20 research outputs found
Research on wetland vegetation and road effects on grassland degradation in Xilin River Basin, Inner Mongolia
通过群落生态学和景观生态学方法,结合GIS、RS技术对锡林河流域湿地植被进行了研究。结果表明:流域湿地面积为301.62km2,占流域面积的3%左右。尽管面积相对较小,但是物种丰富,群落结构多样。植被调查数据显示基本确定的植被型4个,植被亚型6个,群系组16个,群系68个,区系成分以泛北极种为主,占69%,相对简单;按照水分生态型划分,中生物种占最多,为44.32%;按生活型分以多年生草本为主占50%以上;科属分布相对复杂,隶属39个科,其中禾本科和菊科是最大的两个科,所占比例仅有17.30%和12.43%,其他科没有明显的优势性,充分说明湿地优越的生境可以满足多种植物共同生长。
多度分布是研究物种多样性分布的重要组分,同时反映了群落结构的特性。以常用的Lognormal、Logseries和Weibull、Exp、Power模型来拟和6个典型草甸群落和踏头草甸群落的物种多度分布,分log-相对多度-物种级数和物种-游程两种形式进行比较;同时,对于典型草甸群落和踏头群落区分常见种、偶然种等进行细化,深入分析群落多度的变化。结果表明,5个模型对于log-相对多度-物种级数在整个群落水平上均不能很好的拟和,50%以上的点都落在95%置信区间以外;但是对常见种和偶然种的拟和情况要好,Weibull、Power和Logseris模型分别对典型草甸群落常见种、偶然种和中间种能很好的拟和,而Logseries和Power模型对于踏头群落的常见种和偶然种拟和较好。5个模型都能较好的拟和物种-游程分布,其中K—S检验结果表明:Lognormal模型对于无脉苔草、针苔草和荸荠这类相对湿润环境下的典型草甸群落拟和较好,对于长叶火绒草和密花风毛菊群落Weibull拟和最好,Power 模型拟和箭叶橐吾最好,踏头草甸拟和最好的是Logseries模型,踏头间拟合最好的是Exp模型。不同的拟和模型应用于不同的群落类型,可以看出湿地群落的复杂性和生境的多样性。区分常见种和偶然种的拟合结果表明典型群落和踏头群落表现一致,即Lognormal模型对所有种拟和是最好的,而Power模型对偶然种的拟和是最好的,同时,Lognormal对典型草甸群落的中间种拟和也是最好。从中可以看出典型草甸群落和踏头群落尽管在表现形式上不同,但是群落的内部仍存在相似的联系,可能跟相似物种的作用有关。
根据湿地表观类型、植被水分状态和航片判别能力,结合实地调查,采用监督分类的方法将锡林河流域的湿地划分为低湿地草甸、盐化草甸和沼泽三种类型。自1984年以来20多年的时间中,锡林河流域的湿地发生了巨大的变化。尽管总的面积没有太大变化,但是湿地类型发生转化。中上游的低湿地草甸面积减少8.94%,沼泽面积减少30.82%,同时,盐化草甸的面积增加了15.98%。增加的盐化草甸主要是另外两种湿地类型转化而成的,中游水库截流,加速中下游草甸的盐化是锡林河流域湿地变化的主要原因。利用GIS技术依据探讨不同湿地的空间变化,分析沙化对湿地变化的影响,结果表明:沙化只对少数湿地有影响,发育良好的湿地即使处在相对强烈的沙化环境下,仍能保持不变。接着,分析了人类直接干扰对湿地变化的影响,缓冲区居民点分析结果表明:近20年来,位于湿地周边的居民点分布格局发生显著的变化。1980年代,居民点分布在盐化草甸周边的最多,到2004年,居民点在沼泽草甸分布数量为最多,该类湿地水、草和资源最为丰富,人类直接的干扰最大,进而转化成另外两类,减少面积最大。低湿地草甸是物种丰富,结构复杂的一种湿地,抗干扰能力强,恢复能力也强,因此相对的变化面积较小。以锡林浩特市水库上下游的湿地植被物种和群落结构的变化,证明了水量减少是湿地数量、结构改变的直接影响因子
滨海湿地灌丛化机制及其生态效应研究进展
Global climate changes and human activities have led to the shift in vegetation dominance from grass to shrub in many coastal wetland ecosystems, which hasconsequently changed the patterns of global vegetation. This paper reviewed the patterns of shrub encroachment in coastal wetlands world widely. We analyzed the influences of global climate factors, such as the minimum tempera ture, air CO2 concentration, precipitation as well as sea level rising, on shrub encroachment in coastal zones. We also discussed the ecological effects of shrub encroachment on coastal environments, biodiversity and the blue carbon functions of coastal wetland ecosys tems. There are, however, important information gaps and technology problems in current researches. Therefore, combination of varied high-resolution remote senses data is needed to accurately evaluate the spatial distribution of shrub encroachment in coastal wetlands on local, regionaland global scales, respectively. Researches in the future should also focus on the feedback mechanism of shrub en croachment in the coastal ecosystems. Finally, we give somecluesforresearches on the shrub encroachment ofcoastal wetlands in North and East China, which is quite different from the mangrove encroachment in South China.</p
