Knowledge Resource Center for Ecological Environment in Arid Area
| 科尔沁沙地生物结皮的形成过程、机制及其生态效应 | |
| 其他题名 | The Forming Processes, Mechanisms and Ecological Effects of Bioligical Soil Crusts in Horqin Sand Land |
| 郭轶瑞 | |
| 出版年 | 2008 |
| 学位类型 | 博士 |
| 导师 | 赵哈林 |
| 学位授予单位 | 中国科学院寒区旱区环境与工程研究所 |
| 中文摘要 | 生物结皮是固沙植被系统演变的一个关键因素，也是干旱、半干旱地区陆地生态系统中的一个重要监测指标。本文以我国北方农牧交错带科尔沁沙地为研究区域，基于一系列的野外调查和室内分析，从生态恢复的角度，研究了沙漠化逆转过程中土壤生物结皮的分布、特征、发育过程、形成机制及生态效应，主要结论如下：\n⑴ 科尔沁沙地不同退化程度沙质草地中生物结皮的主要生物成分有细菌、真菌、放线菌、藻类、苔藓和地衣。其中苔藓植物共4科、6属、10种，以真藓科的银叶真藓（Bryum argenteum）和真藓新纪录种（Bryum kunzei）为优势种，土生对齿藓（Didymodon vinealis）和厚肋流苏藓 （Crossidium crassinerve）为是伴生种，还有芦荟藓（Aloina rigida）和葫芦藓等偶见种。\n⑵ 不同退化程度沙质草地中生物结皮的总盖度为重牧 > 中牧 > 轻牧 > 对照，结皮总盖度与沙质草地的不同退化程度、细沙含量和地形高度呈极显著的正相关关系（p < 0.01），与地表凋落物盖度和极细沙含量呈极显著的负相关关系（p < 0.01）。中牧围栏的苔藓结皮每公顷可固定沙土18381.25 kg/hm2，是对照区结皮固沙量的11.2倍。不同退化程度沙质草地的固沙功能为：中牧 > 重牧 > 轻牧 > 对照。随着地形高度的增加，苔藓结皮代替了藻类结皮的生态位，生物结皮的原生演替由低级向高级发生正向演替。\n⑶ 各沙地类型中结皮层微生物类群数量均为细菌 > 放线菌 > 真菌。结皮层微生物总数为湿润期 > 干旱期；固定沙地 > 丘间低地 > 半固定沙地 > 半流动沙地 > 流动沙地。各沙地类型不同生物结皮下层0-10 cm土壤的微生物数量均大于对应的无结皮对照层。在生物结皮发育良好的固定沙地，雨后微生物总量是同期流动沙地微生物总量的90.05倍。微生物总数量与细菌数量、沙地全C含量、土壤水分、植被盖度、地上生物量、pH、电导率呈极显著的正相关关系（p < 0.01），与全N含量和沙地类型呈显著的正相关关系（p < 0.05）。\n⑷ 随着沙丘生境的恢复，科尔沁沙地的土壤结皮经历了一个由物理结皮逐渐向藻结皮、苔藓结皮发育的演替过程。半流动沙丘、半固定沙丘和固定沙丘分别发育了物理结皮、藻类结皮和苔藓结皮，结皮厚度、紧实度、含水量、细砂含量、全效养分、速效养分及CaCO3含量、电导率和pH值分别随结皮的发育演替呈增长趋势。结皮的形成、发育有细化、紧实下层土壤、富集土壤养分的作用。不同沙丘类型的典型灌丛下分别发育了不同类型的结皮，不同的优势灌木类型、大小、形态等特征为不同类型结皮的形成发育创造了有利条件。灌丛下结皮的发育降低了土壤水分的渗透性。不同人工林下发育的结皮中，樟子松林的林份条件较杨树林更适合结皮发育，且龄份越大，林下土壤基质对结皮及下层土壤的养分含量贡献越大。\n⑸ 人工培养结皮的不同配比基质生长120天后，结皮厚度、盖度在四个不同环境处理下的平均值为：光照-干旱 < 遮阴-干旱 < 光照-湿润 < 遮阴-湿润。人工结皮形成的厚度与施加粘土的数量成正相关；结皮总盖度与结皮物种数、添加的苔藓结皮土和水分呈极显著的正相关（p < 0.01），与光强呈极显著的负相关（p < 0.01）；水分是影响结皮生物量的关键因素，而光强决定结皮的物种分布。结皮物种数与水分呈显著的正相关（p < 0.05），与光强呈极显著的负相关（p < 0.01）。CCA分析表明，光强、水分条件及结皮土、凋落物的状况影响着结皮物种的分布和发育。光照处理下结皮主要物种为蓝藻和高山真藓，遮阴处理下的主要物种有银叶真藓、对齿藓、片叶钱苔、葫芦藓和芦荟藓共9种。随着生境由限制性条件向适宜性条件转变，结皮发育也经历了一个从藻结皮到苔藓结皮的生物演替的过程。\n⑹ 不同地形生物土壤结皮的呼吸速率为丘间低地苔藓结皮 > 背风坡苔藓结皮 > 迎风坡藻结皮 > 丘顶藻结皮。结皮层呼吸速率显著高于无结皮覆盖的土壤呼吸速率，即科尔沁沙地生物结皮的CO2释放量明显的高于裸露沙地的向大气释放的CO2量。结皮呼吸速率与结皮层水分含量、结皮下0-10cm、10-20cm土壤水分之间存在显著（p < 0.05）的线性关系。在日时间变化尺度上，温度是影响结皮呼吸速率的主要因子，而在月时间变化尺度上，环境因子对结皮呼吸的影响作用依次为：水分 > 温度 > 湿度 > 其它因子。\n⑺ 科尔沁沙地的生物结皮层土壤种子库在干旱、湿润两种处理中共出现了6科、15种植物，种子库的组成以一年生草本和中生植物为主，主要是藜科的尖头叶藜，禾本科的画眉草和三芒草。藻结皮上以大戟科和藜科植物为优势种，而苔藓结皮上以藜科植物为优势种，禾本科和菊科植物为亚优势种。两种生物结皮上种子库数量为干旱藻结皮 < 湿润藻结皮 < 干旱苔藓结皮 < 湿润苔藓结皮。在半干旱的科尔沁沙地，生物结皮通过对水分入渗与再分配的调控作用直接影响种子库中种子的萌发。\n⑻ 在苔藓结皮、藻结皮上，大果虫实和尖头叶藜两种一年生草本植物种子的萌发试验表明，结皮种类对大果虫实种子的萌发的影响存在显著的差异（p < 0.05），而尖头叶藜仅在苔藓结皮上干旱和湿润处理的萌发率存在极显著差异（p < 0.05），在藻结皮上差异不显著。影响苔藓结皮上种子萌发的主要因素是结皮完整程度，种子萌发率在破碎苔藓结皮 > 完整苔藓结皮；而影响藻结皮上种子萌发最关键的因素是结皮活性，活性藻结皮 > 失活藻结皮；水分是影响大果虫实和尖头叶藜种子在两种生物结皮上萌发的共同因素。 |
| 英文摘要 | Biological soil crusts are the essential components of healthy desert ecosystems and they are considered to be one of the most important monitoring indexs in arid and semiarid landscapes throughout the world. Based on a series of field investigation and laboratory, the study on the distribution, characteristics, forming processes and development mechanisms of biological soil crusts in the processes of desertification reversion in Horqin Sand Land were carried out. Also, the paper focus on the ecological effect of biological soil crusts as well as on soil properties, seed germination and soil respiration. Some conclusions were drawn as follows:\n ⑴ A study on species identification showed the organism compositions in different degraded sandy grassland were bacteria, fungi, actinomyces, algae, lichen and moss in Horqin Sand Land. There were 4 famlies, 6 genera and 10 species of mosses, Bryum argenteum and Bryum kunzei were eurytopic species that survives on all kinds of habitat, and they also were the dominant component that forms moss synusia. The companion species were Didymodon vinealis and Crossidium crassinerve, with Aloina rigida and Funaria hygrometrica as rare species.