Knowledge Resource Center for Ecological Environment in Arid Area
| 低温和降雪对生物土壤结皮生理生化特性的影响 | |
| 其他题名 | The effects of low temperature and winter snowfall on the physiological characteristics of biological soil crusts |
| 谢敏 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 刘立超 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 生物土壤结皮（ biological soil crusts，BSCs，以下简称生物结皮）是荒漠区生态系统重要组成之一，在生态修复与重建中发挥着重要作用。本研究以腾格里沙漠东南缘人工植被固沙区常见的生物结皮类型（真藓、土生对齿藓、蓝藻、地衣结皮）为研究对象，通过室内模拟冬季低温（-4℃、0℃、4℃、8℃）和野外降雪实验（无降雪、0.5倍降雪、1倍降雪、2倍降雪），分析低温和降雪对生物结皮光合特性、渗透调节物质以及膜脂过氧化程度的影响，探讨生物结皮对低温和降雪的适应和响应机制。主要研究结果如下：一、模拟低温对生物结皮光合能力、渗透调节能力以及膜脂过氧化程度的影响。（1）光合特性：在同一水分条件下，随着温度降低，4种生物结皮的叶绿素a、叶绿素b及类胡萝卜素含量均表现为下降趋势，藻和地衣结皮的变化趋势较藓结皮的略为明显；在同一温度条件下，藓结皮光合色素含量在零下低温处理下表现为高水分条件下含量较低，藻结皮和地衣结皮光合色素含量基本表现为随水分降低而降低；（2）渗透调节物质：在同一水分条件下，随着温度的降低，4种生物结皮的脯氨酸和可溶性糖含量均表现为上升趋势，藻结皮的变化趋势较其他几种更为明显；可溶性蛋白含量呈现出下降趋势。在同一温度条件下，土生对齿藓和地衣结皮的脯氨酸含量在零下低温表现为高水分条件下含量高，真藓和藻结皮脯氨酸含量则表现为随水分降低而增加的趋势；4种生物结皮可溶性糖含量随水分降低而增加；水分对4种生物结皮可溶性蛋白含量影响不显著，但有随水分降低而降低的趋势；（3）膜脂过氧化程度：在同一水分条件下，随着温度的降低，4种生物结皮丙二醛（MDA）含量逐渐积累，其中藻结皮的变化趋势较其他结皮更为明显；在同一温度条件下，藓结皮在零下低温表现为低水分条件下含量较高，其余对水分变化响应微弱，但基本表现为随水分降低而增加的趋势。二、冬季降雪对生物结皮光合能力、渗透调节能力以及膜脂过氧化程度的影响。（1）光合特性：在无降雪处理下，4种生物结皮叶绿素a、叶绿素b及类胡萝卜素含量均表现为最低状态。随降雪量的递增，植株含水量增加，光合色素含量也表现出增加的趋势，但在2倍降雪处理下，藻结皮和地衣结皮光合色素含量却降低；（2）渗透调节物质：在冬季无降雪时4种生物结皮脯氨酸含量和可溶性糖含量均较高、可溶性蛋白含量较低。随降雪量的递增，植株含水量增加，脯氨酸和可溶性糖含量均减少，以维持正常的细胞渗透势来适应低温环境；藓结皮可溶性蛋白含量呈上升趋势，而藻结皮和地衣结皮可溶性蛋白含量先升后降，均在2倍降雪处理下有所降低；（3）膜脂过氧化程度：在无降雪处理条件下，4种生物结皮MDA含量均相对较高。随降雪量的递增，藓结皮MDA含量逐渐降低，而藻结皮和地衣结皮MDA含量先降后升，在2倍降雪处理下有所升高。综上所述，我们的研究表明低温削弱了生物结皮光合能力且加剧了其膜脂过氧化程度，但可以通过其自身的渗透调节积累脯氨酸及可溶性糖来适应低温环境，说明生物结皮在低温仍具有生理活性。同时，适度的降雪对生物结皮的光合生理活性具有促进效应，在冬季生物结皮的碳固存不可忽视。过度降雪抑制了藻和地衣结皮的生理活性，藓结皮的最优含水量相对较高，比藻和地衣结皮更易适应极端降雪环境。不同类型生物结皮对冬季降雪的不同响应和反馈，在一定程度上影响了荒漠地区生物结皮的多样性及组成，进而导致生物结皮生态功能发生改变，这为气候变化大背景下荒漠区生态系统的稳定性和健康研究提供基础依据。 |
| 英文摘要 | Biological soil crusts (BSCs) as one of the most important components in arid and semi-arid communities, play an important role in ecological restoration and reconstruction. In this study, four typical BSCs (Bryum argenteum, Didymodon vinealis, cyanobacterial crusts and lichens) were sampled from a revegetated area in Shapotou, at the southeastern fringe of the Tengger Desert. We conducted the indoor simulation of low temperature experiment (-4℃, 0℃, 4℃, and 8℃) and field snowfall experiment (non-snowfall (control, 0S), half of the ambient conditions (0.5S), ambient snow (S), and double ambient conditions (2S)) to analyze the effects of low temperature and snowfall on the photosynthetic characteristics, osmotic adjustment ability and membrane lipid peroxidation of BSCs, and then to explore the responsive and adaptive mechanism of BSCs to low temperature and snowfall. The main results were as follows:The effects of low temperature to photosynthetic characteristics, osmotic adjustment substances and membrane lipid peroxidation of BSCs. (1) Photosynthetic characteristics: in the same water condition, Chla, Chlb, Chl(a+b) and Car contents decreased with the decrease of temperature, and the change was greater in cyanobacterial crusts and lichens than in mosses; at the same temperature conditions, photosynthetic pigment content of mosses under subzero treatments expressed high moisture content was low, while the photosynthetic pigment content of cyanobacterial crusts and lichens decreased with the decrease of water content. (2) Osmotic adjustment substances: in the same water condition, the proline and soluble sugar contents increased with the decrease of temperature, and the