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Modified TWINSPAN classification in which the hierarchy respects cluster heterogeneity
Abstract
Aim: To propose a modification of the TWINSPAN algorithm that enables production of divisive classifications that better respect the structure of the data.
Methods: The proposed modification combines the classical TWINSPAN algorithm with analysis of heterogeneity of the clusters prior to each division. Four different heterogeneity measures are involved: Whittaker's beta, total inertia, average Sørensen dissimilarity and average Jaccard dissimilarity. Their performance was evaluated using empirical vegetation datasets with different numbers of plots and different levels of heterogeneity.
Results: While the classical TWINSPAN algorithm divides each cluster coming from the previous division step, the modified algorithm divides only the most heterogeneous cluster in each step. The four tested heterogeneity measures may produce identical or very similar results. However, average Jaccard and Sørensen dissimilarities may reach extreme values in clusters of small size and may produce classifications with a highly unbalanced cluster size.
Conclusions: The proposed modification does not alter the logic of the TWINSPAN classification, but it may change the hierarchy of divisions in the final classification. Thus, unsubstantiated divisions of homogeneous clusters are prevented, and classifications with any number of terminal clusters can be created, which increases the flexibility of TWINSPAN.
... The floristic data was captured using the BBPC-program (Bezuidenhout et al. 1996). The data was exported to JUICE (Tichý 2002) from where a first approximation of the plant communities was derived using the modified TWINSPAN (Two-way Indicator Species Analysis) classification algorithm proposed by Roleček et al. (2009). The phi coefficient of association in Juice Programme (Chytrý et al. 2002) was used to determine the fidelity of each community. ...
... The floristic data was captured using the BBPC-program (Bezuidenhout et a data was exported to JUICE (Tichý, 2002) from where a first approximation communities was derived using the modified TWINSPAN (Two-way Indic Analysis) classification algorithm proposed by Roleček et al. (2009). The phi association in Juice Programme (Chytrý et al. 2002) was used to determine each community. ...
... Analysis) classification algorithm proposed by Roleček et al. (2009). The phi coefficient of association in Juice Programme (Chytrý et al. 2002) Entropies such as the Shannon Wiener and Gini/Simpson indices are not considered true diversities and therefore conversion of these to effective number of species is the key to a unified and intuitive interpretation of diversity (Jost 2006). ...
... Numerical classification of the dataset was performed using the modified TWINSPAN method as proposed by Roleček et al. (2009) [61] to classify the data based on the abundance of species in the 36 relevés in the JUICE version 7.1.24 [62]. ...
... Numerical classification of the dataset was performed using the modified TWINSPAN method as proposed by Roleček et al. (2009) [61] to classify the data based on the abundance of species in the 36 relevés in the JUICE version 7.1.24 [62]. ...
The relict communities of Alnus glutinosa on the southern range edge of its biogeographical distribution in the southern
Mediterranean are vital for biodiversity conservation but are threatened by human activities and climate change. To develop effective management and conservation strategies, a comprehensive understanding of their floristic composition and plant community dynamics is essential. We conducted field surveys across the Rif Mountains, collecting 36 vegetation relevés from 11 populations. Our analysis revealed a rich diversity, with 219 vascular plant species belonging to 74 botanical families. Noteworthy findings include the presence of 14 regional endemics and 28 red-listed species. Herbaceous species dominated the communities accounting for 68.5 % of the recorded species, with hemicryptophytes being prevalent among the life forms, comprising 28%of the total species. Phytogeographical analysis indicated a predominance of native species (96 %), with 8% classified as alien. The Mediterranean broad-ranging chorotype was the most common (31.5 %), followed by Paleartic (30.6 %), global (19.2 %), extended (12.3 %), and regional (6.4%) chorotypes. TWINSPAN classification identified two distinct plant communities, influenced primarily by altitude and their associated climatic conditions, as well as anthropogenic factors. Syntaxonomical analysis revealed distinct characteristics of black alder communities, predominantly associated with the Osmundo-Alnion glutinosae alliance. These communities exhibit two main clusters, differentiated by species composition and environmental variables. Our findings highlight the importance of local abiotic and anthropogenic factors in shaping black alder communities in Morocco. It is therefore imperative to implement targeted conservation efforts to preserve these unique and ecologically valuable black alder communities in the southern Mediterranean.
... The two datasets were analysed separately in the JUICE software (Tichý 2002). A modified TWINSPAN analysis (Roleček et al. 2009) was performed on the pistachio open woodlands relevé group (90 relevés from Tajikistan and 20 from Iran) in order to classify them with the use of cutoff levels of 0%, 2%, 10% and 25%. Total inertia was used as a measure of cluster heterogeneity (Roleček et al. 2009). ...
... A modified TWINSPAN analysis (Roleček et al. 2009) was performed on the pistachio open woodlands relevé group (90 relevés from Tajikistan and 20 from Iran) in order to classify them with the use of cutoff levels of 0%, 2%, 10% and 25%. Total inertia was used as a measure of cluster heterogeneity (Roleček et al. 2009). Plant species determined only to the genus level were omitted before the analysis. ...
Aims: To analyse the syntaxonomy of open, deciduous woodlands at the southern margin of the steppe zone in the colline and montane belts of the Pamir-Alai, western Tian Shan and Iranian Mountains (Irano-Turanian region). Study area: Tajikistan (Middle Asia) and Iran (Southwestern Asia). Methods: We prepared two datasets: the first dataset contained 110 relevés from Tajikistan and Iran representing pistachio groves, the second one was a comparative dataset of 1,276 relevés of pistachio groves and floristically related woody and grassland phytocoenoses from the Irano-Turanian and Mediterranean regions. These two datasets were classified separately with the modified TWINSPAN algorithm with pseudospecies cut levels 0%, 2%, 10% and 25%, and total inertia as a measure of cluster heterogeneity. Diagnostic species were identified using the phi coefficient as a fidelity measure. A NMDS ordination was used to explore the relationships between the distinguished groups. Results: We found that Pistacia open woodlands are very distinctive in terms of species composition, including numerous endemics. Our observations in Pamir-Alai, Kopet-Dagh, Zagros, Alborz and other Central and southern mountains of Iran proved that pistachio open woodlands form distinct zonal vegetation of the colline-montane belt. We thus propose a new class Pistacietea verae, with the order Pistacietalia verae and appropriate type alliance Pistacion verae, including two associations: Pistacietum verae and Pistacietum khinjuk. Conclusions: Our research has shown that the Pistacia open woodlands are a distinct vegetation typical of the Irano-Turanian region and due to its specific ecology, phytogeography and unique species composition, should be regarded as a vegetation class Pistacietea verae. It needs further examination and comparison with similar vegetation in the western Irano-Turanian and Hindu Kush regions. Recognizing the unique pistachio open woodlands as a distinct vegetation class in the Irano-Turanian region is crucial for establishing effective conservation strategies in these understudied yet ecologically significant ecosystems, spanning potentially from the Zagros, Alborz and other Central and southern Mountains of Iran to Tajikistan, Afghanistan, Uzbekistan, and Pakistan.
Taxonomic reference: Plants of the World Online (POWO 2023), with World Flora Online (WFO 2023) for some problematic cases and Nobis et al. (2020) for Stipa spp.
Syntaxonomic references: Mucina et al. (2016) for SE European syntaxa, Nowak et al. (2022a, 2022b) for all other syntaxa.
Abbreviations: NMDS = Non-metric multidimensional scaling.
... DCA ordination and DCCA ordination are multivariate analysis techniques used to study the relationship between vegetation and the environment [29,31]. In the present study, the DCA ordination and DCCA ordination of the quadrats and environmental factors (elevation, slope, aspect, and slope position) were performed using CANOCO 4.5 software, and then, the ordination diagram was drawn using CanoDraw for Windows 4.5 [29]. ...
... TWINSPAN quantitative classification is based on indicator species. Generally, five main dominant species are selected as important indicator species to objectively classify vegetation communities using TWINSPAN [28,31]. The method of DCA ordination was proposed by Hill and Gauch after research based on a correspondence analysis [34]. ...
Fire is a common natural disturbance in forest ecosystems and plays an important role in subsequent vegetation patterns. Based on the spatial sequence method, adopted as an alternative to the time successional sequence method, we selected burned areas in different locations in the Anning River Basin, which encompasses typical dry valleys. Quadrat surveys and quantitative classification were used to identify and classify the vegetation and distribution pattern and to carry out environmental interpretation during the natural restoration process after a forest fire. The results showed the following: (1) in the early stage of natural recovery after a forest fire disturbance, the vegetation community could be divided into seven community types, and Quercus guyavaefolia H. Leveille (Qg) was the dominant species in the community; (2) the vegetation samples could be divided into five ecological types, and the classification and distribution pattern of community types in this region changed most notably with altitude; and (3) a detrended correspondence analysis could be used to accurately classify vegetation community types, while a detrended canonical correspondence analysis could reveal the relationships between species and environmental factors. This study provides a scientific basis for guiding the restoration of ecosystem structural stability and biodiversity in burned areas.
... Species covers were square-root transformed prior to the analyses . The classification of the Euxinian Dataset was conducted using Modified TWINSPAN (Roleček et al. 2009) with Whittaker's beta as a measure of heterogeneity of the clusters and three pseudospecies cover cut levels (0, 5, 25%). To select diagnostic species, species-tocluster fidelity was expressed by a phi coefficient (Sokal & Rohlf 1995) based on virtually equalized clusters (Tichý & Chytrý 2006). ...
