Study on Soil Microbiotic Crust and Its Influences on Sand-fixing Vegetation in Arid Desert Region

Based on secular fixed_site data in the artificial sand_fixing vegetation district at the southeast fringe of the Tengger Desert, the formative characteristics of soil microbiotic crusts and its influences on vegetation dynamics were analyzed. Once sand barrier and artificial vegetation have stabilized the surface of the sifting sand, could form aeolian deposition crust and then evolve into algae_dominated crust. Such processes result from the interactions of physical effects of atmospheric dust and silt deposition on sand surface, sinking and raindrop impact, and soil microorganism activities. Under the condition of less than 200 mm precipitation, the presence of microbiotic crust changes the soil hydraulic conductivity, alters the temporal and spatial distribution of the limited precipitation in sand layer and leads to the decline of deep_rooted shrubs. The development of microbiotic crust and subsurface soil affects the plant growth and seed rain distribution, as a result, the diversity of plant species gradually tend to become saturated and finally affects the vegetation stability.

Spatial-temporal dynamics of desert vegetation and its responses to climatic variations over the last three decades:a case study of Hexi region in Northwest China

Analysis of spatial-temporal variations of desert vegetation under the background of climate changes can provide references for ecological restoration in arid and semi-arid areas. In this study, we used the Global Inventory Modeling and Mapping Studies （GIMMS） NDVI data from 1982 to 2006 and Moderate Resolution Imaging Spectroradiometer （MODIS） NDVI data from 2000 to 2013 to reveal the dynamics of desert vegetation in Hexi region of Northwest China over the past three decades. We also used the annual temperature and precipitation data acquired from the Chinese meteorological stations to analyze the response of desert vegetation to climatic variations. The average value of NDVImax （the maximum NDVI during the growing season） for desert vegetation in Hexi region increased at the rate of 0.65x10-3/a （P〈0.05） from 1982 to 2013, and the significant increases of NDVImax mainly appeared in the typical desert vegetation areas. Vegetation was significantly improved in the lower reaches of Shule and Shiyang river basins, and the weighted mean center of desert vegetation mainly shifted toward the lower reaches of the two basins. Almost 95.32% of the total desert vegetation area showed positive correlation between NDVImax and annual precipitation, indicating that precipitation is the key factor for desert vegetation growth in the entire study area. Moreover, the areas with non-significant positive correlation between NDVImax and annual precipitation mainly located in the lower reaches of Shiyang and Shule river basins, this may be due to human activities. Only 7.64% of the desert vegetation showed significant positive correlation between NDVImax and annual precipitation in the Shule River Basin （an extremely arid area）, indicating that precipitation is not the most important factor for vegetation growth in this basin, and further studies are needed to investigate the mechanism for this phenomenon.

Comparisons between Movement Speed of Main Types of Dunes:A Case Study of Desert Areas in Hexi Region of Gansu Province

In desert areas in Hexi region,11 barchan dunes,6 chains of barchan dunes,6 pyramid dunes,6 parabolic dunes and 6 accumulated sand-belts were chosen to study their movement speed based on images obtained by Google Earth in various periods.The results show that among the dunes,the movement of the barchan dunes was the fastest,followed by the chains of barchan dunes,and only the tops of the pyramid dunes swayed,while the parabolic dunes and accumulated sand-belts hardly moved forward.The higher the barchan dunes(or the chains of barchan dunes) were,the slower the movement was.On the contrary,the higher the pyramid dunes were,the faster the swing was.There was a positive correlation between the movement speed of the barchan dunes and the average wind speed of sandstorms.

Research Advances in Allelopathy of Plants in Arid Desert Regions of Northwest China

To investigate allelopathy of plants in desert ecosystems, related research achievements obtained in recent years, reported allelopathic plants, allelochemicals and releasing ways of alleochemicalds were summarized, and then the key problems of research into allelopathic plants in desert ecosystems were indicated. It was considered that the research of allelopathy of plants in desert regions has just started in China, and plants with atlelopathic potential were found in the Compositae, Leguminosae, Rosaceae, Scrophulariaceae and Gramineae; plants in desert regions re- lease allelochemicals mainly via natural volatilization, which is closely related to their growing environment; allelochemicals such as alkaloids, fla- vonoids, terpenoids have been identified. This study can provide theoretical basis and practical value for reasonable adoption of protection meas- ures of desert plants and comprehensive control of desertification.

