【作者】 黄华梅；

【导师】 张利权；

【作者基本信息】 华东师范大学 ， 生态学， 2009， 博士

【摘要】 上海地处长江口，长江携带的丰富泥沙资源造就了上海的淤泥质潮滩，孕育了极其丰富的滩涂湿地资源。滩涂湿地不仅是上海经济发展的重要后备土地资源，也为上海地区提供了强大的生态服务功能和资源环境价值。然而，近年来由于自然过程和高强度的人类活动，长江流域及其河口的环境发生了一系列重大变化，上海地区的滩涂湿地面临着滩涂资源开发与保护的严峻挑战。大尺度的上海市滩涂湿地盐沼植被的空间分布现状及其时空动态研究可以为上海市滩涂资源的合理规划、生物多样性保护和可持续开发利用提供科学依据。本研究以多时相遥感影像为数据源，在几何精校正基础上，进行缨帽变换和归一化植被指数等光谱增强处理后，结合多年的滩涂盐沼植被的光谱信息，对遥感影像进行监督分类。依据多次野外实地调查的数据，对解译的结果进行修正和精度评价。在GIS平台下进行数据合成，分析近20年来上海滩涂盐沼植被空间分布和时空动态。此外，在分析上海地区滩涂盐沼植被分布格局的基础上，结合细胞自动机(Cellular automata，CA)模型，研究了上海滩涂盐沼植被种群的扩散过程。本项研究的主要结果如下：(1)上海滩涂植被资源的空间分布上海滩涂植被资源比较丰富，1990年滩涂盐沼植被组成为本地种芦苇(Phragmites australis)和海三棱藨草(Scirpus mariqueter)群落。互花米草(Spartina alterniflora)在上世纪九十年代后期被引入长江口滩涂，面积逐年扩大，目前已成为上海滩涂上分布面积最大的植被群落。从滩涂盐沼植被总面积的变化来看，上世纪九十年代大规模的滩涂围垦，使上海地区盐沼植被从1990年的17881．95 hm~2下降到2000年的13822．2 hm~2。2000年之后，滩涂盐沼植被面积保持增加的趋势，到2003年，盐沼植被的面积增加到21953．45 hm~2。2003年至2005年间，由于高强度的围垦活动，滩涂盐沼植被的面积又有较大程度的减少，至2005年总面积下降为18314．84 hm~2。从滩涂盐沼植被构成的变化来看，外来物种互花米草群落在上海地区滩涂从无到有，并逐渐增加。到2008年，互花米草群落的分布面积已达到5697．94 hm~2，占上海滩涂植被面积的31%，超过土著种芦苇和海三棱藨草。芦苇群落从1990年的14100．44 hm~2，到2000年面积几乎减少了一半，随后到2003年，面积恢复到10075．43 hm~2，但之后又由于大规模的围垦，芦苇的面积到2008年统计，又下降为5717．51 hm~2。从1990年开始，海三棱藨草的面积一直处于增加的趋势，从1990年的3781．51 hm~2增加到2003的7602．24hm~2。但随后，由于中低滩围垦和互花米草的快速扩散，海三棱藨草的面积有所下降，至2008年，其面积仅为4234．7 hm~2。(2)崇明东滩自然保护区滩涂盐沼植被的时空动态受1992，1998年和2001年三次中高滩围垦和互花米草入侵的影响，崇明东滩芦苇群落的面积大大减少，虽然随着滩涂的淤涨，芦苇群落的面积在围垦后逐年有所增加，但增加速度缓慢。崇明东滩的高滩围垦对海三棱藨草群落的面积影响不大，海三棱藨草的面积从1990年开始一直保持增加的趋势，但2005年之后，随着芦苇和互花米草的扩散，海三棱藨草的面积有所下降，但总面积一直保持在2000 hm~2以上。互花米草自引种后面积一直持续增加，在滩涂植被中所占的比重也越来越大，至2008年，面积也接近崇明东滩滩涂植被总面积的三分之一。(3)上海九段沙自然保护区盐沼植被的时空动态九段沙为长江口河口心滩型沙洲，长江携带的大量泥沙使沙洲处于不断淤涨之中。九段沙沙洲的发育和盐沼植被的演替受人为影响相对较小，植被的演替发育基本上处于自然状态。从1997年到2008年，九段沙盐沼植被的总面积从1094．6hm~2增加到了3600．6 hm~2，以平均每年约230 hm~2的速度增长。从1997年到2003年，九段沙的海三棱藨草群落面积从966．56 hm~2增加到了1 850．22 hm~2。但随后，随着互花米草和芦苇逐渐在中沙和下沙定居扩散，海三棱藨草群落的面积在2003年后有减少的趋势，尤其是互花米草的快速扩散，对海三棱藨草的负面影响较大。随着九段沙滩涂的淤涨，芦苇群落的面积也一直在增加，增长速率约为70 hm~2／a，低于盐沼植被增加的平均速度。互花米草在九段沙沙洲上具有良好的适应性，从1997年引种种植的55hm~2，到2008年已增加到1708．57 hm~2，目前已成为九段沙新生沙洲上分布面积最大的植被，占九段沙滩涂盐沼植被总面积的47．5％。(4)外来种互花米草种群动态CA模型互花米草被人为引种到长江口后，在长江口滩涂湿地表现了良好的适应性，逐渐成为上海滩涂上重要的盐沼植被群落。互花米草在新环境的扩散分为三个不同的典型阶段，即定居期，滞缓期和快速扩散期。在长江口，由于淤泥质潮滩的自然环境极其适合其生长，再加上没有自然天敌，互花米草一般经历了1-2年的定居期和1-3年的滞缓期，随后进入快速扩展期。互花米草是滩涂中扩散最快的植被，扩散速度也远远超过光滩演替为先锋植被的平均速度。景观生态学的核心问题是研究空间格局与生态学过程之间的相互关系，而空间模型是景观生态学研究的有效手段之一，能够把一些重要生态学过程融合到模型的规则和参数中。互花米草种群扩散细胞自动机(CA)模型分析显示，互花米草的扩散能力是芦苇的3-5倍，具有比土著种芦苇更广的生态幅，所以互花米草具有比本地种芦苇更强的竞争能力和竞争优势。从而能够抢先占据更多的有利生境，间接影响芦苇群落的分布。种群动态遥感分析和CA模型研究还表明，在生态位有限的空间，即淤涨很慢或侵蚀性的岸段，如九段沙的中沙，互花米草的增长符合逻辑斯蒂增长模型，尽管经历几年的增长，互花米草的扩散速度会慢下来，但对滩涂湿地的结构和功能的改变却很大，会直接导致本地种海三棱藨草群落的退化甚至消失。而在淤涨型的潮滩上，互花米草扩散符合指数增长模型，随着滩涂的淤涨，不断有适合互花米草的空生态位形成，互花米草的快速增长会持续很长时间。在淤涨型滩涂上，互花米草的扩散会形成大片的单优植被群落，占据大面积的滩涂湿地，从而改变滩涂湿地的生物多样性，影响滩涂湿地的生态服务功能。更多还原