Zelkova (Ulmaceae) represents a relict woody genus comprising six extant species with a disjunctive distribution in eastern and southwestern Eurasia. Zelkova carpinifolia is a deciduous tree limited to the Caucasian Ecoregion and its surroundings. Most of its sites are located in the two essential Tertiary
refugia of the Northern Hemisphere – Colchis (western Georgia, northeastern Turkey) and Hyrcania (northern Iran, southeastern Azerbaijan). In Georgia, Z. carpinifolia stands are recognized as a national priority habitat. However, data on their environmental conditions, structure and species composition were partial, sometimes contradicting and scattered in the literature. Our main goal was to describe Georgian Colchic Z. carpinifolia forests based a novel dataset of vegetation-plot records and to present them in the broader vegetation context using available phytosociological data. To address this issue we led a phytosociological survey of Z. carpinifolia forests in Georgian Colchis and obtained 35 vegetation-plot records supplemented by the original field data on slope inclination, aspect and soil pH. To explore Z. carpinifolia stands within the broader regional vegetation context, we combined our new dataset with relevés of similar vegetation types from northern Iran, northern Turkey and western Georgia extracted from databases and literature. We classified the vegetation datasets using classification algorithms (beta-flexible clustering and Modified TWINSPAN) and examined the resulting clusters with detrended correspondence analysis (DCA) in terms of diagnostic species and selected environmental variables. Colchic Z. carpinifolia forests exhibited a relatively uniform species composition and structure, with Carpinus orientalis and Quercus robur subsp. imeretina representing the most frequent canopy companions of Z. carpinifolia. The evergreen submediterranean species Ruscus aculeatus often dominated the understory, accompanied by forest generalists, while herbs of dry forests and evergreen species were also frequent. The average vascular plant richness was 24.7 species per 100 m2. The investigated forests mainly inhabited soils of slightly acidic to subneutral reaction (average pH 6.2). A numerical comparison of Colchic and Hyrcanian Z. carpinifolia forests revealed significant
differences: The Hyrcanian ones were much more mesophilous, with Hyrcanian endemics and forest esophytes being diagnostic species. The underlying causes of this ecological discrepancy remain unclear. In the context of dry deciduous forests of the Euxinian Province, Colchic Z. carpinifolia forests were most similar to the Colchic-Caucasian association Campanulo alliariifoliae-Carpinetum orientalis
described from western Georgia. However, Z. carpinifolia stands formed their own sharply delimited cluster, indicating deeper differences than just the canopy dominance. Based on the classification results, we described a new alliance Smilaco excelsae-Carpinion orientalis for the Colchic-Caucasian lowland and mid-mountain dry and xeromesophilous deciduous forests. A mixture of species characteristic of the Caucasus and Colchis is diagnostic for this alliance, including Campanula alliariifolia, Klasea quinquefolia, Polygonatum glaberrimum, Quercus robur subsp. imeretina, Vinca major subsp. hirsuta, Z. carpinifolia. Colchic Z. carpinifolia stands face numerous threats, especially overgrazing by cattle, invasions of alien species and infrastructure development.
... en, depending on the characteristics of the data, the interpretability of the results and the history of the survey of the particular vegetation type, different methods were implemented for clustering of the dataset, including mainly hierarchical unsupervised or semi-supervised classification. Among others, we used modified TWINSPAN analysis with down-weighting of rare species and the use of chord distance as a measure of cluster heterogeneity (Hill, 1979;Roleček et al., 2009). For pseudosteppe, fen, mire, and spring vegetation classification, we performed an unsupervised or semi-supervised k-means analysis with Hellinger transformation of species percentage cover values (see Naqinezhad et al., 2021;Świerszcz et al., 2020). ...
Vegetation classification is a tool for organizing the patterns and diversity of plant communities. It is used in nature conservation, and helps to understand the role of vegetation in the biosphere. Given the rapidly diminishing opportunity to understand the vegetation diversity of Tajikistan located in the Middle Asian region, phytosociological surveys using the floristic-ecological approach and the Braun-Blanquet cover-abundance scale were undertaken in 2006. Aer 18 years of research, with a total of 55 research expeditions to Tajikistan, Kyrgyzstan, and Uzbekistan, it is time to summarise and make a first attempt to establish a comprehensive classification system for the entire vegetation of Tajikistan and the surrounding areas. As a first step, the Vegetation of Middle Asia (VMA) database with records from three countries: Tajikistan (4,130 relevés), Kyrgyzstan (1,681 relevés) and Uzbekistan (13 relevés) was created. e internal comparison of all the plots and the analysis of the similarities with the vegetation of Iran, Russia, Afghanistan, Mongolia, Pakistan, and China make it possible to present the comprehensive list of plant communities organized in 45 classes, 47 orders, 83 alliances, 297 associations, and 237 rankless units. In addition to those described in our previous works, we propose also several new sytaxa: Eremogono griffithii-Nepetetea podostachyos, Artemisio persicae-Stipetea drobovii, Festucetea alaico-krylovianae, Carici koshewnikowii-Asperuletea oppositifoliae, Trichodesmo incani-Pachypterygietea brevipes, Aceretalia turkestanici, Juniperetalia seravschanicae, Crataegetalia ponticae, Populetalia pruinoso-euphraticae, Salici capusii- Hippophaeetalia rhamnoidis, Carici stenophylloidis-Stipetalia drobovii, Eritrichion pamirico-subjacquemontii, Stipetum kazachstanicae, Caricetum pamirensis , and Bolboschoenetum affinis . Tis systematic compilation of data, based on our fieldwork and literature data, is not definitive, and certainly the rich and diverse vegetation of Middle Asia requires further studies incorporating also modern LIDAR and satellite techniques.
... Обработка данных проводилась в соответствии с принципами эколого-флористической классификации [18] с помощью пакетов программ TURBOVEG 2.0 [11] и JUICE [15]. Для первичной обработки геоботанических описаний использован алгоритм TWIN-SPAN [13]. ...
... The two-way indicator species analysis of the species plot matrix (TWINSPAN) method divides all samples and species into two main categories, 0 and 1, and then divides each of these two main categories into two categories until the required level of division is reached. The five levels of pseudo-species chosen per species were 0-2, 2-5, 5-10, 10-20, and >20, using the R software TwinspanR package 0.2.2 [27]. ...
Thinning plays a key role in regulating the stand spatial structure (SpS) to improve the development of stand quality, and the stand has different characteristics of stand structure (SS) at different growth and development stages (DSs), so it is most important to reasonably determine the stage of growth and development of the stand to optimize the stand structure. We applied the TWINSPAN two-way indicator species analysis method to classify the different development stages of mixed hard broadleaf forests. We provided a comprehensive stand spatial structure optimization model for three selected plots at different development stages, respectively, to optimize the SpS. The results demonstrated the classified DS of 29 mixed hard broadleaf plots for three forest stages: the establishment stage, competitive stage, and quality selection stage. We then applied the SpS optimization model to our three plots; the Q(x) increased by 124.04%, 333.74%, and 116.83% when compared with those with no harvest, in which, upon the removal of 10% of the trees from the three plots, the maximum RIP values were all observed. Our results indicated that the SpS optimization model could regulate the SS for different growth stages and DSs.
... Data were recorded in an Excel spreadsheet and subsequently imported into the vegetation classification software package JUICE 7.1. The modified TWINSPAN algorithm was then used, which clusters species based on their internal heterogeneity, to delineate the distinct plant communities [27]. A phytosociological table was generated, and plant community names were assigned following the guidelines outlined in [13]. ...
Swahili coastal forests, spanning the Kenyan and Tanzanian coastlines and the Zanzibar Archipelago, are integral to the biodiverse Eastern Arc and Coastal Forest region. These forest ecosystems face considerable anthropogenic threats. This study contributes to the available knowledge on the floral composition and plant community assemblages of Mnemba Island, a small sandy cay in the Zanzibar Archipelago, which helps to establish baseline data for conservation purposes. Two main coastal forest plant communities were identified: (1) the Casuarina cunninghamiana–Suriana maritima open to closed sandy dry coastal forest, and (2) the Eugenia capensis–Mimusops obtusifolia coastal forest. A total of 91 different plant species belonging to 54 plant families were identified for the island. Community 2, an indigenous forest, supports diverse bird breeding colonies and is a crucial habitat for the threatened Aders’ duiker. Understory development is limited due to the historical Suni antelope overpopulation. Environmental factors like salt spray, allelochemicals, herbivore browsing, and climate fluctuations influence the vegetation abundance and composition. The study underscores differences in species diversity and composition between the planted Casuarina community and the natural atoll vegetation. The natural vegetation shows affinities with the Zanzibar–Inhambane edaphic coral-rag scrub forest and the transitional rainforest. Several species characteristic of Indian Ocean atolls were identified, providing insights into invasion ecology and conservation strategies. The study contributes conceptually to our understanding of vegetation dynamics in island ecosystems by highlighting the interplay between plant communities, environmental processes, and human activities. The fragile yet resilient nature of Mnemba’s unique ecosystem is emphasised, offering insights for conservation management, long-term monitoring, and adaptive approaches tailored to island environments.
... Due to the large diversity included in T1, we created subgroups based on their assigned EUNIS codes at level III, e.g., all Alnus-, Salixand Populus-dominated forests were merged in a 'riparian forests' subgroup, both acid and base-rich soil beech forests were merged in one single 'beech forest' and all acid soil Quercus-dominated forests were merged in one 'acidophilous Quercus forests'. We re-classified these groups using the modified Two-Way Indicator Species Analysis (TWINSPAN; Roleček et al., 2009) with three pseudospecies cut levels (0, 15, 25), a minimum group size of 10 relevés, a maximum of 10 final clusters and Sørensen average dissimilarity. We used the NbClust R Package (Charrad et al., 2014) as a guidance for determining the optimum number of clusters within each group, according to the Silhouette, Dunn, Duda, Cindex and Hartigan validity indices. ...
Aims: (i) To classify forest habitat diversity in the Cantabrian Mixed Forests ecoregion, a putative biodiversity refugium in Western Europe, and (ii) to evaluate how the distribution of functional and ecological habitat types is explained by climatic drivers.
Location: Cantabrian Mixed Forests ecoregion (northwestern Iberian Peninsula).
Methods: We compiled a vegetation database for the ecoregion using data stored in the Iberian and Macaronesian Vegetation Information System (SIVIM). Then, we used the EUNIS Habitat Classification expert system, the modified Two-Way Indicator Species Analysis (TWINSPAN) and the semi-supervised k-means classification to classify all Forest plots into regionalised EUNIS habitat types. We determined the environmental space of each ecological forest type with bioclimatic and soil variables, and computed principal components analysis (PCA), generalised linear models (GLMs) and PERMANOVA to evaluate climatic differences among forests.
Results: We identified 24 ecological forest habitat types (12 broadleaved deciduous , seven broadleaved evergreen and five coniferous), whose regional distribution is mainly driven by the oceanic influence and the amount and seasonality of annual precipitation. Most forest types had a specific climatic optimum, but there were also climatic overlaps in habitats traditionally favoured by human activities.
Conclusions: The Cantabrian Mixed Forests ecoregion is a hotspot of forest diversity within the temperate deciduous forest biome in Europe, including multiple functional and ecological forest types. Such forest diversity is explained by present macro-and mesoclimatic heterogeneity, Pleistocene refugia, and the legacy of human intervention during the Holocene.
