A phylogenetic approach identifies patterns of beta diversity and floristic subregions of the Qinghai-Tibet Plateau

Patterns of taxonomic and phylogenetic beta diversity and their relationships with environmental correlates can help reveal the origin and evolutionary history of regional biota.The Qinghai-Tibet Plateau(QTP)harbors an exceptionally diverse flora,however,a phylogenetic perspective has rarely been used to investigate its beta diversity and floristic regions.In this study,we used a phylogenetic approach to identify patterns of beta diversity and quantitatively delimit floristic regions on the Qinghai-Tibet Plateau.We also examined the relationships between multifaceted beta diversity,geographical distance,and climatic difference,and evaluated the relative importance of various factors(i.e.,climate,topography and history)in shaping patterns of beta diversity.Sørensen dissimilarity indices indicated that patterns of species turnover among sites dominated the QTP.We also found that patterns of both taxonomic and phylogenetic beta diversity were significantly related to geographical distance and climatic difference.The environmental factors that contributed most to these patterns of beta diversity include annual precipitation,mean annual temperature,climatic gradients and climatic instability.Hierarchical dendrograms of dissimilarity and non-metric multidimensional scaling ordination based on phylogenetic beta diversity data identified ten floristic subregions in the QTP.Our results suggest that the contemporary environment and historical climate changes have filtered species composition among sites and eventually determined beta diversity patterns of plants in the QTP.

Unveiling evapotranspiration patterns and energy balance in a subalpine forest of the Qinghai-Tibet Plateau:observations and analysis from an eddy covariance system

Evapotranspiration is an important parameter used to characterize the water cycle of ecosystems.To under-stand the properties of the evapotranspiration and energy balance of a subalpine forest in the southeastern Qinghai-Tibet Plateau,an open-path eddy covariance system was set up to monitor the forest from November 2020 to October 2021 in a core area of the Three Parallel Rivers in the Qing-hai-Tibet Plateau.The results show that the evapotranspira-tion peaked daily,the maximum occurring between 11:00 and 15:00.Environmental factors had significant effects on evapotranspiration,among them,net radiation the greatest(R^(2)=0.487),and relative humidity the least(R^(2)=0.001).The energy flux varied considerably in different seasons and sensible heat flux accounted for the main part of turbulent energy.The energy balance ratio in the dormant season was less than that in the growing season,and there is an energy imbalance at the site on an annual time scale.

Extracting water body data based on SDWI and threshold segmentation:A case study in permafrost area surrounding Salt Lake in Hoh Xil,Qinghai-Tibet Plateau,China

There are a large number of lakes,rivers,and other natural water bodies distributed in the permafrost area of the Qinghai-Tibet Plateau(QTP).The changes in water bodies will affect the distribution of water resources in sur-rounding areas and downstream areas,resulting in environmental impact and bringing potential flood disasters,which will induce more serious issues and problems in alpine and high-altitude areas with a fragile habitat(such as the QTP in China).Generally,effective,reasonable,and scientific monitoring of large-scale water bodies can not only document the changes in water bodies intuitively,but also provide important theoretical reference for subsequent environmental impact prediction,and disaster prevention and mitigation in due course of time.The large-scale water extraction technology derived from the optical remote sensing(RS)image is seriously affected by clouds,bringing about large differences among the extracted water result products.Synthetic aperture radar(SAR)RS technology has the unique advantage characteristics of all-weather,all-day,strong penetration,and not being affected by clouds,which is hopeful in extracting water body data,especially for days with cloudy weather.The data extraction of large-scale water bodies based on SAR images can effectively avoid the errors caused by clouds that become prevalent at present.In this paper,the Hoh Xil Salt Lake on the QTP and its surrounding five lakes are taken as the research objects.The 2-scene Sentinel-1 SAR image data covering the whole area on 22 August 2022 was used to verify the feasibility of extracting water body data in permafrost zones.Furthermore,on 22 August 2022,the wealth here was cloudy,which made the optical RS images,e.g.,Sentinel-2 images full of clouds.The results show that:using the Sentinel-1 image and threshold segmentation method to extract water body data is efficient and effective with excellent results in permafrost areas.Concretely,the Sentinel-1 dual-polarized water index(SDWI),calculated by combining dual vertical–vertical(VV)polarized and verti-cal–horizontal(VH)polarized data is a useful index for water extraction and the result is better than each of the VV or VH polarized images.

