The Black Soil Type grassland degradation occurred broadly in Three River Source Region,located in the hinterland of Qinghai-Tibet Plateau,due to the long-term impacts of climatic warm up and overgrazing.The bottleneck to the natural recovery of the Black Soil Type degraded grassland was analyzed by the investigations of soil,environment,and soil seed bank in the center of Three River Source Region and the succession of cultivated grassland in this region was tracked.The results of community succession investigation show that the perennial cultivated grassland could improve the soil micro-environments and provide the zonalic conditions for the plant invasion;meanwhile,it shortened the local vegetation recovery process of the degraded grassland by the connection of vegetation succession and natural invasion.The results of this study would provide the credible theories and methods to the natural recovery of Black Soil Type grassland degradation and the melioration of the ecological environment in Three River Source Region.

三江源区位于青藏高原腹地,长期在气候变暖和超载放牧的双重压力下,草地大片退化,形成大面积"黑土滩"型退化草地,引起源区生态环境的恶化。本研究以三江源区"黑土滩"型退化草地的土壤、环境和种子库为研究对象,分析了三江源区"黑土滩"型退化草地自然恢复的瓶颈;采用以空间代替时间的群落研究方法,对在"黑土滩"型退化草地上建植多年的人工草地演替过程进行了跟踪研究。结果发现:在"黑土滩"型退化草地上建立多年生人工草地,能够改善土壤微环境,为地带性植被的入侵创造适宜条件,实行人工草地植被演替与地带性植被自然入侵的连接,可以大大缩短"黑土滩"型高寒退化草地地带性植被的恢复进程。本研究为"黑土滩"型退化草地的恢复,改善三江源区生态环境,提供可靠的理论依据与措施。

Biological soil crusts 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. As vascular plant cover, BSCs cover is one of most important earth surface cover types as BSCs occupies 40% of the total area of the arid lands, which are significant compositions and features of desert ecosystems and arid landscapes. Therefore, the vital roles of BSCs in the processes of desert landscapes, soil ecological, soil hydrological, soil biological and geochemical processes, as well as in the practice of ecological rehabilitation for arid and semiarid regions have been widely emphasized. 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. In this paper, the new advances and trends for BSCs studies have been reviewed. Based on this, we discuss the future research emphases, and hope these reviews will be benefited to BSCs study in China, and will enhance the understanding for earth surface processes in arid and semiarid regions of China.  

生物土壤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(其盖度达40%)。生物土壤结皮是荒漠生态系统组成和地表景观的重要特征，在不同生物气候区的荒漠景观过程、土壤生态过程、土壤水文过程、土壤生物过程和地球化学循环过程，以及干旱半干旱地区生态修复过程中发挥着重要作用。关于生物土壤结皮的研究是地学和生物学学科交叉的前沿研究领域，已成为国际干旱区地表过程研究的重要核心科学问题之一。综述了国内外该领域最新研究进展，分析了研究的趋势，讨论了其前沿科学问题和未来研究的重点，以期促进我国生物土壤结皮的研究，加深对我国干旱半干旱区地表过程的认识。

Biological soil crusts are significant compositions and features of desert ecosystems and arid landscapes. In recent years, various countries and relevant agencies had continued to increase efforts to study the biological soil crusts. In this paper, we use the bibliometric tools such as Bibexceland NetDraw to analyze the data of Biological Soil Crust researchs from Web of Science.

生物土壤结皮是荒漠生态系统组成和地表景观的重要特征。近年来，各国和各相关研究机构对生物土壤结皮的研究力度不断加大。利用Bibexcel和NetDraw等文献计量工具，对Web of Science数据库中国际生物土壤结皮研究相关文献进行了分析。在对主要国家和机构的发文进行统计分析后发现：美国、德国和西班牙等国的生物土壤结皮研究论文的综合影响力较高；胡安·卡洛斯国王大学和美国地质调查局等机构的论文影响力较大；中国生物土壤结皮研究论文在总量上优势明显，但高质量论文不多；国际生物土壤结皮研究的主要研究热点集中在腾格里沙漠等沙漠地区，氮循环研究和微生物群落研究是研究的重点。

In this paper, the development process and characteristics of restoration ecology research in the arid regions of China were reviewed, and the research frontiers and development trends were analyzed systemically. The study on restoration ecology in arid regions has been promoted by national demands. Revegetation was the main method and approach for ecological recovery and restoration. Future study should focus on vegetation zonal distribution, soil habitat restoration, interaction of arid land ecology and hydrology, plant water relation, biological soil crust, projection based on models and modeling, and so on. The interaction and integration of geography and biology provide a new way of thinking and approach for both theoretical and practical innovations in the development of restoration ecology.

本文评述了中国干旱区恢复生态学研究的历程和特点,系统分析了其研究前沿和未来发展趋势.国家重大需求推动了干旱区恢复生态学研究,植被建设是生态恢复的主要方法和手段;植被分布的地带性规律、土壤生境的恢复、生态水文互馈机理、植物水分关系、生物土壤结皮、基于模型的预测模拟是未来研究的重点;地学与生物学的学科交叉融合为干旱区恢复生态学理论创新和生态恢复实践提供了新的思路和途径.

Cyanobacteria were the major components in biological soil crusts (biocrusts). So far, studies on species composition and distribution of cyanobacteria in the biocrusts in the Loess Plateau region were fresh. Biocrusts from the revegetated grasslands in different erosion regions (wind erosion, water erosion, and the wind-water crisscross regions) of the Loess Plateau region were collected, cultured, observed and identified. Results showed that cyanobacteria were the dominant component of the biocrusts. We found 54 species belonging to 10 genera and 4 families, with filamentous cyanobacteria dominant. The Shannon-Wiener index was used to evaluate diversity of the regions. No significant difference was found between the species diversity of water-wind erosion crisscross region and water erosion regions, while diversity in the wind erosion region was significantly lower than the water erosion region or the wind-water crisscross erosion region. Species composition and dominant species of the three erosion regions were different. Oscillatoriaceae was the dominant family from all the three regions. Cyanobacteria species diversity was greatest (39) in the water-wind erosion crisscross region, followed by the water erosion region (26) and the wind erosion region (20). However, the dominant species were different in the three erosion regions. The dominant cyanobacteria species in water-wind erosion crisscross region, water erosion and wind erosion region were Lyngbya allorgei, Phormidium calciola and Oscillatoria granulate , respectively. Differences in cyanobacteria composition in the three different erosion regions were likely associated with differences in soil texture, soil pH and climatic regimes.