URANIUM MINERALIZATION IN THE MUSCOVITE-RICH GRANITES OF THE SHALATIN REGION, SOUTHEASTERN DESERT, EGYPT

The younger granitoids of the Shalatin district in the Southeastern Desert of Egypt, are of biotite and two-mica granite compositions. The geochemistry of rare-earth elements (REE), yttrium, thorium and uranium forms the basis for many important methods to reconstruct igneous petrogenesis. Since the recognition that REE, Y, Th, U-rich accessories may play an important role in controlling the geochemistry of crustal melts, a considerable amount of work has been done in an attempt to understand their effects. However, this effort has been almost exclusively focused on three minerals: zircon, monazite and apatite. Nevertheless, the variety of REE-Th-U-rich accessories in granite rocks are neither limited to these three minerals nor are they always the main REE, Y, Th carriers. The geochemistry of REE, Y, Th and U reflects the behavior of accessories and some key major minerals such as garnet and feldspars, and may therefore give valuable information about the conditions of partial melting, melt segregation and crystallization of granite magmas in different crustal regimes. The geochemistry of U and Th during magmatic differentiation has been studied in many granites from different areas and it has been known that the U and Th contents of granitic rocks generally increase during differentiation, although in some cases they decrease. The Th/U ratio can either increase or decrease, depending on redox conditions, the volatile content or alteration by endogene or supergene solutions. The accessory assemblage of muscovite-rich granites and high-grade rocks is composed of monazite, xenotime, apatite, Th-orthosilicate, secondary U-mineralization and betafite-pyrochlore. REE, Y, Th and U are not suitable for geochemical modeling of granitoids by means of equilibrium-based trace element fractionation equations, but are still useful petrogenetic tools.

Response of Grassland Vegetation to Air Temperature and Precipitation in Minqin Desert Region

[ Objective] This paper aims to analyze response characteristics of desert grassland vegetation to climate change. [ Method] The responses of grassland vegetation in desert region to air temperature/precipitation changes were analyzed by phenological observations since 1974, observation data conceming vegetation samples and meteorological data during the same period. The changing trend significance was denoted by linear trend line and its regression significance. The interrelation between the two variables was indicated by correlation coefficients. Data were analyzed by the software SPSS 13.0. [Result] （1） The rising rate of annual average temperature in the Minqin desert area since 1961 was greater than both the global level and Ghina＇s level over the past century. （2） Desert plants＇ response to temperature changes were mainly displayed as the advance of spring phenology, the delay of autumn phenology and the extension of growing duration. Plants＇ main response to precipitation changes was that vegetation coverage and pure coverage were decreasing along with precipitation reducing. （3） Both the vegetation coverage and pure coverage mainly had a positive correlation with the annual precipitation. Plant density mostly had a positive correlation with the precipitation in September. （4） The impact of rising temperature on plant phenology in spring was greater than that in autumn. [ Conclusion] The effects of temperature changes on desert grassland plants were the advance of spring phenology, the delay of autumn phenology, the extension of growing season and longer plant growing period than that in other reports. The responses of desert grassland vegetation to precipitation changes were that both vegetation coverage and pure coverage were decreasing along with precipitation reducing, and plant density fluctuated along with precipitation change.

沙漠生态学概念、学科特色、内容及指导作用

生态学是生态文明建设的理论基础。现代生态学学科发展与区域生态特色相结合,已成为生态学特色学科方向发展的显著特征和区域生态文明建设的关键依据。沙漠生态学以沙漠或沙漠化土地为研究区域,以沙漠生物为研究对象,是沙漠学与生态学的交叉融合学科,具有典型的区域性特色。从沙漠生态学的概念和学科定位的角度,分析了沙漠生态学的学科特点和特色优势。基于此,沙漠生态学具有自己的研究范畴和研究内容,在学科层面上存在其他学科无法解决或者解决好的科学问题,并从研究区域和研究对象的角度分析了沙漠生态学形成独立学科方向的必要性。沙漠生态学学科体系建设和基础理论丰富与完善,有利于指导干旱、半干旱区沙漠化的发生原因、过程及原理、沙漠化逆转过程的恢复机理的全面系统研究,为沙漠化综合治理措施与治理实践、沙漠自然资源利用与开发以及沙漠生态系统保护提供关键科技支撑,凸显了沙漠生态学的特色学科方向对区域荒漠化综合防治和“三北”防护林生态工程建设的重要理论和实践指导意义。

