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1.
KARGAR-CHIGANI Hadi 《干旱区科学》2017,9(2):161-175
A considerable proportion of Iran's territory is covered with arid and semi-arid rangelands and mismanagement and overexploitation of those rangelands have resulted in serious ecological degradation. Thus, the need is pressing to examine the present species composition and the relationships with environmental factors for providing the needed scientific references to species conservation and ecological rehabilitation efforts. The aims of this study were to examine the species composition and to delineate the most important factors influencing the distributions of plant species and groups in the northern rangelands of Isfahan Province(Iran) using two-way indicator species analysis(TWINSPAN), detrended correspondence analysis(DCA), principal component analysis(PCA), and canonical correspondence analysis(CCA). Field investigations were conducted in the growing season of 2014 using stratified random method in 22 homogeneous sampling units. In total, 75 plant species belonging to 52 genera and 19 families were identified. The most important families were Asteraceae and Papilionaceae, the most important genera were Astragalus, Cousinia, and Acanthophyllum, and the most important species were Artemisia aucheri and Artemisia sieberi. Plant species were classified into 10 groups using TWINSPAN. DCA was used to estimate the magnitude of changes in species composition along the first two ordination axes to provide gradient length estimations for PCA and CCA ordinations. The first three PCA axes and the first three CCA axes demonstrated similar cumulative percentage of variance, indicating that the environmental factors(selected by PCA) used in CCA ordination were acceptable for explaining the species composition and the distributions. CCA ordination showed that the first axis was closely related to elevation, slope, surface bare soil cover, surface litter cover, gravel proportion, organic matter, total nitrogen, Ca CO3 content, and grazing intensity and that the second axis was closely related to sand proportion, silt proportion, clay proportion, and saturation percentage. Among these factors, elevation was the most effective factor to separate the plant groups and grazing was the major cause of rangeland degradation. 相似文献
2.
Kadry Abdel Khalik Iman Al-Gohary Yassin Al-Sodany 《Arid Land Research and Management》2017,31(3):316-334
The present study aimed to determine floristic composition, the structure of the vegetation, and species distribution at 16 sample plots in Wadi Fatimah, Mecca, Saudi Arabia, highlighting the ecological factors that affect species distribution. The study revealed 100 plant species belonging to 34 families. Fabaceae and Poaceae were the dominant families, and chamaephytes and therophytes were predominant life forms, which demonstrate a typical desert life-form spectrum. Altitude showed a highly significant association with species frequency distribution. The highest species richness value of 23 species per plot was recorded in the coastal plain (Vegetation groups II & III). The lowest species richness value of 9 species per plot was recorded in the littoral salt marsh (Vegetation group I). Chorological analysis exhibited the Saharao-Arabian–Sudano-Zambezian chorotypes, 47% of the studied species were bi-regional. Using TWINSPAN, DCA, and CCA multivariate analysis, four major vegetation groups were classified into three main ecosystems (I) Halopeplis perfoliata, Suaeda fruticosa, Acacia tortilis, and Suaeda fruticosa, representing the littoral salt marsh; (II) Rhazya stricta and Haloxylon salicornicum, characterized by the coastal plain; and (III) Senna italica, Glinus lotoides, and Tribulus macropterus were the leading groups in the inland mountainous country. The CCA ordination showed that the separation of Vegetation group III along the axis was affected by Mg, K, and P concentration, and VG IV was significantly associated with silt, clay, and fine sand content. Furthermore, the Vegetation group I was significantly correlated with Na and Ca concentration, and VG II group was significantly correlated with heavy metal concentrations of elements as Fe, Pb, Zn, Ni, and Cu. 相似文献
3.
2002-2008年,采用样方法对内蒙古典型荒漠区禁牧样地的植物群落进行了调查。以7年的调查结果和数据分析了荒漠植物群落的季节和年度特征,并利用除趋势对应分析(DCA)和典范对应分析(CCA)对植物群落特征与气候因子的相关性进行了排序分析。结果表明:灌木和草本植物的高度、盖度、密度和生物量的季节特征均为夏季和秋季间差异均不显著(P>0.05),而秋季显著高于春季(P<0.05)。灌木植物与草本植物群落特征的年动态具有差异,草本植物群落特征的年间波动大于灌木植物。DCA排序表明荒漠植物群落结构的季节性和年度间差异不明显。CCA排序表明草本植物特征因子与气候因子的相关性大于灌木植物。草本密度与年降水量的相关性较大,草本高度与年均温度的相关性较大,草本生物量与年降水量、年均温度的相关性均较大。 相似文献
4.
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
5.
