蔡家河湿地土壤种子库特征及其与地上植被和土壤因子的关系

The characteristic of soil seed bank and its relationship with vegetation and soil factor in the wetland region of Caijiahe, Beijing

为明确蔡家河湿地土壤种子库特征及其与地上植被和土壤因子的关系,采用野外调查取样和室内萌发实验相结合的方法,对芦苇群落,野艾蒿群落和林下杂草群落3种不同植被类型的土壤种子库密度,物种组成,地上植被以及土壤理化性质进行了调查研究。结果表明:蔡家河湿地3种植被类型的土壤种子库密度分别为(7725±1286)粒·m^-2,(2535±556)粒·m^-2和(5085±984)粒·m^-2;物种数量分别为36种, 28种和39种。3种植被类型土壤种子库的物种丰富度以及多样性均高于地上植被,并且3种植被类型间土壤种子库物种组成的相似性高于地上植被,说明土壤种子库比地上植被具有更高的稳定性。芦苇群落的种子库密度,物种多样性指数以及土壤种子库和地上植被物种组成的相似性均高于野艾蒿群落和林下杂草群落。土壤含水量与土壤有机质是影响土壤种子库物种组成的主要土壤因子,在土壤水分以及有机质含量高的芦苇群落中含有大量湿生植物种子,但在水分和有机质含量低的野艾蒿和林下杂草群落未发现柳叶菜(Epilobium hirsutum)、马先蒿(Pedicularis resupinata)、问荆(Equisetum arvense)等湿生植物的种子。因此,蔡家河湿地土壤种子库已出现一定程度的退化,芦苇群落土壤种子库可用作退化湿地植被恢复的种源,在植被恢复时要满足种子萌发对土壤水分和有机质的需求。

In order to identify the characteristic of soil seed bank and its relationship with vegetation and soil factor, the soil seed density, species composition, aboveground vegetation and soil physical and chemical properties in three vegetation types (reed community, sagebrush community, understory weed community) were conducted with field investigations and seed germination experiments. The results showed that soil seed density of the three vegetation types were 7725±1286, 2535±556 and 5085±984 seed·m^-2, respectively;species numbers were 36, 28 and 39, respectively. Species richness and species diversity of soil seed bank were higher than those in vegetation in three vegetation types, indicating that soil seed bank had higher stabilization than vegetation. Seed bank density, species diversity, the similarity between soil seed bank and vegetation in reed community were all higher than those in sagebrush community and understory weed community. Soil water content and soil organic matter were the main soil factors affecting the soil seed bank composition. There were lots of hygrophyte seeds in reed community, but hygrophyte such as Epilobium hirsutum, Pedicularis resupinata and Equisetum arvense was disappeared in sagebrush community and understory weed community. The results suggested that the seed bank of Caijiahe wetland was degraded, but soil seed bank of reed community could be used for vegetation restoration, and it was necessary to consider the soil water content and soil organic matter in vegetation restoration.