滇东喀斯特山地土壤种子及其分布特征

Seeds and Their Distribution in the Soils of Karst Upland in Eastern Yunnan

土壤种子是潜在的植物种群。在水洗土壤样品过粗细筛后,对云南东部3个不同岩溶地点的3种植被类型下的土壤中的种子进行了萌发实验研究,结果表明岩溶山地各植被类型的土壤中贮藏着丰富的种子,每个10cm×10cm×10cm土柱内储藏有40 9～149 3粒种子,高于贵州喀斯特山地和同纬度的广东森林。相对而言,次生林下的土壤中拥有相对较多的种子种类与数量,而退化草地内则较少,灌丛与二者之间的差异无明显规律。草本种子对密度值的贡献最大,灌木次之,乔木和藤本稀少。所有土壤的种子在水平方向上的分布差异巨大。种子密度随土层的深入而减小,次生林的减小趋势小于退化草地。垂直方向上的这种梯度差异可能与土壤的物理性质有关,次生林的土壤由于有机质含量高而使土壤的疏松程度高,有利于种子在土壤中的移动。

Seeds are the potential populations of plant. Using germination method after washing soil samples through a fine and a course sieve, soil seeds were studied for 3 kinds of soils covered with various vegetations at 3 karst locations in Eastern Yunnan. The results showed that there were abundant seeds stored in soils. There were 40.9～149.3 seeds for each of 10 cm×10 cm×10 cm soil unit which were much higher than that of karst soils in Guizhou and that of forest soils of Guangdong at the same latitude. Generally, seed density of secondary forest soil was higher than that of grassland. There was no any regular trend between seeds of scrub soils and that of grassland. Most of seeds were herbacious, shrub seeds came next, tree and liana were rare. Seeds were unevenly distributed horizontally at all the soils across the vegetation types and locations. Seeds density was dropped down vertically with a slow rate in the soil of secondary forest. The physical characteristics of soil might contribute to this difference of vertical drop rate. Higher organic matter made the soil less compact and easier for seeds to move into deep soil.