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1.
Mangrove wetland restoration and creation efforts are increasingly proposed as mechanisms to compensate for mangrove wetland losses. However, ecosystem development and functional equivalence in restored and created mangrove wetlands are poorly understood. We compared a 20-year chronosequence of created tidal wetland sites in Tampa Bay, Florida (USA) to natural reference mangrove wetlands. Across the chronosequence, our sites represent the succession from salt marsh to mangrove forest communities. Our results identify important soil and plant structural differences between the created and natural reference wetland sites; however, they also depict a positive developmental trajectory for the created wetland sites that reflects tightly coupled plant-soil development. Because upland soils and/or dredge spoils were used to create the new mangrove habitats, the soils at younger created sites and at lower depths (10–30?cm) had higher bulk densities, higher sand content, lower soil organic matter (SOM), lower total carbon (TC), and lower total nitrogen (TN) than did natural reference wetland soils. However, in the upper soil layer (0–10?cm), SOM, TC, and TN increased with created wetland site age simultaneously with mangrove forest growth. The rate of created wetland soil C accumulation was comparable to literature values for natural mangrove wetlands. Notably, the time to equivalence for the upper soil layer of created mangrove wetlands appears to be faster than for many other wetland ecosystem types. Collectively, our findings characterize the rate and trajectory of above- and below-ground changes associated with ecosystem development in created mangrove wetlands; this is valuable information for environmental managers planning to sustain existing mangrove wetlands or mitigate for mangrove wetland losses.  相似文献   

2.
1973-2013年黄河三角洲湿地景观演变驱动力   总被引:5,自引:0,他引:5  
洪佳  卢晓宁  王玲玲 《生态学报》2016,36(4):924-935
1973-2013年间,日益加剧的人类活动和愈发严峻的自然环境对黄河三角洲湿地景观形成巨大威胁。人与自然双重影响下黄河三角洲湿地发生了怎样的变化,哪些因素、多大程度上导致了这种变化的发生,科学解答这些问题对于加强黄河三角洲湿地保护具有重要意义。以Landsat卫星1973-2013年40a的9期影像为数据源,利用人工目视解译方法构建研究区景观数据库,在分析研究区景观特征的基础上,通过主客观相结合的方法,构建了能够反映黄河三角洲地区景观湿地化和人工化状态的表面湿地-人工状态指数(SWCSI)。结合黄河入海水沙、区域降水以及地方生产总值(GDP)、水产品产量和原盐产量,分别从区域尺度和像元尺度上,定量分析了过去40年黄河三角洲湿地景观演变的驱动力及其空间差异。研究表明:(1)过去40年来,黄河三角洲自然湿地面积不断萎缩,人工湿地增加,湿地总面积减小,黄河三角洲整体上呈现出人工化或湿地退化趋势,同时也存在明显的空间异质性:滨海地区以人工化和湿地退化趋势为主,黄河入海口地区以湿地化趋势为主,中西部和西南部传统农耕区基本无变化。(2)黄河三角洲湿地景观的人工化或湿地退化趋势是过去40年来黄河水沙减少、人类活动加剧共同作用的结果。区域尺度上,人类社会经济活动对黄河三角洲湿地景观演变起主导作用,黄河径流量和输沙量的作用明显弱于社会经济因素。像元尺度上,驱动因素的空间异质性是导致黄河三角洲湿地景观演变空间异质性的原因。湿地的发展主要归因于自然因素,以黄河水沙作用最为关键;湿地的人工化或退化过程以人类社会经济活动的强制改造为主导,但是否伴随黄河水沙变化的潜在影响,对特定区域而言应是确定的,但仍很难从像元尺度进行量化。  相似文献   

3.
仝川  罗敏  陈鹭真  黄佳芳 《生态学报》2023,43(17):6937-6950
滨海盐沼、红树林和海草床蓝碳湿地生态系统具有高效的固碳-储碳能力,准确测定滨海蓝碳湿地生态系统碳汇速率,对于评估滨海湿地碳中和能力、生态恢复新增碳汇规模及碳贸易至关重要。深入思考滨海蓝碳湿地生态系统碳汇定义的内涵,提出狭义碳汇和广义碳汇的概念,介绍沉积物碳累积+植被净初级生产力法以及生态系统碳通量收支法2个目前国际上应用最多的滨海蓝碳湿地碳汇速率测定方法,特别是深入分析作为开放系统的滨海盐沼生态系统和海草床生态系统碳汇速率测定面临的诸多问题与挑战,梳理中国红树林、滨海盐沼和海草床生态系统碳汇速率的测定结果及国家尺度滨海蓝碳湿地生态系统碳汇规模,最后提出中国在滨海蓝碳湿地碳汇速率测定实践中急需加强的基础研究领域,以期为科学地计量中国滨海蓝碳湿地生态系统碳汇速率与碳汇规模提供方法参考和技术支撑。  相似文献   