流域-河口-近海系统氮、磷营养盐输移研究综述
综述了流域-河口-近海系统氮、磷营养盐的主要来源、营养盐输移的影响因素等方面的研究,介绍了当前营养盐输移研究的主要方法,并概括了氮、磷营养盐在流域-河口-近海系统的整体性研究。在此基础上,提出了该领域研究存在的主要问题及未来展望,强调了将流域、河口与近海系统作为一个整体,并充分发挥分布式模型的优势开展营养盐输移研究的重要性。
Vegetation water conservation effect in the Jinghe River basin:An analysis based on topography and soil type
植被保水效益是黄土高原地区研究的热点,以往的研究往往将环境因子的异质性忽略,在环境均质的假设下进行小尺度的试验研究。本文基于GIS技术,综合考虑土壤、地形等因子,分析了黄土高原泾河流域的植被保水效益及空间分布特征。结果表明:泾河流域植被平均每年可以保持的水量是3.92×108m3,占泾河流域把口站的流量的1/3;总的保水量大小为草地>农田>森林>灌丛,不同植被类型平均保水效益为农田>森林>灌丛>草地,与前人研究结果不同的是,本文的研究是基于栅格单位的(30m),而前人则是基于点数据的;土壤类型在决定植被保水效益中起重要的作用,本文更客观地反映了流域内植被保水能力及空间分布
基于地形和土壤的泾河流域植被生态系统保水效益分析
植被保水效益是黄土高原地区研究的热点,以往的研究往往将环境因子的异质性忽略,在环境均质的假设下进行小尺度的试验研究。本文基于GIS技术,综合考虑土壤、地形等因子,分析了黄土高原泾河流域的植被保水效益及空间分布特征。结果表明:泾河流域植被平均每年可以保持的水量是3.92×108m3,占泾河流域把口站的流量的1/3;总的保水量大小为草地>农田>森林>灌丛,不同植被类型平均保水效益为农田>森林>灌丛>草地,与前人研究结果不同的是,本文的研究是基于栅格单位的(30m),而前人则是基于点数据的;土壤类型在决定植被保水效益中起重要的作用,本文更客观地反映了流域内植被保水能力及空间分布
Spatial and temporal analysis of solid suspended matter in inshore waters of Jiaodong Peninsula
利用2003-2009年春季的MODIS影像,基于修正的TASSAN模型反演了胶东半岛近岸海域的悬浮泥沙浓度,利用GIS空间分析工具分析了悬浮泥沙的空间变化特征。结果表明:从2003-2009年研究区内整体含沙量逐年递增;区域含沙量近岸高、外海低;半岛北部毗邻海域含沙量自西向东依次递减,南部海岸带地区无规律性变化。胶东半岛海岸带悬浮泥沙的时空变化特征同海岸线类型及用海类型有密切联系
A Study on the Pattern of Wetland Species Abandance Distribution in Xilin River
物种多度分布是研究物种多样性分布的重要组分。以Lognormal模型、Logseries模型和Weibull模型、Exp模型、Power模型来拟和内蒙古锡林河漫滩典型草甸:无脉苔草(Carex enervis)、针苔草(Carex dahurica)、荸荠(Eleocharis intersita)、长叶火绒草(Leontopodium longifolium)、箭叶橐吾(Ligularia sagitta)和密花凤毛菊(Saus-sures acuminata)群落和塔头草甸(包括塔头和塔头间群落)的物种多度分布格局。比较群落整体的物种多度分布和区分成常见种、偶然种及中间种之后的多度分布特征。结果表明,在log-相对多度-物种级数这个水平上,5个模型对于整个群落物种多度分布均不能很好的拟和;但是按照常见种等细化后,Weibull、Power和Log-seris模型分别对典型草甸群落常见种、偶然种和中间种能很好的拟和,而Logseries和Power模型对于塔头群落的常见种和偶然种拟和较好。然而,在物种-游程这个水平上,5个模型则能较好地拟和整个群落物种多度;在区分常见种和偶然种之后,拟合结果更优,且典型群落和塔头群落一致,即Lognormal模型对所有种拟和是最好的,而Power模型对偶然种的拟和是最好的。不同的拟和模型应用于不同的群落类型,可以看出湿地群落的复杂性和生境的多样性。典型草甸群落和塔头群落尽管在表现形式上不同,但是群落的内部仍存在相似的联系,可能跟相似物种的作用有关。
内蒙古锡林河湿地物种多度分布格局
物种多度分布是研究物种多样性分布的重要组分。以Lognormal模型、Logseries模型和Weibull模型、Exp模型、Power模型来拟和内蒙古锡林河漫滩典型草甸:无脉苔草(Carex enervis)、针苔草(Carex dahurica)、荸荠(Eleocharis intersita)、长叶火绒草(Leontopodium longifolium)、箭叶橐吾(Ligularia sagitta)和密花凤毛菊(Saus-sures acuminata)群落和塔头草甸(包括塔头和塔头间群落)的物种多度分布格局。比较群落整体的物种多度分布和区分成常见种、偶然种及中间种之后的多度分布特征。结果表明,在log-相对多度-物种级数这个水平上,5个模型对于整个群落物种多度分布均不能很好的拟和;但是按照常见种等细化后,Weibull、Power和Log-seris模型分别对典型草甸群落常见种、偶然种和中间种能很好的拟和,而Logseries和Power模型对于塔头群落的常见种和偶然种拟和较好。然而,在物种-游程这个水平上,5个模型则能较好地拟和整个群落物种多度;在区分常见种和偶然种之后,拟合结果更优,且典型群落和塔头群落一致,即Lognormal模型对所有种拟和是最好的,而Power模型对偶然种的拟和是最好的。不同的拟和模型应用于不同的群落类型,可以看出湿地群落的复杂性和生境的多样性。典型草甸群落和塔头群落尽管在表现形式上不同,但是群落的内部仍存在相似的联系,可能跟相似物种的作用有关
A Review of Retrieval Algorithms for Suspended Sediment
鉴于二类水体本身光学性质的复杂性及其与人类生产活动的密切关系,利用遥感数据监测二类水体水质受到了国内外学者的普遍关注,成为海洋学领域的热点问题。悬浮泥沙含量是表征水质优劣的一个重要参数,众多研究致力于建立悬浮泥沙反演模型的研究,定量反演二类水体悬浮泥沙浓度。该文总结了近年来二类水体悬浮泥沙遥感反演算法的研究进展。悬浮泥沙定量反演模型大致可分为以下三类:1)利用水体光学特性和水体组分之间关系建立的经验模型; 2)综合经验模型和物理模型构建的半分析模型; 3)基于辐射传输模型和生物光学模型建立的物理模型。针对目前反演算法存在的主要问题,提出未来的研究需加强反射率光谱曲线研究、开发高光谱遥感数据以及综合多源数据信息等方面的内容。
