北京野鸭湖湿地不同植被退化区的土壤种子库特征

Characteristics of Soil Seed Banks in Different Areas of Degraded Vegetation of the Yeyahu Wetlands of Beijing

2010年5月,在北京野鸭湖湿地自然保护区选择废弃鱼塘、耕作苜蓿(Medicago)地、撂荒苜蓿地、天然退化湿地和天然湿地作为实验地,其中,天然湿地作为对照。通过土壤种子库萌发实验,对实验地土壤种子库的基本特征以及与地上植被的关系进行了对比研究。结果表明,5种实验地的土壤种子库共有60种植物,隶属于23科46属。其中,萌发物种最多的是菊科(Compositae)、禾本科(Poaceae)和莎草科(Cyperaceae),分别为11种、10种和8种。废弃鱼塘、耕作苜蓿地、撂荒苜蓿地和天然退化湿地种子平均密度为6 885粒/m^2,天然湿地种子的平均密度为16 083粒/m^2,5种实验地的种子库密度差异极显著(n=300,F=4.828,p=0.001<0.05);各实验地的种子库垂直分布有一致的规律性,各实验地0～6 cm土层的种子库密度明显高于6～12 cm土层;各实验地的土壤种子库与地上植被的相似性系数都不高,土壤种子库物种组成的稳定性要高于地上植被。通过研究发现,退化湿地的土壤种子库中有大量的植物种子储藏和湿地植物的种子,这为野鸭湖退化湿地恢复提供了重要的保障,这些潜在的植物种子在野鸭湖退化湿地生态输水过程中会起到应有的恢复作用。建议野鸭湖湿地自然保护区管理部门继续加强退化湿地区域的土壤种子库保护工作,必须重视水环境的恢复、各种人为干扰的消除以及系统保护的加强。

In this paper,the basic characteristics of soil seed bank and the relationship between soil seed bank and standing vegetation in four types of degraded areas and a natural wetland in Yeyahu Wetland Nature Reserve of Beijing were investigated in May 2010.The discard fishpond,cultivation of the clover field,abandonment of the clover field and natural degraded wetland as the experimental fields.While the natural wetland as the positive control.The results showed that there were 60 species belonging to 23 families and 46 genuses in the total 5 soil seed banks.During these,Compositae,Poaceae and Cyperaceae have the highest germination rate,11 species,10 species and 8 species respectively.The average density of soil seed bank in 4 degraded areas was 6 885 seeds/m2.And the average density of soil seed bank in natural wetland was 16 083 seeds/m^2.According to the analysis of variance,the density differences in 5 soil seed banks were extremely remarkable（n= 300,F=4.828,p=0.0010.05）.The vertical distributions of different part soil seed banks were regular.In terms of the sum of 5 sites,the densities of the soil seed bank in 0-6 cm layer were obviously higher than those in 6-12 cm layer.The similarity coefficient between soil seed bank and standing vegetation was low at each site;but it was more stabile in soil seed bank than standing vegetation.According to this study,there were a huge amount of plant seeds including wetland plants seeds in the degraded wetlands,which provide security to the restoration of Yeyahu wetlands.The potential plant seeds could make it possible to recover the wetland ecosystems during the water delivery.It is necessary,therefore,that measures be taken to restore water resources,rid of jamming and enhance the systemic protection for the conservation of soil seed banks of degraded wetland in Yeyahu Wetland Nature Reserve of Beijing.