... The following parameters were calculated and analyses were performed: In order to compare species composition of firebreak sites with adjacent grasslands, vegetation classification was carried out using JUICE [39]. A Modified TWINSPAN classification [40] analysis was performed. Thereafter, Braun-Blanquet procedures [34] were used to refine the table in both JUICE and Excel for the final classification. ...
Southern African grasslands with a rich flora, shaped by fire, grazing, climate and geology, as well as playing a role in carbon sequestration, are becoming more important in conservation. Fire is often used as a management tool to improve vegetation and to protect property against uncontrolled fire. We therefore attempt to determine the effect consecutive burning has on vegetation. Paired plots along firebreaks were used to collect vegetation data using the Braun-Blanquet cover abundance scale. Soil samples were also collected to determine the impact of fire on below-ground nitrogen (N) and carbon (C) stocks and ratios. The results indicate that there is no difference between the plant communities of the firebreaks and the adjacent grassland; however, there are certain species that are favoured by firebreaks and others by the adjacent grassland. There is also no difference in diversity between the firebreaks and adjacent grassland areas. Carbon and nitrogen stocks as well as C:N ratios did not differ significantly between the firebreaks and the adjacent grassland plots although trends indicate a decline in both C and N with repeated burning.
... In order to homogenise the vegetation dataset, two relevés of shrub and forest vegetation were excluded before the statistical analyses. Numerical classification was performed with species merged into a single layer using the modified TWINSPAN algorithm (Roleček et al. 2009). We used five pseudospecies cut levels (0%, 5%, 25%, 50% and 75%) and total inertia as a measure of cluster heterogeneity. ...
Iris sibirica is a threatened plant species of the Central European flora, but its distribution and vegetation ecology in Slovakia have not been studied so far. Therefore, we aimed to compile a complex chorology of this species and to analyse phytosociological plots with the species occurrence. Our results suggest that Iris sibirica occurs almost in the whole Slovakia, with two distributional centres situated in the south-western region (Pannonian bioregion) and in the southern regions of central Slovakia (Carpathian bioregion), but a higher proportion of recent records was identified in the Carpathians. Vegetation classification using the TWINSPAN algorithm divided 80 vegetation plots into 5 clusters. They were interpreted syntaxonomically as follows: i) Calthion palustris alliance, ii) Deschampsion cespitosae alliance, iii) Molinion caeruleae alliance, iv) vegetation of the successional stages and transitional status between wet meadows ( Calthion palustris and Molinion caeruleae ) and fens ( Scheuchzerio palustris-Caricetea fuscae ), and v) vegetation with a transitional status between hygrophilous, fen vegetation of the alliances Molinion caeruleae , Caricion davallianae , Caricion fuscae and mesic habitats. Variation in the species composition of vegetation plots, analysed using detrended correspondence analysis (DCA) and interpreted using Ellenberg indicator values for vascular plants, showed a shift along the first DCA axis from taxa typical for nutrient-rich and shaded but thermophilic sites to taxa of open and relatively cold habitats on nutrient-poor soils. The second DCA axis corresponded to the moisture gradient, which controlled the pattern of plant species richness.
... Une première étape d'analyses de classification en présenceabsence a été réalisée avec Twinspan (Hill 1979) pour un premier tri puis avec une classification Twinspan modifiée (Modified Twinspan classification -MTC, Roleček et al. 2009). Ces deux types d'analyses de classification sont fondés sur une analyse factorielle des correspondances qui sépare groupes de relevés et groupes d'espèces. ...
À partir de données bibliographiques et de prospections récentes dans des secteurs méconnus, les auteurs font une analyse globale de 638 relevés de groupements à hautes herbes orophiles du Massif central français, puis des analyses partielles qui se concentrent sur 572 relevés de communautés situées de l’étage montagnard moyen jusqu’à l’étage subalpin. Ces groupements comprennent les mégaphorbaies stricto sensu ainsi que les hautes formations graminéennes à Calamagrostis et/ou Patzkea paniculata. Les résultats de cette révision conduisent à la caractérisation de 17 associations végétales dont cinq nouvelles, un groupement et 33 sous-associations et deux variantes. 5 associations précédemment décrites ont été réfutées et déclassées. Ces végétations se répartissent entre deux classes phytosociologiques, les Mulgedio-Aconitetea et les Juncetea trifidi, sept alliances, dont une inédite dans le Massif central, ainsi que quatre sous-alliances nouvelles. Une classification régionale est proposée en accord dans ses grandes lignes avec celle de l’EuroVegChecklist. L’étude approfondie des variables écologiques basée sur des analyses statistiques type ANOVA, DCA et CCA a permis la caractérisation des variables écologiques discriminantes dans la répartition des communautés, ainsi que la description de leurs conditions stationnelles. On assiste à une diminution progressive puis à une disparition des communautés du Calamagrostion dans le sud du Massif central et les Cévennes, en rapport avec un déficit de précipitations estivales sous l’influence croissante du climat méditerranéen. L’abondance et la diversité des communautés étudiées dans les grands massifs volcaniques de l’ouest (Cantal, monts Dore) s’expliquent par un étage subalpin bien développé, ainsi que par un climat océanique favorisant l’existence des mégaphorbaies. Sur un plan dynamique, ces formations sont pour l’essentiel stables et représentent des permaséries, même si certaines peuvent exister au sein de communautés forestières. Ce travail pourra être valorisé dans le cadre des politiques de gestion conservatoires pour l’habitats d’intérêt européen.
... To describe the studied vegetation types, an expert system was created for the classification of vegetation plots, which was developed to reflect an unsupervised classification with the modified Twinspan algorithm (Roleček et al. 2009). At first, the dataset was divided according to dominant species or by occurrence of diagnostic species described mainly by Roussakova (2000). ...
Class Mulgedio-Aconitetea comprises plant communities that develop primarily in the upper montane to subalpine vegetation belts. It is vegetation where tall herb species (forbs, ferns, grasses) occur dominantly; in the Balkans, it was studied only marginally. In this article, based on floristic composition we assess two questios: (1) how diverse is the class Mulgedio-Aconitetea in Bulgaria and (2) what
environmental factors are responsible for the vegetation assemblages in the area? We analyzed 387 plots. We created an expert system that classifies this vegetation and tested environmental variables for their influence on these vegetation types. In total, 15 associations and one uncategorized community were classified using the Braun-Blanquet approach. The length of the growing season (number of growing degree days > 0°C) and climate moisture have a significant effect on the vegetation. Disturbance severity, disturbance frequency and reaction have influence over the species scores. Moreover, all variables significantly differ between the vegetation types.
... Unsupervised classification for both the West Asian and Armenian dataset was done in JUICE 7.0 (Tichý 2002) using the modified TWINSPAN method (Roleček et al. 2009) with three pseudospecies cut levels (0, 5, and 15), and Whittaker's beta-diversity index as a measure of internal cluster heterogeneity. ...
Aim: To provide the first syntaxonomic, plot-based classification of the dry grasslands and thorn-cushion communities in Armenia. Study area: Armenia. Methods: We sampled 111 vegetation plots (10 m²) and recorded environmental and structural parameters. We collected additional 487 relevés from surrounding countries for a broad-scale comparison. We used modified TWINSPAN to derive a syntaxonomic classification system, whose units were then compared among each other regarding species composition, structure, site conditions and distribution. Results: The classification of Armenian vegetation plots resulted in a 12-cluster solution. Unsupervised classification of the broad-scale dataset yielded five main groups, which were used for the high-level syntaxonomic assignments of the Armenian data. We assigned about half of the plots of the Armenian dataset to the Festuco-Brometea, while the remaining represented a potential new class, preliminarily called “Ziziphora tenuior-Stipa arabica grasslands”. Most of the syntaxa below class level are new to science, therefore we provide formal descriptions of three orders (Plantagini atratae-Bromopsietalia variegatae, Onobrychido transcaucasicae-Stipetalia pulcherrimae, Cousinio brachypterae-Stipetalia arabicae), four alliances (Acantholimono caryophyllacei-Stipion holosericeae, Artemision fragrantis, Onobrychido michauxii-Stipion capillatae, Onobrychido transcaucasicae-Stipion pulcherrimae) and six associations. We found significant differences in the topographic, climatic and soil characteristics, and structural parameters, species life forms and distribution range types between the grassland types at different syntaxonomic levels. The mean species richness was 47.3 (vascular plants: 46.8, bryophytes: 0.4, lichens: 0.1). Conclusions: We found remarkable differences of the Armenian dry grasslands from the previously known units and described most of the higher syntaxa and all the associations as new to science. Our study provides arguments for a potential new class of Ziziphora tenuior-Stipa arabica grasslands separate both from the Euro-Siberian Festuco-Brometea and the Anatolian Astragalo-Brometea. Finally, we found plot scale richness of vascular plants clearly above the Palaearctic average of dry grasslands and that of non-vascular plants clearly below, which calls for further biodiversity analyses.
Taxonomic reference: Euro+Med (2023) for vascular plants, Hodgetts et al. (2020) for bryophytes, Nimis et al. (2018) for lichens except for Xanthoparmelia camtschadalis (Ach.) Hale.
Abbreviations: EDGG = Eurasian Dry Grassland Group; DCA = detrended correspondence analysis; ICPN = International Code of Phytosociological Nomenclature (Theurillat et al. 2021); TWINSPAN = two-way indicator species analysis.
... We used TWINSPAN (Two-Way Indicator Species Analysis) modified by Roleček et al. (2009) to classify the data based on the abundance of species in the 155 relevés. The method was run with default settings, including five pseudospecies cut levels (0 %, 2 %, 5 %, 10 %, 20 %), a minimum group size of five, and total inertia as a measure of heterogeneity. ...
