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1.
The Aral Sea Basin in Central Asia is an important geographical environment unit in the center of Eurasia.It is of great significance to the ecological protection and sustainable development of Central Asia to carry out dynamic monitoring and effective evaluation of the eco-environmental quality of the Aral Sea Basin.In this study,the arid remote sensing ecological index(ARSEI)for large-scale arid areas was developed,which coupled the information of the greenness index,the salinity index,the humidity index,the heat index,and the land degradation index of arid areas.The ARSEI was used to monitor and evaluate the eco-environmental quality of the Aral Sea Basin from 2000 to 2019.The results show that the greenness index,the humidity index and the land degradation index had a positive impact on the quality of the ecological environment in the Aral Sea Basin,while the salinity index and the heat index exerted a negative impact on the quality of the ecological environment.The eco-environmental quality of the Aral Sea Basin demonstrated a trend of initial improvement,followed by deterioration,and finally further improvement.The spatial variation of these changes was significant.From 2000 to 2019,grassland and wasteland(saline alkali land and sandy land)in the central and western parts of the basin had the worst ecological environment quality.The areas with poor ecological environment quality are mainly distributed in rivers,wetlands,and cultivated land around lakes.During the period from 2000 to 2019,except for the surrounding areas of the Aral Sea,the ecological environment quality in other areas of the Aral Sea Basin has been improved in general.The correlation coefficients between the change in the eco-environmental quality and the heat index and between the change in the eco-environmental quality and the humidity index were–0.593 and 0.524,respectively.Climate conditions and human activities have led to different combinations of heat and humidity changes in the eco-environmental quality of the Aral Sea Basin.However,human activities had a greater impact.The ARSEI can quantitatively and intuitively reflect the scale and causes of large-scale and long-time period changes of the eco-environmental quality in arid areas;it is very suitable for the study of the eco-environmental quality in arid areas. 相似文献
2.
LIU Weichao FU Shuyue YAN Shengji REN Chengjie WU Shaojun DENG Jian LI Boyong HAN Xinhui YANG Gaihe 《干旱区科学》2020,12(2):215-226
Succession is one of the central themes of ecology;however,the relationship between aboveground plant communities and underground soils during secondary succession remains unclear.In this study,we investigated the composition of plant community,plant-soil C:N:P stoichiometry and their relationships during secondary succession after the abandonment of farmlands for 0,10,20,30,40 and 50 a in China,2016.Results showed that the composition of plant communities was most diverse in the farmlands after secondary succession for 20 and 50 a.Soil organic carbon and total nitrogen contents slightly decreased after secondary succession for 30 a,but both were significantly higher than those of control farmland(31.21%-139.10%and 24.24%-121.21%,respectively).Moreover,C:N ratios of soil and microbe greatly contributed to the changes in plant community composition during secondary succession of abandoned farmlands,explaining 35.70%of the total variation.Particularly,soil C:N ratio was significantly and positively related with the Shannon-Wiener index.This study provides the evidence of synchronous evolution between plant community and soil during secondary succession and C:N ratio is an important linkage between them. 相似文献
3.
通过对呼伦贝尔草地沙化过程中不同演替阶段植被物种组成和生物多样性研究,结果表明:草地沙化,灌丛化明显,群落结构趋干简单化;群落α多样性急剧下降,其中物种丰富度、多样性、均匀性,严重沙化草地分别比潜在沙化草地减少59.4%、54.0%和31.4%,而生态优势度增加44.9%,说明草地沙化后,群落物种数减少,优势种更加突出... 相似文献
4.
Eupatorium adenophorum Spreng. is an important weedy colonizer in early successional communities developing after slash and burn agriculture (jhum) at higher elevations of the north-eastern hill regions of India. The relative performance of this species in terms of fecundity and survivorship in successional plant communities has been worked out. A net population increase occurred through both vegetative and sexual reproduction in early successional fallows up to 6 years old, the increase being greatest in a 6-year fallow. Mortality of seedlings was high in 1- and 3-year fallows, low in a 6-year fallow but reached 100% in older fallows. Seedling mortality was maximal during the monsoon although some seedlings also died during winter as a result of drought and frost. Mortality of vegetative sprouts followed a similar pattern to that of seedlings. The reproductive potential was reduced with increasing age of the successional communities and in a 15-year fallow all individuals were non-reproductive. Since E. adenophorum is able to succeed only in fallows of less than 6 years, repeated short jhum cycles of 4–5 years have had the effect of arresting succession al the weedy stage. 相似文献
5.
