塔克拉玛干沙漠荒漠过渡带空气动力学粗糙度分析

根据塔克拉玛干沙漠北缘荒漠过渡带哈德、肖塘2个试验点的风、温梯度观测数据,利用风速比法计算了中性大气层结、无风沙运动条件的空气动力学粗糙度[WTBX](z0),并分析探讨z0[WTBZ]与下垫面状况、大气稳定度及风速的相互关系。结果表明：哈德、肖塘中性条件下z₀的取值范围分别为 1.81×10^-11～1.20×10^-3m,1.00×10^-11～1.65×10^-3m,平均值为2.70×10^-5m 和6.05×10^-5m,与平坦沙面的值较为接近;z₀随下垫面性质变化明显;空气动力学粗糙度总体上随着理查逊数(R_i)增大而变大,但又呈现出一定的离散程度;空气动力学粗糙度与2 m高度风速呈显著的负指数关系;大气稳定度对空气动力学粗糙度的影响作用有待于进一步确定。      

塔克拉玛干沙漠灌草丘的发育特征及环境意义

对灌草丘的发育条件及沉积特征的研究表明，塔克拉玛干沙漠地区的灌草丘形成在绿洲受风沙入浸，由水沉积转为风沙沉积过程中，气候变化对灌草丘的发育未产生重要影响，但流水在其中起了决定性作用。灌草丘开始发育之后，可以依某一速率持续增长，也可能被埋没（主要是风沙流），或被侵蚀夷平，但部分灌草丘在沙漠的发展过程中保存达数千年之久。有限的测年数据及地表景观显示灌草丘发育的阶段性，实际上也是沙漠发展的阶段性。     

Sand flux estimation during a sand-dust storm at Tazhong area of Taklimakan Desert, China

In this paper, the sand transport during a sand-dust storm in the Tazhong area of the central Taklimakan Desert from 11:29 to 23:56 on July 19, 2008 was observed and measured in real time. The sand flux at Tazhong was estimated using sand transport empirical formulas. The critical friction velocity at Tazhong was 0.24 m/s and the functional relation between the wind speed and sediment discharge at the height of 2 m was established. It was also found that the calculated values by Lettau's sediment discharge formula were close to those of the instrument measurements. The horizontal sand flux and the vertical sand flux during this sand-dust storm at Tazhong were respectively 258.67×10-4 kg/(m·s) and 40.07×10-7 kg/(m2·s).     

Observation of saltation activity at Tazhong area in Taklimakan Desert,China

A two-year field observation of saltation activity was carried out at Tazhong area,the hinterland area of the Taklimakan Desert with highly frequent dust storms.From 1 September 2008 to 31 August 2010,a piezoelectric saltation sensor(Sensit) was used to continuously collect the data on saltation activity at a level sand surface.Analysis on the data suggests that saltation activity can occur at any time of the year when conditions are favorable;however,the necessary conditions are rarely satisfied in most time.In the daytime of spring or summer,saltation activity can persist even over a continuous one-hour-or-so period.It is found that,from 1 September 2008 to 31 August 2010,saltation activity accounts for more than 3% of the total yearly time,and it tends to peak in spring and summer months with strong winds.During winter months when winds are weak,however,it is often at a minimum.It seems that precipitation does not appear to be significant in reducing saltation activity in arid regions like Tazhong.     

