新疆柽柳属植物(Tamarix L.)的分布与群落相似性聚类分析

调查研究了新疆境内柽柳属植物的分布与群落类型。在前人工作基础上绘制了新疆柽柳属植物分布图。研究结果表明，地表水是柽柳群落繁衍的关键，地下水是柽柳群落生存的命脉。水是决定和影响柽柳属植物现代地理分布的关键环境因子。依据柽柳群落所处地形地貌、土壤类型和群落景观等环境特征将柽柳群落划分成9种不同的生态类型。依据群落间物种组成的相似性系数对群落进行了聚类分析，揭示了各类落间的内在关联性和演替规律。     

艾比湖地区植被分布及物种多样性研究

应用重要值计算多样性指数、均匀度指数、优势度指数,对艾比湖流域植被分布及物种多样性进行分析。结果表明：① 研究区域内可划分出10个群落,其中多枝柽柳群落(Form.Tamarix ramosissima)分布最为广泛。② 湖岸植被表现出明显的带状分布特点,并且群落物种多样性随地势发生变化,地势高的地方,物种多样性较高,均匀度较好。③ 在南北断面内,影响植物生长的主要因素为土壤含盐量。随着土壤盐分的增加,物种种类趋向单一,群落结构趋向简单。相反物种多样性随着土壤盐分的减少而增大。④ 受风况和土壤含盐量的影响,南北断面植被组成差异较大,且在近湖岸范围内,南断面植物群落物种多样性和植物生长状态明显优于北断面。     

克拉玛依植物群落物种多样性研究

根据30个样地102个样方的调查资料,采用Simpson多样性指数、Shannon-Wiener多样性指数、Gleason丰富度指数[17]、Simpson优势度指数与Pielou均匀度指数[16]对克拉玛依植物群落进行研究。研究结果表明:克拉玛依植物群落结构简单、物种稀少,群落物种多样性水平较低,群落多样性指数的顺序为:胡杨群落﹥柽柳群落﹥梭梭群落﹥琵琶柴群落﹥芦苇群落﹥假木贼群落﹥猪毛菜群落﹥盐节木群落﹥碱蓬+麻黄群落﹥盐穗木群落。随着水分与土壤盐碱度的变化,群落物种多样性出现相应的变化趋势:乔木群落﹥灌木群落﹥草本群落。     

风沙侵袭影响下绿洲边缘植物群落点格局分析

以塔克拉玛干沙漠南缘策勒绿洲为研究区,运用Ripley’s K(t)函数点格局分析,研究风沙侵袭影响下植物群落结构和点分布格局的变化。风沙侵袭对植物组成种类无影响,均由骆驼刺、柽柳和花花柴组成,但自内侧向外围随着风沙侵袭强度加大,植株密度和盖度会明显降低,组成比例上从以骆驼刺为主向各种群均匀发展,并且骆驼刺的树冠面积随之显著增加,柽柳和花花柴的树冠面积显著减小。种群分布格局具有明显的尺度依赖性,3个种群在30 m的空间尺度上均以聚集分布为主,随风沙掩埋强度增加,3个种群分布类型从聚集变为随机,且聚集分布的尺度范围及聚集峰值所在尺度逐渐减小。研究区内各种群间以负关联为主,随风沙侵袭强度加大,各种群间的负关联程度及尺度范围均呈减弱趋势,最终变为不关联或部分尺度上较弱负关联。风沙掩埋的直接干扰和植物适应性及种间关联关系是种群空间格局变化的主要原因,强烈的风沙掩埋抑制了植物的生长和繁殖,促使群落退化,所以绿洲边缘的流沙深入区是过渡带建设及保护的重点区域。     