咸海的过去、现在与未来 总被引：4，自引：0，他引：4
咸海曾经是世界第四大湖，如今缩小到原来面积的约1/10。咸海究竟如何形成，又经历了怎样的演变过程及其形成机制等，一直是人们关注的问题。咸海水系（阿姆河和锡尔河流域）是青藏高原的隆升，新特提斯海的退却以及新生代全球气候变冷与海平面下降等区域和全球要素共同作用下，构成的一个完整的以青藏高原为中心的亚洲水塔体系的主要组成部分。咸海水系，从形成至大约20世纪中叶，湖泊面积与水文格局大致保持一个相对稳定的状态，只是20世纪下半叶以来，经历了大规模掠夺式的水资源开发和利用，造成了咸海危机。 相似文献
6.
The vertical diversity and distribution of arbuscular mycorrhizal (AM) fungi were investigated in the Mu Us Desert, northwest China. Soils were sampled to 50?cm in depth in the rhizospheres of Hedysarum laeve, Artemisia ordosica, and Psammochloa villosa and 44 AM fungal species belonging to 10 genera were isolated. Several of these species have peculiar morphological features, which are distinct from other habitats. AM fungal diversity and distribution differed significantly among the three host plants and the five soil layers. Spore density, species richness, and the Shannon-Wiener index of AM fungi were 0.55–4.3 spores g?1 soil, 7–36 and 1.78–2.89, respectively. Spore density and species richness had a significant positive correlation with soil total phosphorus content (0.0377–0.1129?mg?g?1), and a negative correlation with soil pH (7.19–7.64). Nonmetric multidimensional scaling, PerMANOVA, and structural equation model analysis demonstrated that host plant species and soil depth significantly and directly influenced the structure of AM fungal communities. We concluded that diversity and distribution of AM fungi might be influenced by plant species, soil depth patterns, and soil nutrient availability in desert ecosystems. This research into AM fungal communities may lead to the development of AM fungi treatment for the mitigation of soil erosion and desertification using mycorrhizal plants, such as H. laeve, A. ordosica, and P. villosa. 相似文献
7.
Impatiens glandulifera is a globally successful invader that primarily spreads along riparian habitats; however, during the last ~20 years, it has started to colonise forests, but little has been published on impacts of this recent spread. Several factors may have contributed to this phenomenon: (i) high propagule pressure from large and widespread riparian populations, (ii) extensive anthropogenic and natural disturbances in the forest ecosystems, (iii) increased use of forest machinery efficiently spreading the seeds together with (iv) a wide environmental tolerance of the species. The impacts of I. glandulifera on native communities in forests are manifold. Contrasting effects are reported on native plant species diversity, richness and growth of saplings of co-occurring species, as well as negative effects on soil mycorrhizal fungi. We suggest that the eradication of I. glandulifera populations in forests is more feasible than along watercourses because the recolonisation in forests is limited and, in some cases, populations are outcompeted by woody species during succession. 相似文献
8.
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. 相似文献
9.
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. 相似文献
10.
Cogongrass ( Imperata cylindrica (L.) Beauv.), an invasive C4 perennial grass, negatively influences native plant communities by forming dense monotypic stands that alter ecosystem properties and lower local species diversity. A hypothesized mechanism by which cogongrass achieves competitive dominance is a novel use of below-ground vegetative disturbance of neighboring vegetation (i.e. puncturing). However, very little empirical evidence is found in the peer-reviewed literature to quantify this phenomenon, much less establish it as a true form of competitive interaction. The present field study was conducted to quantify the occurrence of rhizome-mediated, below-ground vegetative penetration, both interspecifically and intraspecifically, document how this phenomenon is influenced by spatial location relative to the cogongrass stand, and determine the role that above-ground and below-ground biomass might have in the process. Analyses of 100 sod samples indicated that rhizome-mediated, below-ground vegetative penetration is a much larger intraspecific phenomenon than an interspecific one. The data also strongly suggested spatial location as a significant factor, with most penetrations occurring in the interior of a cogongrass stand as opposed to the advancing border. Significant correlations between rhizome-mediated, below-ground vegetative penetration and above-ground cogongrass biomass were found in the overall plot analysis and most strongly in the advancing border of the cogongrass stands. 相似文献
11.
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)。 相似文献
12.