Applying the AHP-FUZZY method to evaluate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau: a case study of Chaidaer-Muli Railway

This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of rubble roadbed engineering in permafrost regions. The AHP(Analytic Hierarchy Process) method is thus employed to establish the evaluation indicator system. The evaluation factor is selected by analyzing the mutual relation between the permafrost environment and roadbed engineering. Thus, a hierarchical structure model is established based on the selected evaluation indices. Each factor is weighted to determine the status in the evaluation system, and grading standards are built for providing a basis for the evaluation. Then, the fuzzy mathematical method is introduced to evaluate the measure effect of rubble roadbed engineering in permafrost regions along the Chadaer-Muli Railway. Results show that most of the permafrost roadbed is in a preferable condition(b) along the Chaidaer-Muli Railway due to rubble engineering measures. This proportion reaches to 86.1%. The proportion in good(a), general(c) and poor states(d) are 0.0%, 7.5% and 6.4%, respectively, in all the evaluation sections along the Chaidaer-Muli Railway. Ground-temperature monitoring results are generally consistent with AHP-FUZZY evaluation results. This means that the AHP-FUZZY method can be applied to evaluate the effect of rubble roadbed engineering measures in permafrost regions. The effect evaluation of engineering measures will provide timely and effective feedback information for further engineering design. The series of engineering measures will more effectively protect permafrost stability.

Regional Differentiation Regularity and Influencing Factors of Population Change in the Qinghai-Tibet Plateau, China

The Qinghai-Tibet Plateau(QTP) is the most unique region of human-land relations, and its main factor is population. By building a population and space dataset of the QTP at the township level from 1982 to 2017, this paper presents the pattern evolvement and regional distribution characteristics of township-level population in the QTP in detail for the first time. By using Geodetector method to analyze the influencing factors of township-level population change in the QTP, this paper provides scientific foundations for studying the Third Pole, ecological environment protection of the QTP, and human-land relations. The conclusions are as follows:1) The population spatial distribution is not balanced at the township level, presents the regional differentiation characteristics of ‘dense in southeast and sparse in northwest’ along the ‘Qilian-Jilong Line’, and demonstrates the phenomenon of population center of gravity moving to the hinterland of the plateau at an accelerated speed;2) The township-level population develops in a decentralized trend in general, and the cold-and hot-spot distribution of population has prominent spatial distribution characteristics. The population hot spots are concentrated in the surrounding areas of Xining, Golmud, Hotan and Lijiang;3) The population of the QTP is increasing, and the inter-annual change of township population has a relatively stable regional regularity;4) The level of per capita income is the leading factor in the change of township population, and its effect intensity is increasing continuously. The relative effect intensity of urbanization level and location conditions on population change has decreased significantly after 2000. The adaptability of living environment,such as topography and climate, has little influence on population change.

Early Permian–Late Triassic Magmatism in the Tuotuohe Region of the Qinghai–Tibet Plateau: Constraints on the Tectonic evolution of the Western Segment of the Jinshajiang Suture

