Vegetation ordination of subalpine meadows using adaptive strategies

1983 ◽  
Vol 61 (12) ◽  
pp. 3117-3127 ◽  
Author(s):  
Roger Del Moral
Keyword(s):  
Indicator Species ◽  
Environmental Gradients ◽  
Detrended Correspondence Analysis ◽  
Niche Differentiation ◽  
Habitat Types ◽  
Relative Growth ◽  
Subalpine Meadows ◽  
Morphological Index ◽  
Sedge Meadows ◽  
Vegetation Ordination

The vegetation of subalpine meadows was investigated by several multivariate analytical methods. Detrended correspondence analysis (DCA) revealed overall patterns of vegetation response to environmental gradients and identified many indicator species. Binary discriminant analysis confirmed these interpretations and identified indicator species with more clarity than did DCA. A plant strategy ordination was developed from a morphological index of competitiveness and from a relative growth rate index. Results converge to these conclusions: (i) the strategy ordination was consistent with habitat types and DCA; (ii) the degree of species niche differentiation within a community varied with productivity and disturbance; (iii) morphological and physiological niche differentiation is least in productive sedge meadows and greatest in mesic grasslands where production and disturbance are moderate. The adaptation spectra of species in a community provide useful insights about site conditions, history, and response to manipulations.

scholarly journals Environmental gradients across wetland vegetation groups in the arid slopes of Western Alborz Mountains, N. Iran

2011 ◽  
Vol 79 (4) ◽  
pp. 295-304
Author(s):  
Asghar Kamrani ◽  
Alireza Naqinezhad ◽  
Adel Jalili ◽  
Farideh Attar
Keyword(s):  
Organic Matter ◽  
Environmental Factors ◽  
Indicator Species ◽  
Aquatic Vegetation ◽  
Environmental Gradients ◽  
Detrended Correspondence Analysis ◽  
Wetland Vegetation ◽  
Wet Meadow ◽  
Factors Affecting ◽  
Alborz Range

Mountain wetlands are unique ecosystems in the arid southern slopes of Alborz range, the second largest range in Iran. The spatial distribution characteristics of wetland vegetation in the arid region of the Alborz and the main factors affecting their distributional patterns were studied. A classification of vegetation and ecological characteristics were carried out using data extracted from 430 relevés in 90 wetland sites. The data were analyzed using Two Way Indicator Species Analysis (TWINSPAN) and detrended correspondence analysis (DCA). The wetland vegetation of Alborz Mountain was classified into four large groups. The first vegetation group was calcareous rich vegetation, mainly distributed in the river banks and characterized by helophytes such as <em>Bolboschoenus affinis</em> as indicator species. The second group was saline transitional vegetation, distributed in the ecotone areas and dominated by <em>Phragmites australis</em>. The third vegetation group is wet meadow vegetation which mainly consists of geophytes, endemic and Irano-Turanian species, distributed in the higher altitudes. This vegetation is mainly characterized by indicator species such as <em>Carex orbicularis</em>, high level concentration of Fe<sup>2+</sup> and percentage of organic matter in the soil. The fourth vegetation group is aquatic vegetation, distributed in the lakeshores. The aquatic group species are mainly hydrophytic such as <em>Batrachium trichophyllum</em>. The TWINSPAN vegetation groups could be also recognized in the DCA graphs and ecologically differentiated by ANOVA of studied variables. Four vegetation groups can be differentiated on two first axes of indirect ordination. There is a gradient of pH, EC and organic matter associated with altitude on the DCA diagram. Correlation analysis between the axes of DCA and environmental factors shows that altitude, soil texture and other dependant environmental variables (e.g. pH) are the main environmental factors affecting the distribution of wetland vegetation groups.

scholarly journals Effects of habitat types and within lake environmental gradients on the diversity of chironomid assemblages