为明确外来入侵植物对本地湿地植物多样性的影响，在北京市湿地选择23个样地共245个样方进行物种多样性调查，并从不同植物性状数据库获取样方中所有植物的株高、叶长、叶宽、叶面积和比叶面积等10个功能性状数据，对比分析入侵群落与本地群落的物种多样性、系统发育多样性和功能多样性特征。结果显示，在北京市湿地共记录到26种外来入侵草本植物，隶属10科19属，其中，菊科外来入侵植物种类最多，有10种。除比叶面积、叶片碳含量和株高的系统发育信号显著外，其余7种植物功能性状的系统发育信号均不显著，表明大多数功能性状未表现出系统发育保守性。入侵群落所有物种的物种多样性指标Shannon-Wiener多样性指数、物种丰富度指数和Simpson优势度指数以及系统发育多样性指标谱系多样性和平均最近谱系发育距离均显著高于本地群落和入侵群落本地物种，而入侵群落本地物种的功能分散指数和Rao''Q二次熵指数均显著高于本地群落，表明外来物种入侵改变了湿地植物的生物多样性，且外来物种入侵后群落谱系多样性趋于发散，说明与本地植物亲缘关系越远的入侵物种越容易在湿地群落中建立种群，符合达尔文归化假说。 相似文献
13.
在样方调查的基础上,应用校正χ2检验,结合Jaccard关联指数、Pearson 相关系数和Spearman 秩相关系数,研究了银川平原湿地植物群落的种间关系, 计算测定了33 种常见植物共528个种对的种间关联关系。结果表明: ① 3种检验方法表达的种间关系相似但不完全相同。 χ2检验共有24个种对正关联, 4个种对负关联,其中有12对极显著正关联,1个种对极显著负关联; Pearson 相关系数检验,有30 个种对正相关,其中有19个种对极显著正相关,无负相关种对; Spearman 秩相关系数检验,有50个种对呈正相关,8个种对呈负相关,其中有31个种对极显著正相关,1个种对极显著负相关。② 银川平原湿地33种常见植物可划分为4个生态种组,即水生植物种组、湿生植物种组、中生植物种组和旱生植物种组,组内植物间多为显著正关联,种组植物间多为负关联。③ 银川平原湿地植物群落存在独立分布格局,植物群落不够稳定, 尚处于不断的演替之中。 相似文献
14.
塔里木河下游植被种间关系与稳定性分析 总被引：1，自引：0，他引：1
在样方调查的基础上,对塔里木河下游的英苏、喀尔达依、阿拉干和依干不及麻4个监测断面的样地植被状况进行调查,在2×2列联表基础上,采用方差比率法(VR),应用联结系数(AC)、χ2检验与M. Godron稳定性测度方法对植被群落进行了种间联结分析与稳定性研究,得到如下结论:①总体相关性检验结果表明,4个断面中没有出现显著正联结的植物群落,塔里木河下游植物群落演替目前尚未达到稳定水平,且阿拉干与依干不及麻断面的植物群落正处于发育初期。②植物群落种间关系不显著,分布松散,更倾向于独立分布。群落的结构不稳定,存在于同一个样地内种对之间的依赖性不强,个别区域植物群落物种之间存在一定的竞争关系与排它作用。③根据已有的种间关系,可将塔里木河下游的植物群落划分为3个生态种组。 相似文献
15.
Magomedrasul Magomedov Mamlakat Magomedova Zalmo Magomedova 《Arid Land Research and Management》2017,31(4):472-484
There are many patterns of coexistence in communities, including partitioning based on spatial, temporal, or food niches. This study considered the partitioning of food between two ecologically similar and sympatric species, the tamarisk gerbil and the midday gerbil, in the Terek-Kuma Lowland of the Republic of Daghestan. The qualitative and quantitative characteristics of the diets of both gerbils were revealed. The species have relatively wide diets; the tamarisk gerbil’s diet consisted of forty-six plant species, and the midday gerbil’s diet consisted of fifty plant species within the study areas. Thirty plant species were present in the diets of the two gerbils. The dietary breadths of both gerbils were similar. The dietary overlap of the two gerbils ranged from low to moderate (average Pianka’s dietary overlap index, 0.476?±?0.08). Finally, under conditions in which food resources are sufficient, the moderate abundance of gerbils and the high diversity of habitats and microhabitats in the study areas allow these two species of gerbils to coexist in a common location. 相似文献
16.