乌拉特荒漠草原群落物种多样性和生物量关系对放牧强度的响应

以内蒙古乌拉特荒漠草原灌丛和草本植物群落为对象,研究这2种植物群落的物种组成、物种多样性及其与地上生物量关系对不同放牧处理(对照、中牧、重牧)的响应。结果表明:①随着放牧强度的增加,灌丛群落中红砂(Reaumuria songarica)和碱韭(Allium polyrhizum)的优势度增大,沙生针茅(Stipa glareosa)的优势度减小;重牧降低草本群落中沙生针茅的优势度,增加了蒙古韭(Allium mongolicum)和碱韭的优势度。②不同放牧处理显著降低了灌丛和草本群落的盖度、高度以及灌丛群落的密度,消除了灌丛和草本群落之间盖度的差异(P> 0. 05)。中牧降低灌丛群落的Pielou均匀度指数,重牧降低灌丛群落的物种丰富度,灌丛和草本群落的其他多样性指数在放牧处理之间无显著差异(P> 0. 05)。除物种丰富度外,其他多样性指数在灌丛和草本群落之间差异显著(P <0. 05)。③不同放牧处理降低了灌丛和草本群落的地上生物量和凋落物量,导致灌丛和草本群落之间地上生物量的显著差异(P <0. 05)。④地上生物量与Simpson优势度指数负相关,与Shannon-Wienner多样性指数和Pielou均匀度指数正相关;放牧处理下地上生物量与密度、物种丰富度正相关。放牧处理改变了荒漠草原植物群落组成、结构和功能,进而改变了群落结构和功能的重要关系。     

克拉玛依植物群落结构和物种多样性研究

采用多样性指数,丰富度指数和均匀度指数对克拉玛依植物群落物种多样性进行了研究。结果表明:各群落类型的物种多样性指数的顺序为:梭梭+碱蓬>花花柴、胡杨>碱蓬+麻黄>柽柳>琵琶柴>猪毛菜>梭梭>芦苇>盐节木>白刺+柽柳;灌木和乔木群落多样性指数和丰富度指数大于草本群落,而均匀度指数在乔木,灌木和草本群落中则表现出多样化的趋势。     

宁夏平原沟渠边坡植物群落多样性的影响因子分析

沟渠边坡是物种传播的廊道之一,在物种传播与演替进程中起重要的作用。采用主分量分析和PCA排序的方法,对宁夏平原沟渠边坡的优势植物群落与其环境影响因子进行了定量分析。结果表明：宁夏平原沟渠边坡植物群落的主要影响因子是土壤水分和土壤有机质,且土壤盐分与植物群落的优势度和生物多样性之间有Y2=0.516-0.005X1+0.506X2的关系,可以根据此模型对宁夏平原沟渠湿地的土壤盐分和植物种群多样性及生态优势度做出具体的数学解释。同时表明,沟渠边坡水分梯度和土壤养分是决定其植物分布的主要影响因素。沟渠作为干旱半干旱区绿洲的重要水利设施,从获取最大用水效率、减少水分损失角度,可以高效地通过植物群落控水控肥;而从沟渠强化水文生态效益的角度,则可以提高沟渠湿地的水文循环效率。     

Response of ants to grazing disturbance at the central Monte Desert of Argentina: community descriptors and functional group scheme

Livestock ranching is one of the main productive activities in arid regions of the world.Grazing produces changes in animal as well as plant communities(e.g.richness,abundance and species dominance relationships).Ants are good biological indicators due to the environmental fidelity of some of their community parameters.We described the functional structure of the ant community in the central Monte of Mendoza,Argentina,and examined the effect of grazing using richness,diversity and the functional group scheme.We used pitfall traps to sample ants at a reserve with 30-year cattle exclusion and at an adjacent ranch.Eleven of the 27 recorded species showed significant differences in their abundance and two species were absent at the ranch.While richness and diversity did not reflect these differences,functional groups did.Hot Climate Specialists were more abundant at the ranch while Cryptic Species and Generalized Myrmicinae increased at the reserve.This study supports the utility of the functional group scheme to study the effects of grazing disturbance in ant communities of arid regions.     

Influence of edaphic factors on plant distribution and diversity in the arid area of Xinjiang,Northwest China

The influence of edaphic factors on plant distribution is essential to community ecology and important for vegetation restoration and management in arid ecosystems. In this study, desert plant distribution and diversity as well as soil water, salinity, and nutrients were measured in the Ebinur Lake Wetland Nature Reserve (ELWNR) in arid Northwest China. We determined relationships between plant distribution and soil factors along a transect with increasing distance from the river and created optimal models using soil factors to explain variations in plant diversity. In general, soil factors decreased with increasing distance from the river. Soil volumetric water content (SVWC), electrical conductivity (EC), pH, nitrogen (N), phosphorus (P), and sulfur (S) were closely related to plant distribution. According to canonical correspondence analysis, plants along the transect were divided into three groups: saline–alkaline tolerant, drought tolerant, and high P-demanding. SVWC, pH, soil organic carbon (C), N, P, and S account for 93.8% of the variations in plant diversity in the ELWNR. Compared with other soil factors, S explained the largest percentage of variations in diversity when single soil variables were considered in generalized additive models (R²?=?38.9%). Our results suggest increases in soil pH, P, N, and S would improve plant diversity significantly. We found differences among species groups in preference for habitat, and N and S content had a significant positive effect of on plant diversity, providing a scientific reference for plant restoration and saline soil remediation in desert ecosystems.     