蓝藻是生物土壤结皮的重要组成部分,具有许多重要的生态功能。迄今为止,黄土高原地区生物结皮中藻类的种类组成及分布鲜有报道。通过野外调查、采样和室内观察、培养、鉴定,对黄土高原水蚀区、水蚀风蚀交错区、风蚀区的生物结皮中蓝藻的多样性及优势种进行了研究。结果表明,黄土高原3个侵蚀类型区生物结皮中蓝藻门植物共发现4科10属54种,其中丝状种类约占87%,占绝对优势;Shannon-Weiner 多样性指数水蚀风蚀交错区最高,水蚀区次之,风蚀区最低,依次为2.22,2.20和2.14。水蚀风蚀交错区和水蚀区蓝藻多样性指数差异不显著,但均与风蚀区差异显著。3个侵蚀类型区的生物结皮中蓝藻的种类组成及优势种均有所差异,但均以颤藻科 (Oscillatoriaceae) 为优势科。水蚀风蚀交错区蓝藻种类最多(39种),以阿氏鞘丝藻( Lyngbya allorgei) 为第一优势种;水蚀区次之(26种),以含钙席藻( Phormidium calciola )为第一优势种;风蚀区最少(20种),以颗粒颤藻 (Oscillatoria granulata) 为第一优势种。黄土高原不同侵蚀类型区生物结皮中蓝藻的多样性差异可能与土壤质地、土壤pH值、气候环境等有关。

Twenty-two lichens belonging to 16 genera, 13 families, and 5 orders from Shapotou region of Tengger Desert are reported in this paper. Bacidia heterochroa, Porina aenea, Buellia alboatra and Buellia venusta are new to China. The research has enriched the knowledge of lichen diversity in the studied region, and will provide more lichen resources for the basic research of desert biocarpet engineering.

报道了腾格里沙漠东南缘沙坡头地区地衣22种，分隶于16属，13科，5目，包括中国新记录4种：异色杆孢衣 Bacidia heterochroa，安奈污核衣Porina aenea，白黑瘤衣Buellia alboatra及美丽黑瘤衣Buellia venusta。该研究丰富了关于该地区荒漠地衣物种多样性的知识，并将为沙漠生物地毯工程的前期研究提供更多的地衣种质资源。

】 The common habitat of bryophytes is restricted to dankness, but some bryophytes, such as the species of Pottiaceae, Grimmiaceae, Bryaceae and so on, are able to survive in arid and semi-arid areas with strong ability of drought tolerance. These bryophytes, in this sense, have to tolerate great heat and drought. Arid and semi-arid environments often support a low cover of vascular plants, which provide a niche for non-vascular plants such as mosses, lichens and liverworts. Under the pressure of extreme desic...

苔藓植物一般生活在阴湿的地方 ,但也有不少种类具有极强的耐旱性 ,在干旱和半干旱地区也有分布。在干旱和半干旱地区 ,影响苔藓植物分布的环境因子包括降水、p H值、Ca CO3 含量、植被盖度、有机质含量以及土壤质地等 ,其中起重要作用的是降水。在干旱环境下 ,苔藓植物作为环境演替过程中主要的先锋植物 ,还参与土壤结皮的形成 ,在生物防沙、固沙和生态小环境的改善中发挥着不可替代的作用。

Biological soil crusts are the organic complexes composed of bacteria, cyanobacteria, algae, lichen and moss with soil particles. They play critical roles in desert ecosystems, including enhancing soil stability and fertility, preventing soil erosion by water or wind, facilitating seed germination. Moss crust is the latest successional stage of biological soil crusts in arid and semiarid land, which perform important functions. Most of the studies focused on the difference of soil properties between moss crust and lack of moss crust. Generally, moss crust distributes in patches in interdune areas of sand dunes, it is a small scale. Little is known about its nutrients distribution at patch scale. The aims of this research are to (1) make sure the strength of soil heterogeneity for moss crust at both quadrate scale and patch scale; (2) support basic data for moss crust according to patch size. In this study, patch's area is calculated by Photoshop CS 5.0. Five soil physiochemical properties were analyzed with standard soil analytical methods. Classical statistics, geostatistic techniques, semivariogram model fitting and mapping methods were used to describe the spatial distribution of soil properties at both scales. The results indicated that there were medium variations for five soil properties of moss crusts at both scales. Coefficient variations of five properties at quadrate scale varied from 12% to 30%. With the exception of total phosphorus, most coefficient valuations of the other four properties at patch scale were less than 20%, which indicated the soil spatial heterogeneity of moss crust at quadrate scale is much stronger than that at patch scale. The spatial autocorrelation of five soil properties at quadrate scale ranged from 65% to 92%. For patch scale, except for total phosphorous, spatial autocorrelations of the other four parameters were over 90%, which means, that the proportion of spatial autocorrelations of moss crust increase with the decreasing of sampling scale. Additionally, the effect of structure factors increased on patch scale with the decreasing proportion of the random factors, which was consistent with the result of spatial autocorrelation. In this study, values of soil water, organic matter and total nitrogen decreased from center of moss patch to edge, however, total phosphorus increased from center to edge at patch scale, which indicated that there was heterogeneity for moss crust patch at micro scale. There was irregular change for total soluble salt at patch scale, but at quadrate scale, total soluble salt content with mosses was much higher than that without mosses, which implied that with the decreasing of sampling scale, the heterogeneity of soil salt disappeared. The autocorrelation ranges of water, organic, total nitrogen and total phosphorus at patch scale were smaller than the diameter of the moss crusts patch, autocorrelation range of total soluble salt was out of patch size, on the whole, autocorrelation ranges in creased with the sampling size. Thus, sampling distance can be increased at quadrate scale, but for patch scale, sampling distance should be reduced to avoid missing the tiny heterogeneity. At both scales, the lowest autocorrelation range of total phosphorus was observed. Therefore, the sampling distance must be short for variation of phosphorus, while for total salt, sampling distance can be increased properly due to its big variation range.

