三江平原沟渠土壤种子库特征及其与地上植被的关系

为了探究三江平原沟渠土壤种子库在湿地植物保护中的作用及其在湿地恢复中的潜力,该文采用幼苗萌发法与样方调查相结合的方法,对三江平原不同开挖年限沟渠的土壤种子库特征及其与地上植被的关系进行了研究。结果表明: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8 973–25 000 seeds·m–2,底泥种子库密度为506–1 488 seeds·m–2。开挖10年、20年和30年的沟渠土壤种子库共有50种植物萌发,隶属于20科41属。开挖10年、20年和30年的沟渠土壤种子库萌发物种数分别为37种、34种和33种,地上植被物种数分别为25种、33种和22种。土壤种子库和相应地上植被的相似性系数分别为38.7%、35.8%和32.7%。随着植物群落演替的进行,地上植被的Simpson指数、Shannon-Wiener多样性指数和Pielou均匀度指数均逐渐增大。三江平原沟渠土壤种子库和地上植被中保存了大量湿地植物,表明沟渠具有保护植物物种多样性的作用,沟渠土壤种子库具有湿地恢复的潜力。随着沟渠开挖年限增加,沟渠植物群落呈现退化特征,建议对沟渠系统加强管理。

Characteristics of soil seed banks and their relationships with aboveground vegetation in ditches in the Sanjiang Plain

Aims Ditches play an important role in preserving plant biodiversity. Our objective was to determine the characteristics of soil seed banks and their relationships with aboveground vegetation in ditches over different times in the Sanjiang Plain.
Methods Soil seed banks were investigated on different sites of ditches, and germination method was used to identify species composition of seed banks. Aboveground vegetation was investigated with quadrate method in ditches where seed banks were sampled.
Important findings Results showed that the seed density in the soil seed banks in ditches was generally high. Seed density on the banks of ditches was 8 973–25 000 seeds·m^–2, higher than that in the sediments of ditches, which was 506–1 488 seeds·m^–2. A total of 50 species were identified in the soil seed banks with the germination method, belonging to 41 genera in 20 families. The number of species found in the soil seed banks was 37, 34, and 33 in ditches with excavation time history of 10 years, 20 years, and 30 years, respectively, corresponding to 25, 33, and 22 species recorded in the aboveground vegetation. Similarity indexes for the comparison between soil seed banks and aboveground vegetation were 38.7%, 35.8%, 32.7%, respectively. Simpson index, Shannon-Wiener index and Pielou evenness index of aboveground vegetation increased with succession. According to this study, there are a large amount of wetland species in the soil seed bank and aboveground vegetation in ditches in the Sanjiang Plain, indicating that ditches play an important role in preserving plant biodiversity and that soil seed bank in ditches have potential to be used in wetland restoration. Plant community degradation with succession in ditches suggests that management of ditches should be strengthened.