In this paper we present new zircon U-Pb ages,whole-rock major and trace element analyses,and zircon Hf isotopic data for magmatic rocks in the Tuotuohe region of the western segment of the Jinshajiang suture.Our aim is to constrain the Early Permian-Late Triassic tectonic evolution of the region.Zircons from the magmatic rocks of the Tuotuohe region are euhedralsubhedral in shape and display fine-scale oscillatory zoning as well as high Th/U ratios （0.4-4.6）,indicating a magmatic origin.The zircon U-Pb ages obtained using LA-ICP-MS are 281 ± 1 Ma,258 ± 1 Ma,244 ± 1 Ma,and 216 ± 1 Ma,which indicate magmatism in the Early Permian-Late Triassic.A diorite from Bashihubei （BSHN） has SiO2 =57.18-59.97 wt％,Al2O3=15.70-16.53 wt％,and total alkalis （Na2O ＋ K2O） =4.46-6.34 wt％,typical of calc-alkaline and metaluminous series.A gabbro from Bashibadaoban （BSBDB） belongs to the alkaline series,and is poor in SiO2 （45.46-54.03 wt％） but rich in Al2O3 （16.19-17.39 wt％） and total alkalis （Na2O ＋ K2O =5.48-6.26 wt％）.The BSHN diorite and the BSBDB gabbro both display an enrichment of LREEs and LILEs and depletion of HFSEs,and they have no obvious Eu anomaly; they have relatively low MgO contents （2.54-4.93 wt％）,Mg# values of 43 to 52,and low Cr and Ni contents （8.07-33.6 ppm and 4.41-14.2 ppm,respectively）,indicating they differentiated from primitive mantle magmas.They have low Nb/U,Ta/ U,and Ce/Pb ratios （1.3-9.6,0.2-0.8,and 0.1-18.1,respectively）,and their initial Hf isotopic ratios range from ＋9.6 to ＋16.9 （BSHN diorite） and ＋6.5 to ＋12.6 （BSBDB gabbro）,suggesting their primary magmas were derived mainly from the partial melting of a mantle wedge that had been metasomatized by subduction fluids.Taking all the new data together,we conclude that the western and eastern segment of the Jinshajiang suture regions underwent identical processes of evolution in the Early Permian-Late Triassic：oceanic crust subduction before the Early Permian,continental collision during the Early-Middle Triassic,and post-collisional extension from the Late Triassic.

Joint Inversion of the 3D P Wave Velocity Structure of the Crust and Upper Mantle under the Southeastern Margin of the Tibetan Plateau Using Regional Earthquake and Teleseismic Data

The special seismic tectonic environment and frequent seismicity in the southeastern margin of the Qinghai-Tibet Plateau show that this area is an ideal location to study the present tectonic movement and background of strong earthquakes in China's Mainland and to predict future strong earthquake risk zones. Studies of the structural environment and physical characteristics of the deep structure in this area are helpful to explore deep dynamic effects and deformation field characteristics, to strengthen our understanding of the roles of anisotropy and tectonic deformation and to study the deep tectonic background of the seismic origin of the block＇s interior. In this paper, the three-dimensional （3D） P-wave velocity structure of the crust and upper mantle under the southeastern margin of the Qinghai-Tibet Plateau is obtained via observational data from 224 permanent seismic stations in the regional digital seismic network of Yunnan and Sichuan Provinces and from 356 mobile China seismic arrays in the southern section of the north-south seismic belt using a joint inversion method of the regional earthquake and teleseismic data. The results indicate that the spatial distribution of the P-wave velocity anomalies in the shallow upper crust is closely related to the surface geological structure, terrain and lithology. Baoxing and Kangding, with their basic volcanic rocks and volcanic clastic rocks, present obvious high-velocity anomalies. The Chengdu Basin shows low-velocity anomalies associated with the Quaternary sediments. The Xichang Mesozoic Basin and the Butuo Basin are characterised by low- velocity anomalies related to very thick sedimentary layers. The upper and middle crust beneath the Chuan-Dian and Songpan-Ganzi Blocks has apparent lateral heterogeneities, including low-velocity zones of different sizes. There is a large range of low-velocity layers in the Songpan-Ganzi Block and the sub-block northwest of Sichuan Province, showing that the middle and lower crust is relatively weak. The Sichuan Basin, which is located in the western margin of the Yangtze platform, shows high-velocity characteristics. The results also reveal that there are continuous low-velocity layer distributions in the middle and lower crust of the Daliangshan Block and that the distribution direction of the low-velocity anomaly is nearly SN, which is consistent with the trend of the Daliangshan fault. The existence of the low-velocity layer in the crust also provides a deep source for the deep dynamic deformation and seismic activity of the Daliangshan Block and its boundary faults. The results of the 3D P-wave velocity structure show that an anomalous distribution of high-density, strong-magnetic and high-wave velocity exists inside the crust in the Panxi region. This is likely related to late Paleozoic mantle plume activity that led to a large number of mafic and ultra-mafic intrusions into the crust. In the crustal doming process, the massive intrusion of mantle-derived material enhanced the mechanical strength of the crustal medium. The P-wave velocity structure also revealed that the upper mantle contains a low-velocity layer at a depth of 80-120 km in the Panxi region. The existence of deep faults in the Panxi region, which provide conditions for transporting mantle thermal material into the crust, is the deep tectonic background for the area＇s strong earthquake activity.