2010–2020年塔里木盆地南部荒漠草地凋落物回收量月动态数据集

中国科学院新疆策勒荒漠草地生态系统国家野外科学观测研究站(以下简称“策勒站”)地处塔里木盆地南缘,南依昆仑山,北临我国最大的塔克拉玛干沙漠。具有植被群落简单,土壤有机质积累缓慢等特点。凋落物是该区域重要的养分来源。基于对策勒站荒漠植物群落的长期定位观测,通过对不同植物凋落物器官(枝、叶、果)分组,本文整理统计得到2010–2020年塔里木盆地南部荒漠草地凋落物的回收量月动态数据,同时记载了观测场群落以及土壤养分的年度变化情况。数据的产生严格遵照CERN生物观测规范执行,数据的审核及质量控制由台站与分中心质控人员共同完成。本数据集以期为深入研究塔里木盆地南部荒漠草地凋落物动态变化提供基础数据,为了解和评估极端干旱荒漠生态系统养分循环过程提供理论支撑。

Noah-MP陆面模式对干旱区不同下垫面水热通量模拟评估

基于干旱区张掖国家气候观象台2021年1月-2022年6月和大满灌区绿洲农田站2020年1-12月的观测数据,评估Noah-MP模式对干旱区荒漠和农田两种下垫面的水热通量的模拟性能。结果表明:Noah-MP模式模拟的干旱区荒漠下垫面辐射与观测值的相关系数均>0.98,泰勒评分>0.93。感热的泰勒评分(0.809)>潜热的泰勒评分(0.504),对辐射及湍流通量的变化特征、峰谷值与观测值总体一致,模拟效果较好。模拟的5 cm土壤湿度对降水过程有明显的响应,表现出明显的冷暖季差异,但其模拟性能仍有待改进。Noah-MP模式模拟的干旱区农田下垫面辐射通量及各层土壤温度的相关系数均>0.98,泰勒评分>0.58,模拟效果较理想。但模拟的潜热通量及各层土壤湿度较观测值偏低,尤其在生长季模拟性能不理想。Noah-MP模式对干旱区荒漠下垫面水热通量的模拟性能优于农田下垫面,优化和发展模式水文过程的参数化方案,在模式中考虑人为作用,是提高干旱区陆面过程模式模拟能力的重要方向。

西北干旱区荒漠植物叶片和细根碳、氮、磷化学计量特征

植物的叶片和细根是植物地上部分和地下部分最重要的营养器官,其碳(C)、氮(N)、磷(P)化学计量特征反映了植物的养分限制状况及叶片与细根间的协同作用,开展叶片与细根化学计量关系的研究,对认识植物养分利用策略及元素间平衡关系有重要意义。对西北干旱区21种荒漠植物叶片与细根C、N、P含量进行了测定,分析了C、N、P含量及其计量比在不同生活型及不同器官间的关系。结果表明:1)西北干旱区荒漠植物叶片与细根C含量相对稳定,叶N、P含量高于细根,说明在干旱生境中,植物对养分的分配侧重于地上部分,以完成其正常的生命活动;叶片与细根的N∶P无显著差异,有明显的保守性,表明植物地上与地下部分养分吸收策略与分配规律具有一致性;2)不同生活型植物叶片和细根的C、N、P含量及C∶N、C∶P存在显著差异,灌木与禾草具有较高的C∶N和C∶P,杂类草具有较高的N、P含量,说明灌木与禾草倾向于保守型养分适应策略,杂类草倾向于快速生长的资源竞争策略;3)21种荒漠植物叶片与细根N、P含量间均存在显著的正相关关系,表明西北干旱区荒漠植物体内N、P元素间存在相互作用;4)植物叶片与细根间C、N、P含量及C∶N、C∶P存在等速生长关系,表明植物光合产物和养分在地上与地下部分间的分配具有平行的比例关系,但这种关系受生活型影响。上述结果表明西北干旱区不同生活型植物在恶劣生境中存在不同的养分适应策略,且地上与地下部分的养分利用策略及分配规律存在协同作用,这为进一步认识西北干旱区荒漠植物的养分利用策略提供了试验基础。