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.     

Succession of soil bacterial and fungal communities of Caragana korshinskii plantation in a typical agro-pastoral ecotone in northern China over a 50-a period

Bacterial and fungal communities play critical roles in reestablishing vegetation structure, function and biodiversity in ecosystem restoration in arid and semi-arid areas. However, the long-term successional changes in bacterial and fungal communities that occur with artificial vegetation development are not fully understood. In this study, we investigated the successional changes in bacterial and fungal communities in Caragana korshinskii Kom. plantation over a period of 50 a (6, 12, 18, 40 and 50 a) and their relationships with key soil environmental factors in a typical agro-pastoral ecotone, northern China. The results showed that bacterial and fungal diversities (α- and β-diversity) were significantly affected by plantation age; moreover, the change in fungal community was more evident than that in bacterial community. Soil samples from 12 a plantation had the highest (P<0.05) bacterial and fungal α-diversity (i.e., abundance-based coverage estimator (ACE) and Chao1 index) at 0-10 cm depth compared with other samples. However, soil samples from plantation at the late recovery stage (40-50 a) had the highest α-diversity at 10-20 cm depth. Soil bacterial community was not significantly affected by plantation age at the genus level; but, soil fungal community was significantly affected at the genus level. Overall, Mortierella and Chaetomium were the dominant genera at natural recovery stage (0 a); Inocybe was the dominant genus at the early recovery stage (6-12 a); Inocybe and Mortierella were the dominant genera at the mid-recovery stage (12-40 a); And Mortierella, Cladosporium and Humicola were the dominant genera at the late recovery stage (40-50 a). Redundancy analysis (RDA) showed that β-glucosidase activity, total nitrogen and soil organic carbon were closely associated with bacterial community composition, while alkaline phosphatase, urease activity and total nitrogen were associated with fungal community composition, indicating that changes in enzyme activity and soil nutrients were the most important determinants of dominant genera. Furthermore, pathogenic microorganisms (Cladosporium and Humicola) were dominant in soils from 40-50 a plantation, which may affect plant growth, resulting in the decline of C. korshinskii plantation. Overall, the findings of this study improve the understanding of ecological patterns of bacterial and fungal communities in artificial vegetation and provide an important scientific basis for comprehensive ecological restoration management in arid and semi-arid areas.     

古尔班通古特沙漠不同类型生物结皮对草本植物多样性影响

选择古尔班通古特沙漠的北部(一号点)、中部(二号点)、南部(三号点)3个不同样点的裸沙和藻结皮、地衣结皮与苔藓结皮3种生物结皮类型,对比研究了草本植物多样性的差异性及其主要环境影响因素.结果表明:(1)不同生物结皮类型的土壤理化性质有明显差异,土壤有机质、全氮、全磷、全钾含量以及黏粒、粉粒和细沙的含量随生物结皮演替显著...     

额尔齐斯河流域灌木昆虫群落特征及对环境因子和植物群落特征的响应

为探究大空间尺度下灌木昆虫群落的分布规律,于2023年6—9月对额尔齐斯河流域阿勒泰地区7个县（市）44个样地内灌木昆虫群落特征进行调查,确定其发生状态,采用回归分析和典范对应分析（canonical correspondence analysis,CCA）方法探讨灌木昆虫物种丰富度与植物群落特征和环境因子的关系。结果显示,44个样地内共采集昆虫1 245头,经鉴定为9目44科117种,其中鳞翅目和鞘翅目为主优势类群,分别为440头和289头,脉翅目和半翅目为次优势类群,分别为214头和157头,其余目为从属类群。额尔齐斯河流域灌木昆虫物种丰富度与海拔和温度均呈显著的三项式拟合关系,与相对多度呈显著的二项式拟合关系,与Pielou均匀度指数呈显著的线性拟合关系,与Simpson多样性指数呈显著的二项式拟合关系,与Margalef丰富度指数呈显著的二项式拟合关系。CCA分析结果显示,温度、经度和海拔是影响灌木昆虫分布的主要环境因子,灌木植物多样性和均匀程度是影响灌木昆虫分布的主要植物群落特征。表明大空间尺度下灌木昆虫分布存在明显驱动力,在全球环境变化下应更加重视对植被结构的调整和对有害灌木昆虫的监测预防。     