In the arid landscapes of South Morocco's Saharan fringe, traditional agroecosystems stand out for their rich diversity of segetal vegetation. This study examines the segetal flora of these unique agroecosystems, investigating their richness, community characteristics and composition. We collected 155 relevés in fields located in the Guelmim province comprising three agroecosystem types: Oases, terraced and floodplain fields (faïd). We found 221 vascular plant species including seven regional endemics and one nationally very rare species. Using TWINSPAN, we identified three plant communities, each restricted to a specific agroecosystem type, displaying differences in species composition, floristic status, life-form and biogeographical spectra. Oasis vegetation had the highest overall number of species, terraced fields had the highest diversity, and therophytes were dominant across all communities, with faïds being the most therophyte-rich. The pan-Mediterranean chorotype dominated all three community types. Apophytes dominated, particularly in faïd and terraced fields, surpassing oasis fields rich in ruderals. We found that traditional cereal agroecosystems in southern Morocco harbor species-rich segetal plant communities created by habitat-based land-use systems. Our results highlight the significance of agricultural practices and local abiotic factors in shaping the agroecosystems, which are adapted to arid environments and sensitive to environmental and social changes.
... Аналіз даних. Для аналізу відібраних описів використовували модифікований алгоритм TWINSPAN (Roleček et al., 2009) з трьома рівнями зрізу псевдовидів (0, 5, 25%). Бету Уіттекера застосовували як міру гетерогенності кластерів (Whittaker, 1972). ...
The article is devoted to syntaxonomy and synphytoindication of steppe vegetation in Mykhailivska Tsilyna Nature Reserve (Sumy Region). Based on phytosociological materials collected in 2021–2022 and literature data, changes of steppe vegetation in the reserve over the past ten years have been analyzed. The plant communities of the class Festuco-Brometea were identified as two subassociations and two variants in three associations, belonging to one alliance and one order. The article provides characteristics of the syntaxa, their ecological requirements, synphytoindication indexes, and results of DCA-ordination of the obtained indexes of ecological factors. It has been found that the main ecological gradients affecting ecological and territorial differentiation of the syntaxa are the soil humidity, nitrogen content in soil, soil aeration, and total salt regime. During the study, an increasing mesophytization of the steppe vegetation was observed, caused by the absence of mowing on the territories that formerly were under the constant mowing regime.
... To reduce spatial clustering of plots with similar vegetation, we classified the vegetation data into eight main vegetation types using the modified Twinspan algorithm (cut levels of percentage cover: 0, 5, 25; Roleček et al., 2009) in the program JUICE (Tichý, 2002) and assigned each plot to a grid cell of 1.25 longitudinal × 0.75 latitudinal minutes, that is, approximately 1.5 × 1.4 km. ...
Aim
In salt-affected environments, salinity shapes ecosystem functions and species composition. Apart from salinity, however, we know little about how soil chemical factors affect plant species. We hypothesized that specific ions, most of which contribute to salinity, co-determine plant niche differentiation. We asked if the importance of ions differs for species with (halophytes) and without (associated species) physiological adaptations to saline soils.
Location
Carpatho-Pannonian region (Central and Eastern Europe).
Time period
2005–2021.
Major taxa studied
Vascular plants.
Methods
We recorded species occurrences and collected soil samples in 433 plots in saline habitats. We measured pH, salinity (electrical conductivity), and concentrations of Ca2+, K+, Mg2+, Na+, SO42− Cl−, CO32− and mineral nitrogen (mN) and calculated the sodium adsorption ratio (SAR). For 88 species, we fitted response curves with Huisman–Olff–Fresco (HOF) models. To study ions' effects on species composition and ions' variance, we compared unconstrained and constrained ordinations and performed a principal component analysis. We used random forests to analyse the importance of ions for individual species and created two-dimensional species niche plots for key ions.
Results
Ion concentration niches varied among species and did not necessarily correspond to soil salinity or alkalinity. We frequently observed monotonic, sigmoidal model responses, while skewed unimodal responses were rare. Ions explained a considerable proportion of species compositional variation. Particularly, Na+, SO42−, Cl−, and CO32− contributed to the ions' variance. Na+, followed by SO42−, Cl−, CO32−, Ca2+, Mg2+, and mN, was most important for the occurrence of individual species. Compared to associated species, Na+, SO42−, and mN were significantly less important for halophytes, whereas Cl− and CO32− played a significant role.
Main conclusions
We show that ion composition co-determines niche differentiation in saline soils, suggesting evolved physiological adaptations in halophytes. Our study calls for incorporating high-resolution data on soil ion composition in ecological research.
... For species that appeared in more than one vertical layer, information on the greatest coverage value was used. Next, a modified version of TWINSPAN (Two-Way Indicator Species Analysis, Roleček et al. 2009) was used to group the species. This is a binary tree-order analysis algorithm used to classify vegetation into homogeneous groups, which had been originally proposed by Hill (1979). ...
Questions
Oceanic islands are global hotspots of endemism and evolutionary radiations but many have been severely degraded by human activities and biological invasions. We evaluated the pace and direction of the natural recovery of ecosystems over 77 years across a subtropical oceanic archipelago including islands of various size, elevation, histories of human settlement and deforestation, and invasions by non‐native plants and mammals. This information is essential to guide the ecological restoration of the archipelago.
Location
Forest vegetation on nine of the Ogasawara Islands in the northwestern Pacific Ocean.
Methods
We first digitized historical vegetation data of the Ogasawara Islands collected during field surveys in 1935. Then, after checking their species compositions, we integrated past and present plant community types. Finally, we identified the landscape‐scale changes in forest vegetation by comparing vegetation maps from 1935, 1979 and 2012.
Results
Over 77 years, the vegetation trajectories of each island varied depending on the introduction of invasive alien species and the remaining proportion of native forest, the latter of which had a strong influence on the recoverability of native forest.
Conclusions
Our results highlight the importance of the history of invasive species introductions and the remaining proportion of native forest—both of which reflect the intensity of anthropogenic disturbance—in determining the degree of human intervention needed for restoration on oceanic islands.
... To identify the dominant and index plant species across sampling units, we employed the TWINSPAN cluster analysis method, a classification technique embedded in the JUICE ver. 7.1 software [50][51][52][53][54]. This method compares sample pieces based on the presence or absence of species and groups together those with more similarity. ...
The edaphic and environmental changes in Bujagh grasslands have led to a gradual decline in the wintering waterbird populations in the associated national park. This has particularly affected foraging habitats for birds, especially migratory geese. Our aim was to identify the reasons for the loss of habitat quality by examining the structure of the plant community and the edaphic factors that have been instrumental in shifting the grass community pattern to a Rush–Rubus type along the succession route. Bujagh National Park is surrounded by marine, riverine fresh water, and lagoon habitats, and the seasonal floodings of the Sefidrud and Ushmak rivers impact the grassland area along the deltaic pathway to the Caspian Sea. We used the TWINSPAN classification function to extract plant groups and their dominant species. Subsequently, we analyzed land cover changes in the study area over two times (2010 and 2020) to identify alterations in the coverage of main plants and land uses. Following the evaluation of unconstrained ordination methods and the selection of NMDS ordination, we compared the dominant species of groups to the main edaphic predictors. The results indicated that the chemicals and heavy metals in the soil did not play a direct role in the shift from grassland to Rush–Rubus plant type. However, these elements could have a significant impact on the evolution of the structure and the competitive capability among the main dominant species of the grass group. In conclusion, the dominance of the Rush–Rubus type is likely related to other unmeasured environmental and anthropogenic factors that support and enhance their reproductive attributes and herbal proliferation in the grassland territory.
... In the first step, we made an analysis of all vegetation plots sampled across the Kyiv urban area (1164 relevés) and distinguished the large groups of relevés which are quite different from each other by their species composition. For this purpose, we used a modified TWINSPAN algorithm (Roleček et al., 2009), with three pseudospecies cut levels (0, 5, 25%) and with Sørensen coefficient (Sørensen, 1948) as a measure of cluster heterogeneity. Thereafter we selected those clusters, which corresponded to the class Artemisietea vulgaris according to the list of diagnostic species provided by Mucina et al. (2016). ...
The article is a continuation of the study on ruderal vegetation of Kyiv City and provides summarized results of syntaxonomic research of the class Artemisietea vulgaris. We identified 14 associations and one derivative community belonging to three orders and four alliances. Using ordination and phytoindication analyses, the synmorphology of the communities, their ecological requirements, and habitat preferences were described. It has been shown that the vegetation of Artemisietea vulgaris is distributed throughout all districts of the city. According to ecological requirements, we found that main environmental gradients that determine the ordination of different types of stands of Artemisietea vulgaris within Kyiv City are thermoregime and light. The diversity of man-made habitats and regional environmental conditions appeared as the most important factors affecting the territorial differentiation of this vegetation type within the city. The contributed data can be used for strategic planning and practical implementation of measures for sustainable urban development and optimization of the urban environment.
... Потім на основі програми JUICE 7.0. та кластерного методу двостороннього аналізу індикаторних видів Modified TWINSPAN Classification (Roleček et al. 2009) розроблялася класифікація рослинності. Для ідентифікації синтаксонів використовували зведення Л. Муцини (Mucina at al. 2016) та «Продромус рослинності України» (Dybuna et al. 2019), а для біотопів − роботи Я.П. ...
Викладено методологію (підходи, методику) щодо оцінки еколого-топологічної диференціації рослинності (біотопів) та проілюстровано її використання на прикладі Дністровського каньйону. Проведено критичний аналіз відповідних термінів та запропоновано схематичну структуру їх співвідношень. Базовим поняттям топологічної структури є екомера, що на висотно-регіональному рівні представлена макрокомбінаціями біотопів, катенно-ландшафтному – мезокомбінаціями, фаціально-локальному – мікрокомбінаціями. Дністровський каньйон розглядається як модель еколого-топологічної диференціації катени долини річки, що включає мезокомбінації схилів та заплави. Основною одиницею мезокомбінації є ланки, які характеризуються відповідними фітоценозами (біотопами). За впливом зовнішніх факторів виділяються ряди, а за ознаками зміни ценотичної структури – геосерії. На основі порівняльного аналізу еколого- ценотичних профілів різних рядів та геосерій виділено 16 екосигмет, номінація яких дається на основі характерного синтаксону. Для прикладу проілюстровано специфічні петрофітно-трав’яний (Poetosigmetum versicoloris) та чагарниково-лісовий (Corno-Quercosigmetum) екомери. На основі синфіто- індикаційної оцінки та сучасних математичних методів (головних компонент РСА-ординації та побудови «теплових» матриць кореляційної залежності) встановлено характер взаємозалежностей між зміною показників екофакторів та їх вплив на диференціацію рослинних угруповань (біотопів). Отримані результати оцінки топологічної диференціації та їх кількісні (бальні) показники важливі для подальшого моніторингу, порівняльного аналізу та прогнозування можливих змін рослинного покриву.
