基于RS与GIS的北京近30年湿地景观格局变化分析

利用RS图像处理和GIS信息提取和分析功能,确定北京市区域湿地的景观分类系统,获取北京湿地景观数据。同时,基于Fragstats软件,运用景观生态学原理,通过选取景观面积指数、斑块数及斑块密度、斑块聚集度、景观形状指数、斑块分维数和景观多样性指数等空间结构指标,从景观水平上研究了1978—2005年近30年来北京湿地景观分布格局特征的动态变化过程。结果表明:1)北京地区的湿地资源面积呈现显著退化趋势,湿地面积由1978年的68491.63hm2减少到2005年的31416.31hm2,减少了54.0%;2)1978—2005年,北京湿地斑块趋向于不规则化,破碎程度急剧增加,导致湿地易消退、湿地功能难以发挥;3)随着人类干扰强度的增加,北京湿地类型多样性指数值在1.2以上,与均匀度指数呈明显正相关关系,二者均有增加趋势。     

东北地区沼泽湿地空间分布格局及其影响因素分析

在分析东北地区沼泽湿地空间分布格局的基础上,利用逐步回归模型筛选出影响湿地空间分布的生态因子。研究结果表明,沼泽湿地的空间分布格局受气候、水文、地貌和人类活动等条件的制约,其中相对湿度和年平均降雨量有利于沼泽湿地的形成,而人口密度、坡度和气温不利于沼泽湿地的形成。     

Response of seasonal pond plant communities to upland forest harvest in northern Minnesota forests,USA

Small seasonally flooded forest ponds have received increased attention due to a growing recognition of their abundance in many landscapes, their importance as habitat for a variety of organisms, and the contributions they make to species and ecosystem diversity. There also is concern over potential negative effects of forest management in adjacent uplands on seasonal pond ecology. Several studies have examined invertebrate and songbird responses to upland harvest around seasonal ponds. Less attention has been given to examining how seasonal pond plant communities respond to adjacent forest harvesting. We studied the response of seasonal pond plant communities to adjacent upland timber harvests, assessing whether buffers around ponds (15.25 m uncut and partially cut) mitigated changes in species abundance and community composition, relative to changes in ponds that were clearcut to the pond margin. We addressed our objective using an operational-scale experiment in northern Minnesota, which included pre-harvest sampling, replicated treatments, and uncut controls. After treatment, changes in tree basal area and canopy openness in the pond basins reflected reductions in upland basal areas. Specifically, control ponds had significantly higher basal area and lower openness than ponds cut to their margins, while ponds with uncut buffers and partially cut buffers were intermediate. Changes in plant communities were evident in the ground layer and shrub/large regeneration layer. After treatment and over time, the control stands did not change significantly in ground layer structure or shrub/large regeneration layer composition. The three upland harvest treatments displayed increasingly greater deviation from their starting conditions and from the control along a gradient of increasing treatment intensity, from the buffer treatment to the partially cut buffer to the clearcut. The response in the ground layer was largely associated with increased sedge and grass cover, while the response in the shrub/large regeneration layer was associated with increases of Salix sp., Alnus incana, and Populus tremuloides. Our results indicate that adjacent upland timber harvest can lead to altered plant communities within seasonal ponds, at least temporarily. Moreover, uncut forest buffers (∼15.25 m) surrounding seasonal ponds can mitigate plant community changes to some degree. If seasonal ponds are an important resource on the management landscape and a high percentage of upland forest is in a recently cut condition at any given time, than use of harvest buffers around seasonal ponds may be an appropriate approach for mitigating short term alteration of pond plant communities.     

人工湿地植物应用现状与问题分析

为了在人工湿地设计与施工时更好地确定植物类型,在分析中国目前人工湿地植物的主要应用类型的基础上,提出了水生类型、湿生类型、陆生类型的人工湿地植物分类新方法。同时,对人工湿地不同植物品种和不同季节的去污效果研究进行综述,最后分析出人工湿地植物研究存在着应用的植物种类少、景观价值低、受环境影响大、二次污染、植物净化机制有待进一步加强了解的5个主要问题,并提出研究发展的3个方向。     

Noncontinuous Development of Reducing Conditions in Wetland Soils

Abstract

Soil aeration status in relation to water table was analyzed by contour mapping in a forested wetland, an emergent marsh, and an irrigated rice field. Two soil aeration status indicators, oxygen (O₂) and redox potential (Eh), showed a significant correlation (P<0.01). Soil O₂ and Eh levels generally decreased with the water table rise in the forested wetland and marsh, but with a noncontinuous pattern. The results indicate that soil aeration status could be temporally improved at an optimum water table level, probably due to O₂ transport by wetland plants. The soil Eh in the rice fields clearly showed a seasonal pattern regardless of the water tables.     

