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    沙柳方格沙障对土壤种子库的影响

    Effects of Salix psammophila checkerboard sand barrier on soil seed banks

    • 摘要: 以流动沙丘上设置7年的沙柳方格沙障为研究对象,对不同部位沙障内不同点位的土壤种子库进行研究。结果表明:沙障具有拦截植物种子和补充土壤种子库的作用,不同沙丘部位沙障内植物种组成与种子库密度不同,水平分布表现为迎风坡下部>中上部>中部>顶部,背风坡密度为0,垂直分布则随土层深度的增加而明显减少;不同部位沙障内种子库的生物多样性指数均呈迎风坡中上部>下部>中部>顶部的变化趋势,其土壤种子库种类组成中等相似,且相邻部位沙障内种子库组成的相似性较高,间隔部位的相似性系数较小;沙障内不同点位的种子库组成及密度分布不同,种子库密度的空间分布在沿风向方向(沙障西北角到东南角对角线上的A、B、C、D、E 5个点位)与垂直于风向方向(沙障障格内部北边中心F与南边中心G)的大小顺序为沙障西北角(A)>距西北角1/4处(B)>障格内部北边中点(F)>沙障东南角(E)>障格内部南边中点(G)>距东南角1/4处(D)>对角线的中点(C),且在障格内形成2个密度分布较大区和2个密度分布较小区;不同点位除Margalet丰富度指数外,其余指标均表现为障格内部南边中点(G)>沙障西北角(A)>距西北角1/4处(B)>对角线中点(C)>沙障东南角(E)>距东南角1/4处(D)>障格内部北边中点(F),各点位种子库组成的相似性系数变化较大。研究结果可为沙障条件下的植被恢复评价提供理论依据。

       

      Abstract: The soil seed banks of different point positions at different locations in moving dune with Salix psammophila checkerboard sand barrier of seven years were studied. Results show that sand barrier could intercept plant seeds and supplement the soil sand banks. Species composition and density of the soil seed banks were different. Their descending order in horizontal distribution was the lower part, the upper part, the middle part, the top part of windward slope, and the density was 0 on leeward slope. In the vertical distribution they significantly decreased as the increase of soil depth. The declining order of the biodiversity index of the soil seed banks was the upper part, the lower part, the middle part and the top part of windward slope. Species composition of the soil seed banks is medium similarity, but high similarity in sand barrier on neighboring position and low similarity in sand barrier on spaced position. Species composition and density of the soil seed banks at different locations were different. The declining order of the spatial distribution of density along the wind ( the five points A, B, C, D and E on the diagonal from the northwest corner to the southeast corner of the Salix psammophila checkerboard sand barrier) and perpendicular to the wind (the north and south borders inside the Salix psammophila checkerboard sand barrier) was the northwest corner of the sand barrier (A), the point at the quarter of the diagonal to the northwest corner (B), the midpoint of the north border inside the sand barrier (F), the southeast corner of the sand barrier (E), the midpoint of the south border inside the sand barrier (G), the point at the quarter of the diagonal to the southeast corner (D) and the midpoint of the diagonal (C). There were two greater density parts and two smaller density parts in sand barrier. Except for richness index of Margalet on different point positions, the order of other indices was the midpoint of the south border inside the sand barrier (G)>the northwest corner of the sand barrier (A)>the point at the quarter of the diagonal to the northwest corner (B)>the midpoint of the diagonal (C)>the southeast corner of the sand barrier (E)> the point at the quarter of the diagonal to the southeast corner (D)>the midpoint of the north border inside the sand barrier (F). The similarity coefficient of floristic composition of soil seed banks of different point positions changed greatly. The study could provide theoretical basis for vegetation restoration evaluation under the condition of sand barrier.

       

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