作 者 ：张显强,张来,何跃军,冯晓英,孙敏*
期 刊 ：生态学报 2010年 30卷 12期 页码：3108~3116
关键词：喀斯特石漠化；结皮；细尖鳞叶藓；吸水机制；耐旱适应性；
Keywords:karst rocky desertification, crusts, T. aomoriense, water uptake mechanism, desiccation-tolerant adaptation,
摘 要 ：生物结皮是由隐花植物和相关土壤微小生物与表层土壤颗粒胶结而形成的复合体，与维管束植物覆盖一样，它是干旱区地表的重要覆盖类型。苔藓是荒漠植被演替过程中常见的一类先锋植物，同时也是生物结皮中生物量最大的2个类群之一。研究了结皮细尖鳞叶藓的吸水机制和耐旱适应性。结果表明：细尖鳞叶藓最大吸水量和持水率分别达到干重的9.74倍和700%以上，动力学总吸水过程的表观Km值和Vmax值分别为21.67 g、10.42 g?g-1?DW?min-1，外吸水过程为28.91 g和8.56 g?g-1?DW?min-1，内吸水过程为43.18 g和1.76 g?g-1?DW?min-1。可溶性糖含量从142.6 mg?g-1?DW（CK）上升到344.3 mg?g-1?DW，增长近2.4倍，而游离脯氨酸积累微弱。抗氧化酶SOD活性变化不明显，在0.04U?g-1?FW上下浮动；POD活性在PEG6000胁迫浓度在20%之前呈大幅度上升状态，以后趋于缓和，30%时达最高的131 U?g-1?min-1?FW，增加近2倍；CAT活性的变化情况与POD变化趋势相同，但变化量较小。膜脂过氧化指标MDA先略有升高又逐步回落，说明细尖鳞叶藓抗氧化酶系统利用提高POD和CAT活性清除SOD在清除超氧阴离子自由基过程中产生的H2O2。因此，在喀斯特石漠化缺少土壤、极度干旱且保水能力弱的环境区域，结皮藓类植物以其特有的吸水特征、持水功能和抗旱机制等生态功能在石漠化治理、退化生态系统的恢复中具有十分重要的作用。
Abstract:Biological soil crusts(BSC) are complex organic integrities of cyanobacteria, green algae, lichens and mosses, fungi as well as soil microorganism, cementing with surface soil fine particles by their exude mucilaginous material. They are common cryptogamic communities in various arid and semi-arid regions of the world. Mosses are not only a common pioneer plant in the process of vegetation succession but also one of two groups with the highest biomass in the biological soil crusts. As pioneer plants, mosses are indispensable in the process of establishing the biological soil crusts, which play an important role in desert ecosystems, namely indicating vegetation type, holding soil, fixing sand, and preventing from erosion by water or wind. With regards to BSCs, up to now, it not only becomes one of international key scientific issues for earth surface processes in arid regions, but also cross highlight between geographical and biological knowledge. The mechanism of water absorption and adaptability of tolerant to drought of Taxiphyllum aomoriense were studied in this paper. The results indicated that the maximal water holding rate and amount of water uptake of the mosses were 9.74 times and 7 times higher than the dry mosses, respectively. According to the dynamic curve, Km value, Vmax value, inter water absorption and outer water absorption were 21.67 g and 10.42 g?g-1?DW?min-1, 28.91g and 8.56 g?g-1?DW?min-1, and 43.18 g and 1.76 g?g-1?DW?min-1, respectively. The concentration of soluble sugar was increased from 142.6 mg?g-1?DW to 344.3 mg?g-1?DW, which was 2.4 times higher than the control. However, the concentration of free proline was increased slightly. The activity of the antioxidant enzymes superoxide dismutase（SOD）did not change significantly, fluctuating over 0.04U?g-1?FW; and under the PEG6000 concentration stress that peroxydase（POD） was increased significantly until 20% of the state, after easing, and finally up to 131 U?g-1?min-1?FW, an increase of nearly 2 times content; the catalase（CAT）of the changes alike POD in tendency, but with less variation. Indicators of membrane lipid peroxidation MDA content first increased slightly and gradually fell down. The explanation that the systematic use of antioxidant enzymes to improve POD and CAT activity synergy SOD superoxide anion radical and to remove generated of H2O2 under superoxide anion radical action in cells of T. aomoriense. Therefore, the results indicated that the moss crusts were able to absorb and reserve water, and desiccation-tolerant adaptation. Besides, moss crusts had great effect on pedogenesis, which was very important to control rock desertificationin karst regions.
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