Limnologica ◽  
2015 ◽  
Vol 53 ◽  
pp. 26-34 ◽  
Author(s):  
Diána Árva ◽  
András Specziár ◽  
Tibor Erős ◽  
Mónika Tóth
Keyword(s):  
Environmental Gradients ◽  
Habitat Types ◽  
Chironomid Assemblages

scholarly journals A vegetation survey of the Tsitsikamma Coastal National Park

Koedoe ◽  
1989 ◽  
Vol 32 (1) ◽  
Author(s):  
N. Hanekom ◽  
A. Southwood ◽  
M. Ferguson
Keyword(s):  
Correspondence Analysis ◽  
Indicator Species ◽  
National Park ◽  
Detrended Correspondence Analysis ◽  
Indicator Species Analysis ◽  
Vegetation Survey ◽  
Afromontane Forest ◽  
Species Analysis ◽  
North And South

Sampling plots (5 m x 10 m in fynbos, 10 m x 10 m in forest) were analysed in the littoral, coastal escarpment, and north and south facing inland escarp- ment zones of 17 transect sites along the length of the Tsitsikamma Coastal National Park. Cover- abundance values were estimated for each species in the sampling plots. A detrended correspondence analysis (using CANOCO) and a two way indicator species analysis (TWINSPAN) were carried out on these data to determine the communities sampled. The vegetation of the park was classified into an Afromontane Forest, a Littoral Herbland and two Mesic Mountain Fynbos Communities. The distribution and extent of these communities were determined and their conservation discussed.

Diversity of subalpine and alpine vegetation of the eastern part of the Nízke Tatry Mts in Slovakia: major types and environmental gradients

Biologia ◽  
2009 ◽  
Vol 64 (5) ◽  
Author(s):  
Lucia Sekulová ◽  
Michal Hájek
Keyword(s):  
Plant Communities ◽  
Environmental Gradients ◽  
Ecological Factors ◽  
Detrended Correspondence Analysis ◽  
Dwarf Shrub ◽  
Soil Reaction ◽  
Data Set ◽  
Entire Data ◽  
Second Gradient ◽  
One Year

AbstractChanges in composition and structure of alpine and subalpine plant communities in relation to ecological factors were analysed in the Nízke Tatry Mts, Slovakia. Species cover values of vascular and non-vascular plants in each vegetation plot were recorded on the nine-degree scale. A data set of 156 relevés of alpine and subalpine vegetation was sampled recently during one year in the eastern part of the Nízke Tatry National Park. The data set was analysed by cluster analysis and Detrended Correspondence Analysis. analyses were carried out on the entire data set, including the subset of short grassland and dwarf-shrub vegetation. Major gradients and clusters were ecologically interpreted using Ellenberg indicator values. In the entire data set, the major gradient in species composition was associated with nutrient availability and the second most important gradient with light. In the case of short grassland and dwarf-shrub vegetation, the gradients were different. The first one was associated with soil reaction and the second gradient was associated with moisture. Clusters proposed by numerical classification reproduced many traditional phytosociological associations, namely Seslerietum distichae, Sphagno capillifolii-Empetretum nigri, Junco trifidi-Callunetum vulgaris, Juncetum trifidi, Dryopterido dilatatae-Pinetum mugo, Luzuletum obscurae, Agrostio pyrenaiceae-Nardetum strictae, while some other associations were less clearly differentiated (communities of the alliances Calamagrostion villosae, Adenostylion alliariae, Trisetion fusci, Cratoneuro filicini-Calthion laetae or Salicion herbaceae). The next clusters included Vaccinium and Festuca supina dominated communities and artificial roadside grasslands sown 50 years ago. Bryophytes and lichens were highly represented among diagnostic species of particular associations. Distribution pattern of particular plant communities was strongly influenced by site position either on northern or southern slope of the mountains.

scholarly journals Uncovering the Horseshoe Effect in Microbial Analyses

mSystems ◽  
2017 ◽  
Vol 2 (1) ◽  
Author(s):  
James T. Morton ◽  
Liam Toran ◽  
Anna Edlund ◽  
Jessica L. Metcalf ◽  
Christian Lauber ◽  
...  
Keyword(s):  
Dimensionality Reduction ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Niche Differentiation ◽  
Distance Metrics ◽  
Reduction Techniques ◽  
Dimensionality Reduction Techniques ◽  
High Level ◽  
Community Dissimilarity ◽  
Microbiome Data