【Abstract】 Shanghai,with the huge amount of silt brought by the Yangtze River,is blessedwith plentiful coastal intertidal wetlands,which are also the potential land resourcesfor economical development.Intertidal wetlands could also provide ecological serviceand environmental value as well.The salt marsh communities colonized on thewetlands also have various functions such as improving water quality,mitigatingclimate change and conserving biodiversity.The results of this research on theintertidal vegetation populations dynamics in Shanghai will provide a sound basis forresource management and planning,preservation of biodiversity,sustainabledevelopment and utility of wetlands in the region.This study investigated spatial and temporal dynamics of salt marsh populationsof Yangtze River Estuary wetlands during the 1990 and 2008.A set of multi-temporalLandsat thematic mapper (TM) images were used,which basically covered the stateof the low tide at the time the images were taken and the areas of different stagesunder the impacts of human activities.These satellite images were geometricallycorrected by a series of nautical charts,using ERDAS software.Two spectralenhancement methods,Tasseled Cap (K-T) Transform and Normal DifferenceVegetation Index (NDVI),were used to interpret satellite images more efficiently.Moreover,several in situ field surveys were carried out to revise the imageclassifications and for the classification accuracy assessment.The main results of thisstudy were summarized as follows:1.The spatial distribution of salt marsh in Shanghai regionBefore the introduction of exotic plant Spartina alterniflora,the salt marshcommunities in intertidal zone of Shanghai region were mainly Phragmites australisand Scirpus mariqueter communities.S.alterniflora,as an ecological engineeringvegetation,was introduced to Shanghai intertidal zone during 1990s,and over the past10 years this species has gradually invaded large areas which could have been coveredby P.australis and S.mariqueter.P.australis was the dominant species by 1990 on the Yangtze River Estuarywetlands,it covered about 14100 hm~2,accounting for 80% of the total salt marsh area. However,half of the P.australis had been lost during 1990 and 2000.The mainreason was the1990s’ reclamations,which happened in the high tidal mudflat,wheremainly colonized by P.australis communities.At the same time,S.alterniflora beganto establish on the Yangtze River Estuary wetlands.During 2000 and 2003,the areasof all the salt marsh vegetations kept increasing.To the August of 2003,the total areaof all the salt marsh vegetation had reached 21953 hm~2,including 7602 hm~2 of S.mariqueter,10075 hm~2 of P.australis and 4276 hm~2 ofS.alterniflora.After 2003,thetotal salt marsh began to decline mainly due to intense reclamation.Both S.mariqueter and P.australis communities shrunk by half.On the other hand,the exoticspecies S.alterniflora was still keeping increasing.To 2008,S.alterniflora haddominated 5698 hm~2 of the intertidal wetlands in Shanghai,accounting for the largestarea among all the salt marsh species.2.The spatial-temporal dynamics of salt marsh vegetation for ChongmingDongdan National ReserveIn Chongming Dontan,P.australis communities experienced serious degradationsince 1990 mainly because of the high altitude reclamation happen in 1992,1998 and2001.Afterwards,the P australis community began to increase slowly.There waslittle impact on S.mariqueter community from high altitude