苔藓结皮是生物结皮的高级阶段，它在防风固沙、改善土壤水分、养分等方面具有十分重要的生态作用，但前期研究多是对结皮区和无结皮覆盖区土壤性状的比较，对结皮斑块内土壤理化因子的空间分布情况尚不明确。运用经典统计学，地统计学以及克里格插值法探讨了土壤水分、有机质、全氮、全磷、总盐在样方和斑块两个尺度的空间变异特征，旨在阐明不同尺度藓类结皮土壤空间异质性的强度，明确不同尺度土壤各性状合适的取样距离。研究结果表明藓类结皮土壤性状在两种尺度均表现出中等程度的变异，随着取样尺度减小，自相关性在空间异质性中占的比重增加，结构因素的影响增强，随机因素的影响减弱。样方尺度的空间异质性大于斑块尺度异质性，且土壤性状的变程较大，采样时可适当增大取样间距；两种尺度下5个土壤性状中，全磷的变程最小，实际取样时应适当缩小取样距离，总盐变程大，自相关程度低，因而取样间距可适当放大。斑块尺度，藓类结皮土壤性状由边缘向中心递增（磷递减）的现象与斑块的边缘效应有关。

The study area, Shapotou district (37°27′N, 104°57′E) of Ningxia Hui Autonomous Region is situated in the southeastern fringe of the Tengger Desert of China. A study of species identification, coverage and biomass in the soil microbiotic crusts of fixed sand dunes was conducted in Shapotou district, from which we found two families, seven genera and sixteen species of mosses. Didymodon constrictus (Mitt.) Saito and D. tectorum (C. Muell.) Saito were reduced to synonymy of D. vinealis (Brid.) Zand. by Zander and Redfearn. Crossidium chloronotos (Brid.) Limpr., Crossidium aberrans Holz. & Bartr. Aloina obliquifolia (C. Muell.) Broth. and Tortula atrovirens (Sm.) lindb. are new to Shapotou district. Bryum argenteum is an eurytopic species that survives on all kinds of habitat, and is the dominant component that forms moss synusia. The community of Didymodon vinealis, D. rigidulus Hedw. var. ditrichoides and Syntrichia bidentata are found on hillocks and are randomly distributed in crusts. Diversity of species is the highest in this area in the natural fixed dunes, with sixteen species, followed by five species of mosses (31.3%) in the fixed dunes of 1956, four species of mosses (25.0%) in the fixed dunes of 1964, and only two species of mosses (12.5%) in the fixed dunes of 1981. The total coverage of mosses and algae increased with the fixed-sand time. In different ages, the coverage of mosses and algae exist in an equal distance gradient, while in the fixed dunes they exist along the slope with the coverage of mosses decreasing as that of algae increased. A determination of biomass and binding-sand quantity of the dominant species—Bryum argenteum showed that its biomass (944.03 kg·hm-2) and binding-sand (3.925×104 kg·hm-2) quantity increased when the fixed sand time prolonged in moss crusts of the fixed dunes of 1950s. While the rate of binding-sand of Bryum argenteum decreased, its saturated water absorption had a positive correlation with biomass of 7.06×103 kg·hm-2. Therefore the results indicate that the moss crusts had a strong ability to absorb and reserve water, which is of ecological significance in arid desert region.

根据对沙坡头固定沙丘生物结皮的物种调查、鉴定及盖度和生物量的研究，藓类植物共2科，7属，16种，以真藓（Bryum argenteum）为优势种。随着固沙时间的延长，生物结皮中藓类和藻类总盖度呈上升趋势；沿不同年代固定沙丘坡面向上等距离梯度，藓类盖度显著下降，而藻类盖度则平稳上升。对不同年代固定沙丘生物结皮优势种真藓的生物量和固沙量的测定表明，随沙丘固定年代的增加，真藓的生物量和固沙量增加，50年代固沙区结皮层真藓生物量是944.03 kg·hm-2，固沙量是3.925×104 kg·hm-2，但固沙率随时间的增加而减少。真藓的饱和吸水量与生物量呈正相关，50年代固定沙丘藓类结皮层可吸水7.06×103 kg·hm-2，说明藓类结皮层具有很强的吸水和保水能力，对于干燥少雨的沙漠地区具有十分重要的生态学意义。

Algae and mosses are not only two common pioneer plants in the process of vegetation succession but also two groups with the highest biomass in the biological soil crust. As pioneer plants, algae and mosses are indispensable in the process of establishing the biological soil crust, which plays an important role in the desert ecosystem, namely, indicating vegetation type, soil holding, preventing from erosion by water or wind, and sand fixation. This paper reviews the recent research into algae and mosses which in arid and semi-arid areas and focuses on the ecological separate functions and relations of alg-ae and mosses. Some suggestions are proposed for researching algae and mosses, especially research into the symbiotic mechanism of algae and mosses in the biological soil crust. Ecologically, such research has important significance and prac-tice value for further analyzing the influence and demonstrating the ecological relations between algae and mosses.

藻类和苔藓植物是荒漠植被演替过程中常见的两类先锋植物, 同时也是生物结皮中生物量最大的2个类群。该文综述了近年来干旱半干旱荒漠地区生物结皮中藻类和苔藓两大类植物区系及其生态作用的研究进展, 重点介绍藻类结皮、苔藓结皮的生态作用以及二者之间存在的生态学关系。在此基础上对荒漠生物结皮中藻类与苔藓植物的研究前景进行了展望, 指出荒漠生物结皮中藻类与苔藓共生机理的探讨是未来的研究重点, 这对进一步探明生物结皮中藻类和苔藓植物之间的相互作用, 揭示它们的生态学关系具有重要的理论意义和实践价值。

We investigated the influences of algae crust and moss crust universally spreading in southeast of the Tengger Desert with four developing phrases (24-, 41-, 50-year-old crusts in the sand-binding vegetation areas and crusts in natural vegetation) on desert plants. Variable treatments (natural field condition, greenhouse and shadow) were assigned, and two soil moisture regimes were designed to investigate how desert plants responded under different moisture regimes of crusts. Our results showed that seed bank storage was significantly higher in moss crust than in algae crust. With the development of crusts, seed bank storage increased in moss crust while decreased in algae crust. With regard to the moisture, Significant differences in crust moisture were found among four developing phases for both algae and moss crust ( p p >0.05). For moss crust, more seed germination occurred under higher surface temperature, contrarily, more seed germination occurred under lower temperature on algae crust.