\n⑵ The coverage of biological soil crust in fenced sandy grassland were followng tendency of post heavy grazed restoration plot > post middle grazed restoration plot > post light grazed restoration plot > control plot. The total coverage of crusts had signifcant positive relationships with different types of fenced sandy grassland, fine fraction content and topographic relative height（p < 0.01）, and signifcant negative relationship with litter cover and very fine sand content（p < 0.01）. It was showed that post middle grazed restoration plot had the highest fixing-sand capacity (18381.25 kg), that was 11.2 times of which in control plot. The sand fixing capacity was following post middle grazed restoration plot > post heavy grazed restoration plot > post light grazed restoration plot > control plot. Biological soil crusts had the positive original succession in Horqin Sand Land along the environment change better.\n⑶ The distribution pattern of the microorganisms composition following the order of bacteria > actinomyces > fungi in each kind of sand dune types. The quantitative of microorganisms in humid period (July) is higher than that in arid period (June) . The total number of microorganisms decreased following fixed sand dune > interdune lowland > semi-fixed dune > semi-mobile dune > mobile dune. Moreover, the microorganisms of 0-10cm soil layer under biological soil crust always higher than its respective control (0-10cm soil layer without crust covering) in each kind of habitats. It was showed that the total number of microorganisms in sand-fixed dune in June was 90.05 times of that in mobile dune on the same time. The Pearson’s Correlation between microorganism numbers and 13 ecological factors showed that there was a strong, significant positive correlations between the total number of biological soil crust microorganism and quantity of bacteria, fungi, actinnomyces, organica matter, soil water content, vegetaion coverage, aboveground biomass, pH and electrical conductance (p < 0.01）, and there was a positive relationship with total-N content and sand dune types (p < 0.05）.\n⑷ In the vegetation restoration and sand dune fixation, soil crust in Horqin Sand Land experienced a succession from physical crust to algae and moss crust. Semi-mobile dune, semi-fix dune and fix dune were developed soil crust, algae crust and moss crust, respectively. The thickness, hardness, water content, silt and clay content, total and available nutrients, CaCO3, pH, and electronic conductivity of crusts were gradually increasing along with the desertification reversion. Meanwhile, crust enhanced the bulk density, fine fraction content, and accumulated nutrients of the soil under it, on an increaseing tendency from semi-mobile dune to fix dune. The different types of crusts developed under different kinds of shrubs were mainly owing to the establishment of shrubs. Different shrub species create differences in stemflow volumes, size, and canopies which provide benefit conditions for dust deposition and crust development. In addition, the formation of biological soil crust under shrubs deduced soil water-holding capacity. Under different ages of artificial forest of mongolica plantation, it had better condition for crust development in contrast to Populus simonii forest, and the older the ages, the more contributions to the soil nutrition under forest.