... With subplot-based IVI data, we classified the forest vegetation at LFDP into three 253 vegetation types by modified two-way indicator species analysis (modified TWINSPAN; 254 Hill 1979; Roleček et al. 2009), using R package "twinspanR" (Zelený 2021). In modified 255 TWINSPAN, pseudospecies cut levels were set to 0, 2, 5, 10, and 20%, and Bray-Curtis distance 256 was used to measure compositional dissimilarity. ...
To understand the vegetation-environment relationships within the Chamaecyparis montane mixed cloud forest in Taiwan, we established a 1-ha Lalashan Forest Dynamics Plot (LFDP) in northern Taiwan (24°42'N, 121°26'E). We established the plot in July 2019 and finished the first census of all woody species in August 2020. We collected environmental factors related to the topography and soil properties, measured microclimate and soil moisture within the plot, and collected further microclimatic data with a nearby weather station. In total, we recorded 5220 individuals belonging to 65 species, 42 genera and 29 families, with a basal area of 69.1 m2 ha-1, dominated by Chamaecyparis obtusa var. formosana, Rhododendron formosanum and Quercus sessilifolia. Modified TWINSPAN classified vegetation into three types (ridge, east-facing slope and valley). Unconstrained ordination showed that the main gradients behind compositional changes are related to windwardness and convexity. The prevailing wind direction in the area is from the northeast, linked to the winter monsoon. Both east-facing slope type and valley type have relatively lower temperatures than ridge type, especially during summer. Convexity is related to soil moisture gradient (from dryer convex to wet concave sites). Fog frequency is seasonal, with the highest values during autumn and winter months. From soil properties, pH is negatively and phosphorus is positively related to topographical convexity. Litter decomposition is linked to both topographical, soil and biotic variables. Collected data will serve as a baseline for future resurveys and monitoring changes within this montane cloud forest.
... We used TWINSPAN (Two-Way Indicator Species Analysis) modified by Roleček et al. (2009) to classify the data based on the abundance of species in the 155 relevés. The method was run with default settings, including five pseudospecies cut levels (0 %, 2 %, 5 %, 10 %, 20 %), a minimum group size of five, and total inertia as a measure of heterogeneity. ...
... An initial classification was done using modified TWINSPAN (Roleček et al. 2009), with average Sørensen as distance measure, but without using pseudospecies. This classification resulted into four clusters, which were interpreted as representing (i) wetlands and associated grasslands, (ii) a transition zone between the Thornbush savanna and the Karstveld (both sensu Giess 1998), (iii) Kalahari type vegetation on deep aeolian sands and (iv) the true Karstveld types. ...
Aims : The Karstveld in Namibia has been recognized as an area of high plant diversity. However, this area is also recognised as a hotspot of various forms of degradation including bush encroachment. Minimal baseline data on the composition and diversity of vegetation in this area is available, therefore this paper is a first attempt to rectify this data deficiency. Study area: The Karstveld in Namibia is formed around the Otavi Mountain Range in northern Central Namibia, consisting of strongly karstified carbonate bedrock, rising up to 2000 m a.s.l. The Karstveld includes the Ovambo Basin plains with shallow calcrete soils north of the range, up to the Omuramba Ovambo. Because of orographic effects, the area receives some of the highest rainfall in Namibia, with up to 600 mm per year. Methods: A set of 889 relevés with 868 species was selected from the GVID ID AF-NA-001 database. A partial data set, using trees, shrubs, dwarf shrubs and grasses only, was used for the classification with modified TWINSPAN. The initial result yielded four main groups, according to which the data was split and further classified. Several vegetation types observed during field surveys were not reflected in the classification results; these were refined using Cocktail with known characteristic species. Results: The four main units represented wetlands and grasslands with six associations, a Thornbush savanna – Karstveld transition zone with four associations, Kalahari vegetation with four associations and the Karstveld proper with eight associations. The latter are grouped together as the Terminalietea prunioides , with two orders and three alliances recognised under them. We describe 16 associations according to the ICPN. Conclusions: Although the associations presented in this paper are clearly defined, there exists a high degree of diversity within these. The Karstveld is also extraordinary species rich within the context of the arid to semi-arid Namibian environment.
Taxonomic reference : Klaassen and Kwembeya (2013) for vascular plants, with the exception of the genus Acacia s.l. ( Fabaceae ), for which Kyalangalilwa et al. (2013) was followed.
Abbreviations : ga = annual grass; gp = perennial grass; GPS = Global Positioning System, referring to a hand-held ground receiver; hl = herb layer, containing all hemicryptophytes, therophytes and geophytes, but excluding grasses ( Poaceae ); ICPN = International Code of Phytosociological Nomenclature (Theurillat et al. 2021); MAP = mean annual precipitation; NMS = nonmetric multidimensional scaling (Kruskal 1964); RDL = Red Data List (IUCN Species Survival Commission 2001); s1 = tall shrubs, i.e. multi-stemmed phanerophytes between 1 and 5 m; s2 = short shrubs, i.e. chamaephytes or ‘dwarf shrubs’ below 1 m; SOTER = Global and National Soils and Terrain Digital Database (FAO 1993); t1 = tall trees, > 10 m; t2 = short trees, between 5 and 10 m; t3 = low trees, i.e. single-stemmed phanerophytes between 2 and 5 m; TWINSPAN = Two Way Indicator Species Analysis (Roleček et al. 2009); WGS84 = World Geodetic System, 1984 ensemble.
... To find out the phytosociological affiliation of B. spicant, JUICE software (Tichý, 2002) was used for cluster analysis and further vegetation classification. In particular, we used modified TWINSPAN (Roleček et al., 2009) with Whittaker's beta as a measure of clusters' heterogeneity and cover of 0-5-25% as pseudospecies cut levels. Due to the small number of vegetation plots, we did not use the fidelity measure (Chytrý et al., 2002) as a value of species' diagnosticity for syntaxa. ...
The article contains data about the historical and current distribution patterns of Blechnum spicant (Blechnaceae) in Ukraine. This species is quite common in the Carpathian Mountains but is very rare in other regions of Ukraine. Until recently , there were only two known localities of B. spicant in the Western Forest-Steppe (within the Podolian Upland) and only one in Crimea. We discovered one new locality of B. spicant in the Polissian (Polesian) Lowland, in Volyn Region. The article provides phytosociological and topographic data on the Polissian population. This population consists of two sub-populations , which are located not far from each other. Both of them were found in an immature birch-pine forest aged approximately 20 years, in an area of former agricultural lands. We summarise the data on the general distribution of B. spicant in Ukraine. The article also provides phytosociological, biotopic and populational information on localities of B. spicant.
... TWINSPAN quantitative classification is based on indicator species. Generally, five main dominant species are selected as important indicator species to objectively classify vegetation communities using TWINSPAN (Cho et al. 2015, Jan et al. 2009). DCA ordination was proposed by Hill and Gauch after further research on the basis of correspondence analysis. ...
Fire is a common natural disturbance in forest ecosystems and plays an important role in subsequent vegetation patterns. Based on the spatial sequence method instead of the time successional sequence method, this study selected burned areas in different locations in the Anning River Basin, which contains typical dry valleys. Quadrat surveys and quantitative classification were used to identify the vegetation classification, distribution pattern, and environmental interpretation during the natural restoration process after forest fire. The results showed that: (1) the vegetation community in the early stage of natural recovery after forest fire disturbance could be divided into seven community types, and Quercus guyavaefolia H. Leveille (Qg) was the dominant species in the community; (2) vegetation samples could be divided into five ecological types, and the classification and distribution pattern of community types in this region changed most obviously with altitude; and (3) detrended correspondence analysis could clearly classify vegetation community types, and detrended canonical correspondence analysis could well reveal the relationships between species and environmental factors. This study provides a scientific basis guiding the restoration of ecosystem structural stability and biodiversity in burned areas.
... On the other hand, 243 species were deleted from the dataset because they were not included in any of the pollen types observed in the ice core. The obtained matrix was clustered using a Modified TWINSPAN clustering (Roleček et al. 2009), which is a hierarchical divisive clustering technique that identifies species communities based on the main ordination axis provided by a Detrended Correspondence Analysis. This technique converts species into several pseudo-species based on cut levels of the cover values, which have been set at 5% and 25% for our analyses to emphasize the role of rare species in the species composition of clusters. ...
Context
Syntheses of vegetation responses over the last century are rare for the Alps, and limited in chronological and taxonomical resolution. We propose that pollen records from glaciers can be used to fill this gap.
Objectives
Our aim is to evaluate the reliability of glacier pollen records as historical archives of biodiversity to obtain plant diversity data and landscape changes. In detail, we aim at reconstructing taxa and vegetation trends in central sector of the Italian Alps over the last century integrating pollen-inferred vegetation trends with drifts in spatially explicit land-cover.
Methods
Our study area is the Lombardy region (Italy). We performed pollen analyses of Adamello glacier cores, and reconstructed trends of single taxa and main vegetation types since the 1950s. Pollen-inferred vegetation trends were calculated using pollen indicators obtained from a database of vegetation-plot observations. The reliability of these trends is evaluated by comparison with spatially explicit tendencies reconstructed with a time-series of land-cover maps.
Results
Pollen records well represent the natural vegetation types as the temperate and the riverine forests, and the anthropic vegetation as crops and alien species. From the 1980s a thermophilisation took place, and warm-demanding native and alien species expanded. The contraction of cultivated land since the 1970s, and the decline of the riverine forest appear driven by socio-economic factors.
Conclusions
We conclude that pollen-inferred vegetation trends from glaciers can be used to obtain large scale biodiversity information. This is relevant also for areas where biodiversity data are scarce but needed for landscape management planning.