研究了腾格里沙漠东南缘在不同自然条件(风、温度、水分)下，人工固沙植被区(24龄、41龄、50龄)和相邻天然植被区的两种生物土壤结皮对荒漠土壤种子库和种子萌发的影响。结果表明，荒漠土壤种子库在苔藓结皮上的储量显著高于藻类结皮。随着生物土壤结皮的发育，种子萌发量在苔藓结皮上增加，在藻类结皮上减少。生物土壤结皮层的含水量对种子萌发有显著的影响( p p >0.05)，但总体而言，对于苔藓结皮，植物种子在较高温度下的萌发量略高于在较低温度下的萌发量，而对于藻类结皮，植物种子在较低温度下的萌发量略高

In arid and semi-arid lands, the vegetation cover is usually sparse or absent. Nevertheless, in open spaces among higher plants, the soil surface is generally covered by a community of highly specialized organisms, such as mosses, lichens, liverworts, algae, fungi, cyanobacteria, and bacteria. These communities are usually referred to biological soil crusts, or cryptogamic, cryptobiotic, microbiotic, microphytic soil crusts. Biological soil crusts, given their extraordinary abilities to survive desiccation and extreme high temperatures, high pH and high salinity, have been found in desert areas all over the world and may constitute as high as 70% of the living cover in some plant communities. They play a significant role in ensuring the proper functioning of desert ecosystem, such as involvement in the process of formation, stability and fertility of soil, prevention of soil erosion caused by wind or water, augment of vascular plant colonization, and stabilization of sand dunes. The biological soil crust resulting from the colonization of soil surface by communities of filamentous cyanobacteria were mainly dominated by Microcoleus, which occurs as a cluster of filaments surrounded by a gelatinous sheath. Other important taxa are Lyngbya, Anabaena and Xenococcus lyngbyge. At this developmental stage, the main contributors for sand fixation were changed from bacteria to filamentous cyanobacteria. Microscopic examination of this kind of crust revealed an intricate network of filamentous cyanobacteria and extracellular polymer secretions, which binds and entraps mineral particles and finer particles stick on the filament surface. These effects enhance soil cohesion and resistance to erosion. Two major mechanisms are suggested for maintaining sand surface stabilities: (1) the ability of exopolysaccharides from some microorganisms (mainly bacteria) to cohere sand particles, and (2) formation of network by the filamentous microbes and cryptogam (cyanobacteria, algae, lichen and moss). With the alternation of crust-related species from cyanobacteria, algae and lichen to moss, the main agents maintaining microstructure of biological soil crust changed accordingly from glutinous exopolysaccharides to filamentous algae and hyphae of lichen and moss. Generally, the development of biological soil crust can be divided into three phases: original succession phase (including soil microorganisms and soil enzymes), algae crust phase and lichen-bryophyte crust phase. The establishment of former phase crust serves as a basis for the next phase of crust succession. Under drought conditions, soil crust is brittle, and can be crushed easily when subjected to compressional or shear forces. When the surface crust is broken, the unconsolidated loose sand grains below the crust are exposed to wind, resulting in severe soil erosion. Under favorable environmental conditions, such as sufficient water supply and moderate temperature, the less developed biological soil crust may surpass the intermediate phase and develop into higher level biological soil crust.

中国科学院知识创新工程重要方向项目（KZCX2-YW-336）;国家自然科学基金资助项目(No.40771114)

The classifying and clustering are equally important in grassland classification,based on this the idea the Integrated Orderly Classification System of Grassland(IOCSG) has been set up and follow six principles,namely,the Framework for a grassland classification system,Comprehensiveness of a grassland classification system,Relative stability of parameters used in grassland classification,Comparability of parameter stability at a given level of classification,Definitive power of parameters in grassland classification and Universality of a grassland classification system.The IOCSG contains three main levels.'Class',categories with moisture and temperature as their index;'sub-class',categories characterized by their edaphic conditions and 'types',classified according to their vegetation conditions.The IOCSG also contains seven thermal ranks and six humidity grades.According to the IOCSG 42 classes of natural grasslands may be identified globally and 41 of them present in China.The authors also investigated the IOCSG practical values in dealing with determining the habitat adaptive of species,prediction of evolution direction of grassland succession due to global changes and turf species introduction.The paper further enforces the significant influences of the grassland classification research on the grassland sciences in their fundamentals and practice.

本文阐明分类与聚类在草原分类中同等重要。据此建立的草原综合顺序分类系统(IOCSG)应遵循6项原则,即草原分类要素的完整性原则、草原分类体系内涵的综合性原则、草原分类指标的相对稳定性原则、草原分类同级指标的可比性原则、草原分类特征指标的确限性原则和草原分类体系普适的周延性原则。该分类系统含有类(以地带性水热特征为指标)、亚类(以土地特征为指标)和型(以植被特征为指标)3个基本级别;7个热量级和6个湿润度级。依据本分类系统全球天然草原分为42类,中国有41类。本分类系统在生物种适宜度计算、全球变化对草原类型演替方向的预测、草坪引种等方面进行了论证。该文阐明了草原类型学对草业科学的基础理论意义和实践意义。

Soil bio-crust (SBC) widely distributes in arid and desert regions, and plays a key role in the functioning of arid and desert ecosystems. However, not all the arid lands and deserts are covered by SBC. At global and regional scales, the distribution of SBC is positively related to the annual precipitation, dew, and soil moisture content, while the effects of temperature on the distribution vary with the species composition of SBC. At local and small scales, the distribution of SBC is affected by soil texture and nutrients availability. At present, the effects of vascular plants on the distribution of SBC are uncertain. Moderate disturbance has little effects on the distribution and ecological functions of SBC, but severe disturbance can induce the decrease of SBC cover and the deterioration of the structure and function of SBC. The effects of global change on SBC distribution, the mechanisms of the adaptive distribution and succession of SBC, as well as the ecological functions of SBC in its recovery process, would be the hot topics in the future.