荒漠植物红砂(Reaumuria soongorica)的保育效应及其对群落物种多样性的影响

红砂(Reaumuria soongorica)是我国北方温带荒漠的主要先锋植物,也是一种潜力巨大的水土保持和荒山绿化物种,但是该乡土物种是否具有保育植物的特征,目前尚未有这方面的研究。文中通过研究生长于半干旱区的荒漠植物红砂群落不同分布格局和群落特征,分析红砂盖度变化对群落多样性的影响,探究保育效应的发生条件及其对群落物种多样性影响机理。研究结果表明:群落的植物物种多样性随着红砂植被盖度和地上生物量增大而逐渐增大,然而,当红砂总盖度超过48.73%(地上生物量为35.62g/m2)时,虽植被盖度和地上生物量继续增大,目标物种碱蓬(Suaeda glauca),蓍状亚菊(Ajania achilleoides)多度明显增加,但植物物种多样性并没有显著的变化。这些说明在干旱区,当红砂的盖度增加到一定程度之后,才能通过冠层遮阴产生保育效应。因此,在植被稀疏、物种多样性较低的干旱地区,可以充分利用红砂物种的保育效应,促进和加快植被自然恢复进程,调控物种多样性和群落结构。     

Plant community dynamics in arid lands: the role of desert ants

Ants (Formicidae, Hymenoptera) play an important role in seed bank, seedling establishment andplant composition of arid ecosystems. Thus, knowing plant-ant interaction provides useful information formanagers to design restoration and conservation plans. In this study, the roles of desert harvester ants (Messorintermedius and Messor melancholicus) and scavenger ants (Cataglyphis nodus and Lepisiota semenovi) on plantcommunities were investigated in arid ecosystems of southeastern Iran. Two vegetation types weredistinguished in the study area and the nest density of ant species was determined. Furthermore, plantcomposition and soil seed bank were estimated at different distances from the ant nests. Results showed thatthe density of M. intermedius and M. melancholicus nests was higher in dwarf shrub-shrub vegetation type and thedensity of C. nodus and L. semenovi nests was higher in dwarf shrub vegetation type. The harvester and scavengerants had enhanced the seed bank to 55% and 70%, respectively. Therefore, the role of scavenger ants on theplant communities' seed bank was greater than that of harvester ants. Although the scavenger ants were moreinfluential on the annuals and the invasive plant species, the radius impact of the harvester ants on theperennials was greater, i.e., a positive interaction existed between the perennial plants and the harvester ants. C.nodus and L. semenovi played an important role in enhancing the ecosystem's potential for restoration throughestablishment of pioneer species in early stage of succession. The activity of M. intermedius is crucial for thedevelopment and maintenance of climax plant communities in arid ecosystems through assisting the plantspecies' establishment in late stage of succession. It is essential to preserve the diversity of these key ant speciesfor the maintenance and sustainability of shrubs in arid ecosystems.     

奇台荒漠草地自然保护区典型植物群落物种多样性分析

以重要值为测度指标,选择反映群落物种多样性、丰富度、优势度和均匀度的7个测定指数对奇台荒漠草地自然保护区荒漠植物群落物种多样性进行了研究。结果表明:在整个研究区荒漠植物群落中,白梭梭、梭梭、碱蓬、琵琶柴、沙蓬、驼绒藜和沙漠娟蒿等物种有较高的重要值。依据群落外貌结构和植物种类组成等特征,按照样方中建群种和优势种的重要值,将研究区植物划分为14个典型群落,各群落类型的物种多样性指数(Shannon-wiener指数H′)的顺序为:梭梭+角果藜(2.0740)>白梭梭+驼绒藜(1.9037)>白梭梭+羽毛三芒草(1.8909)>梭梭+芦苇(1.8474)>梭梭+雾冰藜(1.7434)>芦苇+猪毛菜(1.7278)>梭梭+白茎娟蒿(1.6723)>白梭梭+琵琶柴(1.5410)>白梭梭+沙蓬(1.4886)>白梭梭+假木贼(1.4530)>梭梭+碱蓬(1.4437)>白梭梭+刺木蓼(1.4277)>白梭梭+角果藜(1.3637)>白梭梭+沙漠娟蒿(1.3362)。     

新疆北屯绿洲弃耕农田的植被变化特征

在北屯绿洲选择了3组不同年限的次生盐渍化弃耕农田,分别计算了样地内每种植物的重要值,采用Shannon-Wiener指数、Pielou指数、Simpson指数测定了生物多样性.结果表明:3组群落组成存在显著差异,优势种更替明显.3组群落构成依次为,一年生草本、一年生草本 多年生小半灌木、多年生草本 灌木.物种多样性表现为2年群落＞5年群落＞13年群落;群落均匀度表现为2年群落＞5年群落,而5年与13年群落相当,但是生态优势度却表现出与物种多样性相反的趋势,即2年群落＜5年群落＜13年群落.     

