湖南茶陵湖里沼泽种子库与地表植被的关系

Relationship between seed banks and standing vegetation in Huli marsh, Chaling, Hu′nan Province

研究了湖南茶陵湖里沼泽中水毛花 (Scirpus triangulatus)、疏忽蓼 (Polygonum p raetermissum) ,普通野生稻 (Oryzarufipogon)和莼菜 (Brasenia schreberi) 4种植被类型的种子库和地上植被的物种组成及两者之间的关系。 4种类型中共萌发了2 9种植物 ,种子平均密度为 5672粒· m- 2。不同植被类型的种子库的物种数和平均密度存在显著差异 ,疏忽蓼斑块的种子库中萌发 2 2种 ,平均密度是 10 0 89粒· m- 2 ;而普通野生稻斑块种子库中只有 14种 ,平均密度仅 2 50 0粒· m- 2。在地表植被中共鉴定出 18种植物。 4种植被类型中 ,其地表植被的物种数和 Shannon多样性指数均低于种子库。地表植被与种子库的物种相似性系数的范围从 0 .43 75至 0 .692 3。每种植被类型中 ,均有一些物种只在种子库中出现 ,而另有一些物种只在植被中出现。表明种子库在湿地保护和受损湿地的恢复中具有不可替代的作用。采用移植法进行湿地植被恢复时 ,应综合考虑种子库与地表植被、以及不同植被类型之间的物种组成的特点 。

Relationships between the standing vegetation and soil seed bank in relation to species richness and species composition were studied in communities dominated by four vegetation types (Scirpus triangulatus Comm. (ST), Polygonum praetermissum Comm. (PP), Brasenia schreberi Comm. (BS) and Oryza rufipogon Comm. (OR)) in Huli marsh, a subtropical upland shallow water marsh in Hunan Province, South China. Persistent seed banks were estimated from five replicate soil samples (each 6.8 cm diameter×5cm depth) within each vegetation type. Samples were exposed to moist soil (no standing water) in an unheated greenhouse for up to 156 days. A total of 29 species germinated in the experiments, and the average seed density was 5672 seeds·m^(-2). Seed bank sizes differed among vegetation types (ST: 20 species, 7822 seeds·m^(-2); PP: 22 species, 10089 seeds·m^(-2); BS: 18 species, 2278 seeds·m^(-2); and OR: 14 species, 2500 seeds·m^(-2)). Overall, the percent contribution of perennial and annual species was similar (54.5 and 45.5% respectively) but the percentage of seeds from perennials (79.9%) was much higher than from annuals (20.1%). Eighteen species were found in the standing vegetation survey. Species number was not significantly different among the four types of vegetation (ST 12 species; PP 14 species; BS 12 species; OR 12 species). Species number and diversity in the seed bank were greater than those in each community type. Coefficients of species similarity between the seed bank and the vegetation ranged from 0.438 to 0.692. Overall, 4 species were present in the vegetation, but not in the seed bank, whereas 14 species were present only in the seed bank. This suggests that the seed bank is vital to the natural persistence of the established plants as well as to the recovery of the community following natural or human disturbances.