塔克拉玛干沙漠腹地植物引种试验

塔克拉玛干沙漠腹地历经10a植物引种栽培试验表明,许多植物能通过引种驯化,在沙漠腹地正常生长、发育和繁殖,甚至能够自然更新或人工辅助更新。沙漠腹地引种植物应具有耐高温、耐干旱、耐盐碱、耐风蚀、耐沙埋和较强繁殖能力的特点。根据不同的地形、地貌和土壤条件选择具有不同生理生态特性的植物类型。宜以灌木、半灌木和多年生草本为主,少量引种乔木。流沙地防风固沙植物选择灌木和半灌木,不宜采用乔木。根据植物演替和更新的特点,植物的配置既要选择先锋种又要有替代种,形成多种植物的混交林,保证防风固沙林的持续和稳定性。同时,防风固沙植物应具有生长迅速、根幅大、寿命长,能够自然更新或人工辅助更新的特点。     

塔克拉玛干沙漠土壤种子库特征初探

通过野外采样和室外萌发的方法,研究了塔克拉玛干沙漠公路沿线6种立地类型的土壤种子库特点.其主要结论:①所有立地类型的土壤种子库密度都很小.立地类型I,Ⅱ,Ⅲ,Ⅳ,V,Ⅵ的土壤种子库密度分别为:(46.20±4.45)粒/m2,(27.50±5.58)粒/m2,(15.00±3.37)粒/m2,(6.52±0.87)/m2,(10.00±2.42)粒/m2和(50.00±5.50)粒/m2.②所有立地类型土壤种子库中所出现的物种数量都很少.③所有立地类型土壤种子库中出现的物种生活型,一年生草本并不占优势.④在塔克拉玛干沙漠空间分布上,沙漠南缘和北缘的土壤种子库密度和物种多样性较大,而中部的密度和物种多样性较小.     

塔克拉玛干沙漠腹地建立农业生态体系的初步研究

塔克拉玛干沙漠腹地生态条件恶劣 ,建立农业生态体系需采取特别的措施。两年试验表明 ,供试 71种作物大部分适应性较差 ,蔬菜产量相对较低 ;能量的产投比低 ,养分的利用率低。因此 ,在塔克拉玛干沙漠腹地建立农业生态体系时 ,应采取科学的田间管理措施 ,充分利用地力     

塔克拉玛干沙漠不同土壤发育条件下土壤性状特征

本文将塔克拉玛干沙漠土壤发条条件分为稳定，不稳定，极不稳定三类，它们对于土生状有着不同的影响。在稳定的土壤发育条件下，土壤剖面有可以鉴别的诊断层，其中一性状特征沿剖面分异明显。在不稳定土壤发育条件下，土壤的诊断层表现不突出，造成它的性状特征沿剖面分异不十分明显。     

塔克拉玛干沙漠腹地滴灌种植肉苁蓉的试验研究

在塔克拉玛干沙漠腹地的人工梭梭林,利用咸水滴灌技术,对种植肉苁蓉（Cistanche deserticola）的开挖方式、播种方式、接种深度以及稳产技术等进行了试验研究。结果表明：① 提高肉苁蓉种子和寄主根系接触的几率是提高人工接种肉苁蓉效果的有效途径。不同种植方式的肉苁蓉出土率为：沟种>打洞>穴种,撒种>种植带（种植纸）。② 采用开沟、撒种方式种植肉苁蓉,随播种量增加,出土肉苁蓉数量呈增加趋势,但存在一个上限值。在沙地滴灌种植肉苁蓉适宜的播种量为300粒/m。③ 接种深度应控制在寄主根系主要分布层以内,并结合作业方式及作业成本来综合确定,在沙地滴灌接种深度不宜超过60 cm。④ 人工接种肉苁蓉具有一次接种,多年采收的效果,但肉苁蓉出土率年际间差异较大。接种后第2 a至第4 a为主要收获期。采用沟种、撒种技术春季接种肉苁蓉,接种后连续3 a平均出土率可以保持在1株/m以上,肉苁蓉鲜重产量达1 800 kg/hm²,经济效益显著。     

Stable oxygen-hydrogen isotopes reveal water use strategies of Tamarix taklamakanensis in the Taklimakan Desert,China

Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities.Consequently,T.taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources(deep soil water and groundwater),reflecting its adaptations to the different habitats in the arid desert environment.These findings improve our understanding on determining the water sources and water use strategies of T.taklamakanensis in the Taklimakan Desert.     