change of cyanobacterial crusts was slightly obvious than others; at the same temperature conditions, the proline contents of D.vinealis and lichens under subzero treatments expressed high moisture content was high, while the proline contents of B.argenteum and cyanobacterial crusts increased with decrease of water content, and the soluble sugar contents of BSCs increased with the decrease of water content. In the same water condition, the soluble protein content of BSCs decreased with the decrease of temperature, mosses had no significant difference above frezzing temperature treatments, but a sharp decline at -4℃, and the change of cyanobacterial crusts was slightly obvious than others; at the same temperature conditions, there were no significant differences under water conditions, but slightly decreased with the decrease of water content. (3) Membrane lipid peroxidation: in the same water condition, the malondialdehyde (MDA) content of BSCs increased with the decrease of temperature, and the change of cyanobacterial crusts was slightly obvious than others; at the same temperature conditions, the MDA content of mosses under subzero treatments showed low moisture conditions was higher, others decreased with the decrease of water content, but slightly. The effects of winter snowfall to photosynthetic characteristics, osmotic adjustment substances and membrane lipid peroxidation of BSCs. (1) Photosynthetic characteristics: the Chla, Chlb, Chl (a+b) and Car contents of BSCs were at the lowest conditions under 0S, with the increase of snowfall, the photosynthetic pigment contents increased, but the photosynthetic pigment contents of cyanobacterial crusts and lichens decreased under 2S. (2) Osmotic adjustment substances: the proline and soluble sugar contents of BSCs were relatively high under 0S, and then decreased with the increase of snowfall; the soluble protein content of BSCs was at the lowest content under 0S, and with the increase of snowfall, the soluble protein content of mosses increased, while the soluble protein content of cyanobacterial crusts and lichens decreased under 2S. (3) Membrane lipid peroxidation: the MDA content of BSCs was relatively high under 0S, and with the increase of snowfall, the MDA content decreased, while the MDA content of cyanobacterial crusts and lichens increased under 2S. In summary, low temperature inhibited the photosynthesis activity and increased membrane lipid peroxide level of BSCs, but enhanced the ability of osmotic adjustment through proline and soluble sugar accumulation, and then to adapt to the low temperature. At the same time, it was found that moderate snowfall had a positive effect on the physiological activity of BSCs. While excessive snowfall inhibited the physiological activity of algal crusts and lichens, and the optimum water content of mosses was higher, so mosses can adapt to extreme snowy weather events than that of algal crusts and lichens. This study provides a theoretical basis and data support for studying the physiological response mechanism of BSCs to low temperature and snowfall. |
| 中文关键词 | 低温 ; 降雪 ; 生物土壤结皮（生物结皮） ; 光合色素 ; 渗透调节 ; 膜脂过氧化程度 |
| 英文关键词 | low temperature snowfall biological soil crusts (BSCs) photosynthetic pigment osmotic adjustment membrane lipid peroxidation |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287955 |
| 推荐引用方式 GB/T 7714 | 谢敏. 低温和降雪对生物土壤结皮生理生化特性的影响[D]. 中国科学院大学,2017. |
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