东洞庭湖湿地持久土壤种子库分布特征

Distribution characteristics of persistent soil seed bank on east Dongting Lake wetland

沿水位梯度设置三种类型样地,即高水位区、中水位区、低水位区,研究了东洞庭湖湿地持久土壤种子库的数量及分布特征。结果表明,持久土壤种子库主要由13种植物种子组成,其中高水位区最多,为7种,中水位区为6种,低水位区为4种。种子库密度在高水位区最大,为1 818.18粒/m^2,中水位区次之,为1 168.83粒/m^2,低水位区最小,为649.35粒/m^2。土壤种子主要集中在0-15 cm的土层中,且随着土壤深度加深而明显减少。对持久土壤种子库进行丰富度分析表明,三种区域土壤种子库的Margalef丰富度指数与Shannon-Wiener多样性指数均差异明显。其中,Margalef丰富度指数在高、中、低水位区分别为0.56、0.54、0.46,Shannon-Wiener多样性指数分别为0.51、0.43、0.34。可见,水位是影响湿地土壤持久种子库数量及分布最为重要的生态因子。

Amounts and distribution characteristics of persistent soil seed bank（PSSB） in east Dongting Lake wetland were investigated on three sample plots,i.e.high water level area（HWLR）,medium water level area（MWLR）,low water level area（LWLR）,which were set up according to their water depth.Results showed that PSSB were consisted of 13 plants species and 7 species in HWLR,6 species in MWLR,4 species in LWLR.Seed banks density were 1818.18 seeds·m-2 in HWLR,1168.83 seeds·m-2 in MWLR,649.35 seeds·m-2 in LWLR,which indicated that seed banks density increased with increased water depth.Soil seeds mainly concentrated on the soil layer of 0~15cm and decreased with increased soil depth.In addition,abundances of PSSB were analyzed and results showed that differences of Margalef richness index and Shannon-Wiener diversity index in three areas were significant.Margalef richness indexes were 0.56 in HWLR,0.54 in MWLR,0.46 in LWLR and Shannon-Wiener diversity indexes were 0.51 in HWLR,0.43 in MWLR,0.34 in LWLR.So,water level was the most important ecological factor to amounts and distribution characteristics of PSSB.