基于改进域对抗网络的新能源基地风光时序功率曲线生成方法

准确刻画风光时序功率曲线对于加快推动新能源大规模并网、指导联合发电系统规划运行具有重要意义。针对我国沙漠、戈壁、荒漠等地区新建大型风电光伏发电基地无历史功率数据可利用的现状,该文提出基于改进域对抗网络(improved domain adversarial neural networks,IDANN)的新能源基地风光时序功率曲线生成方法。以历史气象和功率数据充足的新能源场站作为源域,仅有气象数据的新建基地作为目标域。将源域上学习的输入气象信息到输出风光功率的非线性映射知识迁移到目标域,并添加最大均值差异(maximum mean discrepancy,MMD)作为度量域间特征分布相似性的损失函数以降低目标域泛化误差。最后采用实际风光场站算例验证所提方法的有效性,并进一步表明该方法的实用价值和意义。

新疆农田和荒漠生态系统土壤有机碳储量及其影响因素

基于中国生态系统研究网络(CERN)长期监测数据,选取新疆维吾尔自治区代表暖温带干旱区的绿洲农田生态系统(阿克苏站)、代表暖温带荒漠区(策勒站)以及温带荒漠区(阜康站)的绿洲农田和荒漠生态系统综合观测场、辅助观测场和农户调查点2005—2020年0—100 cm土层的土壤有机碳(SOC)储量数据,分析新疆农田和荒漠生态系统SOC储量的影响因素。研究结果表明,2005—2020年0—100 cm土层SOC总储量平均值为阿克苏站(5.17 kg/m^(2))>阜康站(4.20 kg/m^(2))>策勒站(2.96 kg/m^(2))。0—20 cm、20—40 cm、40—60 cm土层的SOC分别约占0—100 cm土层储量的27.3%—35.3%、23.1%—24.6%和15.8%—17.5%。在阿克苏站,施肥量最高、灌溉量最低的农户调查点SOC储量最高;而在策勒站和阜康站,农户调查点和辅助观测场的施肥和灌溉措施分别最有利于提高SOC储量。总体来看,土壤含水量、地上生物量与SOC储量呈正相关关系;年平均气温与0—40 cm土层的SOC储量呈负相关关系。在单一生态站的生态系统尺度,年平均气温与SOC储量相关性不显著;地上生物量与策勒站和阜康站的SOC储量呈正相关关系,但是与阿克苏站0—40 cm土层的SOC储量呈负相关关系;施纯钾量与策勒站0—60 cm土层的SOC储量呈正相关关系,但与阜康站40—100 cm土层的SOC储量呈负相关关系。总之,与自然状态下的荒漠和农田不施肥相比,灌溉和施肥的农田管理措施有利于增加干旱区SOC储量。不同生态站要根据自身区域特点制定合理的农田管理模式,以维持较高的SOC储量。

北山荒漠戈壁浅覆盖区萤石矿定位技术研究

在我国的西北部地区,特别是东天山—北山成矿带中新生界覆盖区广泛分布,仅戈壁、沙漠覆盖区就占据了全国陆地总面积的12.3%。随着东部矿产资源的开发程度日益提高,西北部大面积的戈壁荒漠浅覆盖区有望成为有利的矿产资源接替基地。因此,在戈壁、沙漠等中新生界覆盖区开展矿产综合定位预测工作是当前形势下最佳的选择之一。

荒漠浅覆盖区萤石矿定位预测技术研究

北山地区是中国西北部重要的萤石成矿带,区内成矿地质条件优越,但地处戈壁荒漠,受浅覆盖层影响,地表仅可观察到极少量露头,需开展综合地球物理研究为区域成矿潜力及覆盖区下方矿脉赋存空间进行定位预测研究。以北山成矿带东段花石头山地区为示范,采用高精度磁法、激电中梯、地面伽马能谱测量、便携式X射线荧光分析及音频大地电磁测深等技术手段进行综合探测,其中面积性激电和磁法工作可有效识别隐伏赋矿空间分布,地面伽马能谱测量、便携式X射线荧光分析约束赋矿空间的矿化异常,音频大地电磁测深构建了隐伏萤石矿赋存位置深部结构模型,并通过工程验证方法组合的有效性。本研究建立了综合地质-地球物理定位预测技术方法组合,可为北山成矿带及戈壁荒漠浅覆盖区萤石矿定位预测提供理论和技术支持。