ABSTRACT The horseshoe effect is often considered an artifact of dimensionality reduction. We show that this is not true in the case for microbiome data and that, in fact, horseshoes can help analysts discover microbial niches across environments. The horseshoe effect is a phenomenon that has long intrigued ecologists. The effect was commonly thought to be an artifact of dimensionality reduction, and multiple techniques were developed to unravel this phenomenon and simplify interpretation. Here, we provide evidence that horseshoes arise as a consequence of distance metrics that saturate—a familiar concept in other fields but new to microbial ecology. This saturation property loses information about community dissimilarity, simply because it cannot discriminate between samples that do not share any common features. The phenomenon illuminates niche differentiation in microbial communities and indicates species turnover along environmental gradients. Here we propose a rationale for the observed horseshoe effect from multiple dimensionality reduction techniques applied to simulations, soil samples, and samples from postmortem mice. An in-depth understanding of this phenomenon allows targeting of niche differentiation patterns from high-level ordination plots, which can guide conventional statistical tools to pinpoint microbial niches along environmental gradients. IMPORTANCE The horseshoe effect is often considered an artifact of dimensionality reduction. We show that this is not true in the case for microbiome data and that, in fact, horseshoes can help analysts discover microbial niches across environments.

Autecology of Erythronium grandiflorum in western Canada

2001 ◽  
Vol 79 (4) ◽  
pp. 500-509 ◽  
Author(s):  
Dawn C Loewen ◽  
Geraldine A Allen ◽  
Joseph A Antos
Keyword(s):  
Canopy Cover ◽  
Detrended Correspondence Analysis ◽  
Coniferous Forests ◽  
Deciduous Trees ◽  
Growth Stages ◽  
Western Canada ◽  
Percent Cover ◽  
Subalpine Meadows ◽  
Associated Species ◽  
Erythronium Grandiflorum

Habitat requirements of the yellow glacier lily, Erythronium grandiflorum Pursh, were studied at 38 sites in southern British Columbia and southwestern Alberta. At each site we recorded densities of E. grandiflorum growth stages from seedling to flowering, environmental characteristics of the site, and percent cover of associated plant species. We carried out detrended correspondence analysis (DCA) of the sites based on cover of associated species, and examined rank correlations between site environmental variables and site ordination scores. Variation among sites was related primarily to elevation and the presence of deciduous vs. coniferous trees. All growth stages of E. grandiflorum were less abundant in coniferous forests than in open areas or sites with deciduous trees, suggesting that evergreen canopies restrict the species on many sites where it could otherwise grow. Although E. grandiflorum populations were most commonly found in subalpine meadows, they flowered more abundantly in low-elevation populations. Recruitment was frequent, with seedlings occurring at many sites; we also showed that detached bulb segments can give rise to new ramets. The present widespread distribution of E. grandiflorum may derive from a post-glacial period with extensive meadow habitat that was favourable for rapid spread.Key words: canopy cover, elevation, yellow glacier lily, post-glacial migration, subalpine meadows.

The contemporary moss assemblages of a high arctic upland, northern Ellesmere Island, N.W.T., Canada

1989 ◽  
Vol 67 (2) ◽  
pp. 491-504 ◽  
Author(s):  
Catherine LaFarge-England
Keyword(s):  
Environmental Gradients ◽  
Specific Conductivity ◽  
Detrended Correspondence Analysis ◽  
Distribution Patterns ◽  
High Arctic ◽  
Organic Content ◽  
Ellesmere Island ◽  
Physical Parameters ◽  
Major Species ◽  
Species Groups

A quantitative analysis of contemporary moss assemblages is presented for a fault block at the southern end of Piper Pass, northern Ellesmere Island, N.W.T. (82°12′N, 68°31′W). Twenty-eight stands are analyzed using the two-way indicator species analysis, resulting in seven major species groups and five major stand groups. Physical parameters correlated with the stand data show soil moisture and slope to be the most important factors influencing the distribution of moss assemblages. Sodium, organic content, and specific conductivity are also correlated with the vegetation data. Detrended correspondence analysis confirms these stand relationships. The interdependence of physical, chemical, and vegetation data is also discussed. Distribution patterns of the species groups within the stand groups are analyzed by means of a percent frequency diagram. A direct gradient analysis of the vegetation below a late-lying snowbank also demonstrates the selective distribution of species in terms of environmental gradients.