... The phytosociological data were processed in Juice 7.1 (Tichý 2002). To analyze the dataset's structure and distinguish the main communities, we applied modified TWIN-SPAN with Whittaker's Beta as a measure of inner heterogeneity of the groups and 0%, 5%, and 25% for pseudospecies cut levels (Roleček et al. 2009). Diagnostic species of the communities were determined by the phi coefficient (Sokal and Rohlf 1995). ...
https://rdcu.be/dhEmw
Relict vegetation of water-splashed petrifying rocks with calcareous tufa formation dominated by the fern Adiantum capillus-veneris and wetland bryophytes (phytosociological class Adiantetea) was investigated in Georgia, Caucasus biodiversity hotspot. The study brings the first phytosociological data on this scarce community in the Caucasus based on a novel dataset of vegetation plot records. A classification analysis revealed two main vegetation communities. They are represented by the Caucasian community recorded in the Mtkvari River valley inside the Tbilisi city (E Georgia) and the Colchic community developed under the humid, warm-temperate climate of Colchis (W Georgia), one of the key refugia of Tertiary flora across W Eurasia. To compare newly recorded vegetation types and so far described associations of the Adiantetea class, we used a broader dataset of the analogous communities reported from Europe and surroundings. It associated the Caucasian community with the pan-Mediterranean association Eucladio-Adiantetum. It was characterized by subhalophytes (e.g. Samolus valerandi), Eucladium verticillatum as a dominant bryophyte, and the absence of relict or endemic vascular plant species. The Colchic community represented a previously undescribed community. Therefore, we designated a new association Saxifrago
cymbalariae-Adiantetum capilli-veneris delineated by the characteristic species of the Colchic-Caucasian territory (e.g. Hedera colchica, Saxifraga cymbalaria) and Palustriella commutata as the dominant bryophyte. Both associations belong
to the Mediterranean-Atlantic alliance Adiantion. Described communities require conservation attention for their rarity, refugial character and presence of relict and endemic species. Modifications of the hydrological regime and construction
activities are among their most important potential threats.
For Staatsbosbeheer (the Dutch Forestry Commission), an evaluation of the quality of the mat-grass swards (Nardetea grasslands) on its properties was carried out, on the basis of existing (monitoring) data from vegetation mapping projects, plant species inventories as well as data from several large databases.
At the Staatbosbeheer properties, 7 mat-grass sward types are present, 5 of which are classi-fied as well-developed: the Galio hercynici-Festucetum ovinae (basic quality), Gentiano-Nardetum, Botrychio-Polygaletum, Betonico-Brachypodietum, and Polygalo-Nardetum (all four high quality). Two types (basal communities of Nardus stricta and Deschampsia flexuoso) are only marginally developed.
On the basis of vegetation mappings from 2012 onwards, we determined the distribution and areas of these grassland types. A total of about 180 ha of basic quality mat-grass swards was mapped and 90 ha of high quality. Marginal quality mat-gras grasslands covers an area of ca. 170 ha. The largest areas of well-developed swards (basic + high quality) are found in Drenthe (about 50 % of the total), Friesland and Gelderland (together another 30 %). The largest area of high quality mat-grass swards is found in Friesland (Botrychio-Polygaletum at the Friesian Wad-den Isles). The top objects in terms of area and number of types combined are the Bargerveen, the Drentse Aa and the Dwingelderveld, all part of the Natura 2000 network.
A more detailed analysis of the value of the mat-gras swards was carried out for 6 sites. This involved, among others, the occurrence of the “quality species” in the grasslands in the select-ed sites. It appeared that in these sites the quality species are not specially linked to the occur-rences of mat-grass swards. This may be partly be the effect of the very small patches in which mat-grass swards often occurs, which is the reason they are not mapped. This can be indirectly deduced from the common occurrence of the quality species, often in narrow strips or zones. Probably these cases are unmapped (or: unmappable) occurrences of mat-grass swards along paths and tracks in e.g. heathlands. In sites with wet heaths, fenn grasslands and/or dune grass-lands, the quality species of mat-grass swards are also (and mainly) present in these ecosys-tems.
The analyses showed that the available data from vegetation mappings are not sufficient for a thorough quality assessment at the site level: 1.) too few relevés are made, 2.) the variation in vegetation is not analysed in inductive typologies and 3.) the assignment of the relevés to the national reference contains demonstrable inaccuracies in many cases. As a result, quality ana-lyses and analyses of changes between mapping years at the site level are not reliable.
Проведен анализ фитоценотического разнообразия луговой растительности лесостепной зоны Приобского плато посредством формализованных методов обработки данных. С помощью кластерного анализа 516 геоботанических описаний в программе JUICE 7.0 алгоритмами Modified TWINSPAN Classification и TWINSPAN выделено шесть типов луговых сообществ: солонча-коватые луга, сырые лесные луга, сухие лесные луга, остепненные солонцеватые луга, остепненные луга, настоящие суходольные луга. Определено положение выделенных типов в системах двух классификаций: флористической на уровне классов, порядков, союзов; доминантной на уровне формаций, групп и классов формаций. Показано соответствие синтаксонов двух систем классификации. С использованием формализованных критериев выделены дифференцирующие виды с различной степенью стенотопности, индицирующие различные условия увлажнения, богатства и засоления почв, что подтверждено ординацией сообществ с использованием фитоиндикационных шкал. Показана роль этих факторов в дифференциации луговой растительности исследуемой территории.
Plant outstanding biodiversity among mesophilous alluvial hay meadows in the lower Loire river valley is highlighted through the proposal of 7 new phytocoenotical associations. These plant communities are ranked along an ecological gradient based on humidity, trophic and alluvium characteristics, the later based on sand proportion and pH ranging around neutral values. Group 1 encompasses mesoxerophilous to mesophilous meadows at highest topographical level with a Carici ligericae-Festucetum rubrae ass. nov. hoc loco mesotrophic, neutrophilous to calciclinous, a Vicio hirsutae-Arrhenatheretum elatioris ass. nov. hoc loco mesotrophic and neutrophilous and a Trifolio subterranei-Galietum veri ass. nov. hoc loco mesotrophic, acidoclinous. In the floodplains meadows, these plant communities pass on the baton to lower mesophilous levels with a Fritillario meleagridis-Arrhenatheretum elatioris ass. nov. hoc loco oligomesotrophic to mesotrophic, a Trifolio maritimi-Galietum veri ass. nov. hoc loco oligomesotrophic and an Eryngio campestris-Oenanthetum pimpinelloidis ass. nov. hoc loco mesotrophic wich is characterised by both mesoxerophilous and mesohygrophilous species on well drained soils. Lastly, a Cirsio arvensis-Arrhenatheretum elatioris ass. nov. hoc loco is represented in mesophilous eutrophic meadow to which all these communities converge through fertilization. A high floristic unity among these communities suggests the existing of a new phytosociological sub-alliance of mesophilous hay meadow on sandy to silty and neutral alluviums differing from the Poo angustifoliae-Arrhenatherenion elatioris Felzines 2012 found in the higher Loire river basin, over acidoclinous more less coarse sandy soils.
Background. Peat bog complexes are self-sufficient ecosystems in which unique microclimatic conditions leading to a significant diversity of valuable plant communities are formed. Such communities are sensitive to the effects of climate change or any anthropogenic intervention. The lack of reliable information on their distribution on the territory of the Syra Pogonia peat-bog massif of the Rivnenskyi Nature Reserve necessitates a detailed study of the bog vegetation. Therefore, the purpose of the work was to classify the community of peatland vegetation of the Syra Pogonia massif and to determine the features of their syntaxonomic and ecological differentiation for further development of environmental management strategies.
Materials and Methods. The study of the peculiarities of peatland vegetation was conducted on transects that represent the variety of local conditions of the complex system. A total of 141 relevés were analysed using the Braun–Blanquet method. The material was analysed using TURBOVEG 2.79 and JUICE 7.0.83 software. Vegetation units were separated using the method of two-factor indicator species analysis (TWINSPAN). Diagnostic species of syntaxa were determined by the fidelity coefficient phi, the fidelity threshold for which was > 25 %. The statistical significance of the phi coefficient was determined with the Fisher’s test at P < 0.001. The DCA-ordination method was used to identify an ecological differentiation of units.
Results. Peatland vegetation of the Syra Pogonia massif of the Rivnenskyi Nature Reserve was analysed. We identified 7 associations belonging to 6 alliances, 6 orders and 4 classes and compiled a vegetation syntaxonomic scheme. The leading factor of ecological differentiation of community is humidity of the area. The greatest diversity is inherent in mesotrophic areas, rare species are found and grouped according to different ecological conditions. The species composition of 7 associations includes 79 plant species, of which 65 are vascular and 14 are bryophytes. Using methods of phytosociological analysis, we established that the distribution of community in multi-dimensional space of ecological factors occurs under the conditions of their complex action. At the same time, changes in the humidity regime are of crucial importance for the selected syntaxa (Andromedo polifoliae-Sphagnetum magellanicі). The results of the phytoindicative analysis proved that the associations identified on the territory of the Syra Pogonia peat-bog complex are acidophilic in terms of acidity, and oligotrophic in terms of the requirements for the content of nutriens.
Conclusions. As orders, and result of the analysis of relevés, 7 associations, which belong to 6 alliances, 6 orders and 4 classes were selected. Based on the results of the dataset analysis, a vegetation classification scheme was compiled. As a result of the cluster analysis of 7 associations, a significant difference between communities of watered and wet habitats was revealed. We established that the differentiation of the vegetation on the territory of the peat massif of Syra Pogonia mainly depends on the change in the moisture regime.
Aims: This study aimed at classifying, mapping and describing the plant communities of the Karoo National Park using floristic surveys in conjunction with Sentinel-2 and topo-morphological data. Study area: Karoo National Park, Western Cape, South Africa. Methods: The vegetation of the Karoo National Park was delineated into homogenous physiognomic-physio-graphic units using Sentinel-2 images. A total of 128 survey plots (100 m 2 each) were surveyed within the different homogeneous units during the period 2016 to 2020. Within each survey plot, all rooted species were identified and their cover abundance estimated. Each plot was photographed and its geolocation recorded. The floristic data were captured using the Braun Blanquet Personal Computer suite and exported to the JUICE Software programme. A modified TWINSPAN classification was done to derive a first tabled synopsis of the plant communities. The different plant communities were subsequently classified and described according to their diagnostic and dominant species gleaned from the synoptic table. Species richness was determined by counting the number of different species per plant community while the ShannonÀWiener Index and Rich-GiniÀSimpson Index of diversity (D) were used to derive indices of species diversity per plant community. Results: 12 major communities and two sub-communities that are distinctly linked to various abiotic factors were identified, described and mapped. The higher-lying rocky steep midslopes as well as the valley bottom-land areas had the highest diversity and species richness. Conclusions: This study proves the efficacy of using Sentinel-2 and topo-morphological data in classification, description and mapping vegetation of extensive natural areas. The vegetation map and classification of plant communities provide a baseline to inform management decisions.
