Effects of ecological factors on plant communities of Ziwuling Mountain, Shaanxi Province, China

This paper explores the relationships between environmental factors and community patterns. In 60 plots in the Malan Forest Region of the Loess Plateau, 17 variables were used as indicators of spatial position, soil and topography characteristics. Plant community types were analyzed by TWINSPAN (Two-way Indicator Species Analysis). Significant environmental factors were selected by forward selection and Monte Carlo tests. The relationship between communities and environmental factors was identified by DCCA (Detrended Canonical Correspondence Analysis). Partial CCA (Canonical Correspondence Analysis) partitioned observed compositional variation into components explained by environment, locality and covariation between them. The results showed that: (1) the plant communities can be divided into 13 types including 4 different successional stages. (2) Salt and alkali-hydrolyzable nitrogen are the significant factors related to plant community distribution at early stage. Elevation and humus thickness are the significant factors in the transitional stage. Elevation, slope, aspect, thickness of forest floor, humus thickness and pH are the significant factors for the sub-climax stage. Elevation, slope, aspect, pH and available phosphorus are the significant factors for the climax stage. (3) The ecological characters and the distribution patterns of plant communities in different successional stages are consistent with environmental gradients. (4) As succession proceeds, the impact of environmental conditions on plant communities increases, while the total influence of spatial location, and the interaction between the spatial location and environmental factors decrease.     

陕西子午岭生态因素对植物群落的影响

为探讨生境对植被格局分布的影响,对黄土高原马栏林区60块样地进行植被学调查的基础上,采用17个环境指标刻画植物群落的空间位置、地形和土壤特征;利用双向指示种分析(TWINSPAN)划分了该区不同演替阶段的植物群落类型;利用前向选择法(forward selection)及Monte Carlo检验对不同演替阶段植物群落物种组成影响显著(p＜0.05)的环境因子进行筛选;利用去势典范对应分析(DCCA)排序方法分析不同演替阶段植物群落分布格局与环境的关系;利用偏典范对应分析(partial CCA)定量分离环境、空间及其交互作用对植被格局总体变异的影响.结果表明:(1)马栏林区的植物群落可划分为13个类型,分别属于4个不同的演替阶段;(2)对演替初期阶段群落影响显著的环境因子是土壤含盐量和碱解氮,对演替过渡阶段群落影响显著的环境因子是海拔和腐殖质厚度,对演替亚顶级阶段群落影响显著的因子是海拔、坡向、枯落物厚度、腐殖质厚度和pH值,而对演替顶级阶段群落分异影响显著的因子是海拔、坡向、pH值和速效磷;(3)不同演替阶段群落的生态学特性和分布规律与环境空间的生态梯度格局吻合较好;(4)随着演替的进行,环境因子单独对植物群落的影响越来越大,而样地位置单独作用和样地位置与环境因子的交互作用之和越来越小.     

Classification and ordination of plant communities in Abune Yosef mountain range,Ethiopia

Understanding how topography-soil-disturbance drives spatial distribution of vegetation is the interest of ecologists. This study was, conducted to investigate the topography-soil-disturbance and vegetation relationships in Abune Yosef mountain range, Ethiopia. A total of 85 nested sample plots measuring 400 m², 25 m² and 1 m² were established for trees, shrubs and herbs respectively. Topographic, soil and disturbance variables were also assessed from each plot. Plant community classification was described and identified by agglomerative hierarchical clustering using Ward's minimum variance clustering methods. Shannon diversity index was employed to determine community diversity. After detecting the length of the first Detrended Correspondence Analysis (DCA) axis, Canonical Correspondence Analysis (CCA) forward and backward stepwise selection of environmental variables was performed based on their p-value by running permutation tests. The first axis explained 43.63% of the overall inertia and is correlated with Elevation, pH, slope aspect, total Nitrogen, soil organic Carbon & Clay. On the other hand, the second axis explained 32.06% of the total inertia and is correlated with bulk density, slope, logging, & available Phosphorus. The present study revealed that topographic variables have a profound influence on vegetation spatial distribution than soil and disturbance factors.     