The demography of a dominant Amazon liana species exhibits little environmental sensitivity

2015 ◽  
Vol 32 (1) ◽  
pp. 79-82 ◽  
Author(s):  
Luciana de Campos Franci ◽  
Jens-Christian Svenning ◽  
Henrik Balslev ◽  
Fernando Roberto Martins ◽  
Jacob Nabe-Nielsen
Keyword(s):  
Dominant Species ◽  
Environmental Gradients ◽  
Floristic Composition ◽  
Environmental Variation ◽  
Common Species ◽  
Amazon Forest ◽  
Vegetation Density ◽  
Vital Rates ◽  
Relative Growth ◽  
Positive Effect

Abstract:Despite its high plant diversity, the Amazon forest is dominated by a limited number of highly abundant, oligarchic tree and liana species. The high diversity can be related to specific habitat requirements in many of the less common species, but fewer studies have investigated the characteristics of the dominant species. To test how environmental variation may contribute to the success of dominant species we investigated whether the vital rates of the abundant liana Machaerium cuspidatum is sensitive to canopy height, topographic steepness, vegetation density, soil components and floristic composition across an Ecuadorian Amazon forest. The population was inventoried in 1998 and in 2009. Plants were divided into seedling-sized individuals, non-climbers and climbers. Out of 448 seedling-sized plants 421 died, 539 of 732 non-climbers died, and 107 of 198 climbers died. There was weak positive effect of dense understorey on the relative growth rate of climbers. The mortality of seedling-sized plants was higher in areas with intermediate slope, but for larger plants mortality was not related to environmental variation. The limited sensitivity of the vital rates to environmental gradients in the area suggests that ecological generalism contributes to the success of this dominant Amazonian liana.

scholarly journals Grassland communities of Stol mountain (eastern Serbia ): Vegetation and environment al relationships

2013 ◽  
Vol 65 (1) ◽  
pp. 211-227 ◽  
Author(s):  
Svetlana Acic ◽  
U. Silc ◽  
S. Vrbnicanin ◽  
Svjetlana Cupac ◽  
G. Topisirovic ◽  
...  
Keyword(s):  
Species Composition ◽  
Environmental Gradient ◽  
Environmental Gradients ◽  
Detrended Correspondence Analysis ◽  
Ecological Indicator ◽  
Vegetation Types ◽  
Indicator Values ◽  
Grassland Vegetation ◽  
Data Set ◽  
Grassland Communities

The systematic survey of grassland communities was performed on Mt. Stol (eastern Serbia). The main aims of the research were to: (1) determine grassland vegetation types of the researched area; (2) correlate the impacts of the soil and environmental conditions on the occurrence of certain plant communities, and (3) comment on the conservational value of the grasslands in the researched area. The data set included 60 phytosociological relev?s of grasslands recorded between 2001 and 2004. The main environmental gradients of species composition were analyzed by Detrended Correspondence Analysis (DCA). For the ecological interpretation of ordination axes, ecological indicator values were used. Three associations were distinguished: Danthonietum calycinae, Asperulo-Agrostietum vulgaris and Ranunculo bulbosi- Arrhenatheretum elatioris belonging to two alliances and two classes: Chrysopogono-Danthonion - Festuco-Brometea and Arrhenatherion - Molinio-Arrhenatheretea. The results of the DCA support our assumption that the main environmental gradient in the species composition of the grasslands is related to nutrients and moisture. The conservational value of grasslands in the researched area is discussed.

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