红壤侵蚀区植被恢复过程中土壤种子库变化特征

Variation characteristics of soil seed bank during vegetation restoration in red soil erosion area

土壤侵蚀作为一种自然营力和自然干扰形式对土壤种子库的次分布与物种组成具有一定的影响。本研究对典型红壤侵蚀区裸地(Ⅰ号)、马尾松林地(Ⅱ、Ⅲ、Ⅳ号)和次生林(Ⅴ号)等5处不同植被恢复区的土壤种子库物种组成、储量及分布格局进行研究,探究在植被恢复过程中土壤侵蚀对土壤种子库的影响。结果表明:研究区土壤种子库共统计到21种物种,物种丰富度低,以草本种类为主。各样地土壤种子库密度为56.7~793.3粒·m-2,样地间差异显著,土壤种子库密度随着土壤侵蚀强度加重而明显下降。各样地浅层0~2 cm土壤种子库密度随着上坡-中坡-下坡的变化均呈增加趋势;剧烈侵蚀地和强烈侵蚀地土壤种子库主要分布在5~10 cm深层土壤内,且中上坡0~2 cm土层几乎没有种子。土壤侵蚀使得土壤种子库在土层中的分布呈现深层化,植被恢复后深层种子库积累仍需要较长的时间。

As a natural disturbance agent, soil erosion could affect secondary distribution and species composition of soil seed bank. The composition, storage and distribution pattern of the soil seed banks in five different vegetation recovery areas, including bare ground(Ⅰ), pine forest land(Ⅱ-Ⅳ) and secondary forest(Ⅴ) in the typical red soil erosion area, were studied to explore the effects of soil erosion on soil seed bank during vegetation restoration. The results showed that a total of 21 species were recorded in the soil seed bank. Species richness was low, and dominated by herbaceous species. The density of soil seed bank varied from 56.7 to 793.3 seeds·m-2 and differed significantly among the sampling plots. Further, the density of soil seed bank decreased obviously with the increasing soil erosion intensity. The seed bank density of 0-2 cm soil layer increased along uphill, middle slope, and downhill. The soil seed banks of severely eroded and strongly eroded plots were mainly distributed in the 5-10 cm soil layer, with almost no seeds in 0-2 cm soil layer on the middle slope and uphill. Soil erosion made the distribution of soil seed bank to deeper soil layer, the accumulation of which will need a long time after vegetation restoration.