生物土壤结皮广泛分布于干旱荒漠地区，在干旱和荒漠生态系统中，有重要的生态功能。然而，并不是所有的干旱荒漠区都有生物土壤结皮的分布。在全球和区域尺度上，生物土壤结皮的分布与年降水、凝结水量和土壤含水量呈正相关趋势；温度对生物土壤结皮分布的影响因组成生物土壤结皮的物种而异。小尺度范围内，生物土壤结皮的分布受土壤类型、质地和养分的限制；维管植物对生物土壤结皮分布的影响，暂没有一致的结论。适度干扰对生物土壤结皮分布和生态功能无明显影响，但高强度干扰导致生物土壤结皮结构、功能和分布的退化与减少。全球变化背景下生物土壤结皮的分布变化、不同区域生物土壤结皮分布和演替的差异机理以及受损后恢复过程中的生态功能，将成为以后工作的重点

Biological soil crusts (BSC) are a universal and common feature in arid-semiarid habitats and polar regions. They contribute to the biodiversity of these ecosystems, and play significant roles in soil stability,ecosystem stability maintenance, nitrogen fixation, biomass production, and soil fertility. It was described that succession development of BSC′s different successional age and distribution of BSC in different areas. Responses of BSC to elevated UV-B radiation, climate warming and rainfall variation were separately introduced. It is prospected that making progress in research of BSC responses to climate changing, especially arid and semi-arid regions, at regional scale.

生物土壤结皮在干旱、半干旱区和极地、亚极地区等脆弱生态区广泛存在，生物土壤结皮对脆弱生态系统的稳定、碳氮循环和生态平衡等具有重要的生态意义。概述了脆弱生态区生物结皮的碳氮循环与气候变化关系，综合分析了脆弱生态区生物结皮对气候变暖、降水变化和UV-B增加的响应。分析认为应该加强区域尺度下干旱与半旱区生物结皮对气候变化响应研究。

In this paper, the development process and characteristics of restoration ecology research in the arid regions of China were reviewed, and the research frontiers and development trends were analyzed systemically. The study on restoration ecology in arid regions has been promoted by national demands. Revegetation was the main method and approach for ecological recovery and restoration. Future study should focus on vegetation zonal distribution, soil habitat restoration, interaction of arid land ecology and hydrology, plant water relation, biological soil crust, projection based on models and modeling, and so on. The interaction and integration of geography and biology provide a new way of thinking and approach for both theoretical and practical innovations in the development of restoration ecology.

本文评述了中国干旱区恢复生态学研究的历程和特点,系统分析了其研究前沿和未来发展趋势.国家重大需求推动了干旱区恢复生态学研究,植被建设是生态恢复的主要方法和手段;植被分布的地带性规律、土壤生境的恢复、生态水文互馈机理、植物水分关系、生物土壤结皮、基于模型的预测模拟是未来研究的重点;地学与生物学的学科交叉融合为干旱区恢复生态学理论创新和生态恢复实践提供了新的思路和途径.

Biological soil crusts play an important role in increasing the accumulation of organic matter and nitrogen in re-vegetated mining wastelands. The diversity of nitrogenfixing microorganisms in three types of biological soil crusts (algal crust, moss crust and algalmoss crust) from two wastelands of copper mine tailings were investigated by polymerase chain reactiondenaturing gradient gel electrophoresis, based on the  nifH  gene of diazotrophs, to investigate:  The diversity of  nifH  gene in the crusts of mine wastelands, and whether and how the nifH  gene diversity in the crusts could be affected by the development of plant communities. The algal crust on the barren area displayed the highest nifH  gene diversity, followed by the algalmoss crusts within vascular plant communities, and the moss crust displayed the lowest  nifH  gene diversity. The diversity of diazotrophs in algalmoss crust within vascular plant communities decreased with the increase of height and cover of vascular plant communities. No significant relationship was found between wasteland properties (pH, water content, contents of organic matter, nitrogen and phosphorus and heavy metal concentration) and nifH  gene diversity in the crusts. Sequencing and phylogenetic analysis indicated that most nitrogenfixing taxa in the crusts of mine wastelands belonged to Cyanobacteria, especially nonheterocystous filamentous Cyanobacteria.

生物土壤结皮能够有效提高矿业废弃地有机质和氮的积累,促进植被的恢复.本研究基于固氮微生物的 nifH 基因多样性,以铜陵铜尾矿废弃地3种类型的生物土壤结皮(藻结皮、藓结皮和藻-藓混合结皮)为对象,利用变性梯度凝胶电泳(DGGE)技术研究生物土壤结皮中固氮微生物的多样性以及废弃地植物群落发育对其产生的影响.结果表明： 尾矿库裸地表面的藻结皮的固氮微生物多样性最高,其次为维管植物群落下的藻-藓混合结皮,苔藓结皮的固氮蓝藻多样性最低;随着维管植物群落高度和盖度的增加,固氮微生物多样性降低,铜尾矿废弃地的pH、水分、有机质、养分含量(氮和磷)以及有效态和总重金属浓度对固氮微生物多样性的影响均不显著.测序和系统发育分析表明,废弃地结皮中固氮微生物以蓝藻为主,主要为不具有异形胞的丝状蓝藻.  

Gurbantunggut Desert, the largest fixed and semi-fixed desert in China, are mostly covered by well-developed biological crust. The distribution of biological crusts has selective characteristics at different positions on sand dune surface. The species composition, thickness and compression strength vary with different types of biological crust. Such selective distribution of biological crusts and their eco-environmental condition on longitudinal dune surface were studied in 2002. The results showed that moss crusts mainly distributed in the interdune area, where sand surface was stable and the dominant grain size were fine and extra-fine sands. The soil moisture could reach 5% in early spring and ephemeral plants grew well. Lichen crusts mainly distributed from lower to middle slopes, where the dominant grain size was fine sands. The soil moisture in spring was about 4% and also possessed rich ephemeral plants. Algae crusts occurred from upper slope to the top of dune, where the sand surface was active and the soil moisture content was the lowest, which indicated that Algae crust is the most adaptable species to rigorous habitats.