Protective equipment for emergency rescue in alpine-cold region

Alpine-cold regions are characterized as hypoxia,strong wind,heavy rain,cold climate,huge temperature difference between day and night,and vertical climate. All these make it difficult for an emergency rescue when a natural disaster such as earthquake happens. Based on the characteristics of emergency rescue in alpinecold region,several multifunctional protective equipments have been developed by the Quartermaster Equipment Institute of General Logistics Departmen(tGLD)of the Chinese People's Liberation Army(CPLA). These equipments are lightweight,durable and environment adaptable.

自救式加压发热止血带的研制

目的:设计一款适用于高原寒区肢体创伤后大出血的自救式加压发热止血带,以降低高原寒区肢体创伤后大出血伤员的致死率和致残率。方法:止血带整体结构为长条形,由产气发热装置、可充气袖带、减压装置、微型计时器4个部分组成。产气发热装置主要由内缸和外缸组成,二者采用螺钉固定;可充气式袖带包括上肢款和下肢款2种,外侧为固定用布料,内侧设置气囊;减压装置主体为加压阀;微型计时器使用电子计时器,通过一个插入式卡扣与产气发热装置上的卡槽进行固定。结果:采用该止血带可使高原寒区肢体创伤后大出血伤员在1~2 s完成止血自救操作,且能有效防止伤员患肢失温。结论:该止血带具有操作简便、止血保温效果较好的特点,且可视情况调节压力,对于提高高原寒区肢体创伤后大出血伤员的自救能力具有重要意义。

高原露天台阶上部冻层破断规律数值分析

上部冻层是影响高原露天台阶爆破效果的主要因素之一,为明确高原露天台阶上部冻层在爆破荷载作用下的破断规律,利用颗粒流数值方法模拟了天然单冻层和人工复合双冻层分别在单、双排炮孔作用下的破断过程,分析了冻层破断过程的速度、冲击压力和破断后的块度特征。结果表明:冻层在爆破荷载作用下经历了产生裂隙-局部隆起-宏观断裂的破坏过程,对于人工复合冻层,由于上部增加了碎石土层,冻层厚度增大,削弱了冻层整体的隆起趋势,导致破碎块度增大。双排炮孔之间冻层受到的冲击压力率先达到峰值,但靠近自由面的冻层受到的冲击压力峰值更高。单、双冻层在爆破荷载作用下的破断问题可简化为冲击压力作用下的结构断裂问题。双冻层台阶爆破大块率比单冻层大块率高4%~6%,建议在高原露天矿山爆破中,优先通过冻土层厚度确定需要进行特殊处理的区域,并通过调整延期时间达到降低大块率,提高铲转挖运效率的目的。