Desert vegetation distribution and species-environment relationships in an oasis-desert ecotone of northwestern China

Environmental heterogeneity significantly affects the structure of ecological communities. Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mechanism(s) driving vegetation succession, especially in the ecologically fragile areas. In this study, based on the quantitative analysis of plant community and environmental factors in 68 plots at 10 different transects in the Minqin oasis-desert ecotone(ODE) of northwestern China, we investigated desert vegetation distribution and species-environment relationships using multivariate analysis. Two-way indicator species analysis(TWINSPAN), detrended correspondence analysis(DCA), and canonical correspondence analysis(CCA) methods were used. A total of 28 species, belonging to 27 genera in 8 families, were identified. Chenopodiaceae, Zygophyllaceae, Gramineae, and Leguminosae were the largest families. Annual and perennial herbs accounted for 28.60% of the total number of plants, while shrubs(42.90%) were the most dominant. Nitraria tangutorum was the constructive species of the desert plant community. We divided the 68 plots surveyed in this study into 7 community types, according to the results of TWINSPAN. The distribution of these 7 communities in the DCA ordination graph showed that species with a similar ecotype were clustered together. Results of CCA indicated that groundwater was the dominant factor influencing vegetation distribution, while distance between plot and oasis(Dis) and soil electrical conductivity(EC) were the local second-order factors. Our study suggests that optimizing the utilization of groundwater in oases is key to controlling the degradation of desert vegetation. The favorable topographic conditions of sand dunes should be fully utilized for vegetal dune stabilization, and the influence of soil salinity on the selection of afforestation tree species should be considered.     

乌兰布和东北部荒漠-绿洲生态交错带植被特征及其群落多样性研究

以2009年9月乌兰布和沙区植物群落样方调查资料为基础,对其农牧交错带内不同生境的植被特征及其物种多样性进行研究。结果表明：在区域干旱气候的共同背景下,由于受人工绿洲灌溉水分水平运动影响的强度不同,导致该生态交错带内山前洪积扇、人工绿洲周边、绿洲外围植被的组成及其群落多样性差异显著,水平空间尺度上群落变异性大,构成群落...     

Patterns, magnitude, and controlling factors of hydraulic redistribution of soil water by Tamarix ramosissima roots

Tamarix spp.(Saltcedar)is a facultative phreatophyte that can tolerate drought when groundwater is not accessed.In addition to deep water uptake,hydraulic redistribution(HR)is another factor contributing to the drought tolerance of Tamarix spp.In this study,data on soil volumetric moisture content(θ),lateral root sap flow,and relevant climate variables were used to investigate the patterns,magnitude,and controlling factors of HR of soil water by roots of Tamarix ramosissima Ledeb.in an extremely arid land in Northwest China.Results showed evident diurnal fluctuations in θ at the depths of 30 and 50 cm,indicating "hydraulic lift"(HL).θ increased remarkably at 10 and 140 cm but decreased at 30 and 50 cm and slightly changed at 80 cm after rainfall,suggesting a possible "hydraulic descent"(HD).However,no direct evidence was observed in the negative flow of lateral roots,supporting HR(including HL and HD)of T.ramosissima.The HR pathway unlikely occurred via lateral roots;instead,HR possibly occurred through adventitious roots with a diameter of 2-5 mm and a length of 60-100 cm.HR at depths of 20-60 cm ranged from 0.01-1.77 mm/d with an average of 0.43 mm/d,which accounted for an average of 22% of the estimated seasonal total water depletion at 0-160 cm during the growing season.The climate factors,particularly vapor pressure deficit and soil water potential gradient,accounted for at least 33% and 45% of HR variations with depths and years,respectively.In summary,T.ramosissima can be added to the wide list of existing species involved in HR.High levels of HR may represent a considerable fraction of daily soil water depletion and substantially improve plant water status.HR could vary tremendously in terms of years and depths,and this variation could be attributed to climate factors and soil water potential gradient.