reclamation.From 1990the area of P.australis community had kept increasing for more than 15 years.Withthe rapid range population expansion of S.alterniflora,the area of P.australis beganto decrease since 2005,but the area of this species always maintained more than 2000hm~2.For exotic vegetation S.alterniflora,it had kept expanding from its initialintroduction,and had accounted for almost one third of the total intertidal salt marshat Chongming Dongtan Natural Reserve by 2008.3.Salt marsh population dynamics at Jiuduansha ShoalsJiuduansha Shoals are new formed neonatal islands,and they grow very fast dueto their unique location at Yangtze Estuary.The Jiuduansha shoals have never beencolonized by humans and have been in a natural condition since they were formed.From 1997 to 2008,the total salt marsh area had increased from 1094.6 hm~2 to 3600.6hm~2,with a mean increasing rate of 230 hm~2/a.S.mariqueter increased from 966.56hm~2 in 1997 to 1850.22 hm~2 in 2003,whereas the area of S.mariqueter began to decrease afterwards with the rapid range expansion of S.alterniflora population inMiddle Shoal and Lower Shoal.The mean increasing speed for P.australiscommunity was 70 hm~2/a,and the area increased from 168 hm~2 in 1997 to 924 hm~2 in2008.S.alterniflora had showed strong competitive capacity at Jiuduansha Shoals.Itsexpanding rate exceeded any of the indigenous species.The area of S.alterniflora hadincreased to 1708.57 hm~2 by 2008,accounting for 47.5% of the total salt marshvegetation,and had dominated the largest area on Jiuduansha Shoals.4.A CA model for population expansion of Spartina alternifloraAfter the initial introduction to Yangtze Estuarine wetlands,S.alterniflora hadshowed well adaptability in this region.It had become the dominant species in theintertidal zone of this area.The population expansion pattern of S.alterniflora wascompatible with the common feature of invasion,i.e.the initial colonization,a lagtime and the rapid range expansion.The intertidal environment was very suitable for S.alterniflora to grow and reproduct.In addition,there were little natural predators,sojust after 1-2 years of colonization and less than 3 years of lag time,S.alterniflorabegan its rapid population growth and range expansion.S.alterniflora had strongercapacity of competition and broader niche,which made it possible to invadesuccessfully in the intertidal zone.CA model of S.alterniflora population also indicated that in the region withlimited niche,such as Middle Shoal of Jiuduansha Shoals,the expansion of S.alterniflora was conformed with Logistic Growth model,whereas in the area withunlimited niche,such as Lower Shoal of Jiuduansha Shoals,the expansion of S.alterniflora was consistent with Exponential Growth model.So with the developmentof intertidal flat,more and more niches that suit for S.alterniflora would be formed,the range expansion ofS.alterniflora will be expected to continue well into the future,which means large area of intertidal wetlands will be dominated by S.alterniflora,putting seriously threaten to local ecosystem.更多还原