数法、离散度方法及颜色模型变换方法,能够有效增强海陆对比度,基于最大类间方差法的局部自适应Canny算子能够自动检测出增强后遥感影像高精度边缘;(3)利用水边线的空间关系和光谱特征,能够由计算机自动实现水边线的识别与连接工作;(4)本文提出的水边线提取方法速度快、自动化程度高,分别继承了阈值分割法的连续性强的优点和Canny算子定位精度高、细节呈现能力强的优势。研究结果对于海岸带动态变化、陆海相互作用机制、海岸带资源保护与开发及近海工程管理等研究具有重要的参考价值。     

滩涂水边线Landsat-5影像提取方法以长江口崇明东滩为例

快速获取遥感影像水边线时空变化信息具有重要意义,滩涂水边线提取一直是遥感技术应用的难点问题。水边线在遥感影像上具有独特的空间关系与光谱特征。本文综合使用颜色模型变换法、信息熵计算法、最大类间方差法及边缘检测方法。以长江口崇明东滩为研究区,研究了Landsat-5卫星影像海陆对比度增强及不同尺度下的边缘提取,重点给出了基于热红外波段的水边线空间特征与光谱特征的计算方法,在面向对象技术框架下提出了一种顾及空间关系和光谱特征的遥感影像水边线快速提取方法。实验结果表明：(1)基于最大类间方差法的局部阈值分割法能够自动提取band 6的水边线,水边线连续、完整,空间信息丰富;(2)综合使用最佳指数法、离散度方法及颜色模型变换方法,能够有效增强海陆对比度,基于最大类间方差法的局部自适应Canny算子能够自动检测出增强后遥感影像高精度边缘;(3)利用水边线的空间关系和光谱特征,能够由计算机自动实现水边线的识别与连接工作;(4)本文提出的水边线提取方法速度快、自动化程度高,分别继承了阈值分割法的连续性强的优点和Canny算子定位精度高、细节呈现能力强的优势。研究结果对于海岸带动态变化、陆海相互作用机制、海岸带资源保护与开发及近海工程管理等研究具有重要的参考价值。     

淤泥质潮滩剖面冲淤演变数值模拟分析——以河北省沧州市为例

为全面剖析淤泥质潮滩变化规律及演变特征,运用修改后的输沙公式建立了淤泥质潮滩演变数值模型。经2000,2007年野外实测数据验证,表明该模型各参数设置准确,较真实地反演了滩涂剖面变化过程,可用于淤泥质潮滩的模拟计算。根据数值模型计算结果得出如下结论:1987-2010年河北省沧州市淤泥质潮滩坡度不断增大,但增长速率变化不大,为0.002×10-3。0 m等深线上部坡度逐渐变缓,年均降低0.021×10-3;下部坡度不断变陡,年均增长0.022×10-3。研究区潮滩未达平衡状态,其坡度将进一步变陡。该输沙模型及研究结论对淤泥质潮滩的保护具有重要的理论指导意义,为其科学开发管理提供实际参考依据。     

全新世大暖气广西钦州湾红树林衰退的红树林源有机质贡献示踪及其对亚洲季风的响应

The response of mangrove ecosystems to the Asian monsoon in the future global warming can be understood by reconstructing the development of mangrove forests during the Holocene climatic optimum(HCO), using proxies preserved in coastal sediments. The total organic matter in sediments of a segmented core, with calibrated age ranges between 5.6 and 7.7 cal. ka BP and corresponding to the HCO, from the Qinzhou Bay in Guangxi, China, is quantitatively partitioned into three end-members according to their sources: mangrove-derived, terrigenous,and marine phytoplanktonic, using a three-end-member model depicted by organic carbon isotope(δ13Corg) and the molar ratio of total organic carbon to total nitrogen(C/N). The percentage of mangrove-derived organic matter(MOM) contribution is used as a proxy for mangrove development. Three visible drops in MOM contribution occurred at ca. 7.3, ca. 6.9, and ca. 6.2 cal. ka BP, respectively, are recognized against a relatively stable and higher MOM contribution level, indicating that three distinct mangrove forest degradations occurred in the Qinzhou Bay during the HCO. The three mangrove forest degradations approximately correspond to the time of the strengthened/weakened Asian winter/summer monsoon. This indicates that even during a period favorable for the mangrove development, such as the HCO, climatic extremes, such as cold and dry events driven by the strengthened/weakened Asian winter/summer monsoon, can trigger the degradation of mangrove forests.     

Hydrodynamics and sedimentation induced by large-scale coastal developments in the Keum River Estuary, Korea

The macro-tidal Keum River Estuary located in the eastern Yellow Sea has been suffering siltation and morphological change since 1994. To understand the effects of the large-scale coastal developments on the sedimentation processes in the estuary, hydrodynamic and sedimentary data collected from 1985 to 2002 were analyzed and numerical experiments of hydrodynamics were performed. The sedimentation rate in the estuary increased by a factor of 1.9, from 3.5 × 10⁶ to 6.7 × 10⁶ m³ y⁻¹, after the construction of a dam in the upper reaches of the estuary in 1994. Large part of the estuary is veneered by the muddy sediments noticeably, which were rarely found before dam construction. Since then, siltation has concentrated in the upper estuary rather than the lower. The upstream transport and accumulation of fine-grained sediments is due to: (1) the change to flood-dominance in the main channel, i.e. the relative intensification of flood current and the flood-directed residual current; and (2) the decrease in transport capacity in the upper estuary, i.e. the marked decrease in current velocity, which was induced by dam construction. The former has resulted in the ebb-dominance of the Gaeya channel, a distributary in the north of the main channel. The tidal pumping of fine sediments was reinforced not by the freshwater/saltwater interaction but by the residual tidal circulation. The sediment fluxes observed in 2001–2002 demonstrate year-round net inflow both at the entrance of the jetties and at the Gaeya channel, which implies that the sediments delivered by the Keum River are entirely confined to the estuary, incapable of escaping to the sea. The net inward transport of fine sediments may accumulate pollutants adsorbed to or absorbed in the sediment grains in the estuary, thus deteriorating the benthic environment gradually and the water quality eventually.     

Morphological evolution of a large sand bar in the Qiantang River Estuary of China since the 1960s

A large sand bar develops in the inner Qiantang River Estuary, China. It is a unique sedimentary system,elongating landwards by about 130 km. Based on long-term series of bathymetric data in each April, July, and November since the 1960 s, this study investigated the morphological behavior of this bar under natural conditions and the influence of a large-scale river narrowing project(LRNP) implemented in the last decades. The results show that three timescales, namely the seasonal, interannual a...