【作者】 刘庆艳；

【导师】 姜明；

【作者基本信息】 中国科学院研究生院(东北地理与农业生态研究所) ， 自然地理学， 2013， 硕士

【摘要】 本文通过幼苗萌发法与野外植被调查相结合的方法，对三江平原不同年限沟渠的土壤种子库及地上植被进行研究，阐述沟渠植被的时间变化规律；分析多级沟渠系统土壤种子库特征，并与邻近开垦农田、孤立湿地土壤种子库进行比较，探讨沟渠系统土壤种子库的空间分布格局，进而揭示沟渠植物群落演替特征及其在维持湿地生物多样性方面的作用。三江平原沟渠具有较大规模的土壤种子库，边坡种子库显著大于底泥种子库。边坡种子库密度为8973~25000粒/m~2，底泥种子库密度为506~1488粒/m~2。3个年限沟渠种子库共萌发50种植物，隶属20科41属。随着沟渠年限的增加，土壤种子库萌发物种数量以及湿地植物呈减少趋势。地上植被调查共发现16科41属50种植物，随着沟渠年限的增加，地上植物群落中多年生物种的比重逐渐增大；由于植物群落在物种分布上趋于均匀，Simpson多样性指数、Shannon-Wiener多样性指数和Pielou均匀度指数都逐渐增大。土壤种子库与地上植被的相似性系数介于32.7%与38.7%之间，整体处于较低水平。多级沟渠系统的土壤种子库密度高于孤立湿地，而与邻近开垦10年的农田没有显著差异，其种子库大小在6784~15226粒/m~2之间。多级沟渠系统的土壤种子库共萌发了18科33属39种植物，优势科为禾本科、莎草科和菊科。其中多年生植物居多，占物种总数的59%；湿地植物占物种总数的71.8%，高于农田种子库中湿地植物物种数。随着沟渠等级的增大，土壤种子库的Simpson指数、Shannon-Wiener指数和Pielou均匀度指数都呈递减趋势，农田种子库的三个多样性指数都小于沟渠系统的最低值，孤立湿地种子库的三个指数接近沟渠系统的最高值，表明沟渠系统土壤种子库的物种多样性介于农田和孤立湿地之间。沟渠土壤种子库和地上植被中保存了大量湿地植物，表明沟渠具有维持植物多样性的作用以及进行湿地恢复的潜力。但随着沟渠年限的增加，沟渠植物群落呈现退化特征，说明沟渠长期维持湿地植物多样性的作用有限，对湿地植被退化过程起到了一定的缓冲作用，需要对沟渠系统加强管理。更多还原

【Abstract】 Germination method and vegetation investigation method were used to studycharacteristics of soil seed banks and aboveground vegetation in ditches of different yearsin the Sanjiang Plain. Characteristics of seed banks in multi-stage ditches system werestudied and compared with that of farmland and isolated wetland nearby. Spatial andtemporal characteristics of soil seed banks in ditch systems were discussed to exploresuccession characteristics of plant communities in ditches and their potential role inwetland biodiversity conservation.The results showed that the density of seed bank in ditches in the Sanjiang Plain washigh. Seed density of ditch banks was8973~25000seeds/m~2, higher than that of sedimentin ditches, which was506~1488seeds/m~2. A total of50species germinated belonging to20families,41genera. The number of species germinated from seed banks decreased withsuccession, the same as wetland plants.50species germinated belonging to16families,41genera were recorded in aboveground vegetation. Percentage of perennial species inaboveground vegetation gradually increased with succession. At the same time, Simpson,Shannon-Wiener indices and Pielou evenness increased, as species distribution tend to beuniform. Similarity index of seed bank and aboveground vegetation was low, which was32.7%~38.7%.Seed density of multi-stage ditches system was6784~15226seeds/m~2, higher than thatof isolated wetland. And there was no significant difference between multi-stage ditchessystem and10yrs farmland. In multi-stage ditches system, a total of39species germinatedbelonging to18families,33genera, and gramineae, cyperaceae and compositae plantswere dominant. Perennial species were in majority, accounting for59%. Wetland speciesaccounted for71.8%, and the number of wetland species was higher than that of farmland. Simpson, Shannon-Wiener indices and Pielou evenness decreased with the increase of ditchlevel. Species diversity was the lowest in farmland compared with multi-stage ditchessystem and farmland.According to this study, there were a large amount of wetland species in seed bankand aboveground vegetation in ditches, indicating that ditches play an important role inmaintaining plant diversity and have potential to be used in wetland restoration. Plantcommunity degradation with succession in ditches suggests that the function of ditches forbiodiversity conservation was limited for the long term. Management of ditches should bestrengthened.更多还原