拉萨河流域植物群落的数量分类与排序

青藏高原植物群落空间分异格局是异质生境条件下物种性状、种间相互作用等生态学过程共同作用的结果,对其分析有助于深入理解群落形成与环境因子之间的关系。基于拉萨河流域自然植被样带调查,采用双向指示种分析(TWINSPAN)和典范对应分析(CCA)等方法,探讨了群落的结构组成及影响其结构分异的主导环境因子。结果表明:(1) TWINSPAN数量分类将拉萨河流域草地系统划分成12个群系类型,即圆叶合头菊+唐古拉翠雀花群系;紫花针茅群系;青藏臺草群系;雪层杜鹃+鲜卑花-西藏嵩草群系;高山嵩草群系;小叶金露梅群系;硬叶柳+杯腺柳群系;水栒子+拱枝绣线菊-高山嵩草群系;绢毛蔷薇-冷蒿+白草群系;大果圆柏-垂穗披碱草群系;铺地柏-藏橐吾+高原荨麻群系;醉鱼草+砂生槐群系。12种群系类型包含了较多的植被类型,包括高寒灌丛草甸、高寒灌丛草原、稀树草原、高寒草甸和高寒草原等。(2) CCA排序表明:影响拉萨河流域植物群系分布的主要环境因子是年均温度、海拔和经度和纬度,其次是年均降雨量。(3) TWINSPAN分类与CCA排序结合反映了群系分布格局变异与环境因子之间的关系,可为拉萨河流域草地的保护和可持续利用,以及相关的植被群落研究提供参考。     

中国特有植物短丝木犀(Osmanthus serrulatus Rehd.)群落结构及其环境解释

为了解环境因子对短丝木犀植物群落的影响,研究了四川省宝兴县东拉山短丝木犀植物群落地区的环境因子、TWINSPAN分类、物种和多样性指数与环境因子的DCCA排序。结果表明:1)TWINSPAN将东拉山短丝木犀24个植物群落里划分为12个群落类型,分类结果在空间上反映了东拉山植物群落的演替变化趋势。2)短丝木犀植物群落生长在土壤含水量较高、郁闭度较高,并处于西南和南坡向的沟边。短丝木犀群落的主要伴生物种为鹅耳枥Carpinus turczaninowii、宝兴木姜子Litsea moupinensis、领春木Euptelea pleiosperma、云锦杜鹃Rhododendron fortunei、宝兴过路黄Lysimachia baoxingensis、糙苏Phlomis umbrosa和铁角蕨Asplenium trichomanes。3)DCCA排序结果验证了TWINSPAN分类结果的合理性,同时指出影响东拉山短丝木犀植物群落类型及空间分布的重要环境因子是土壤有机质和腐殖质含量。     

丹江口水库水滨带植物群落空间分布及环境解释

探讨了环境因素对丹江口水库(南水北调中线水源地)水滨带植物群落空间分布的影响。通过对水滨带植物群落和环境因素的实地调查,用双向指示种分析(TWINSPAN)对201个水滨带植物群落进行分类;结合地形、土壤和水文因素用除趋势典范对应分析法(DCCA)分析环境因素对水滨带植物群落的影响;并对环境因素的解释能力进行定量分离。结果表明:(1)水滨带植物群落包括7种类型,分别是萹蓄群落、苘麻群落、细叶水芹+狗牙根群落、狗牙根群落、响叶杨-狗牙根群落、杜梨-白刺花-狗牙根群落和侧柏-牡荆-三穗苔草群落;(2)海拔和水淹影响对水滨带植物群落空间分布具有主导作用。海拔升高,水淹影响减弱,植物群落呈现由草本植物群落向木本植物群落变化的格局;(3)土壤因素的解释能力大于地形因素,水文因素的解释能力最小。各类环境因素之间存在交互作用,地形、水文和土壤因素三者间的交互作用最大,地形和土壤因素之间的交互作用最小。环境因素共解释水滨带植物群落空间分布的21.99%,未解释部分为78.01%。结果证明环境对植被的解释能力是由植被的复杂程度决定的,植被越复杂,环境的解释能力越低。     