黄土高原马栏林区森林群落生态梯度分析 总被引：2，自引：1，他引：1
应用TW INSPAN,CCA和partialDCA方法,对黄土高原马栏林区45个森林群落样地进行多元分析,揭示该区不同森林群落类型之间在环境梯度上的生态关系。结果表明:①45个森林群落可划分为8组群落类型;②CCA排序表明,枯枝落叶层厚度、坡向、海拔和有机质含量是影响该区森林群落类型分布的重要实测环境因素;而partialDCA排序表明,干扰是影响该区森林群落类型分布最重要的潜在环境因素;③各森林群落类型在排序图中有规律的分布是群落中物种适应环境的结果,且人工油松林有向天然油松林恢复的趋势;④CCA与partial DCA相结合是研究植物群落生态梯度的一种非常有效的方法。 相似文献
6.
Distribution patterns and traits of weed communities along an urban–rural gradient under rapid urbanization in Shanghai,China 
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下载免费PDF全文 In order to better understand the effects of urbanization on weed communities, the distribution of weed communities in Shanghai, China, was systematically investigated. The diversity of weed communities and four environmental factors, including the relative light intensity, soil moisture, soil compaction and soil pH, were measured in 1375 plots along an urban–rural gradient. The species diversity indices in each area along the urban–rural gradient were compared by using a one‐way ANOVA. The weed communities were identified by using clustering methods that were based on relative dominance information. A canonical correspondence analysis was used to reveal the relationships between the species composition and the environmental factors at the community level and the Spearman's rank correlation test was used to test the relationship between the number of weed communities and each environmental factor. A total of 183 species, belonging to 41 families and 123 genera, was recorded. It was found that the species richness, Shannon–Wiener diversity index and Pielou evenness index followed a unimodal curve along the urban–rural gradient. The 1375 plots were divided into 133 weed community types. All four environmental factors significantly affected the species composition of the weed communities, but only soil compaction had significant effects on the number of weed communities. It was concluded that the diversification of habitat type and environmental change along the urban–rural gradient led to more weed communities in rural areas and fewer weed communities in urban areas. Based on the species' habitats and distribution patterns, the weeds were divided into “widespread”, “urban” and “rural”. 相似文献
7.
JAVAD Mirzaei 《干旱区科学》2017,9(3):368-378
This study assesses the effects of vegetation patterns and environmental factors on the abundance of natural tree and shrub regeneration in semi-arid forests of the Zagros Mountains, western Iran. We sampled 120 releves at different topographic positions in a protected area of the studied region. Floristic composition, slope, elevation and soil properties were recorded at each releve, and woody seedling density was measured. We have first discerned five floristic groups using two-way indicator species analysis(TWINSPAN), detrended correspondence analysis(DCA), and canonical correspondence analysis(CCA) and then explored the relationships among the floristic group compositions, environmental factors and seedling densities. The indicator species of the five groups were Quercus brantii, Acer monspessulanum, Cerasus microcarpa, Rhamnus arvensis and Astragalus licyoides. Our results indicated that these groups were significantly affected by elevation and soil properties and the soil properties refer to: EC(electrical conductivity), N(nitrogen), K(potassium), OM(organic matter), and bulk density. Woody regeneration was composed of Q. brantii, A. monspessulanum, C. microcarpa, Amygdalus scoparia and Crataegus pontica seedlings. The highest density of seedlings was found for Q. brantii(97.14(±48.00) plants/hm~2) and the lowest for A. scoparia(2.28(±1.50) plants/hm~2). Quercus brantii was the dominant species and the seedling density was positively correlated with soil p H and P(phosphorus) values. Amygdalus scoparia regeneration was negatively correlated with elevation, and the seedling density peaked in C. microcarpa group. There was no significant variation in distribution of C. pontica seedlings among the groups, but the seedling density of this species was positively correlated with slope and K. Cerasus microcarpa seedlings were more abundant in the Q. brantii group than in other groups. This study showed that the regeneration of tree and shrub species was unequally distributed in different floristic groups for some species(A. scoparia and C. microcarpa) but not for other(Q. brantii and C. pontica) and was generally correlated with some environmental factors, particularly elevation, slope and soil nutrients(P and K). These results are a first step to implement future management and restoration strategies for promoting forest regeneration. 相似文献
8.
塔里木河干流荒漠河岸林植物群落多元分析及其土壤环境解释 总被引：1，自引：0，他引：1
应用对应分析(CA)与典范对应分析(CCA)排序方法,对塔里木河干流荒漠河岸林植物群落进行了多元统计分析,并给出各群落类型的土壤环境定量解释。结果表明:塔里木河干流荒漠河岸林地区多数物种出现频次不高,物种丰富度低;CCA排序结果显示出土壤含水率、总盐、HCO3-是决定植物群落分异的主导土壤环境因子,得到CCA第一轴、第二轴与环境因子之间的多元回归方程,并将样地划分为4种群落类型,定量地揭示研究区植物群落类型的分布与土壤环境之间的关系。 相似文献
9.