Diurnal dynamics of soil respiration and the influencing factors for three land-cover types in the hinterland of the Taklimakan Desert,China

Knowledge of soil respiration and the influencing factors in desert ecosystems is essential to understanding carbon dynamics and responses of biotic and abiotic processes in soils to climate change. In this study, soil respiration rate(R_s) for three land-cover types(shifting sandy land, sandy land with straw checkerboard barriers, and shelter forest land) in the hinterland of the Taklimakan Desert was measured in May 2015 using an automated soil CO_2 flux system. The effects of soil temperature(T_s) and soil water content(W_s) on R_s were also analyzed. The results showed that R_s values in shifting sandy land, sandy land with straw checkerboard barriers, and shelter forest land were all low and exhibited obvious diurnal fluctuations. The establishment of straw checkerboard barriers in sandy land had no significant effect on R_s, while the establishment of shelterbelts significantly increased R_s. Shifting sandy land and sandy land with straw checkerboard barriers were carbon sinks at night and early morning and were carbon sources in the daytime, while shelter forest land always acted as a carbon source during the whole day. The synergistic effect of T_s and W_s could better explain the diurnal dynamics in R_s than single factor. In shifting sandy land and sandy land with straw checkerboard barriers, W_s was identified as a limiting factor influencing the diurnal dynamics of R_s. Furthermore, a relatively strong hysteresis loop existed between R_s and T_s. In contrast, in shelter forest land, R_s was significantly influenced by T_s, and a relatively weaker hysteresis loop existed between R_s and W_s.     

Impact factors of soil wind erosion in the center of Taklimakan Desert

The development and progress of soil wind erosion are influenced by the factors of climate,terrain,soil and vegetation,etc. This paper,taking Tazhong region,a town in the centre of the Taklimakan Desert,as an example and using comparative and quantitative methods,discussed the effects of climate,surface roughness(including vegetation cover) and surface soil properties on soil wind erosion. The results showed that the climate factor index C of annual wind erosion is 28.3,while the maximum of C is 13.9 in summer and it is only 0.7 in winter. The value of C has a very good exponential relationship with the wind speed. In Tazhong region,the surface roughness height is relatively small with a mean of 6.32 × 10-5 m,which is in favor of soil wind erosion. The wind erosion is further enhanced by its sandy soil types,soil particle size,lacking of vegetation and low soil moisture content. The present situation of soil wind erosion is the result of concurrent effects of climate,vegetation and surface soil properties.     

Characteristics of air pollution events over Hotan Prefecture at the southwestern edge of Taklimakan Desert,China

Hotan Prefecture is located at the southwestern edge of Taklimakan Desert, the world's largest shifting sand desert, of China. The desert is one of the main sources for frequent sand-dust weather events which strongly affect the air quality of Hotan Prefecture. Although this region is characterized by the highest annual mean PM_(10) concentration values that are routinely recorded by environmental monitoring stations across China, both this phenomenon and its underlying causes have not been adequately addressed in previous researches. Reliable pollutant PM_(10) data are currently retrieved using a tapered element oscillating microbalance(TEOM) 1400 a, a direct real-time monitor, while additional concentration values including for PM_(2.5), sulfur dioxide(SO_2), nitrogen dioxide(NO_2), carbon monoxide(CO) and ozone(O_3) have been collected in recent years by the Hotan Environmental Monitoring Station. Based on these data, this paper presents a comparison of the influences of different kinds of sand-dust weather events on PM10(or PM_(2.5)) as well as the concentrations of other gaseous pollutants in Hotan Prefecture. It is revealed that the highest monthly average PM10 concentrations are observed in the spring because of the frequent occurrence of three distinct kinds of sand-dust weather events at this time, including dust storms, blowing dust and floating dust. The floating dust makes the most significant contribution to PM_(10)(or PM_(2.5)) concentration in this region, a result that differs from eastern Chinese cities where the heaviest PM_(10) pollution occurs usually in winter and air pollution results from the excess emission of local anthropogenic pollutants. It is also shown that PM_(10) concentration varies within typical dust storms. PM_(10) concentrations vary among 20 dust storm events within Hotan Prefecture, and the hourly mean concentrations tend to sharply increase initially then slowly decreasing over time. Data collected from cities in eastern China show the opposite with the hourly mean PM_(10)(or PM_(2.5)) concentration tending to slowly increase then sharply decrease during heavy air pollution due to the excess emission of local anthropogenic pollutants. It is also found that the concentration of gaseous pollutants during sand-dust weather events tends to be lower than those cases under clear sky conditions. This indicates that these dust events effectively remove and rapidly diffuse gaseous pollutants. The analysis also shows that the concentration of SO_2 decreases gradually at the onset of all three kinds of sand-dust weather events because of rapidly increasing wind velocity and the development of favorable atmospheric conditions for diffusion. In contrast, changes in O_3 and NO_2 concentrations conformed to the opposite pattern during all three kinds of sand-dust weather events within this region, implying the inter transformation of these gas species during these events.     