高山寒旱区高原夏菜新品种引种试验初报

甘肃是我国的高原夏菜主要产地和重要的出口型加工地区,为筛选出适宜在位于高山寒旱区的甘肃高原夏菜主产区天祝县种植的优良蔬菜品种,为当地高原夏菜品种选择提供参考,引种观察了莴笋、贡菜、甘蓝、结球生菜、西兰花等5类高原夏菜30个品种的生育期、农艺性状及经济性状。结果表明,莴笋品种以富盛红笋王表现最佳,其生育期短,抽薹率最低,为7.00%;折合产量最高,为71250.0 kg/hm^(2),较对照品种紫龙显著增产18.66%。贡菜品种以云南贡菜表现最佳,其株高中等,株幅最小,肉质茎短且粗,不抽薹,商品性好,产量最高,为123211.5 kg/hm^(2),较对照品种北方贡菜显著增产7.80%。甘蓝品种以中甘21号表现最佳,其叶球紧实度中等,商品性好,产量最高,为91815.0 kg/hm^(2),较对照品种精品中甘显著增产6.90%;结球生菜品种以玛丽娜表现最佳,其商品性好,产量最高,为91035.0 kg/hm^(2),较对照品种富盛结球生菜显著增产9.68%;西兰花品种以对照品种耐寒优秀表现最佳,其花球紧实,球形指数较高,单株球重最重,折合产量较高,为67650.0 kg/hm^(2)。因此认为莴笋品种富盛红笋王、贡菜品种云南贡菜、甘蓝品种中甘21号、结球生菜品种玛丽娜、西兰花品种耐寒优秀等适应性较强、产量高、商品性好,是适宜在位于高山寒旱区的甘肃高原夏菜主产区天祝县及甘肃高原夏菜其余主产区进行推广的优良高原夏菜品种。

高原高寒砂金矿区生态修复治理模式与关键技术

我国西藏地区历史遗留废弃矿山数量众多,因其地处高原高寒,生态修复难度大、周期长。该文以西藏某矿区为例,针对高原高寒矿区面临的地质安全隐患、草地退化、土地损坏、水系破坏、水土流失等矿山生态问题,基于辅助再生、后期管护和监测的综合技术措施等关键技术,提出水系重建与分区治理的模式,可为高原高寒地区废弃矿山生态环境修复提供一定的参考价值。

Quantifying urbanization levels on the Tibetan Plateau with high-resolution nighttime light data

The Tibetan Plateau(TP)is undergoing rapid urbanization.To improve urban sustainability and construct eco-logical security barriers,it is essential to quantify the spatial patterns of urbanization level on the TP,but the existing studies on the topic have been limited by the lack of socioeconomic data.This study aims to quantify the urbanization level on the TP in 2018 with Luojia1-01(LJ1-01)high-resolution nighttime light(NTL)data.Specifically,the compounded night light index is used to quantify spatial patterns of urbanization level at mul-tiple scales.The results showed that the TP had a low overall urbanization level with a large internal difference.The urbanization level in the northeast,southeast and south of the TP was relatively high,forming three hotspots centered in Xining City,Lhasa City and Shangri-La City,while the urbanization level in the central and western regions was relatively low.The analysis of influencing factors,based on the random forest model,showed that transportation and topography were the main factors affecting the TP’s spatial patterns of urbanization level.The comparison analysis with socioeconomic statistics and traditional NTL data showed that LJ1-01 NTL data can be used to more effectively quantify the urbanization level since it is more advantageous for reflecting the spatial extent of urban land and describing the spatial structure of socioeconomic activities within urban areas.These advantages are attributed to the high spatial resolution of the data,appropriate imaging time and unaf-fected by saturation phenomena.Thus,the proposed LJ1-01 NTL-based urbanization level measurement method has the potential for wide applications around the world,especially in less-developed regions lacking statistical data.Using this method,we refined the measurement of the TP’s urbanization level in 2018 for multiple scales including the region,basin,prefecture and county levels,which provides basic information for the further urban sustainability research on the TP.