艾比湖湿地植物群落的数量分类和排序 总被引：3，自引：0，他引：3
应用双岐指示种分类法(TWINSPAN)和非度量多维标度(NMDS)排序方法分析了新疆艾比湖湿地25种主要植物在47个调查样地的存在-缺失数据,研究了艾比湖湿地植物群落的数量分类和排序。结果表明:TWINSPAN将艾比湖湿地25种主要植物种划分为8个群落类型,各群落内的植物种之间具有相似的生境。NMDS排序第一轴反映了土壤含水量梯度,第二轴反映了海拔梯度,样地在排序轴的分布与实际情况相吻合。TWINSPAN对样地和植物种的分类结果与NMDS方法对样地和植物种的排序结果一致,两种方法都能有效处理艾比湖湿地植物种分布数据的稀疏性。 相似文献
10.
以乌鲁木齐南部山区小渠子林场54个样方岩面生叶状地衣调查结果为依据,应用典范对应分析法对群落物种分布与环境参数之间的关系进行了分析。结果表明:小渠子林场岩面生叶状地衣共26种,属于8科、11属、4个目,它们组成了菊叶黄梅+淡肤根石耳+托敏氏褐梅;暗褐梅+膜地卷;网脊平石耳+垫脐鳞衣+皮果衣三个叶状地衣群落。地衣分布与海拔高度、森林郁闭度、大气湿度等有关。人为干扰和基物对岩面生叶状地衣分布的影响不显著。 相似文献
11.
通过对珍稀濒危的沙冬青属2种沙冬青群落的区系组成、生活型、生态型组成、群落中物种恒有度、群落结构、多度、盖度特征的对比研究,发现其群落组成均以藜科、菊科、豆科占优势,以温带分布和泛地中海分布为主,且旱生的多年生草本、半灌木等比重较大,均表现出草原化荒漠的特点,群落结构中灌木层和草本层明显,具较强的相似性;二者共有科、属虽较多,但共有种数少,群落中常见种不同,蒙古沙冬青群落物种组成和区系组成比新疆沙冬青丰富,结构也较复杂,群落类型较多,多度和盖度也大,但均一性较差;新疆沙冬青群落旱化程度较高.从整体上看,2种沙冬青群落结构简单,物种多样性较低,多度、盖度不高,很容易受到破坏,新疆沙冬青群落比蒙古沙冬青群落更容易被破坏. 相似文献
12.
喀什—巴楚北部荒漠植被 总被引：2，自引：0，他引：2
1986年,中国科学院新疆资源开发与生产布局研究考察队环境生态组在对南疆西部地区进行植物、生态、环境考察时,笔者对巴楚县北的三岔口至喀什市、喀什市至其西北的图鲁噶尔特山口(以下简称喀图线)一带的荒漠植被予以了特别注意,现就所收集资料整理成本文。 相似文献
13.
准噶尔盆地东南缘绿洲-荒漠交错带土壤甲螨群落结构 总被引：1，自引：0，他引：1
为了查明准噶尔盆地东南缘绿洲-荒漠交错带土壤甲螨群落特征,2011年4月、7月、9月、11月中旬对该交错带的自然林、灌木林、防护林、荒草原、耕地、菜瓜地和荒漠等7种不同生境进行调查。结果表明:该区域共捕获土壤甲螨成体3767头,28科36属43种,其中覆盖头甲螨、萨勒盖头甲螨、新疆尖棱甲螨和普通尖棱甲螨为优势种,截合若甲螨、长单翼甲螨属、白上罗甲螨大洋亚种为亚优势种,优势种和亚优势种占总数的72.45%。7种不同生境土壤甲螨群落组成和数量分布均有明显的差异(P<0.05),在自然林种类(30种)和个体数(1001头)最多,而在菜瓜地种类(9种)最少,荒漠个体数(118头)最少。不同生境土壤甲螨的个体数具有明显季节变化差异(P<0.05),秋季数量最高、冬季次之、夏季其次、春季最低。MGP分析结果表明,该交错区土壤甲螨群落均属于O型,但G群的种类明显高于M群和P群。甲螨的群落异质性高,各生境间的多样性指数(H)有一定的差异,其中防护林最高,而菜瓜地最低。生境间相似性分析表明,自然林、灌木林、防护林生境之间是中等相似(0.50～0.70),荒漠和荒草原与其他生境间为中等不相似(0.25～0.50)或极不相似(0.00～0.25)。研究表明气候、植被和土壤差异是影响土壤甲螨群落的主要因素。 相似文献
14.