在样方调查的基础上,对塔里木河下游的英苏、喀尔达依、阿拉干和依干不及麻4个监测断面的样地植被状况进行调查,在2×2列联表基础上,采用方差比率法(VR),应用联结系数(AC)、c2检验与M.Godron稳定性测度方法对植被群落进行了种间联结分析与稳定性研究,得到如下结论：① 总体相关性检验结果表明,4个断面中没有出现显著正联结的植物群落,塔里木河下游植物群落演替目前尚未达到稳定水平,且阿拉干与依干不及麻断面的植物群落正处于发育初期。② 植物群落种间关系不显著,分布松散,更倾向于独立分布。群落的结构不稳定,存在于同一个样地内种对之间的依赖性不强,个别区域植物群落物种之间存在一定的竞争关系与排它作用。③ 根据已有的种间关系,可将塔里木河下游的植物群落划分为3个生态种组。 相似文献
17.
《干旱区科学》2016,(6)
Saline wetlands are rare ecosystems in Saharan areas,which are important for conservation of many endemic and rare plant species.In this study,we investigated five saline wetland sites of the Oued Righ region,located in the northeastern Algeria,to determine the environmental factors controlling the composition and distribution of plant communities.We established a total of 20 transects to measure the vegetation parameters(density and cover) and soil characteristics(electrical conductivity,moisture,pH,CaSO_4,CaCO_3,organic matter,Na~+,K~+,Mg~(2+),Ca~(2+),SO_4~(2–),Cl~–,NO_3~– and HCO_3~–).A total of 17 plant species belonging to seven families were identified.The natural vegetation was composed of halophytic and hydro-halophytic plant communities,presented specially by the species of Amaranthaceae family.Soils in the studied wetlands were moist,gypsiferous,alkaline,salty to very salty with dominance of chloride and calcium.Results of the Canonical Correspondence Analysis(CCA) showed that community structure and species distribution patterns of vegetation were mainly dependent on soil characteristics,mainly being soil salinity(CaSO_4,K~+,Ca~(2+) and Cl~–) and moisture.The distribution of plant species was found to follow a specific zonal pattern.Halocnemum strobilaceum was observed to grow in highly salt-affected soils,thus being the more salt-tolerant species.Phragmites communis plants were widely distributed in the study area with a high density at the edges of accumulated water body.Juncus maritimus,Tamarix gallica and Salicornia fructicosa grew in soils that are partially or completely flooded in winter.Suaeda fructicosa,Traganum nudatum,Arthrocnemum glaucum,Aeluropus littoralis,Cressa cretica and Cynodon dactylon were distributed in salty and moist soils away from the open water body.Plants of Zygophyllum album,Limonastrirum guyonianum,Cornulaca monacantha,Cistanche tinctoria,Mollugo nudicaulis and Sonchus maritimus were found in soils with less salty and moisture.They constituted the outermost belt of vegetation in the studied wetlands.This study will provide a reference on introducing the salt-tolerant plant species as a fodder resource in saline habitats and regenerating the degraded saline wetlands. 相似文献
18.
The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impacted distributions and characteristics of dominant plant communities. However, besides groundwater depth, the community composition and species diversity were also influenced by physiognomy of the habitat. Based on the similarity coefficient, the differences between dominant plant communities were significant at different groundwater depths. Compared with other results relating to desert vegetation and groundwater depth, variations of community distribution were similar at the large spatial scale. However, in this extremely arid region, there were significant differences in community type and community succession when compared with other arid regions, especially in relationship to deep groundwater depth. With groundwater depth from deep to shallow, communities transformed with the sequence of Alhagi communities, Tamarix spp. communities, Populus communities, Phragmites communities, and Sophora communities. At groundwater depth of less than 6.0 m, the community type and composition changed, and the species diversity increased. Among these dominant species, Tamarix exhibited the biggest efficiency in resource utilization according to niche breadth, which means it possessed the best adaptability to environmental conditions at the oasis margins. 相似文献
19.
青海湖流域沙柳河草甸群落结构与数量特征 总被引：1，自引：0，他引：1
沿青海湖流域沙柳河河岸,选取多个断面进行样方调查,分析沿沙柳河距河流入湖处不同距离、垂直河岸方向上草甸群落结构、地上生物量以及物种多样性的变化特征,并讨论影响群落结构变化的生境因子。结果表明：① 在所调查的样地中,有草本植物52种,隶属39属,13科。平均总盖度为70%,平均地上生物量为131 g•m-2。② 随着离湖距离的增加,Shannon-Wiener指数、物种丰富度、物种均匀度指数、地上生物量呈现先增加后略微减小的趋势,盖度的变化趋势是先增加后不变。土壤含水量和土壤含盐量、海拔等可能是影响植物群落空间分布差异的主要原因。③ Shannon-Wiener指数、物种丰富度与地上生物量呈现不明显的线性关系。 相似文献
20.
克拉玛依植物群落物种多样性研究 总被引：3，自引：0，他引：3
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。 相似文献