Kedrovaya Pad Reserve is located in the southwestern part of Primorye Territory, Russian Far East. This nature reserve was established more than 100 years ago aiming to preserve unique stands of virgin south Manchurian mixed forest with Abies holophylla, Pinus koraiensis and numerous broadleaf species. The structure of vegetation was studied thoroughly, however, classification was performed with the emphasis on dominant species and geographical characteristics of the location (Vasilyev et al., 1984), which can be rather useful for forestry but usually does not reflect all peculiarities of described community. Proposed here classification based on Braun-Blanquet approach provides another glance on vegetation structure and allows to consider results within the frames of the existing syntaxonomic system for Northeast Asia. We analyzed 109 relevés, which we collected during the years 2008–2018 (Fig. 1). Cover of each species was estimated in percent. We applied unsupervised classification — modified TWINSPAN (Roleček, 2009) via JUICE 7.0 (Tichý, 2002) to receive seven clusters (Fig. 2, Table 1). Clusters experienced expert revision and were turned into seven groups. These groups were interpreted as associations or subassociations (Table 2). Diagnostic species were identified basing on calculated constancy and phi coefficient (Chytrý et al., 2002). The studied forest vegetation of Kedrovaya Pad Reserve is presented by six associations and three subassociations. One of the seven groups incorporates three relevés, which describe deciduous communities on freshly formed alluvial soils. However, these relevés differ significantly between each other and obtained group doesn’t have any syntaxonomic meaning. Spodiopogono sibirici–Quercetum mongolicae ass. nov. hoc loco Holotypus: relevé 18 in Table 4. Diagnostic species: Artemisia keiskeana, Polygonatum humile, Spodiopogon sibiricus. Communities of this association prefer steep and moderate south or west slopes with mild water deficiency. Trees form one or two strata. Quercus mongolica dominates the canopy, often accompanied by Tilia amurensis. Second tree stratum, if presented, formed by Acer pseudosieboldianum and, again, Tilia amurensis. Typical for the shrub layer is Lespedeza bicolor. Most noticeable species of the herb layer are Artemisia keiskeana, Carex siderosticta & C. nanella, Melampyrum roseum, Spodiopogon sibiricus and Calamagrostis brachytricha. Viti amurensis–Quercetum mongolicae ass. nov. hoc loco Holotypus: relevé 10 in Table 5. Diagnostic species: Chloranthus japonicus, Geranium eriostemon, Heracleum dissectum, Vitis amurensis. Important feature of the habitats for communities of this association is sufficient amount of moisture and this can be met in the lower parts of the slopes, as well as on the top of the ridges (450–500 m a. s. l.), where sea fogs bring additional humidity. Trees form two strata. Quercus mongolica, Tilia amurensis and Fraxinus rhynchophylla form the upper one. Acer mono is ordinary in the second stratum. Shrub layer is dominated by Corylus mandshurica, other species are Rubus crataegifolius, Philadelphus tenuifolius and Weigela praecox. Vines — Vitis amurensis, Schisandra chinensis and Actinidia kolomikta are also common. In the herb layer there are no strong dominants, most characteristic are Carex lanceolata & C. siderosticta, Artemisia stolonifera and several Vicia species. Rhododendro mucronulati–Betuletum schmidtii ass. nov. hoc loco Holotypus: relevé 9 in Table 6. Diagnostic species: Betula schmidtii, Carex nanella, Rhododendron mucronulatum. Communities of this association occupy moderate slopes or tops of the ridges, facing north-east or north-west; soils are rocky and dry. Quercus mongolica and Betula schmidtii form the highest stratum. Acer pseudosieboldianum presents second stratum. Rhododendron mucronulatum dominates in shrub layer. Carex nanella, C. siderosticta and young shoots of vine Schisandra chinensis prevail in the herb layer. Matteuccio struthiopteridis–Juglandetum mandshuricae ass. nov. hoc loco Holotypus: relevé 13 in Table 7. Diagnostic species: Brachybotris paridiformis, Cardamine leucantha, Carex pallida, Filipendula palmata, Hylomecon vernalis, Juglans mandshurica, Matteuccia struthiopteris, Oxalis obtriangulata, Phlomoides maximowiczii, Sanicula rubriflora, Stellaria bungeana, Valeriana fauriei. Communities of this association can be met within river terraces, which are most close to the floodplain. Amount of moisture is sufficient or excess. Upper trees belong to the vast number of species; most common are Tilia amurensis, Fraxinus mandshurica, Juglans mandshurica, Pinus koraiensis, Abies holophylla. Second stratum is also rich in species, with constant Acer mono. The latter one along with Carpinus cordata forms the third stratum. In the shrub layer common are Eleutherococcus senticosus, Viburnum sargentii and several Lonicera species. Among numerous species typical for the herb layer are diagnostic ones. Two subassociations of this association are distinguished. M. s.–J. m. typicum subass. nov. hoc loco occupies the same habitat as specified for association and has the same set of diagnostic species. M. s.–J. m. chrysosplenietosum villosi subass. nov. hoc loco prefers more wet habitats with poorly drained soils. From the aforementioned subassociation it differs by the composition of the herb layer. Holotypus: relevé 6 in Table 7. Diagnostic species: Chrysosplenium pseudofaurie, C. villosum, Cornopteris crenulatoserrulata, Geum aleppicum, Pseudostellaria japonica. Polysticho tripteron–Pinetum koraiensis typhicum Gumarova et al. ex Krestov et al. ex Krestov et al. 2023 Releves belonging to this syntaxon are presented in Table 8. Communities belonging to this subassociation occupy north facing gentle or moderate slopes. The tree layer consists of three strata. The upper one is formed by Abies holophylla up to 50 m high. Besides fir, Tilia amurensis, Quercus mongolica, Pinus koraiensis and Kalopanax septemlobus are common. The second stratum is built by Abies holophylla and Tilia amurensis, accompanied by Acer mono. Acer pseudosieboldianum and Carpinus cordata form the lowest tree stratum. In shrub layer Philadelphus tenuifolius dominates. Species of the herb layer can be divided into two groups: constant with low abundance — Phryma asiatica, Maianthemum dilatatum, Thalictrum filamentosum и T.tuberiferum, Carex siderosticta; and ferns Dryopteris crassirhizoma & D. expansa, Osmundastrum asiaticum with the cover 5–50 % each. Vines Schisandra chinensis, Actinidia arguta & A. kolomikta are well pronounced. Weigelo praecocis–Aceretum ukurunduensis ass. nov. hoc loco Holotypus: relevé 4 in Table 9. Diagnostic species: Euonymus maximowicziana, Gymnocarpium dryopteris, Weigela praecox. Communities of this association were observed only on the slopes of Mt. Uglovaya higher than 600 m a. s. l. The tree layer consists of two or three strata. Abies nephrolepis, Tilia amurensis and birches — Betula costata or B. lanata form the highest one. Lower strata are built by Acer ukurunduense, A. pseudosieboldianum & A. tegmentosum. For the shrub layer common are Weigela praecox, Philadelphus tenuifolius, Deutzia amurensis. In the herb layer Carex siderosticta is abundant, other noticeable group is ferns and vine Actinidia kolomikta.
Environmental flow is increasingly used in restoring degraded riparian vegetation. To assess the impact of environmental flow on plant community characteristics and to provide a scientific basis for the subsequent restoration and management of the riparian vegetation at Yongding River (Beijing Section), field surveys were conducted before and after environmental flow application in 2022. Before environmental flow application, sixty-nine species were identified, and the number of species increased to ninety-six species after environmental flow application. Community similarity analysis found that riparian vegetation communities were dominated by emergent hygrophytic plants and the introduced Xanthium italicum had the largest contribution before environmental flow application. The environmental flow increased the proportion of submerged plants, four submerged plant species were among the top ten species contributing to dissimilarity. Canonical correspondence analysis found that soil total nitrogen and organic matter significantly influenced riparian plant richness. Non-metric multidimensional scaling analysis showed that after environmental flow application, the similarity of plant communities in the mountain and plain sections increased. However, it is worth noting that the invasive species Bidens frondosa became dominant in the mountain section, whereas the invasive species Xanthium italicum was widely distributed in the plain section after environmental flow application. The results showed that environmental flow increased mountain section’s vegetation uniformity and plant species richness in the plain section, enhancing plant communities similarity in both regions. Environmental water application supports the spread of both native and invasive species; thus, future management should prioritize the timing of environmental flow to prevent invasive species’ widespread dissemination.
The current state and syntaxonomic structure of anthropogenic vegetation of the classes Galio-Urticetea and Bidentetea are revealed. The class Galio-Urticetea is represented by 3 phytosociological orders, 6 alliances, and 32 associations. The class Bidentetea unites 8 plant associations of 1 order and 2 alliances. The territorial differentiation of the studied plant communities is caused by the limiting factors: soil moisture and the changing hydrological regime. Thus the phytocoenoses of these classes are confined to the natural zones of Polissia and forest-steppe. Based on detrended correspondence analysis, the leading factors differentiating vegetation units were identified. Within the class Galio-Urticetea, they include the continentality of climate, precipitation regime, and concentration of mineral nitrogen in the soil. The factors of major significance for Bidentetea were soil moisture and the concentration of mineral nitrogen in the substrate.
Despite Saudi Arabia being an interesting area from a floristic perspective, its vegetation is still relatively poorly studied. This certainly applies to the Hijaz Mountains and adjacent coastal zones. We aim to describe the flora and vegetation of the foothills of the Hijaz Mountains regarding the environmental conditions. Hijaz Mountains and adjacent coastal zones, Saudi Arabia. We studied the vegetation at the Hijaz Mountains’ foothills along two transects of vegetation surveys, one along the coast and one more inland. In addition, soil samples were taken and analyzed for soil texture, pH, electrical conductivity, organic matter, calcium carbonate and the concentration of the elements N, Na, K, Ca, Mg, Fe and Mn were determined. We calculated the data clustering tendency (Hopkins’ test analysis) and its optimal number of clusters (Elbow method). We used modified TWINSPAN to cluster the data and validated the resulting communities using the Silhouette algorithm. Seven plant communities resulted, each one dominated by a different plant species, namely: Haloxylon salicornicum , Lycium shawii , Senegalia hamulosa , Vachellia tortilis , Zygophyllum coccineum , Vachellia flava and Stipagrostis plumosa , and were described based on their floristic composition and could be further grouped into three vegetation clusters. The communities had varying ranges of occurrence in the study area, some dominating certain sections, with latitude and altitude being the biggest distinguishing environmental variables between the communities. We present a description of the vegetation of the Hijaz Mountains foothills. Our study is considered an important basis for decision-making of nature conservation and in-depth surveys of the area.
