滨海盐沼位于陆地生态系统和海洋生态系统的交互地带,是一种特殊的湿地类型,具有“源-汇”双重功能,在全球物质循环中有重要意义,同时也是受到人类活动影响的敏感区域。盐沼植被在盐沼生态系统中具有重要作用,对盐沼物质循环有重大影响。盐沼植被演替过程会导致盐沼系统结构和功能上的变化,进而对盐沼物质循环产生影响。以围垦为主的人类活动显著改变了盐沼沉积物的性质,对盐沼物质循环也产生了巨大影响。本文以杭州湾南岸盐沼作为研究对象,采用沉积学与生物地球化学的基本方法,系统探讨了植被演替和人类活动对盐沼物质循环产生的影响,为阐明植被演替过程和人类对盐沼的开发所引起的环境变化提供依据。本项研究在杭州湾南岸庵东浅滩盐沼不同的植被带（本地种和外来种）以及盐沼围垦区内、外采集了一系列柱状和表层沉积物样品,在实验室内测量沉积物粒度、沉积物总碳（TC）含量、总氮（TN）含量、有机碳（TOC）含量、含水率、210Pb活度以及地下生物量等相关参数。计算了沉积速率、TOC含量的贡献率和TOC埋藏速率等参数,在此基础上,分析了植被演替和围垦对于沉积物组分、沉积速率以及碳氮含量的影响。研究结果表明,盐沼区植被从海三棱藨草向互花米草演替时,沉积物颗粒发生细化。潮间带的颗粒物自海向陆逐渐变细,光滩沉积物最粗。围垦区沉积物颗粒发生粗化现象,表层沉积物特征与光滩类似,柱状沉积物颗粒大小则介于光滩与海三棱藨草滩沉积物之间。沉积速率大小依次为海三棱藨草滩（2.81 cm·yr-1）＞互花米草滩（2.36 cm·yr1）＞植被交错区（2.05cm·yr-1）＞光滩（1.59 cm·yr-1）＞围垦区（1.2 cm·yr-1）。其中,最靠近光滩的海三棱藨草滩由于植被分布接近低潮区,增加了水流阻力,为水体悬浮物沉降提供了可能,直接阻挡并导致水体中粒径较大颗粒物沉降,互花米草滩由于对沉积物捕获能力更强,但是受限于沉积物被海三棱藨草大量捕获,所以沉积速率次之;围垦区由于围垦导致物质来源迅速减少,沉积速率最低。表层沉积物碳氮含量具有如下规律:1)TC、TN呈现“互花米草滩＞围垦区＞海三棱藨草滩＞植被交错区＞光滩”的规律。2)TOC呈现“互花米草滩＞围垦区＞光滩＞海三棱藨草滩＞植被交错区”的规律。通过柱状样分析垂向碳氮含量规律,天然盐沼表现出了自海向陆变化的规律:随着高程的增加以及植被的演替沉积物碳氮含量显著增高;而围垦区柱状TOC含量比光滩显著降低,平均降低1.26‰,表现出了碳释放的特征。从物质来源方面来看,碳氮比（C/N）揭示表层光滩具有明显的陆源特征,而植被带内由于植物本身碳氮物质输入的影响,C/N会受到一定的影响。以光滩TOC含量作为系统的输入源估算TOC贡献率,结果发现海三棱藨草滩植被TOC贡献率为18.85%,植被交错区为27.10%,互花米草滩为45.48%。而围垦区TOC含量大幅降低,由储碳固碳向碳释放转变。利用柱状样TOC平均含量与柱状样沉积速率计算TOC埋藏速率,结果表明TOC埋藏速率具有“互花米草滩（159g·m-2.a-1）＞海三棱藨草滩（140 g·m-2·a-1）＞植被交错区（119 g·m-2·a-1）＞光滩（63 g·m-2·a-1）”的特征,在互花米草滩与海三棱藨草滩之间形成了TOC埋藏速率的低谷,表明外来物种互花米草和本地先锋物种海三棱藨草对于TOC埋藏的方式有所区别。总体来看,在杭州湾南岸滨海盐沼的演化过程中,植被演替和人类围垦活动的影响是截然不同的。当植被从海三棱藨草演替到互花米草时,沉积物颗粒逐渐变细,碳氮含量显著增加,盐沼的碳埋藏能力增加。而围垦活动主要导致沉积物颗粒发生粗化,碳氮物质在围垦区表层沉积物中富集,在垂向上迅速减少,整体上减少了碳埋藏量。

