【作者】 陈彦芹；

【导师】 赵允格；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2009， 硕士

【摘要】 土壤侵蚀及荒漠化是当今国际社会极为关注的全球性环境问题,生物土壤结皮是干旱、半干旱地区普遍存在的地被物,其主要组成物—藻类、苔藓和地衣是常见的先锋拓殖物种,能够在干旱缺水、营养贫瘠、生境恶劣的环境中生长繁殖,并且能通过其代谢方式改变环境,在防风固沙、防治土壤侵蚀和区域生态环境变化等方面具有重要作用。本文以陕北黄土丘陵区自然发育的藓结皮为研究材料,通过室内培养试验探索了藓结皮人工培养适合的接种方法、接种量,适宜的培养温度和土壤水分条件,葡萄糖以及氮、磷、钾、镁、等几种营养物质对藓结皮形成发育的影响。研究表明,在一定条件下,采用人工接种的方法培养藓结皮切实可行,但接种方式、培养温度、土壤水分及营养物质种类不同,对藓结皮形成发育各项指标影响不尽相同。研究在藓结皮的接种方法、接种量及藓结皮培养条件等方面取得重要进展,可为黄土丘陵区生物土壤结皮的人工修复,及其在土壤侵蚀及沙漠化防治中的应用提供技术支撑。主要结论如下:1、相同培养条件下,在所采用的混合结皮、茎叶碎片和孢子接种3种方法中,混合结皮法接种有利于藓结皮盖度的形成,不同的接种量对藓结皮形成发育影响显著,茎叶碎片接种萌发成肉眼可辩的绿色配子体最快。在温度20℃,光照5230Lx,光周期12h/d条件下,采用混合结皮法接种,经80d的培养,藓结皮盖度、密度分别达到了76%和59株/cm2。混合结皮法接种量在500-750g/m2时藓结皮的盖度和藓类植物的密度生长较高。茎叶碎片接种萌发成肉眼可辩的绿色配子体最快,约4-5d,混合结皮稍慢需7d左右,孢子用时最长,至少20d。2、温度和土壤含水量显著影响藓结皮的形成和发育。试验条件下,17℃较11℃、22℃、27℃有利于藓结皮形成发育,单位面积藓类植物的数量及生长态势良好,藓结皮盖度和藓类植物密度生长稳定,并保持持续增长。60%田间持水量是藓结皮萌发的下限,只有土壤含水量>60%时,才有藓结皮形成。当土壤含水量达到超饱和含水量,近地面处空气相对湿度接近饱和时更有利于藓结皮的形成和发育。3、添加合适浓度的某些营养物质有利于藓结皮的形成和发育,其中以葡萄糖和硫酸镁最为显著。在土壤中添加葡萄糖和硫酸镁可以显著增加藓结皮盖度和藓株密度生长。其中以施用葡萄糖培养基上生长的藓结皮盖度、藓株密度和藓株高三个指标生长均为最高;藓结皮的形成发育与葡萄糖施用量明显正相关。黄土丘陵区藓结皮人工土培较适宜的葡萄糖施用浓度是30g/L;低浓度硝酸铵可以提高单位面积藓类植物的数量及生长态势,高浓度有抑制作用。研究区藓结皮形成发育较适宜的硝酸铵浓度为1.0g/L,当硝酸铵浓度达到8.0g/L时不利于藓结皮形成发育;磷酸二氢钾对藓结皮形成发育没有影响;硫酸镁能够促进藓结皮形成发育,对藓株高生长没有影响,在所设几种浓度处理中,以0.25g/L浓度处理下藓结皮盖度和密度生长最高。更多还原

【Abstract】 Soil erosion and desertification as the most important environmental problems were considered and studied worldwide. Biological soil crusts, which were consisted mainly by cyanobacteria, algae, mosses and lichens, play important roles in arid and semi-arid region, including soil erosion controlling. Mosses, which were an important organism in biological soil crusts, are a well-known pioneer flora that could survive and reproduce in the drought, poor nutrients and severe habitats. In order to promote the formation and restoration of moss crusts in Hilly Loess Plateau region, the suitable inoculation methods, inoculation amounts, cultivated conditions (temperature and soil moisture) and nutrition conditions (Glucose, ammonium nitrate, potassium, dehydrogenated phosphate, magnesium sulfate) were studied by using a growth chamber under laboratory controlled conditions. In the study, the natural moss crusts from Hilly Loess Plateau region were taken as the propagation materials. The results showed:1. Among the three inoculation methods, including spores inoculated, moss fragments inoculated and mixed crust, mixed crust inoculated was the most favorable methods for the formation of moss crusts when cultivated at the same conditions. There was a significant effect of different inoculation amount on the formation and development of moss crust. Mosses gametophyte formed firstly when inoculated by moss fragments. The coverage and moss density of crusts were 76% and 59 plant/cm2 after 80 days’cultivated at 20℃under a 12 h/d 5230 lx photoperiod. For mixed moss crusts, the coverage and mosses density were much better for 500-750g/m2 inoculated amount than the others. Compared with mixed crusts and spores inoculation, moss fragments inoculation showed the fastest formation of moss gametophyte, which was approximately 4-5d later; And then was mixed moss crusts, about 7d and the slowest was mosses’spores, which need at least 20d.2. Temperature and soil moisture showed a significant effect on the formation and development of moss crusts. Under our experiment conditions, compared with 11℃, 22℃ and 27℃,17℃was the favorable temperature for moss crusts formation. The moss density and growth speed could be sustained when cultivated at 17℃. Both formation and development of moss crusts were affected by soil moisture significantly. And the moss crusts could be formed after inoculated only when soil moisture was over 60% field water capacity. The formation and development of moss crusts could be enhanced by supersaturated soil moisture and high air humidity near soil surface.3. The formation and development of moss crusts could be increased by adding appropriate concentrations of nutrients to soils, such as glucose and magnesium sulfate. There were significant increases in coverage and mosses density when adding glucose and magnesium sulfate to soils. The coverage, mosses’density and mosses’height were the highest for soils that added glucose solution; there was a positive correlation between crusts’formation and glucose concentration, and 30g/l was the favorable concentration for soils from the research region. A little bit ammonium nitrate could increase the amount of mosses and the growth speed, while higher concentrations had an inhibited effect. The suitable concentration of ammonium nitrate in Hilly Loess Plateau region was 1.0 g/l, moss crusts’formation and development were inhibited and when the concentration of ammonium nitrate over 8.0 g/l. Potassium dehydrogenated phosphate had no effect on the mosses formation and development. Magnesium sulfate could promote the mosses formation, while had no effect on the mosses’height. In the concentration treatments, the coverage and mosses density were the highest when the concentration was 0.25g/l.更多还原