戴云山黄山松群落与环境的关联

基于戴云山黄山松群落类型31个样地(20 m×20 m)野外调查,筛选4个地形因子和11个土壤环境因子,采用除趋势典范对应分析法(DCCA)探讨黄山松群落分布格局与环境之间的关联,定量分析环境因子间相互关系及其对黄山松群落格局的影响。结果表明:(1)DCCA第一排序轴主要反映黄山松群落的海拔变化,第二轴主要反映坡向变化,即沿第二轴从上到下,坡向越朝向阳坡,黄山松群落分布越明显。(2)DCCA表明第一轴与海拔的相关系数达0.5570,即海拔是黄山松群落分布起着决定性作用的环境因子,呈现海拔越高,黄山松优势种群越显著,在海拔1400-1600 m表现突出。(3)黄山松群落主要物种在DCCA排序图的相对位置,反映坡向、坡位、有机质、人为干扰因素是影响黄山松群落分布的重要因素。(4)DCCA排序图中黄山松群落种类排序轴与环境排序轴的相关系数高于DCA,且消除CCA的 "弓形效应",更能凸显海拔、有机质等环境因子对黄山松群落的影响,即黄山松群落与环境因子之间关联以DCCA排序方法为最佳。     

High-Andean vegetation and environmental gradients in northwestern Patagonia,Argentina

Abstract. We analysed the heterogeneity of high-elevation vegetation on three mountains along a west-east transect at 41 °S lat. in the Andes of northwestern Patagonia, Argentina. In this area, high-Andean vegetation occurs as islands on mountain tops above Nothofagus pumilio forests ? with the timberline at ca. 1700 m a.s.l. We recorded floristic, topographic and substrate data in 166 sites stratified according to longitude, altitude, slope and aspect. Vegetation data were classified with TWINSPAN and ordinated with Detrended Correspondence Analysis. The relationship between environmental and floristic variation was analysed using Canonical Correspondence Analysis. In order of importance, geographical longitude, altitude and aspect were the major determinants of vegetation variation, whereas substrate texture and slope appeared less important. The combination of these factors resulted in two main vegetation gradients. The first gradient is related to a moisture availability gradient, primarily determined by longitude and secondarily to variation in wind exposure (east vs. west aspect). The second vegetation gradient is related to variation in temperature, primarily determined by altitude, and secondarily by variation in insolation related to the contrast between north and south aspects. The four communities obtained with TWINSPAN are therefore associated with four characteristic habitat types: moist-cold, moist-warm, dry-cold and dry-warm. The community of warm and dry environments is the richest and has elements in common with dry steppe communities situated at lower elevations to the east, while the vegetation of the cold-moist habitat type has unique elements that are typical of the southern Andes. Although current climatic factors appear to be the major determinants of high-Andean vegetation gradients, historical events of Pleistocene times probably also affected the vegetation patterns we see today.     

Macrophyte community structure and species occurrence in relation to environmental determinants in the ephemeral aquatic habitats of Gavdos,Greece

The aims of this study were to explore the environmental factors that determine the distribution of plant communities in temporary rock pools and provide a quantitative analysis of vegetation–environment relationships for five study sites on the island of Gavdos, southwest of Crete, Greece. Data from 99 rock pools were collected and analysed using Two-Way Indicator Species Analysis (TWINSPAN), Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) to identify the principal communities and environmental gradients that are linked to community distribution. A total of 46 species belonging to 21 families were recorded within the study area. The dominant families were Labiatae, Gramineae and Compositae while therophytes and chamaephytes were the most frequent life forms. The samples were classified into six community types using TWINSPAN, which were also corroborated by CCA analysis. The principal gradients for vegetation distribution, identified by CCA, were associated with water storage and water retention ability, as expressed by pool perimeter and water depth. Generalised Additive Models (GAMs) were employed to identify responses of four dominant rock pool species to water depth. The resulting species response curves showed niche differentiation in the cases of Callitriche pulchra and Tillaea vaillantii and revealed competition between Zannichellia pedunculata and Chara vulgaris. The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities. Generalised Additive Models are a powerful tool in investigating species response curves to environmental gradients. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in Mediterranean ephemeral pools. Handling editor: S. M. Thomaz     