Artificial coastal dykes have been widely built to prevent erosion, or to accelerate sedimentation processes in saltmarshes. To investigate the sediment dynamic changes induced by construction of dykes, three observation stations were set around a dyke within an expanding Scirpus mariqueter saltmarsh, in southern Hangzhou Bay. The hydrodynamics of the study area was dominated by tidal currents. The presence of dyke, in combination with the adjacent tidal creek, altered the hydrodynamic boundary conditions, thereby affecting the flow field. When the tidal flows approaching the dyke, the speed was accelerated at the head of the dyke and then decreased at the rear, due to the narrowing effect of the dyke head. Turbulence intensity around the dyke showed a similar pattern to that of the tidal flows. The net sediment input behind the dyke is approximately 2.3 times of that at the dyke head, illustrating sediment deposition in the back region of the dyke. As a result, flows entrained the sediments and then deposited behind the dyke to cause a local accretion to promote saltmarsh vegetation succession. The construction of dykes should be taken into account for future coastal wetland management.

为揭示盐沼植物斑块空间竞争和沉积动力地貌过程之间的双向交互作用，本项目以杭州湾庵东浅滩盐沼作为研究对象，综合运用高分辨率遥感影像时间序列分析、机载激光雷达测量、沉积动力学现场观测、生物学现场调查和植物温室移植实验等手段，开展了快速淤积海岸本地种—外来种交错型盐沼内互花米草和海三棱藨草植物斑块的生物地貌过程研究。在项目执行期间，定制了8景高分辨率遥感影像，完成了11次野外现场观测，采集了15个柱状样和100多个沉积物样品用于实验室分析，在温室内培育了120盆植物并完成了本地种—外来种生长对比实验。通过以上工作，取得了以下几点认识:1从遥感影像分析结果来看，该区域的盐沼呈现快速扩张的趋势，整体呈现“双峰态”模式，两者的竞争结果与高程有关，而潮沟的存在对外来物种水平扩散起到了一定的促进作用;2本地种和外来物种盐沼植物斑块对沉积动力过程的调制作用存在差异性，互花米草呈现线性，而海三棱藨草呈现非线性特征，结合两者的空间自组织形式差异，发现10-15m直径是两种植物斑块发生临界状态转换的特征尺度;3通过现场观测，庵东浅滩的沉积速率年内可以达到10cm以上，属于快速淤积环境，而室内植物移植实验表明，两种植物对沉积物输入量的响应具有明显差异性，当沉积物厚度超过6cm时会影响两者的竞争结果;4以上结果说明沉积物输入量和植物斑块大小是盐沼本地种—外来种交错带的生物地貌学的关键因素，共同决定了系统的临界状态。通过本项目的执行，不仅在理论上检验了生物地貌过程对于盐沼植被群落演化的重要影响，而且在技术上发展了ADV波流分离、盐沼内机载激光雷达地形数据提取等相关算法。基于本项研究的结果，提出了“大型促淤堤如何影响本地种—外来种空间竞争格局”这一新的科学问题，建议开展下一步研究。本项目的研究成果共20项，包括论文、著作、专利等，可以应用在将来的盐沼生态修复、外来物种防控、海岸带监测新技术等应用领域。

沉积物的活动性是指在一定时段内海底沉积物处于运动状态的时间占总时间的百分比。从全世界范围来看,长江是流域建坝蓄水拦沙导致入海沉积物通量锐减的典型案例。在此背景下,长江口及其邻近海域的沉积物活动性不仅关系到长江水下三角洲

