天津滨海典型盐碱湿地土壤种子库特征及CCA分析

Soil seed bank of typical saline wetlands in Tianjin Binhai District and CCA analysis

选取天津滨海地区典型盐碱湿地,进行土壤种子库采样及萌发试验,同时测定土壤理化性质。采用典范对应分析法(CCA)对土壤种子库和土壤特征因子的关系进行研究。结果表明:4个样地土壤种子库储量较大,但物种组成单一,为滨海地区指示性盐生植物。与人工湿地相比,自然保护湿地具有物种丰富度高,群落结构稳定的优点,但受到干扰最小,种子库密度却最低。种子库种子萌发率曲线呈不规则的抛物形状,萌发数量曲线呈"S"型分布,土壤板结程度对萌发率有较大影响。土壤种子库垂直分层结构明显,随土壤深度加深,种子库密度降低,10～15 cm采样层仍保留大量活性种子。通过CCA分析,发现土壤种子库呈现明显的3个聚类;且土壤种子库受全盐量、有机质、pH影响较大,但土壤通透性这一因素也不容忽视。

Samples from typical coastal saline wetlands were selected for soil germination experiment. Meanwhile,the soil physicochemical properties were determined. The relationship between soil seed bank（SSB） and soil characteristic factors were studied by using CCA ordination（ canonical correspondence analysis）. The results showed that the reserves of SSB in four plots were abundant,but most species were coastal indicator halophytes,and its species composition was simple. Compared with artificial wetlands,conserved natural wetlands had the lower seed density,but higher species richness and stable vegetation community structure. The curves of seed germination rate represented an irregular parabolic shape,while the curve of seed quantity represented an S-shaped distribution. The degree of soil compaction had a great influence on soil germination. Soil seed bank showed a significant vertical hierarchy,and the density of SSB decreased with the increase of soil depth. Large numbers of seeds remained in the 10- 15 cm soil layer. By CCA analysis,three obvious clusters were presented. The total salt content,organic matter content and pH were main factors affecting the soil seed bank distribution. However,the permeability of soil was also an important factor that couldn＇t be ignored.