4.
Sea level rise (SLR) threatens coastal wetlands worldwide, yet the fate of individual wetlands will vary based on local topography, wetland morphology, sediment dynamics, hydrologic processes, and plant‐mediated feedbacks. Local variability in these factors makes it difficult to predict SLR effects across wetlands or to develop a holistic regional perspective on SLR response for a diversity of wetland types. To improve regional predictions of SLR impacts to coastal wetlands, we developed a model that addresses the scale‐dependent factors controlling SLR response and accommodates different levels of data availability. The model quantifies SLR‐driven habitat conversion within wetlands across a region by predicting changes in individual wetland hypsometry. This standardized approach can be applied to all wetlands in a region regardless of data availability, making it ideal for modeling SLR response across a range of scales. Our model was applied to 105 wetlands in southern California that spanned a broad range of typology and data availability. Our findings suggest that if wetlands are confined to their current extents, the region will lose 12% of marsh habitats (vegetated marsh and unvegetated flats) with 0.6 m of SLR (projected for 2050) and 48% with 1.7 m of SLR (projected for 2100). Habitat conversion was more drastic in wetlands with larger proportions of marsh habitats relative to subtidal habitats and occurred more rapidly in small lagoons relative to larger sites. Our assessment can inform management of coastal wetland vulnerability, improve understanding of the SLR drivers relevant to individual wetlands, and highlight significant data gaps that impede SLR response modeling across spatial scales. This approach augments regional SLR assessments by considering spatial variability in SLR response drivers, addressing data gaps, and accommodating wetland diversity, which will provide greater insights into regional SLR response that are relevant to coastal management and restoration efforts.  相似文献   

5.
Coastal wetlands have the capacity to retain and denitrify large quantities of reactive nitrogen (N), making them important in attenuating increased anthropogenic N flux to coastal ecosystems. The ability of coastal wetlands to retain and transform N is being reduced by wetland losses resulting from land development. Nitrogen retention in coastal wetlands is further threatened by the increasing frequency and spatial extent of saltwater inundation in historically freshwater ecosystems, due to the combined effects of dredging, declining river discharge to coastal areas due to human water use, increased drought frequency, and accelerating sea‐level rise. Because saltwater incursion may affect N cycling through multiple mechanisms, the impacts of salinization on coastal freshwater wetland N retention and transformation are not well understood. Here, we show that repeated annual saltwater incursion during late summer droughts in the coastal plain of North Carolina changed N export from organic to inorganic forms and led to a doubling of annual NH4+ export from a 440 hectare former agricultural field undergoing wetland restoration. Soil solution NH4+ concentrations in two mature wetlands also increased with salinization, but the magnitude of increase was smaller than that in the former agricultural field. Long‐term saltwater exposure experiments with intact soil columns demonstrated that much of the increase in reactive N released could be explained by exchange of salt cations with sediment NH4+. Using these findings together with the predicted flooding of 1661 km2 of wetlands along the NC coast by 2100, we estimate that saltwater incursion into these coastal areas could release up to 18 077 Mg N, or approximately half the annual NH4+ flux of the Mississippi River. Our results suggest that saltwater incursion into coastal freshwater wetlands globally could lead to increased N loading to sensitive coastal waters.  相似文献   

6.
Phytoremediation in Wetland Ecosystems: Progress,Problems, and Potential   总被引:1,自引:0,他引:1  
Assessing the phytoremediation potential of wetlands is complex due to variable conditions of hydrology, soil/sediment types, plant species diversity, growing season, and water chemistry. Conclusions about long-term phytoremediation potential are further complicated by the process of ecological succession in wetlands. This review of wetlands phytoremediation addresses the role of wetland plants in reducing contaminant loads in water and sediments, including metals; volatile organic compounds (VOC), pesticides, and other organohalogens; TNT and other explosives; and petroleum hydrocarbons and additives. The review focuses on natural wetland conditions and does not attempt to review constructed wetland technologies. Physico-chemical properties of wetlands provide many positive attributes for remediating contaminants. The expansive rhizosphere of wetland herbaceous shrub and tree species provides an enriched culture zone for microbes involved in degradation. Redox conditions in most wetland soil/sediment zones enhance degradation pathways requiring reducing conditions. However, heterogeneity complicates generalizations within and between systems. Wetland phytoremediation studies have mainly involved laboratory microcosm and mesocosm technologies, with the exception of planted poplar communities. Fewer large-scale field studies have addressed remediation actions by natural wetland communities. Laboratory findings are encouraging with regards to phytoextraction and degradation by rhizosphere and plant tissue enzymes. However, the next phase in advancing the acceptance of phytoremediation as a regulatory alternative must demonstrate sustained contaminant removal by intact natural wetland ecosystems.  相似文献   