Waves, currents, and related sediment transport are important factors driving the development of saltmarshes. Separating the effects of waves and currents accurately from simple field observations is a technical challenge in shallow water environments with limited inundation such as saltmarshes. In this paper, the estimation method of both wave and current information was studied mainly through the data obtained by a solely used field ADV (Acoustic Doppler Velocimeter, Vector). Phase and pressure inversion wave methods were both used to estimate wave parameters, which were then compared to synchronous observation by wave loggers at the front of a saltmarsh. Our results show that ADV is able to achieve simultaneous observations of tidal currents and waves independently. The pressure inversion wave method (r(2) similar to 0.996) is more effective than the phase method (r(2) similar to 0.876) in estimating wave energy when comparing with wave logger results. However, the former is more restricted by submergence depth and duration in field, while the latter provides cut-off frequencies for the pressure inversion wave method. Both methods can be combined to best estimate wave parameters from field ADV data. Further, hydrodynamic observation on a Scirpus mariqueter patch at the front of a saltmarsh was used as an application to indicate the importance of obtaining both wave and current information from field data. The patch was found to mainly reduce the advection of tidal currents, but it slightly increases wave energy. Therefore, it is necessary to consider the different effects of plants on tidal currents and waves simultaneously in field observations. This study confirms that ADV and associated analysis can detect waves and currents at reliable accuracy at the marsh edge, which is vital in assessing the long-term resilience of marshes to sea level rise and increased storm severity.

Continentalcollision zones have been proposed as primary sites of net continental crustal growth. Therefore, studies on syn-collisional granitoids with mafic magmatic enclaves (MMEs) are essential for testing this hypothesis. The Baojishan (BJS) and Qumushan (QMS) syn-collisional plutons in the North Qilian Orogen (NQO) on the northern margin of the Tibetan Plateau have abundant MMEs in sharp contact with host granitoids, sharing similar constituent minerals but with higher modal abundances of mafic minerals in MMEs. The QMS host granitoids have high Sr/Y and La/Yb ratios, showing adakitic compositions, which are differentfrom the BJS granitoids. Based on bulkrock compositions and zircon U-Pb age-dating, recent studies on these two plutons proposed that MMEs represent cumulates crystallized early from the same magmatic system as their host granitoids, and their parental melts are best understood as andesitic magmas produced by partial melting of the underthrusting upper ocean crust upon collision with some terrigenous sediments under amphibolite facies. Here, we focus on the trace-element geochemistry of the constituent mineral phases of both MMEs and their host granitoids of the QMS and BJS plutons. Weshow that different mineral phases preferentially host different trace elements; for example, most rare earth elements (REEs and Y) reside in titanite (only found in the QMS pluton), amphibole, apatite, epidote and zircon (mostly heavy-REEs); and high-field-strength elements (HFSEs) reside in biotite, titanite, amphibole and zircon. Based on the mineral chemical data, we show that for these two plutons, MMEs are of similar cumulate origin, crystallized from primitive andesitic melts in the early stage of granitoid magmatism. The primitive andesitic melts for these syn-collisional granitoids are most likely produced by the partial melting of the oceanic crust, supporting the hypothesis of continental crustal growth considering the syn-collisional granitoids represent juvenile continental crust. As evidenced by distinct mineral compositions, the two plutons have different parental magma compositions, for example higher TiO2 content and higher Sr/Y and La/Yb ratios in the QMS parental magmas, a signature best understood as being inherited from the source. The higher TiO2 content of the parental magma for the QMS pluton leads to the common presence of titanite in the QMS pluton (absent in the BJS pluton), crystallization of which in turn controls the trace-element (REE, Y, Nb, Ta and others) systematics in the residual melts towards an adakitic signature. Therefore, parental magmas with high TiO2 content and high Sr/Y and La/Yb ratios, as well as their further fractionation of titanite, are important factors in the development of adakitic compositions, as represented by the QMS host granitoids. This model offers a new perspective on the petrogenesis of adakitic rocks. The present study further demonstrates that, in general, mineral chemistry holds essential information for revealing the petrogenesis of granitoid rocks.

生物地貌学研究生物过程和地貌过程之间的双向交互作用,是一门新兴的交叉学科。早期的生物地貌学关注陆地生态系统,近期海岸带成为生物地貌学研究的热点地区,尤其是滨海湿地（如盐沼、红树林）成为研究生物地貌学过程和机理的重要区域。本文回顾了生物地貌学研究的概念、历史发展和方法,选取滨海湿地作为生物地貌学的主要研究对象,并就其研究方向、重要因素以及核心机制展开综述。最后对生物地貌学在海岸带生态系统修复工作中的应用进行梳理,分析了生物地貌学在红树林修复、滨海盐沼湿地修复和互花米草入侵防控上的应用展望。