Mohamed Neji Mohamed Moncef Serbaji Olivier Hardy Mohamed Chaieb 《Arid Land Research and Management》2018,32(3):291-315
Knowledge about vegetation patterns along disturbance gradients is essential for conservation and management of coastal habitats in arid regions. This study focuses on the floristic diversity and the factors controlling the vegetation structure in the Gulf of Gabès (Tunisia). For this purpose, the floristic diversity of 120 relevés belonging to three coastal sites with different disturbance levels (40 relevés per site) was analyzed in relation with 10 environmental and anthropogenic factors. Therophytes constitute 54% of the 237 plants species belonging to 44 families identified in the present study. The species richness and floristic diversity indices exhibited a similar trend and peaked in the slightly disturbed site (H′?=?3.38; S?=?176). The similarity between sites was relatively low and reached its maximum between the little and the highly disturbed sites. Two-way indicator species analysis and detrended correspondence analysis applied on the floristic data resulted in groups mainly determined by disturbance level by explicitly segregating the three sites. Canonical correspondence analysis (CCA) indicated that the spatial pattern of species composition was mainly influenced by anthropogenic variables. Partial CCA revealed that the effect of anthropogenic variables on floristic composition was thrice higher than the effect of environmental variables (57.5% vs. 18.4%, respectively). Overall, this study provides a broad understanding of the floristic diversity and vascular plant richness in the Gulf of Gabès. The obtained results reflected a disturbance–diversity pattern and thus revealed the obvious importance of maintaining the intermediate disturbance for biodiversity conservation and monitoring. 相似文献
15.
《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
16.
Analysis of nematodes and soil-borne fungi fromAmmophila arenaria (Marram grass) in Dutch coastal foredunes by multivariate techniques 总被引：2，自引：0，他引：2
P. C. E. M. de Rooij-van der Goes W. H. van der Putten C. van Dijk 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(2):149-162
A survey was carried out at nine locations in the Dutch coastal foredunes to identify the species of soil borne fungi and nematodes associated withAmmophila arenaria (Marram grass).Ammophila arenaria is a sand binding grass that is very important for the stabilization of coastal foredunes. Degeneration of the plants occurs at stabilized sites and is supposed to be caused by a combination of soil-borne fungi and nematodes. Canonical correspondence analysis (CCA) and two-way indicator species analysis (TWINSPAN) were used to examine which fungal and nematode species usually coexist in the rhizosphere of vigorous and early declining stands ofA. arenaria. In total, 47 species of fungi and 10 genera of plant-parasitic nematodes were found. According to CCA, the community of soil organisms of stands that were more than 10 years old was significantly different from recently established stands of 3 years old. Also, the community of soil organisms isolated from calcareous locations differed significantly from that of lime-poor locations. No relationship between the vigour of the plants (vigorous vs. early declining) and the soil borne species composition was found, although in roots of vigorous stands, the number of nematodes was higher than that of early declining stands. A relatively large group of soil organisms occurred generally. This group possibly contains an ubiquitous pathocomplex that cause the growth reducing effects of biotic origin which generally occur inA. arenaria. Analysis of this group of nematodes and fungi by TWINSPAN resulted in 9 different combinations of concurring soil organisms of which 5 combinations were present at all investigated locations. Two of the latter combinations contained both nematodes and fungi. The first contained three endoparasitic nematodes (Meloidogyne maritima, Heterodera spp. andPratylenchus sp.) that concurred with the fungusMucor hiemalis. The second group containedHeterodera spp.,Telotylenchus ventralis, Filenchus sp. together with the potentially plant-pathogenic fungiMicrodochium bolleyi and Fusarium culmorum, as well as the fungiMortierella sp. andTrichoderma harzianum, all in relatively high numbers.It is concluded that both CCA and TWINSPAN are valuable exploratory techniques, especially when used in combination, to detect possible combinations of soil organisms which may be involved in the degeneration ofA. arenaria. Further identifications of harmful organisms should be obtained from experiments. 相似文献
17.
18.
本文根据四种插值公式计算与野外实测数据的对比分析,利用优先关系定序法,筛选出一种较适合于荒漠植被种群分布格局研究的模式——三角形方法。它揭示了新疆莫索湾沙区荒漠植被群落结构的基本特征,具有失真小、精确性高、实用价值大等优点,为研究荒漠植被群落演替动态,提供了一个定量方法。 相似文献
19.
Xue-Ni Zhang Xiao-Dong Yang Yan Li Xue-Min He Jian-Jun Yang 《Arid Land Research and Management》2018,32(1):38-56
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. 相似文献
20.
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