7.
将盐城国家级自然保护区核心区划分为人工管理区和自然湿地区两种模式,根据1987年、1997年、2007年3个时相的景观资料,运用RS、GIS技术和景观生态学方法,分析不同驱动力下湿地景观格局的变化差异。结果表明:(1)人工管理区,景观斑块平均面积由205.31 hm2降至55.60 hm2,景观多样性指数1.4284降低到1.2928,优势度从0.3634上升到0.7766,表明景观破碎化明显,景观多样性呈降低趋势,优势度则呈上升趋势。景观变化的结果导致景观带状特征变弱,镶嵌性特征十分明显;1987—1997年期间,景观格局空间演变表现为从陆地向海洋的单向演替;而1997—2007年,景观演替呈现多向性特征。(2)自然湿地区,景观优势度呈下降趋势,从0.4844下降到0.3164;而景观多样性呈上升趋势,其指数从0.9019上升到1.4754。景观带状格局发育更加明显,各景观带宽趋于均匀,并且景观从陆地向海洋呈单向演替特征。(3)影响海滨湿地景观格局演变的驱动因素是:自然湿地区主要受海洋潮汐作用影响,其主要自然过程如地貌过程和植物群落演替过程等呈连续性变化,从而导致景观演变呈带状连续性发展;人工管理区主要受人为管理影响,人为管理往往使生态过程的连续性发生突变,从而使景观演变呈多向性特征。  相似文献   

8.
Evaluating the adequacy of created wetlands to replace functions of lost natural wetlands is important because wetland mitigation is a major tool used to offset wetland losses. However, measurements such as vegetative cover and wildlife presence may not be evidence enough that created wetlands are functioning properly and thus, examining the ecology of wetland biota such as amphibians may be a more useful surrogate for function. Our objectives were to measure the diet composition of adult red-spotted newts (Notophthalmus viridescens viridescens) and compare the selection of prey by newts between created and natural wetlands. Newts were trapped during the spring and summer of 2009 and 2010, and the stomach contents of 149 newts were obtained with gastric lavage. Invertebrate prey availability was obtained within a 5 m radius of each captured newt. Selection of prey by newts was nonrandom, but was only minimally affected by wetland type. Both dietary breadth and prey selection were affected primarily by time of year, likely driven by temporal variation in invertebrate abundance. Our results suggest that the function of providing an adequate prey base for a generalist wetland predator such as the red-spotted newt is being fulfilled for the created wetlands that we examined.  相似文献   

9.
Coastal wetlands are considered to be amongst the most productive ecosystems and can provide invaluable ecological services. However, coastal wetlands are listed amongst the most threatened ecosystems suffering from anthropogenic activities. The loss or degradation of coastal wetlands has drawn a high level of attention to wetland restoration. Improvement of the structure and function of degraded, damaged and destroyed wetlands may be achieved through ecological restoration. Large numbers of restoration projects have been conducted worldwide based on different restoration goals and different methods. It is undoubtedly important to evaluate whether coastal wetland restoration is successful. However, coastal wetland restoration assessment has become challenging because of current disagreement on definitions and concepts of restoration evaluation. We reviewed the methodology of coastal wetland restoration and criteria for success evaluation, and then summarized the issues for current wetland restoration and success evaluation based on literature review. Moreover, we used an estuarine wetland affected by urbanization as a sample to demonstrate how to establish a success indicator system for guiding wetland restoration and evaluating the success of wetland restoration.  相似文献   

10.
Wetlands are among the worlds' most important, but also most threatened, environmental resources. Wetland losses have been in progress particularly from the industrial revolution onwards, because wetland functions could not successfully compete for space with other land uses. Wetlands became recently foci of conservation efforts because of the increased awareness of their importance in water management and wildlife conservation, and because of the diversity of their habitats. The Netherlands are relatively rich in wetlands: 16% of its' territory is regarded as internationally important wetland and 7% has been registered as such. The major Dutch wetland types are: coastal ecosystems, large riverine systems, base-rich freshwater systems, and nutrient-poor freshwater systems. Most threats to the Dutch wetlands are of man-made origin. They comprise: (1) Changes in hydrology leading to changed discharges, currents and desiccation; (2) Acidification; (3) Eutrophication; and (4) Toxification. Long-term threats are largely climate-change related, and concern temperature rise and the UV-B increase in irradiation. General conservation goals also apply to wetlands but Ramsar-registered wetlands have a special status. Conservation of the Dutch wetlands is difficult, because of the high population density of the country and its inherent threats. However, ecological targets and standards are increasingly set in national Policy Plans and international agreements. Rehabilitation and creation of wetlands is presently widely advocated, and sometimes realised. For ecological research, the sustainability of wetlands should get top priority. Such a research programme would focus on understanding the underlying ecological processes in natural and man-dominated wetland systems to prescribe conservation, rehabilitation and management strategies that would enhance the sustainability of these systems. Within this framework special attention should be directed to studies (1) At the ecosystem level of ecosystem parameters, of which natural oscillations and trends in time, and on which the impact of disturbances are quantified. Particularly these studies, in which often simulation models are used as tools for interpretation, can provide the basis for extrapolations in space and time; (2) On adaptation capacity and mechanisms of (groups of) species to extreme environmental conditions; (3) On (mutual) relationships between plants, animals and microorganisms (e.g. competition, grazing and mineralization); (4) On dispersion between small wetlands. For the contemporary quantitative assessment of the long-term effects of climate changes, the effects of temperature rise and increase in UV-B irradiation on individual species, communities and ecosystems should also be studied.  相似文献   

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