Study on the Landcover Changes Based on GIS and RS Technologies: A Case Study of the Sanjiangyuan National Nature Reserve in the Hinterland Tibet Plateau, China

With global warming and increased human activity, more and more ground surface areas have been affected, which leads to the creation of many problems. To understand the ecological environment changes in a typical alpine region, information on landcovers changes in the study area from 2000 to 2020 was obtained by combining remote sensing, geographic information system, and traditional statistical analysis for the Sanjiangyuan National Nature Reserve on the Qinghai-Tibet Plateau, China. The results show that the changes of surface cover in Sanjiangyuan National Nature Reserve are relatively concentrated, mainly distributed in the sections of south, northwest, central, and northeast, with the area of the changed regions and the unchanged regions being 31,127.45 km2 and 271,941.37 km2, respectively. The transformation between the various types of ground landcover is mainly characterized by a shift from other types to grassland and from grassland to bare land. And the regions of change are mostly concentrated between 3500 - 4600 m in elevation.

基于沥青路面温度特征的沥青混合料冻融损伤分析

针对青藏高寒区沥青混合料冻融损伤对沥青路面服役性能的严重危害,通过沥青路面温度特征对真实工况下沥青路面冻融损伤劣化进行研究。采用统计学方法对影响沥青路面温度特征的气象参数进行分析,利用有限元方法建立沥青路面温度场模型,分析沥青路面温度特征;借助室内冻融循环试验揭示沥青混合料冻融循环损伤劣化过程,基于沥青路面温度特征,结合冻融强度划分准则得到沥青面层遭受的冻融作用次数;同时充分考虑冻融过程中温度与水分的影响,提出饱水率折减系数与冻融折减系数修正室内冻融影响,利用正弦函数拟合冻融作用下沥青混合料模量随时间历程变化趋势。结果表明:2018年那曲地区沥青面层上面层共发生211次冻融;冻融作用对沥青混合料的力学性能影响显著,6年内沥青混合料抗压回弹模量衰减了28%,其中第1年衰减了17%,随后衰减幅度逐年减小。研究可为青藏高寒区沥青路面性能保持提升提供参考。

高海拔特长隧道长距离独头掘进施工通风技术

施工通风是保证隧道内空气质量、人员健康、机械工作效率的重要工序,特别是高海拔特长隧道的施工通风更是一大技术难题。以某高海拔特长铁路隧道为工程依托,明确通风控制标准,通过理论计算方式得到需风量及风压,基于需风量要求计算不同漏风率、不同风机工效情况下的合理通风距离,并结合风机选型结果和隧道施工组织制定适用于高海拔特长隧道长距离独头掘进的施工通风方案。研究成果对后期高海拔特长隧道施工通风方案制定具有一定借鉴意义。

高海拔地区桩基混凝土硬化时期热力响应特性现场试验

高原地区高海拔、大温差和低气压的特殊环境,会导致早龄期混凝土水化热问题区别于其他地区。目前,针对减小高原地区早龄期混凝土水化热温差、加快高原地区混凝土水化热消散机理尚不清楚。通过在桩基混凝土结构中埋设换热管,建立循环换热系统,开展高原地区桥梁桩基早龄期混凝土水化热消散现场试验。实测桩基混凝土的水化热温度和热致应变变化,获得埋管式循环系统对桩身水化热温度场和应力场的规律,并初步探讨与其他地区的差异性。研究结果表明:本文试验条件下,通过水泵、循环水管、水箱等设备组成的埋管式循环系统可以用于加快高原地区早龄期混凝土的水化热消散以及减小高原地区早龄期混凝土温差;与桩-土之间的热传导相比,埋管式循环系统能够加速混凝土的水化热消散进程,通过循环管中的换热介质将水化作用的热量传递到地面外部环境中,可降低水化热的峰值温度约2~4℃,相应龄期提前约37~58 h;埋管式循环系统能够明显降低桩底部的应变变化范围,能够减小桩基早龄期混凝土的桩身应力,桩身最大约束应力(0.7倍桩长处)降低约23.6%;埋管式循环系统还能够降低混凝土水化进程中的第二零应力温度,提高早龄期混凝土的温降裂缝能力。研究结果对高原地区桩基早龄期混凝土的水化热进程控制和抗裂性能分析有一定的参考价值。

基于PSO-BP神经网络的高原寒地维修器材换算系数研究

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