中文摘要：

研究了物种库限制与生态位限制在湖滨湿地植物分布格局形成过程中的相对重要性。在龙感湖湖滨湿地具有明显水位梯度的湿生植物区、挺水植物区和沉水植物区采集种子库土样,采用幼苗萌发法确定了不同水位区种子库的物种成分;并将不同水位区的种子库土样分别置于0、25和50cm3个水位下萌发和生长,45和90d后比较不同取样区种子库在不同水位处理下所建立的植物群落的异同。结果表明,不同取样区的种子库物种成分有显著差异,沿水深梯度呈现明显的带状分布格局。水位处理实验表明,0cm水位条件下的群落主要由湿生植物和挺水植物组成,而25和50cm水位下只有沉水植物,表明不同功能群的物种对水深有不同的耐受力,生态位限制是决定湿地植物分布格局的关键因子。同时,挺水植物区的种子库置于沉水条件下,以及沉水植物区的种子库置于0cm水位下都只能形成极为简单的植物群落,表明物种库限制对湿地植物群落的形成同样具有显著影响。研究表明,湿地植物的群落构成与分布格局是由生态位限制和物种库限制共同决定的,两者的相对重要性可能取决于水体的稳定性。

英文摘要：

Aims Much research has focused on the effects of competition and stress tolerance on plant zonation in wetlands, but few studies have explored the role of propagule availability. This study examined the relative importance of niche limitation and species pool limitation in structuring lakeshore plant communities. Methods We sampled the soil seed banks from the hygrophyte, emergent-plant and submerged-plant zones in a subtropical lakeshore marsh, Longgan Lake, China and used the seedling germination method to examine the density and species composition of seed banks. To assess the effects of species pool and water depth on community establishment, we exposed seed bank samples to three water-level treatments （depths of 0, 25 and 50 cm） and, 45 and 90 days later, compared the species richness and functional groups of the communities that established. Important findings Species of the seed banks were grouped according to their ability to tolerate or respond to water-depth gradients. The established vegetations varied significantly among sites and treatments. For all three sites, mud-flat and emergent communities established at the 0 water-level treatment, while submerged communities established at the 25 and 50 cm water-level treatments, show-ing that the species belonging to different functional group have different tolerances to water depths and that water depth （niche limitation） was important in shaping plant zonation in freshwater marsh. Only the simplest community developed when the seed bank of the emergent-plant zone was exposed to the 25 and 50 cm water-level treatments, as well as when the seed bank of submerged-plant zone was exposed to the 0 water-level treatment. This shows that community species richness depends primarily on the composition and viability of the seeds in the soil seed bank. These findings suggest that the structure and distribution pattern of the wetland community were determined by both niche limitation and species pool limitation. Their relative importance may depend on the sta