古尔班通古特沙漠广泛存在的生物结皮,对地貌部位有极强的选择性分布,其实质是生物对环境条件综合适应的一种生态表现。2002年3~11月在个体沙丘表面初步开展了生物结皮类型小尺度环境分异规律研究。结果表明:苔藓结皮、地衣结皮和藻类结皮依次分布于垄间、沙垄两坡中部和坡上部,从垄间往垄顶,生物结皮盖度逐渐减小,厚度变薄,抗压性减弱。苔藓结皮分布区的物质组成以细沙和极细沙为主,春季表层土壤水分在5%以上,短命植物广泛发育,基质稳定;坡中部的地衣结皮分布区以细沙为主,春季表层土壤水分在4%左右,短命植物亦有广泛分布,地表受风沙活动影响较小;沙垄上部和顶部的藻类结皮分布区,是沙垄表面活动性最强和土壤水分最差的区域,物质组成以中沙为主,高等植物中白梭梭为优势种,可见藻结皮是三类结皮中最能适应恶劣环境的生物结皮类型。

Biological soil crusts (BSCs) occur extensively in the southern part of the Gurbantunggut Desert, and serve as one of the important biological factors relating to sand surface fixation. As a winter rangeland, the desert is trampled by grazed livestock widely. Lichen crusts are the main type of BSCs in the southern part of the Gurbantonggut Desert and serve as one kind of the important nitrogen resources. They are also one of the sensitive biomonitors of desert ecosystem health, habitat heterogeneity and humaninduced disturbances. This study investigated the effect of trampling on cover of BSCs. The results were as follows: (1) The local disturbance rate mainly ranged from 10% to 20%, which was a relatively safe range against wind erosion; (2) The total coverage of BSCs was decreased due to the grazed livestock disturbance. The response of BSCs to grazing disturbance was different. Holistically, trample of grazed livestock reduced the coverage of dominant crusts, especially the lichen crusts. When disturbance rate was exceeded 30%, the average coverage of lichen crusts was lower than 30%. Because of the destroyed structure of fungalalgae symbiont, the quantity of fungi was increased ( P P <0.01).

古尔班通古特沙漠地衣结皮对放牧踩踏干扰及其所引起的生境异质性具有重要的指示作用。研究表明：① 放牧踩踏干扰主要集中于结皮层（0~5 cm），随机调查的样方中，90%的样方干扰率均低于30%,生物土壤结皮(BSCs)破损尚处于较安全的范围；② 放牧踩踏干扰降低了BSCs总盖度，不同类型的结皮对践踏干扰的反应具差异性，其中，真菌-藻类共生形成的地衣结皮与干扰率呈极显著负相关（ P 30%的样方中,抗风蚀能力较强的苔藓结皮、地衣结皮盖度均显著低于未受干扰样方，地衣共生体的破坏导致真菌数量显著增加（ P 30%的样方中各指标均低于未受干扰样方。其中，土壤容重是对放牧干扰比较敏感的指标，与地衣结皮盖度亦呈极显著正相关（ P P <0.05）。

２００５－２０１２年，进行了青藏高原高寒草甸主要分布地区草地状况的调查，禾草－矮嵩草群落是青藏高原高寒嵩草草甸的典型地带性植被，对处于不同退化程度的小嵩草群落采取封育或减牧后，均可恢复到禾草－ 矮嵩草群落，但由于退化程度的不同，恢复所需要的时间具有极大的差异。青海果洛地区高寒草甸多处于以小嵩草群落草毡表层剥蚀和杂类草－黑土型退化草地演替阶段，玉树地区处于矮嵩草群落向小嵩草群落的演替阶段，祁连山区处于禾草－矮嵩草群落，藏北高原则处于矮嵩草群落向小嵩草群落转化期或正常小嵩草群落时期。禾本科、莎草科等可食牧草逐渐减少和杂类草盖度急剧增加的趋势反映了高寒草甸退化演替过程植被变化的基本特征，草地退化造成了土壤容重增加，且表层土壤对放牧的敏感性高于底层，土壤０～１０，１０～２０和２０～４０ｃｍ 容重分别增加了（０．５０±０．０８）ｇ／ｍ ３ ，（０．１６±０．０７）ｇ／ｍ ３ 和（０．０４±０．０３）ｇ／ｍ ３ 。同时，有机质大幅降低，其降低幅度高达１９．３％ ～５３．２％，并随着土层的加深，降幅趋于减小。

生态系统健康的研究主要经历了３个发展阶段。第１个阶段，生态系统健康的思想萌芽；包括２个亚阶段：环境健康与生态系统的知识积累，生态系统健康的思想准备。第２个阶段，生态系统健康学的形成；包括基础理论构建与方法论构建２个亚阶段，分别以“生态系统健康”术语的出现与ＶＯＲ 评价方法的确立为标志。第３个阶段，生态系统健康评价的实践，以ＣＶＯＲ 的理论与实践为代表。生态系统健康评价方法的发展，经历了单因子罗列法、单因子复合法、功能评价法和界面过程法４个阶段，体现关键生态过程是指标选择的重要标准，多指标的综合化是健康评价的发展趋势。生态系统健康是多学科交叉的产物，健康的评价体现了阈值的思想，生态系统的健康具有层次性。

Biological soil crust(BSC) is one of the most important vegetation components in arid and semi-arid areas and has very important ecological functions which attract more and more attentions to its effects on soil and water conservation.In summary,there are three different opinions about the effect of BSC's on infiltration:increase,decrease,and no function.In order to explore artificial cultivation method of BSC and evaluate its effects on soil and water conservation,BSC was artificially cultivated in laboratory and field in water-wind erosion crisscross region of loess plateau,China and the runoff and sediment were measured during the simulated rainfall in laboratory and after natural rainfall in field.The results show: 1.It was feasible to inoculate and cultivate artificial BSC using the method of crushing and broadcast sowing natural BSC collected from research area;2.The artificial BSC's coverage reached to 30%-60% after a rainy season and the main components was same to natural BSC;3.The artificial BSC had obvious function of soil and water conservation.The artificial BSC in the laboratory decreased 49%-64% of runoff and eliminate soil erosion and in field had no significant effects on runoff and decreased 26% of sediment in the plot without vegetation,decreased 11% of runoff and 39% of sediment in the plot with Caragana korshinskii Kom.,respectively.Those results confirm that it could be effective to cultivate artificial BSC and use it to control the loss of soil and water in research area.