甘肃民勤荒漠区植物群落土壤的理化性质和酶活性分析

对甘肃民勤连古城国家级自然保护区内霸王〔Zygophyllum xanthoxylum(Bunge)Maxim.〕、红砂〔Reaumuria songarica(Pall.)Maxim.〕、猫头刺(Oxytropis aciphylla Ledeb.)、针茅(Stipa capillata Linn.)群落0~20、20~40和40~60 cm土层土壤的理化性质和酶活性进行比较,并对土壤理化指标与土壤酶活性的关系进行分析。结果表明:总体上,4种植物群落土壤中,红砂群落的土壤总有机碳、全氮、速效磷和速效钾含量及蔗糖酶活性最高,针茅群落的土壤全磷含量最高,猫头刺群落的土壤全钾含量最高;霸王群落的土壤脲酶、淀粉酶、纤维素酶和碱性磷酸酶活性最强。总体来看,4种植物群落土壤理化指标均随着土壤深度增加而降低,4种植物群落的土壤脲酶、过氧化氢酶、蔗糖酶和碱性磷酸酶活性以及霸王、红砂和针茅群落的土壤淀粉酶活性也随着土壤深度增加而减弱。Pearson相关性分析结果表明土壤理化指标与土壤酶活性多呈显著(P<0.05)或极显著(P<0.01)正相关。冗余分析结果显示:第1和第2轴分别能够解释民勤荒漠区植物群落土壤理化性质与土壤酶活性关系的61.01%和18.63%,并且,土壤总有机碳含量、速效钾含量、pH值和含水量对土壤酶活性的影响较大;蒙特卡罗检验结果显示土壤铵态氮含量、pH值、总有机碳含量和含水量对土壤酶活性影响的贡献率分别为31.6%、12.7%、11.8%和11.6%,且影响均达到显著水平。综上所述,甘肃民勤荒漠区4种植物群落总体表现为红砂群落的土壤理化性质最好,霸王群落的土壤酶活性最强,并且,土壤越深,指标数值越小。土壤总有机碳含量、pH值和含水量对该区域4种植物群落土壤酶活性的影响较大。

干旱荒漠区三种典型灌丛植物凋落物混合分解效应研究

为探究干旱荒漠区混合凋落物的分解特征,本研究以红砂(Reaumuria soongarica(Pall.)Maxim)、泡泡刺(Nitraria sphaerocarpa Maxim)和珍珠(Salsola passerina Bunge)为研究对象,分析了单一和混合凋落物质量损失率和养分残留率的变化,揭示了混合凋落物分解的加性与非加性效应。结果表明:各凋落物质量损失率随分解时间延长呈增加趋势;各凋落物C和N残留率随分解时间推移为降低趋势,说明C和N养分元素呈释放模式;混合凋落物质量损失率表现为加性效应,C残留率在分解前期为加性效应,分解末期为拮抗的非加性效应,N残留率在分解前期为拮抗和协同的非加性效应,分解末期为加性效应;凋落物混合后,较高的物种丰富度会导致养分残留率的非加性效应增强。综上,混合凋落物分解中养分变化的混合效应因分解时间而不同,混合凋落物物种丰富度会影响养分元素的混合效应,能改善干旱荒漠生态系统的养分循环。

我国沙漠地区光伏产业与生态治理分析

我国沙漠地区目前正在大力发展光伏产业,但是由于其生态脆弱性,光伏产业的落地对沙区生态环境有何种影响至今仍是争议热点。为厘清光伏产业和生态治理的关系,通过对前人研究结果进行归纳总结,从光伏产业的生态问题、治理措施、效益评估等方面,论述了生态环境在风蚀、沙尘等方面对光伏产业的影响,以及光伏产业运行生产后对周边土壤、植被及小气候的影响,同时归纳总结了沙区光伏产业包括沙地整地、锁边林带、工程固沙、植物固沙以及光伏桩防护等方面的生态治理措施。针对以上问题,针对光伏产业规划选址,提出了将社会效益、生态效益共同纳入考虑范围的综合选址策略;针对光伏产业发展提出了开发多产业复合模式,促进经济、资源、环境的全面协调可持续发展;针对环境保护,分别在建设期和运营期提出了合理施工、制定生态保护应急预案等方案,以及产业全周期生态保护的发展建议。以期为沙区的合理利用提供技术支撑,助力落实沙区“发展为要、生态优先”的发展理念。