上海海岸带及邻近岛屿植物分布特点和环境因子分析

上海海岸带及邻近岛屿发育至今,生物、非生物环境因子起着重要作用。其中,成岛年龄、高程、土壤种类、土壤养分、土壤含盐量、土壤pH值等影响着诸岛植物群落的形成、定居与演替。在多年野外调查基础上,本文以时空跨度,运用PC-ORD生态学多变量分析软件中的典范对应分析（CCA）二维排序方法,阐述了上海海岸带及邻近岛屿植物群落的植物多样性,报导了上海海域诸岛的植物种类,并对该区域多种生境下植物群落的演替现状和所适应的环境因子进行了分析,为研究分析上海海岸带及邻近岛屿植被及其整个生态系统提供了基础资料。     

甘肃祁连山国家自然保护区植物群落分布格局及其与环境因子的关系

植物群落分布格局是环境因子和人类活动共同作用的结果,尤其是海拔梯度被认为是植物群落分布格局的决定性因子,为探求甘肃祁连山国家自然保护区植物群落分布格局与环境因子的关系及其驱动机制,该文在野外调查的基础上,运用数量分类和除趋势典范对应分析(DCCA)排序等方法,探讨了研究区内植物群落特征及其与环境因子的关系。结果表明：(1)88个样方共记录物种85种,隶属30科56属,利用双向指示种分析法(TWINSPAN)将其分为9个植物群落。(2)9个植物群落在DCCA排序图上聚集分布,呈现出较好的环境梯度,其中海拔对植物群落分布格局影响最大,其次为降水、温度、坡度、坡向和土壤腐殖质。(3)影响植物群落空间分布格局的变量中,环境因子占25.24%,空间因子占13.21%,空间因子和环境因子交叉作用占9.03%,群落分布格局未被空间因子和环境因子解释部分占52.52%,这部分主要反映了人类活动对研究区植物群落分布格局的影响。该研究成果对区域内植被的生态恢复和生物多样性的稳定维持具有重要意义。     

DCCA排序轴分类及其在关帝山八水沟植物群落生态梯度分析中的应用

首次在ＤＣＣＡ排序的基础上使用排序轴分类法（ＯＡＣ）,将其发展为一个新的典范分类方法,并应用这种方法对山西关帝山八水沟的植物群落进行了数量分类,共划分出５类,效果较好。方差分析与多重比较表明,环境与群落结构因子在不同群落之间存在较为显著的差异,表明ＤＣＣＡ排序轴分类法能较好地反映群落与环境的变异。因为ＤＣＣＡ排序轴分类同时结合了植被因子与环境因子,所以它能较好地表达植物群落的环境梯度和结构梯度,反     

陕西子午岭植物群落演替过程中物种多样性变化与环境解释

采用空间代替时间的方法研究了黄土高原子午岭植物群落自然演替过程中不同层α物种多样性的变化规律,并通过CCA分析了物种多样性与环境间的关系。结果表明:(1)随演替的进展,草本层物种丰富度、均匀度及物种多样性均逐渐降低(P0.05);灌木层物种的丰富度与物种多样性均呈现相似的"J"形变化趋势,而均匀度(虎榛子(Ostryopsis davidiana)群落除外)差异不显著(P0.05);乔木层物种丰富度、均匀度以及物种多样性差异均不显著(P0.05);群落总体物种丰富度随演替进展呈现明显的单峰模型,与中期物种丰富度假说一致。(2)林冠郁闭度是影响草本层和灌木层物种组成的主要环境因子(P0.01),其次为土壤养分和坡位;而坡位对乔木层物种组成的影响极显著(P0.01),这可能与乔木树种的更新差异有关。(3)群落演替是物种扩散和环境筛综合作用的过程,物种对演替过程中变化光照资源的响应差异可能是该区不同层物种多样性变化的主要原因。     