探讨生物结皮的人工培育技术,并对其发育初期的水保功能进行评价。结果表明:撒播粉碎后的自然生物结皮,培育1个雨季即可形成盖度高达30%-60%的人工生物结皮,其主成分不变;人工生物结皮具有较好的水保效应,其中室内培育的生物结皮在坡度5°、雨强46.8mm°h -1 、历时1h的模拟降雨条件下可减少49%-64%的径流,消除土壤侵蚀;同条件下野外培育的生物结皮在无植被时对径流影响不明显,但全年可减少26%的土壤侵蚀,有柠条植被时全年可减少11%的径流和39%的土壤侵蚀;在黄土高原侵蚀区以人工生物结皮进行大规模的水保治理成本较低,切实可行。

Biological soil crust,formed by different combinations of mosses,lichens,liverworts,algae,fungi,cyanobacteria and bacteria,is a common and widespread phenomenon in desert areas all over the world thanks to its extraordinary ability to survive desiccation and extreme temperatures,high pH and salinity.Despite its unassuming appearance,biological soil crusts play a significant role in desert ecosystems,including involvement in the process of formation,stability and fertility of soil,preventing soil erosion by ...

对新疆古尔班通古特沙漠生物结皮影响下的土壤有机质分异特征进行了定量研究。结果表明,该沙漠典型沙垄不同部位具有不同的土壤有机质特征,且土壤有机质含量具有明显的分层特征。无论是结皮覆盖区还是非覆盖区,土壤有机质的积累均以表层0~5cm土层为主,由表及里呈递减趋势。这种地表有机质分布的规律在该沙漠地表普遍存在。虽然如此,生物结皮却强烈影响着地表0~5cm土层有机质的含量的积累,它的存在使得该层有机质含量极显著地高于无结皮覆盖区0~5cm土层的有机质含量(t检验,p 0.05),说明生物结皮对土壤有机质含量的影响范围仅限于表层0~5cm,对更深层次土壤的有机质含量则无显著影响。

Taking  three typical types of biological soil crusts (BSCs),  i.e ., cyanobacterialalgal crust, lichen crust, and moss crust, in the southeast fringe of Tengger Desert as test objects, this paper studied their nitrogen fixation potential, seasonal fluctuation, and responses to the environmental factors from June 2010 to May 2011. During the whole study period, the nitrogenase activity (NA) of the cyanobacterialalgal, lichen, and moss crusts had significant difference, being 14-133, 20-101, and 4-28 μmol·m -2 ·h -1 , respectively, which indicated the critical role of the species composition of BSCs in nitrogen fixation. The NA of the three crust types had similar response characteristics to environmental factors. The NA had less correlation with the precipitation during the study period, but was positively correlated to the i.e. , decreased after an initial increase. The NA of cyanobacterialalgal and lichen crusts declined rapidly when the temperature exceeded 30 ℃, while the NA of moss crust began to decline when the temperature exceeded 25 ℃, suggesting that different types of BSCs had different optimal temperature range of nitrogen fixation. The seasonal change of the NA of the three crust types was in the order of autumn > spring > summer > winter. The high air temperature in summer and the low air temperature (<0 ℃) in winter inhibited the NA of the crusts, while the suitable water and heat conditions in late spring and early autumn promoted the NA, which implied that the seasonal fluctuation of the NA was mainly controlled by the joint effect of the water and heat conditions. Under humid condition, the BSCs in the temperate desert zone had nitrogen fixation capacity throughout the year, and the controlling effects of environmental factors on the nitrogen fixation were hierarchical. Water condition was the key factor affecting the nitrogen fixation rate and duration of the crusts, while under the conditions of sufficient water supply and carbon storage, heat condition dominated the crusts nitrogen fixation rate. 

以腾格里沙漠东南缘广泛分布的3类典型生物土壤结皮(藻类结皮、地衣结皮和藓类结皮)为研究对象，在野外环境下连续一年(2010年6月至2011年5月)测定了不同类型结皮的固氮潜力、季节变化，及其对环境因子的响应特征.结果表明：整个试验期间，藻类、地衣和藓类结皮的固氮活性分别为14～133、20～101和4～28 mol·m -2 ·h -1 ，差异显著，这种差异主要是由结皮种类组成的差异所致.3类结皮固氮活性对环境因子的响应特征基本一致.3类结皮固氮活性与降水量关系不显著，但与试验前3天小于3 mm的降水量均呈显著的正相关关系，说明该地区3类结皮在3 mm降水条件下即可达到最大固氮速率.3类结皮固氮活性与试验期温度均呈显著的二次函数关系，随气温升高均呈先上升后下降的趋势，藻类和地衣结皮的固氮活性在超过30 ℃后即迅速下降，而藓类结皮的固氮活性在超过25 ℃后即开始下降，说明不同类型结皮具有不同的固氮适宜温度区间.3类结皮固氮活性的季节变化均表现为秋季>春季>夏季>冬季，夏季高温和冬季低温抑制了结皮固氮酶活性，而春末秋初适宜的水热条件促进了其固氮活性的提高，结皮固氮活性的季节变化主要受水热因子的共同调控.温带荒漠区生物土壤结皮在湿润条件下全年均具有固氮能力，环境因子对其氮固定的控制作用层次分明，水分是影响其固氮速率和持续时间的关键因子，在水分和碳源充足的条件下，温度则是制约其固氮能力的主要因子.

在荒漠地区的固定、半固定沙地和流动沙地上,微生物、藻类植物及地衣、苔藓植物能参与并形成生物结皮,其在干旱和半干旱荒漠地区具有重要生态意义.其中土壤微生物因其极强的适应性和生存能力,在生物结皮形成各阶段都起着积极的作用.土壤微生物的生长和活性与土壤酶活性的变化具有良好的相关性,它的组成、分布和数量因沙丘类型和沙土层深度的不同而有所变化,也受到季节和植被的影响.土壤微生物的生理代谢活动及数量变化可以改变沙土表面理化性质,在土壤结皮的形成、植物营养的转化过程中发挥积极作用,为植物生长创造了良好的条件.

Biological soil crusts (BSCs) have been found in deserts all over the world and may constitute as high as 70% of the living cover in some plant communities. BSCs can directly or indirectly influence seed germination and establishment of vascular plants,and seeds biological characteristics (such as seed appendages) also play an important role on seed germination.However, the interactive effects of BSCs and seed appendages on seed germination are poorly understand.In this study, our objective was to know more about BSCs-seed appendages interaction on seed germination of dominant vascular plants in the Gurbantunggut Desert of western China.We chose four typical, widely distributed Chenopodiaceous species ( Haloxylon ammodendron,Salsola subcrassa, Ceratoides ewersmanniana and Ceratocarpus arenarius ) which owned different seed appendages. Seeds belonged to two treatments (appendages were removed and remained) were sown at the surface of three matrices (moss crusts, lichen crusts, bare sand) and their emergence was observed. Final germination results showed that seed's bracts appendages of H. ammodendron and S. subcrassa significantly inhibited germination rate.Hair appendages of C. ewersmanniana and spine appendages of C. arenarius had no significant effects on seed germination. Moss crusts should be noted because they significantly inhibited seed germination of all species. Although lichen crusts significantly inhibited seed germination of S. subcrassa , they had no obvious effect on the rest three species. Among the four species,the seed germination of S. subcrassa was significantly inhibited due to the BSCs-seeds appendages interaction.Hence, BSCs have different effects on seed germination of desert plants that with different appendages, resulting in the spatial heterogeneity of seed germination of vascular plants, and affect the distribution and diversity of vascular plants.

