| 摘要: |
| 【目的】研究围栏和退化对西藏邦杰塘高山嵩草草甸土壤种子库的影响，并探讨土壤种子库在地上植被群落构建中的作用，为高寒地区退化草甸生态系统的恢复与重建提供理论参考。【方法】采用幼苗萌发法，研究在围栏、退化条件下，西藏邦杰塘高寒草甸地上植被群落的物种组成、土壤种子库中物种种类、种子数量等特征及地上植被与土壤种子库物种组成之间的关系。【结果】围栏样地的地上植被群落中共出现18个物种，多年生禾本科、莎草科植物占主要地位；退化样地地上植被群落中共出现15个物种，以杂草类植物占据优势，其大多属于菊科、蔷薇科、毛茛科和龙胆科等。退化样地土壤种子库密度达5 489.4粒/m2，显著P＜0.05）高于围栏样地的4 029.3 粒/m2，退化样地土壤种子库密度主要依赖于菊科、龙胆科、蔷薇科等杂草类种子的输入，3个科的植物种子数占种子总数的64.6%；与退化样地比较，围栏样地土壤种子库的物种多样性指数和丰富度指数均显著提高（P＜0.05）。围栏样地土壤种子库与地上植被物种组成之间相似性较低，Sorensen相似性指数仅为0.44；退化样地中嵩草属植物严重退化，地上植被群落中依靠种子繁殖的杂草类所占比例较高，地上植被与土壤种子库表现出较高的相似性，相似性指数为0.72。【结论】种子库在地上植物群落构建中起到重要作用，但其对地上植被的贡献大小在围栏和退化条件下表现不同。围栏样地以高山嵩草、大花嵩草、紫花针茅为优势种，围封措施减少了环境的扰动，但其土壤种子库密度较低，说明在群落更新过程中，多年生禾本科、莎草科植物的种子萌生苗只起到辅助作用。 |
| 关键词: 高山嵩草草甸 围栏 退化草地 土壤种子库 物种多样性 植物生活型 |
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| 基金项目:国家科技支撑计划项目(2011BAD17B05-4，2011BAC09B03）；国家自然科学基金项目（31160312）；西藏大学农牧学院青年基金项目（2012022） |
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| Comparison of soil seed banks under fenced and degraded conditions in alpine meadow of Tibet |
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WANG Xiang-tao,GAO Yang,MIAO Yan-jun,et al
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| Abstract: |
| 【Objective】This paper studied the effects of fencing and degradation on soil seed banks in alpine meadow of Bangjietang area in Tibet to understand the role of soil seed bank in construction of aboveground vegetation communities,which would provide theoretical basis for the restoration and reconstruction of degraded ecosystems in alpine regions in Bangjietang,Tibet.【Method】Seedling germination method was adopted to survey species composition of aboveground vegetation and features of soil seed banks including species types and seed numbers under fenced and degraded conditions in alpine regions in Bangjietang,Tibet.Moreover,the relationship between vegetation aboveground and composition of seed banks was discussed.【Result】In the fenced sample area,18 species were observed in the aboveground community with the dominating species of Poaceae and Cyperaceae.There were 15 species in the degraded sample area.Forbs dominated in aboveground vegetation community and most of which belonged to four families including Asteraceae,Gentianaceae,Rosaceae,and Ranunculaceae.The seed density in degraded sample area was 5 489.4 seeds/m2,significantly greater than that in fenced sample area (4 029.3 seeds/m2) (P<0.05).The seed density in the degraded sample area mainly relied on the inputs of Forbs seeds such as Asteraceae,Gentianaceae,and Rosaceae,and the seed number from the three families accounted for up to 64.6% of the total seed number.Compared with degraded sample area,both species diversity indexes and richness index were significantly increased in fenced sample area (P<0.05).The similarity between the soil seed banks and the vegetation compositions in the aboveground vegetation was low,and the Sorensen index was only 0.44 in the fenced sample area.In the degraded sample area,the degeneration of Kobresia was severe.The proportion of forbs which relied on seed propagation from the aboveground vegetation community was high,and the similarity between aboveground vegetation and soil seed bank was as high as 0.72.【Conclusion】The soil seed bank played an important role in the plant community construction.However,its contributions to the aboveground vegetation behaved differently in fence and degraded conditions.The dominated species in the fenced sample area were Kobresia pygmaea,Macrofloral kobresia,and Stipa purpurea.Fencing decreased the environment disturbance,but decreased the soil seed bank density,indicating that seedling sprouts of Gramineae and Cypereraceae plants only played a supporting role in the process of community regeneration. |
| Key words: Kobresia pygmaea alpine meadow fence degraded grassland soil seed bank species diversity plant form |