塔克拉玛干沙漠腹地横向沙丘表面紧实度分异特征

沙丘表面紧实度是量化沙丘紧实程度的一个综合性指标,紧实度指标与沙丘的风蚀与堆积成因关系密切,对风成沙丘的形成具有重要意义。基于对塔克拉玛干沙漠腹地垄间平地的4种简单横向沙丘〔饼状沙丘(PD)、盾状沙丘(SD)、雏形新月形沙丘(PCD)、新月形沙丘(TCD)〕表面紧实度、容重、孔隙度和平均粒径的测量,通过最小显著差异法(LSD)分析和多重比较,对简单横向沙丘表面紧实度的空间分异特征及其形成机制进行了分析。研究结果表明:1 4种沙丘的沙面紧实度均具有较大的空间差异性,并且此差异性具有方向性,纵向差异性最大,横向差异较小;2 4种沙丘表面紧实度平均值表现为:盾状沙丘饼状沙丘雏形新月形沙丘新月形沙丘,而紧实度空间差异性却表现为:饼状沙丘盾状沙丘雏形新月形沙丘新月形沙丘,最大值和最小值点出现的位置也不同;3沙丘表面紧实度和容重、孔隙度具有很好的相关性,在质地相似的沙物质中,容重和孔隙度均可以作为衡量紧实度的指标。     

塔克拉玛干沙漠腹地塔克拉玛干柽柳根系构筑型研究

在塔克拉玛干沙漠腹地,采用根系跟踪法挖取成年塔克拉玛干柽柳(Tamarix taklamakanensis)根系,对其构筑型进行了研究.结果显示:①在塔克拉玛干沙漠腹地,塔克拉玛干柽柳水平根系占绝对优势,其根幅与冠幅之比近36[JP20]∶1,根系最大水平半径为27 m,主根的垂直分布深度在100 cm左右,侧根主要集中在50～150 cm的土层,植株主要通过下扎到地下水位的细根(直径小于2～3 mm)吸收水分.②根系拓扑结构复杂,拓扑指数TI=0.58,接近于叉状分支结构.③根系具有很好的分形特征,整体分形维数为1.590 3(R2=0.998 8),且不同方向根系分形维数与根系的长度、分根数之间存在很好的相关关系.研究发现,塔克拉玛干柽柳根系发达,主要通过增加次级根系的分支来扩大其分布范围,从而保证植株在环境中获取更多的水分和营养物质.通过根系构筑型的研究表明,塔克拉玛干柽柳具有很好的根系适应性,从而创造了良好的水分营养环境,以保证其正常生存.     