西北干旱区荒漠戈壁两次极端沙尘事件的对比研究

为深入理解极端沙尘暴事件的演变过程和驱动因子,结合多源卫星遥感及再分析数据,挑选2007年3月31日(“3·31”事件)和2021年3月14日(“3·14”事件)爆发于西北干旱区荒漠戈壁的两次沙尘暴事件,对比分析了其时空演变、高低空环流配置、近地面气象要素的变化。结果表明:(1)两次极端事件分别爆发于塔克拉玛干沙漠及戈壁荒漠,均受高低层天气系统影响。其中,“3·31”事件受地面冷锋和高空脊控制,脊前西北冷空气与地面冷锋引起的垂直运动配合,将沙尘往下游输送;而“3·14”事件则受蒙古气旋和高空槽影响,气旋后的偏北风和气旋引发的垂直运动将沙尘卷起至高层大气,并通过槽后西北风将其往下游输送;(2)两次极端沙尘事件均有持续时间长的特点,区别在于“3·31”事件主要受高压脊、均压场和周边地形影响,大气层结稳定,沙尘不易沉降和输送,而“3·14”事件则因中国北部持续性高压导致的偏南风和偏东风阻止了沙尘向下游扩散;(3)两次极端沙尘事件爆发前,塔克拉玛干和戈壁荒漠均出现了高温、降水减少及土壤水分枯竭现象,即强风和干燥土壤。为极端沙尘事件的爆发创造了有利的动力条件和物质基础。

沙区生物土壤结皮演替对表层土壤养分和微生物群落组成的影响

生物土壤结皮是旱地生态系统的重要组成部分,在土壤表面生物和非生物因子的相互作用中发挥着重要作用。研究了腾格里沙漠南缘不同类型生物土壤结皮及其下0~2 cm和2~5 cm层土壤理化性质、微生物群落组成和酶活性,分析了土壤微生物群落组成和酶活性随结皮演替的变化特征及其与土壤理化性质的关系。结果表明:(1)随着结皮向着以藓类为优势的群落演替,结皮层及下层土壤有机碳、全氮、全磷、电导率(EC)及黏粉粒含量均呈显著增大趋势,但随着土层深度的增加而显著减小;pH、容重及砂粒含量则呈相反趋势。(2)结皮层总PLFAs、细菌和真菌PLFAs均表现为藓结皮>地衣结皮>藻结皮,藓结皮与藻结皮相比分别增加了24%、15%和39%;与藻结皮相比,藓结皮真菌和细菌PLFAs的比值(F:B)增加了20%。结皮下0~2 cm和2~5 cm土层微生物群落组成表现出相似的规律,但各参数均随土层深度的增加而显著减小。(3)结皮层及其下0~2 cm和2~5 cm层土壤蔗糖酶、过氧化氢酶、纤维素酶、淀粉酶、多酚氧化酶、过氧化物酶、脲酶和碱性磷酸酶活性均随结皮演替而显著升高,但其活性均随土层深度的增加而显著减小。(4)土壤微生物群落组成和酶活性与土壤有机碳、全氮、全磷、EC和黏粉粒含量呈显著正相关,而与pH、容重及砂粒含量呈显著负相关。结构方程模型分析表明结皮演替引发的土壤化学属性的变化是微生物群落和酶活性的关键驱动因子。

戈壁滩地区水稳砂砾材料组成设计与工艺控制

以新疆G575线巴哈公路项目为依托,通过室内水泥稳定砂砾基层配合比设计、收缩性能试验研究,结合试验段试铺及施工工艺参数指标分析,提出适合戈壁滩地区的水泥稳定砂砾基层组成设计及相关施工工艺,可为同类条件施工项目提供参考。