Construction ofWetland Ecological Networks under Four Kinds of Resistance of Rivers in the Yellow River Delta and Their Comparison
Ecological network is an efficient tool to increase the landscape connectivity which plays important roles in maintain of ecosystem integrity and protection of key habitats. Resistance surface is one of the most important features of ecological network, determining the effectiveness of ecological network construction. The main objective of this paper was to analyze how water resistance surface can influence the connectivity of potential wetland ecological corridors in a typical coastal wetland of the Yellow River Delta. Four water resistance surface schemes were designed based on the values of water resistance cost, respectively: (1) a basic cost value, according to the current references; (2) half of the basic value, (3) the minimum cost value, and (4) decreasing of the cost interval. The cost distances and potential wetland ecological corridor for these four schemes were generated based on the least cost path method. The structure features and landscape connectivity characteristics of these networks of the four different schemes were evaluated using both network constructive indices and landscape connectivity indices. The results showed significant differences among the four potential wetland corridors. Both water cost and the cost interval had affected the ecological corridors significantly. When the value of water cost was decreased by half, the pattern of network 2 was similar with that of the network 1 which based on the referenced value. The number of nodes, the pattern of the potential corridors and their total length have changed slightly. However, when the cost value was the minimum, the number of nodes and the length of potential corridors had increased greatly. The potential corridors have overlapped with the real river networks, especially in the Yellow River tail channel and old channels. In addition, when the cost interval was decreased, the structure of network 4 became complex and the number of nodes, length of potential corridors have also increased. The assessment results of network connectivity also showed that the four designations were able to generate the closed networks and the landscape connectivity indices have increased due to the increasing of threshold values. In particular, when the threshold values were larger than 12 km, the landscape connectivity of network of the third scheme was the highest. The results also showed that the density of new nodes was more intensive in inland areas than that in other parts of the delta, indicating a more fragmented landscape pattern. Consequently, the connection between these wetland habitats should be strengthened. This research could give scientific suggestions for protection and management of the wetlands in the Yellow River Delta