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古尔班通古特沙漠生物土壤结皮对土壤种子库多样性与分布特征的影响

邢旭明1,2,马晓东1,张元明2*   

  1. (1新疆师范大学生命科学学院, 新疆特殊环境物种多样性应用与调控重点实验室, 乌鲁木齐 830054; 2中国科学院新疆生态与地理研究所干旱区生物地理与生物资源重点实验室, 乌鲁木齐 830011)
  • 出版日期:2016-03-10 发布日期:2016-03-10

Effects of biological soil crusts on soil seed bank diversity and distribution characteristics in Gurbantunggut Desert.

XING Xu-ming1,2, MA Xiao-dong1, ZHANG Yuan-ming2*   

  1. (1Key Laboratory of Species Diversity Application and Control in Xinjiang, College of Life Sciences, Xinjiang Normal University, Urumqi 830054, China;  2Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China)
  • Online:2016-03-10 Published:2016-03-10

摘要: 古尔班通古特沙漠地表广泛分布着生物土壤结皮,研究其覆盖下的土壤种子库,有利于了解生物土壤结皮的生态功能及当地植被更新与恢复的潜力。本文研究了该地区3种生物土壤结皮(藻结皮、地衣结皮、苔藓结皮)对土壤种子库分布特征和多样性的影响。结果表明:在种子库水平分布上,相比于裸沙,生物土壤结皮增加了种子库密度,且不同结皮类型对种子库的影响程度不同。地衣结皮土壤种子库的密度最大(5905±778粒·m-3),其对种子的捕获作用最为明显,其次是苔藓结皮(1138±380粒·m-3),藻结皮与裸沙无显著差异;水平分布上的差异与结皮的发育程度、种子的形态、不同生物土壤结皮空间分布的异质性有关。在垂直分布方面,结皮发育土壤,种子库集中分布在土壤浅层(0~2 cm),这与裸沙种子库的垂直分布特征基本一致,说明结皮的存在并没有显著改变种子库的垂直分布格局。此外,从裸沙到苔藓结皮,土壤种子库和地上植被的相似性不高(0.14~0.29),土壤种子库中的物种多样性和丰富度指数不及地上植被高。该研究区土壤种子库在植被恢复中的潜力可能较小,但相对于裸沙,生物土壤结皮的存在有益于土壤种子库的保持,对荒漠生态系统物种多样性的维持和稳定具有重要意义。

关键词: 杉木, 生物量分配, 幼苗出土, 形态可塑性, 遮阴, 天然更新

Abstract: Biological soil crusts are widely distributed on the surface soil in the Gurbantunggut Desert. Studies on soil seed bank with the coverage of biological soil crusts can facilitate our understanding of the ecological functioning of biological soil crusts and vegetation renewal and succession. In this study, we focused on three types of biological soil crusts (cyanobacterialalgal crusts, lichen crusts and moss crusts) regarding the dominant functional group in crusts and investigated soil seed bank diversity and distribution in the Gurbantunggut Desert. In the horizontal distribution of soil seed bank, soil seed bank density was significantly higher in biological soil crusts than in bare sand, and it differed among the three types of crusts. Soil seed band density was highest in lichen crusts (5905±778 seeds·m-3), suggesting lichen crusts has the largest potential to entrap seeds. Seed bank density in moss crusted soil was 1138±380 seeds·m-3; cyanobacterialalgal crusts showed no difference in seed bank density with bare sand. The degree of biological soil crust development, the seed morphology, the spatial distribution difference of different biological soil crusts were the reasons for the difference of the horizontal distribution of soil seed bank. Seeds were primarily distributed in the shallow soil layer of 0-2 cm in biologically crusted soil, consistent with that in bare sand. This demonstrates that biological soil crusts exert no impacts on the vertical distribution of seeds. The similarity index of soil seed bank with vegetation was very low, ranging from 0.14 in bare sand to 0.29 in moss crusted soil. The species diversity and abundance in seed bank were lower than those of the plant community. This result, to some extent, suggests a limited role of soil seed bank in vegetation restoration in this region. However, the inhabitation of biological soil crusts facilitates the reservoir of soil seed bank and is important to sustain species diversity and ecosystem stability in the deserts.

Key words: seedling emergence, morphological plasticity, shade, Chinese fir, biomass allocation, natural regeneration