Determinants of Benthic Diatom Community Structurein Boreal Streams: the Role of Environmental and Spatial Factors at Different Scales

Benthic diatoms were sampled at 197 sites in Finnish boreal streams. The diatom distribution patterns were related to environmental and spatial factors at three spatial scales using Canonical Correspondence Analysis (CCA). The results emphasized the predominance of chemical‐constituent concentration and ion composition on structuring benthic diatom communities in running waters. Within a river system, physical factors had notable influence on diatom community structure reflecting mainly only minor changes in water chemistry within a watershed. Partial CCA revealed that pure spatial component explained ca. 20% of explainable variation in diatom data at each of the three scales. Environmental factors captured 53–78% of explained variation in species data at ecoregion and river system level. According to Procrustean Randomization Test, spatial coordinates of the study sites and patterns in diatom community structure were strongly concordant (m² = 0.862, p = 0.001) across the largest spatial scale. Similarly, at smaller spatial scales in southern and central Finland, congruence was significant. These data support the view that diatom communities exhibit a rather strong spatial component especially at largest, national scale.     

Multi-scale segregations and edaphic determinants of marsh plant communities in a western Pacific estuary

Whether and how the roles of environmental factors in producing vegetation patterns in coastal marshes vary with spatial scale is not well understood. We investigated the relationship between plant communities and edaphic factors in the Yangtze estuary at three spatial scales. Plant communities and edaphic factors were quantified at high and low tidal levels in both freshwater and salt marshes. Canonical correspondence analyses were conducted to examine the relationship between plant communities and edaphic factors at the landscape scale (freshwater vs. salt marsh), the zonation scale (high vs. low tidal level) and the patch scale (dominant vs. other species). Soil salinity, moisture content, pH, bulk density, and organic carbon could well explain segregations of plants at the landscape and zonation scales. However, the same factors exhibited only very weak relationships to plant communities at the patch scale. These results suggest that plant communities in the Yangtze estuary are segregated at different spatial scales by different environmental factors. As spatial scale is often not explicitly addressed investigating community assembly rules, our study underscores the importance of scaling for an improved understanding of community organization in coastal wetlands.     

Identifying plant species and communities across environmental gradients in the Western Himalayas: Method development and conservation use

Phytosociological attributes of plant species and associated environmental factors were measured in order to identify the environmental gradients of major plant communities in the Naran Valley, Himalayas. The valley occupies a distinctive geographical setting on the edge of the Western Himalaya near the Hindukush range and supports a high biodiversity; pastoralism is the main land use. There have been no previous quantitative ecological studies in this region. This study was undertaken to (i) analyze and describe vegetation using classification and ordination techniques, (ii) identify environmental gradients responsible for plant community distributions and (iii) assess the anthropogenic pressures on the vegetation and identify priorities for conservation. Phytosociological characteristics of species were measured alongside environmental variables. A total of 198 species from 68 families were quantified at 144 stations along 24 transects across an elevation range of 2450–4100 m. Correspondence Analysis techniques i.e., Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) were used to determine vegetation–environment relationships. Results show vegetation changes with altitude from moist-cool temperate communities characterized by woody species, to more dry-cold subalpine and alpine herbaceous communities. Plant species diversity is optimal at middle altitudes (2800–3400 m); at lower altitudes (2400–2800 m) it is reduced by anthropogenic impacts and at higher altitudes (3400–4100 m) by shallow soils and high summer grazing pressure. A large number of plant species of conservation concern were identified in the study and an assessment made of the main threats to their survival.     