地统计学在湿地土壤养分空间异质性研究中的应用

在地统计学的区域化变量理论和变异函数的基础上建立了一套对湿地土壤养分的空间异质性进行定量化的较系统且完整研究的方法,通过向海湿地的案例研究证实了该方法在湿地土壤养分空间异质性研究中具有较强的操作性和准确性。     

人工湿地的研究进展

人工湿地具有相当显著的生态环境效益,不仅可作为自然湿地在量上的有效补充,更可缓解现存自然湿地所受到的威胁和环境压力,是湿地保育的有力措施。通过查阅大量资料探求人工湿地相关问题,对其研究现状进行归纳、阐述,分析人工湿地研究中存在的问题,并对其在不同领域的应用做了展望。     

试论鄱阳湖湿地资源可持续发展的制度创新

以可持续发展战略为指导 ,站在市场经济的角度 ,运用西方经济学和新制度经济学的原理 ,分析指出鄱阳湖湿地资源保护与合理开发利用的经济本质是实现湿地资源的有效配置 ,并从理论上探讨了产生鄱阳湖湿地问题的制度根源———市场和政府配置湿地资源手段失灵 ,提出了解决鄱阳湖湿地问题必须进行制度创新的切入点 ,即构建绿色经济制度。     

Determining tolerance limits for restoration and phytoremediation with Spartina patens in crude oil-contaminated sediment in greenhouse

Oil spills may detrimentally damage sensitive coastal habitats, such as coastal wetlands. Successful restoration of oiled habitats primarily depends on the tolerance of vegetation transplants to oil. In this study, tolerance limits of the dominant coastal brackish marsh plant Spartina patens to South Louisiana crude (SLC) oil and its phytoremediation effectiveness on petroleum hydrocarbons in wetland sediments were investigated in the greenhouse environment. Spartina patens was transplanted into brackish marsh sediments contaminated with SLC oil at concentrations of 0, 40, 80, 160, 320, 640 and 800 mg SLC oil g^?1 dry sediment. High oil concentrations adversely affected plant stem density, aboveground biomass and belowground biomass even one year after transplantation. At the 320 mg g^?1 oil dosage, plant belowground biomass was significantly lower than the control although aboveground variables were not significantly different from the control. All plant parameters mentioned above at the 640 mg g^?1 oil dosage were less than 50% of the control. Spartina patens did not survive the 800 mg g^?1 oil dosage. The tolerance limit of S. patens to SLC was estimated about 320 mg oil g^?1 dry sediment. In addition, S. patens transplants enhanced oil degradation in the sediment; concentrations of residual total petroleum hydrocarbons (TPH) in the sediments vegetated by S. patens were significantly lower than those of un-vegetated sediments for both the surface and subsurface sediment at the 40 and 160 mg g^?1 SLC oil dosages. Decreases in the concentrations of polycyclic aromatic hydrocarbons (PAHs) further demonstrated the capacity of S. patens to phytoremediate residual oil; residual total targeted PAHs in the phytoremediation treatment were less than 20% of the un-vegetated treatment at the 40 mg g^?1 oil dosage. These results demonstrated the potential of phytoremediation with S. patens to simultaneously restore and remediate petroleum-contaminated coastal marsh habitats.     

Impact of seawater intrusion control on the environment,land use and household incomes in a coastal area

Agricultural production in the coastal wetlands of Asia is often hindered by salinity intrusion caused by tidal fluctuation. This paper reports changes in environmental and socio-economic conditions that followed the phased construction and operation of sluices for controlling seawater intrusion from 1994 –2000 in a coastal area of the Mekong River Delta, Vietnam. Canal water salinity decreased rapidly upstream of sluices, allowing rice cropping intensification and increased rice production in the eastern part of the study area. However, the livelihoods of farmers in the western part were adversely affected due to cessation of supply of brackish water that was needed for brackish-water shrimp farming, while the acid sulphate soils present there posed problems for rice cultivation. The poor farmers and landless people suffered more because the fishery resource that they depended on declined sharply due to reduced salinity and increased acidity in the canal water. The findings confirmed that the environment and resource use in the coastal lands are very sensitive to external intervention. A clear understanding of the socio-economic and environmental impacts of salinity control measures in coastal areas can help planning to enhance farmers' incomes while minimizing negative environmental impacts. Land-use policy formulation, planning and management should adopt a more holistic approach, taking into account the interests of all resource users, especially the poor, instead of focusing on any particular sector.