塔中紫外辐射与气象要素的关系

分析2007年塔克拉玛干沙漠腹地紫外辐射特征和影响因子与气象要素的相关性,并依据有关要素拟合出紫外辐射的估算方程。结果表明：紫外辐射年总量达到305.64 MJ/（m2.a）,7月最大,12月最小,全年瞬时强度峰值在6月,为67.11 W/m2。紫外辐射的变化与总辐射变化呈显著正相关,且紫外辐射在总辐射中所占比例夏季大...     

塔克拉玛干沙漠腹地10种灌木光合器官的滞尘能力评价

通过全株光合器官取样,利用质量差减法,对塔中植物园10种灌木的滞尘能力进行多指标比较。结果表明：① 植物光合器官滞尘量与所处环境条件有关,在沙漠地区同种植物光合器官滞尘量大于沙漠以外区域。② 梭梭和沙拐枣的光合器官退化为同化枝,形态类似针叶树种的针叶,但尚有极度退化的叶片,其滞尘量大于其他区域针叶树种;与沙拐枣相比,梭梭同化枝节间距较短,叶片数量相对较多,因此梭梭的滞尘能力大于沙拐枣。③ 柽柳属植物虽然叶片也极度退化,但具有数量众多、分布密集、被覆绒毛、分泌盐分等特性,而且树冠光合器官密度大,具有很强的滞尘能力,光合器官滞尘量大于梭梭和沙拐枣,也大于阔叶灌木和阔叶乔木;由于光合器官表面滞尘特性、叶片数量以及树冠光合器官密度的差异,柽柳属植物光合器官滞尘能力也存在种间差异。④ 全植株光合器官滞尘量、单位重量光合器官滞尘量、单位表面积光合器官滞尘量都只能从一个侧面反映植物光合器官的滞尘能力,而单位树冠体积的光合器官滞尘量则可较全面地反映植物光合器官的滞尘能力。以单位体积树冠空间光合器官滞尘量为评价指标,10种灌木光合器官滞尘能力的排序为：甘蒙柽柳>长穗柽柳>华北柽柳>紫杆柽柳>刚毛柽柳>多花柽柳>多枝柽柳>沙生柽柳>梭梭>头状沙拐枣。     

Damage by wind-blown sand and its control measures along the Taklimakan Desert Highway in China

Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the'Dead Sea'due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.     

塔克拉玛干沙漠植被的生态学性质和持续发展

塔克拉玛干沙漠生态环境十分亚酷，植物多样性的组成有限。大多数植物的生存与一定的浅层地下水相联系，是一些中生、盐生和耐盐的种类，典型的沙生和旱生植物不多，由它们所形成的大多数植物群落也是中生性的。其分布格局明显受沙漠中水分状况的支配，表现为隐域分布性质。其中，荒漠河岸林的兴衰和更新，与荒漠河流水文特征适应，使其种群得以持续繁衍，保证了这一古老的第三纪落叶阔叶林，在沙漠中各大河流沿岸整体上的相对稳定性     

塔克拉玛干沙漠腹地高大复杂纵向沙垄区简单横向沙丘形态特征的空间变异

为了探讨小尺度风沙地貌形态的空间变异过程,对塔克拉玛干沙漠腹地高大复杂纵向沙垄横断面上简单横向沙丘形态特征进行了研究。沙丘形态野外测量采用RTK(real-tim e k inem atic)技术,并通过南方测绘软件(South Survey)量算形态特征参数。结果表明:简单横向沙丘形态特征参数及其相互关系具有空间变异性。在8个地貌部位之间,沙丘形态特征参数(不包括迎风坡度)存在显著性差异,主要体现在:垄顶、沙垄背风坡、其他地貌部位(包括垄间地和沙垄迎风坡)三者之间的差异。地貌部位、输沙风强度以及沙丘活动强度是驱动沙丘形态空间变异的因素。沙丘高度与翼展度余弦有负对数关系,发育指数与高度、迎风坡度成负线性相关,这些相关性的显著程度在垄顶、背风坡较高,在垄间和迎风坡较低。