Eco-Floristic studies of native plants of the Beer Hills along the Indus River in the districts Haripur and Abbottabad,Pakistan

The present study was conducted to elaborate vegetation composition structure to analyze role of edaphic and topographic factors on plant species distribution and community formation during 2013–14. A mixture of quadrat and transect methods were used. The size of quadrat for trees shrubs and herbs were 10 × 5, 5 × 2, 1 × 1 meter square respectively. Different phytosociological attribute were measured at each station. Primary results reported 123 plant species belong to 46 families. Asteraceae and Lamiaceae were dominant families with 8 species each. PCORD version 5 were used for Cluster and Two Way Cluster Analyses that initiated 4 plant communities within elevation range of 529–700 m from sea level. Indicator species analyses (ISA) were used to identify indicator species of each community. CANOCO Software (version 4.5) was used to measure the influence of edaphic and topographic variables on species composition, diversity and community formation. Whereas Canonical Correspondence Analysis (CCA) was used to measure the effect of environmental variables which showed elevation and aspect were the stronger environmental variable among topographic and CaCO₃ contents, electric conductivity, soil pH were the stronger edaphic factors in determination of vegetation and communities of the Bheer Hills. Grazing pressure was one of the main anthropogenic factors in this regard.     

Classification and ordination of plant communities along an altitudinal gradient on the Presidential Range,New Hampshire,USA

An analysis of vegetation along an altitudinal gradient on the Presidential Range, New Hampshire, USA, using the Braun–Blanquet approach followed by multivariate data analysis is presented. Twelve main plant communities have been distinguished. Floristic information is presented in twelve tables and one appendix. The relationships of the communities to complex environmental gradients are analyzed using Correspondence Analysis. Floristic composition and community structure are controlled primarily by the altitudinal gradient (temperature, precipitation), and by mesotopographic conditions (snow accumulation, exposure and cryoturbation, slope position, and soil moisture).     

武夷山风景名胜区景观格局与环境因子的多尺度响应研究

在3S技术平台支撑下,用典范对应分析排序方法对武夷山风景区景观格局与环境因子的关系及其尺度效应进行了分析。结果表明,在6个取样尺度上(粒度分别为30 m、90 m、150 m、210 m、300 m和450 m),排序轴总特征值呈递减趋势,依次为9.626、7.814、5.708、4.019、3.386、2.310;前4轴累积景观环境解释量变化程度小(97.3%~98.8%),前2轴各尺度平均累积解释量为89.4%,景观-环境的相关系数呈先减后增趋势。6个尺度中环境因子与景观格局的平均相关系数依次为郁闭度(0.7989^**)>腐殖质层厚度(0.7248^**)>海拔(0.6083^**)>坡度(0.6132^**)>经度(-0.4064^**)>土层厚度(0.3696^**)>纬度(0.0614)>坡向(0.0295)。风景区景观类型可划分为3类,即与海拔因子密切相关的裸地、河流、建设用地、农田景观,与土壤因子密切相关的杉木林、马尾松林、阔叶林景观,以及受人类活动密切相关的茶园、经济林、竹林、灌草丛景观。因此,风景区景观格局与环境因子间的关系具有尺度效应,各环境因子对排序轴相关系数的影响规律在6个取样尺度内可尺度推绎。     

大兴安岭呼中林区粗木质残体贮量及其环境梯度

对大兴安岭呼中林区主要植被类型、兴安落叶松不同林型内粗木质残体贮量进行对比研究,并利用除趋势典范对应分析对其环境梯度进行定量分析.结果表明：云杉林粗木质残体贮量较高,为0.20 m³·hm^-2,且不同植被类型之间呈显著性差异;兴安落叶松不同林型粗木质残体贮量在0～0.28 m³·hm^-2,其中偃松群落最高,为0.28 m³·hm^-2,泥炭藓-杜香-落叶松林最低（0）,且各林型之间差异不显著.粗木质残体贮量分布格局较复杂,受多因素交叉影响;海拔、坡位等地形因子和林分年龄、郁闭度等林分条件是影响森林粗木质残体贮量的主要环境因子,二者综合作用表达了该地区森林粗木质残体贮量的空间生态梯度.