\n⑸ After 120 days of crust cultivaion artifically, crust coverage and thickness had great diffences in four different treatments, they were illumination-dry < overshadow-dry < illumination-humid < overshadow-humid. The thickness of cultivated crust has positive relationship with the clay amount added, and there was significant positive relationship between the crust coverage and crust species number, moss crust powder amount and water condition, a negative relationship between the crust coverage and illumination. Water content restrained the biomass of the cultivated crust, while illumination determined crust species distribution. It was showed that the crust species number had significant positive relationship with water content, while had negative relationship with illumination. In CCA analysis, illumination intensity, water condition, crus powder and litter content directly effected the formation and distribution of the crust species. There were only Cyanophyta and Bryum alpinum in illumination treatment, while 9 species in overshadow treatment, including Bryum argenteum, Didymodon vinealis, Riccia crystallina, Funaria hygrometrica and Aloina rigida. With the environmental condition changed form restriction to aptly condition, the species successed from algae crust to moss crust correspondingly. \n⑹ The respiration of biological soil crusts in different topography were following moss crust in inter dune > moss crust in leeward of sand dune > algae crust in windward of sand dune > algae crust in the top dune. Respiration of biological soil crusts was absolutely higher than soil without crust covering. Compared with sandy dune, biological soil crusts released more CO2 efflux to the air. There was a significant linear relationship between crust repiration and crust water content, 0-10cm and 10-20cm soil water content under crust. Temperature was the key idex at the scale of daily change, while at the scale of month changes, the effects of environmental factors were following the order of water > temperature > humidity > other factors.\n⑺ There were 15 kinds of plant species belong to 6 family germinated in the two sorts of biological soil crust seed bank, mainly Chenopodium acuminatum, Eragrostis pilosa and Aristida adscensionis, and the dominant species were annual herbaceous plants and mesophyte in the crust seed banks. The number of seed bank in two kinds of crust surface under two water conditions was on the tendency of dry algae crust < humid algae crust < dry moss crust < humid moss crust. In semi-arid Horqin Sand Land, biological soil crust changed seed germination by controlling and reassigning the water infiltration.\n⑻ The germination trial of two annual plant species, Corispermum macrocarpum and Chenopodium glaucum, on the surface of algae and moss crust with different water condition, different integrity degree and activity degree showed that: Crust species had siganificant affect to the germination of Corispermum macrocarpum seed, while the seed germination of Chenopodium glaucum only had siganificant affect to moss crust with arid or humid water condition. The key factor which affect seed germination in moss crust was the crust integrity degree, that was the germinaiton rate on crashed moss crust was higher than completely intregritied moss crust; While the activity degree was the main idex to affect seed germination in algae crust, germinaiton rate was active algae crust > dead algae crust. Most of all, water was the most important factor which affect the seed germination for both Corispermum macrocarpum and Chenopodium glaucum. |
| 中文关键词 | 科尔沁沙地 ; 生物结皮 ; 结皮理化性质 ; 结皮层呼吸速率 ; 结皮土壤种子库 ; 种子萌发 ; 人工培养结皮 |
| 英文关键词 | Horqin Sand Land biological soil crust physicochemical properties of crust crust respiration crust s |
| 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/2XILL650/286657 |
| 推荐引用方式 GB/T 7714 | 郭轶瑞. 科尔沁沙地生物结皮的形成过程、机制及其生态效应[D]. 中国科学院寒区旱区环境与工程研究所,2008. |
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