生物土壤结皮能直接或间接地影响维管植物种子萌发与群落建成，种子本身的生物学特征（如种子附属物等）对萌发也存在一定影响。本研究选取古尔班通古特沙漠4种常见的具有不同形态附属物的藜科植物（梭梭（ Haloxylon ammodendron ）、粗枝猪毛菜（ Salsola subcrassa ）、心叶驼绒藜（ Ceratoides ewersmanniana ）和角果藜（ Ceratocarpus arenarius ））种子，设置苔藓结皮、地衣结皮和裸沙3种土壤基质，通过去除或保留种子附属物，对比研究了生物土壤结皮与种子附属物对种子萌发的影响。结果表明：粗枝猪毛菜和梭梭的苞片显著抑制了种子萌发（ p p >0.05）。与裸沙相比，苔藓结皮显著抑制了4种植物种子的萌发（ p p p >0.05）。同时，附属物与结皮对粗枝猪毛菜种子的萌发还具有交互作用，表现为显著抑制种子萌发（ p <0.01）。可见，生物土壤结皮对具有不同附属物的荒漠植物种子萌发具有不同的影响，进而造成维管植物种子萌发的空间异质性，影响维管植物分布和多样性。

By the method of field experiment combined with laboratory analysis, this paper studied the ecological significance of hygroscopic and condensate water on the biological soil crusts in the vegetation sandfixing area in Shapotou region of China. In the study area, 90% of hygroscopic and condensate water was within the 3 cm soil depth, which didn’t affect the surface soil water content. The hygroscopic and condensate water generated at night involved in the exchange process of soil surface water and atmosphere water vapor, made up the loss of soil water due to the evaporation during the day, and made the surface soil water not reduced rapidly. The amount of the generated hygroscopic and condensate water had a positive correlation with the chlorophyll content of biological soil crusts, indicating that the hygroscopic and condensate water could improve the growth activity of the biological soil crusts, and thus, benefit the biomass accumulation of the crusts.

以沙坡头植被固沙区为研究对象，采用野外试验与室内分析相结合的方法，探讨了吸湿凝结水对生物土壤结皮的生态作用.结果表明： 在沙坡头人工固沙植被区内，吸湿凝结水90%分布在表层3 cm以内，不影响土壤表层水分含量；夜间形成的吸湿凝结水在日间参与了地表水分与大气层水汽的交换过程，弥补了日间蒸发作用导致的土壤水分的散失，使表层土壤水分不会迅速降低.吸湿凝结水形成量与生物土壤结皮中的叶绿素含量呈正相关关系，能够提高该区生物土壤结皮的生长活性，有利于其生物量的积累.  

Biological crusts extensively occur in Gurbantünggüt Desert and their distribution exhibits obvious selectivity to landform position. Moss crusts, lichen crusts, algal crusts and algal-lichen crusts are distributed in interridge, middle-lower parts of dunes, upper western slopes and middle eastern slopes, respectively. A certain crust has its unique species composition, thickness, surface features and mechanical resistance. Different crusts also have quite different wind erodibilities. The wind tunnel experiment demonstrated that the presence of biological crusts greatly increase the threshold friction velocity. Under 20～30 m·s -1 wind velocity no sand grain movement and wind erosion are observed on the four types of undisturbed crusts, while the threshold wind velocity on the bare sand surface is only 8.42 m·s -1 . Under the same destruction percentage moss crust has the highest threshold velocity, followed by lichen crust, algal and algal-lichen crusts in succession. Wind velocity of ≥18 m·s -1 occurs frequently in Gurbantünggüt Desert, therefore any disturbances to natural ground surface may lead to sand moving, except for moss and lichen crust-covered surfaces with no more than 20% destruction. Wind erosion rate on bare sand surface is 0.09 g·m -2 ·s -1 at 8.42 m s -1 wind velocity and it reaches (1 214.82) g·m -2 ·s -1 at 25 m·s -1 wind velocity. Under the same wind velocity the wind erosion rates for the four crusts do not exceed 8.95% of that over the bare sand surface. Wind erosion rate greatly increases with the increase in destruction percentage and wind velocity. Moss and lichen crusts show a stronger resistance to wind erosion. When the destruction percentage is larger than 80% the wind erosion rates on algal and algal-lichen crusts are close to that of bare sand surface. According to the experiment results, human activity should not result in over 30% of destruction to crust cover, especially in spring and summer.

古尔班通古特沙漠4种类型生物结皮的风洞实验表明,其对地表风蚀影响甚大,且随结皮类型及其破损度不同而呈明显的变化.在25～30m·s -1 的风速下,未经扰动的4类生物结皮均未发现沙粒起动和地表风蚀现象.相同破损率条件下,起动风速以苔藓结皮最大、地衣结皮次之、藻结皮和藻类地衣结皮最小.裸沙面在8 42m·s -1 的起沙风作用下,风蚀强度为0.09g·m -2 ·s -1 ,25m·s -1 时为1214.82g·m -2 ·s -1 .在同等风速吹蚀下,4类结皮的风蚀率最大不超过裸沙面的8.95%.随着破损率的增大和风速的加强,风蚀强度显著增大.在数量级和变化趋势上以苔藓和地衣结皮相似,变化于0～23.67g·m -2 ·s -1 之间;藻结皮和藻类地衣结皮相近,变化于0～69.00g·m -2 ·min -1 之间.根据该沙漠的风能环境分析和风洞实验结果,为了不致产生风蚀,人类放牧等经济活动应以不造成30%以上的地表结皮破损为宜,特别是在春夏两季的强风盛行期更要谨慎处之.