Graphic abstract
Aims: Developing a hierarchical classification system for classes, orders and alliances of the diverse dry grasslands of the Central and Eastern Balkan Peninsula and translating this into an electronic expert system (ES) for the automatic assignment of plots.
Location: Serbia, Kosovo, North Macedonia, Bulgaria and northern Greece.
Methods: We extracted 5734 plots from the Balkan Dry Grassland Database corresponding to eight classes of dry grasslands reported from the region, using the EuroVegChecklist ES. This dataset and later the plots within each derived subunit were subjected to a new numerical approach: Starting with an initial partitioning (expert-interpreted TWINSPAN classification), diagnostic species were determined based on their phi values for the target vegetation type and the differences in phi values to the next similar types. These diagnostic species were fed into an ES to create a new partitioning, a procedure which was iterated until diagnostic species and species of the ES converged. Then the same approach was applied within each of the derived units to define the units of the next-lower level.
Results: The iterative cluster optimisation (ICO) converged in all cases. The resulting hierarchical expert system (HES) classified 95% of all plots to alliances. We distinguished four classes with eight orders and 12 alliances: (1) Tuberarietea guttatae (Romuleion); (2) Stipo-Brachypodietea distachyi (Clinopodio alpini-Thymion striati); (3) Festuco-Brometea with Brachypodietalia pinnati (Chrysopogono-Danthonion calycinae and Cirsio-Brachypodion pinnati), Festucetalia valesiacae (Festucion valesiacae), an unnamed order of rocky steppes (with Pimpinello-Thymion zygioidis) and Koelerietalia splendentis (Centaureo-Bromion fibrosi, Saturejion montanae and Diantho haematocalycis-Festucion hirtovaginatae); (4) Koelerio-Corynephoretea with Sedo acris-Festucetalia (Festucion vaginatae) and Trifolio arvensis-Festucetalia ovinae (Armerio rumelicae-Potentillion and Minuartio montanae-Poion molinerii all. nov.).
Conclusions: We created a unified hierarchical classification with an electronic ES using diagnostic species defined by phi values. Our new approach (ICO-HES: iterative cluster optimisation for hierarchical expert systems) allows dividing large datasets into meaningful units at several hierarchical levels, and thus has high potential for complex classifications. Importantly, it overcomes the divide between expert system species and diagnostic species and re-unites them into one concept.
We studied the current state of communities and habitats of the Dniester canyon within the Podilski Tovtry National Nature Park. We revealed the patterns in the structure and distribution of communities in their relation to the geomorphologicalpecu-liarities of the canyon. There are three types of vegetation prevailing in the study area:steppes, rocky grasslands, deciduous forestes and shrubs. Based on 16 ecological transects, we created seven combined transects, which reflect different habitattypes combinations. It was found that as steeper slopes are, better natural vegetation is conserved, especially steppes are rocky grasslands. Gentle slopes are covered mostly with meadow-steppe communities of Thymomarschalliani-Caricetumpraecocis and Botriochloetumischaemii, and are intensively grazed. Natural forests within the canyon of Natural Park "Podilski Tovtry" have a fragmentary distribution. Artificial plantations of Pinus sylvestris and Robinia pseudoacacia are prevaling.We evalu-ated the level of influence of anthropogenic factors and the risks of potential losses of coenotic diversity. The highest risk of 92Biological systems. Vol. 13. Is. 1. 2021losses (1 class) have relic communities of Sesleriaheufleriana, which are overgrowing by shrubs. High level of losses (2 class) have the meadow-steppe communities, and the floodplain habitats, which are threatened by anthropogenic influence (fire, rec-reation). Communities of Stipacapillataare well conserved since they occupy steep slopes. According to the results of the conservation assessment, we established that the highest value have steppe and rocky grassland habitats, which include a sig-nificant number of rare species (Allium obliquum, Caraganafrutex,Gypsophillaaltissima, Amygdalus nana, Astragalusmon-spessulanus) and endemics (Schivereckiapodolica, Sesleriaheufleriana, Poa versicolor, Chamaecvtysusblockianus, Euphor-bia volhynica). The most endangered habitat types are floodplain habitats. Based on the obtained data, we believe that the state of Sesleriaheufleriana communities (near Goraivka and Subych), as well as other steppe communities, need to be monitored. If necessary, appropriate management should be carried out to prevent overgrowing by shrubs. In the case of floodplain eco-systems with well-preserved willow stands, reducing the recreational load is needed.ItisalsoneededtocontrolthedistributionofAmorphafruticosaandotheradventivespecies
The syntaxonomical diversity of the ruderal vegetation of the class Artemisietea vulgaris in the territory of Ukraine has been studied in 2015-2020. It is established that this class includes 58 associations from six alliances (Convolvulo arvensis Agropyrion repentis, Arction lappae, DaucoMelilotion, Onopordion acanthii, Medicagini falcataeDiplotaxion tenuifoliae and Rorippo austriacaeFalcarion vulgaris) and two orders (Agropyretalia intermediorepentis and Onopordetalia acanthii). Based on the results of the DCA-ordination analysis, it was found that the distribution of this type of ruderal vegetation is determined by the concentration of mineral nitrogen, the degree of aeration of the substrate, and the variability of moisture. At the level of highrank syntaxa we didn’t find only vegetation that was specific for subMediterranean and Mediterranean regions as well as for eastern part of European russia. At the same time, we determined specific vegetation on the European scale from the territory of Ukraine. This is Crimean submediterranean xero-mesophytic ruderal vegetation and semiruderal meso-xerophytic vegetation united into two alliances – Medicagini falcataeDiplotaxion tenuifoliae and Rorippo austriacaeFalcarion vulgaris. All associations within these alliances are also specific only for the territory of Crimea, characterized by the specific floristic structure and diagnostic species core, and didn’t find in other regions of Ukraine.
The vegetation of calcareous coastal dunes of Holocene age along the south coast of South Africa’s Cape Floristic Region is poorly described. This vegetation comprises a mosaic of communities associated with two biomes, Fynbos and Subtropical Thicket. Previously, expert knowledge rather than quantitative floristic analysis has been used to identify and delimit vegetation units. In many areas, mapped units conflate vegetation on Holocene sand with that on unconsolidated sediments of late Pleistocene age, despite pronounced species turnover across this edaphic boundary. Despite dominance by Cape lineages and fynbos vegetation, dune vegetation in the eastern part of the region has been included in the Subtropical Thicket Biome rather than the Fynbos Biome. The high levels of local plant endemism associated with this dune vegetation and the small and fragmented configuration of these habitats, makes it an urgent conservation priority especially when placed in the context of rising sea levels, increasing development pressures and numerous other threats. Here we provide a quantitative analysis of 253 plots of the 620 km ² of Holocene dune vegetation of the study area using phytosociological and multivariate methods. We identified six fynbos and two thicket communities based on the occurrences of 500 species. Following a long tradition in Cape vegetation typology, we used the Strandveld (beach vegetation) concept as our first-order vegetation entity and identified six units based on the fynbos floras. These were, from east to west, Southeastern Strandveld, St Francis Strandveld, Goukamma Strandveld, Southwestern Strandveld and Grootbos Strandveld. Each unit was differentiated by a suite of differential species, most being Holocene dune endemics. The two thicket communities—Mesic and Xeric Dune Thicket—showed limited variation across the study area and were subsumed into the Strandveld units. We discussed our findings in terms of vegetation–sediment relationships, emphasizing the need for a greater geographical coverage of sediment ages to facilitate a better understanding of deposition history on vegetation composition. We also discussed the role of soil moisture and fire regime on structuring the relative abundance of fynbos and thicket across the Holocene dune landscape. Finally, we address the conservation implications of our study, arguing that all remaining Holocene dune habitat should be afforded the highest conservation priority in regional land-use planning processes.
Aims : To complete the syntaxonomic scheme of subalpine forb steppes in the Pamir-Alai Mountains in Tajikistan with some remarks on its environmental predictors. Study area : Tajikistan. Methods : A total of 149 relevés were sampled in 2014 and 2021 using the seven-degree cover-abundance scale of the Braun-Blanquet scheme. These were classified with a modified TWINSPAN algorithm with pseudospecies cut-off levels of 0%, 2%, 5% and 25%, and total inertia as a measure of cluster heterogeneity. Diagnostic species were determined using the phi coefficient as a fidelity measure. Detrended Correspondence Analysis (DCA) was used to show compositional differences between the distinguished alpine and subalpine grassland units. Results : Our classification revealed 12 clusters of alpine and subalpine grassland vegetation in Middle Asia. A total of nine new associations and three communities were distinguished. New vegetation types at potential class rank for Irano-Turanian subalpine and alpine grasslands have been proposed: forb steppes with Eremogone griffithii and Nepeta podostachys in subalpine and alpine belts and alpine grasslands with Festuca alaica and Festuca kryloviana for mesic habitats in the alpine belt. The main factors differentiating the species composition were the mean diurnal temperature range, the sum of annual precipitation, precipitation seasonality and the minimum temperature of the coldest month. Conclusions : Our study sheds light on the open habitat vegetation in the Pamir-Alai Mountains and has contributed to the consistent hierarchical classification of the vegetation of the eastern Irano-Turanian region. Subalpine and alpine forb steppes are a very interesting and distinct grassland type in Middle Asia. The syntaxonomic position of some of the distinguished communities is still unclear and further research on this type of alpine and subalpine vegetation within the mountains of Middle Asia is needed.
Taxonomic references : The nomenclature of the vascular plants follows Plants of the World Online (POWO 2023) and problematic taxonomic issues were solved according to The World Flora Online (WFO 2023). Nomenclature of Stipa spp. follows Nobis et al. (2020, 2022) and of Geranium spp. Cherepanov (1995). The nomenclature of bryophytes follows Ignatov et al. (2006).
Abbreviations : DCA = Detrended Correspondence Analysis.
The paper is dealt with the study of vegetation of the «Romanivka mire» botanical nature sanctuary of the national importance. It has been found that its vegetation is represented by forest, aquatic, wetland, meadow, shrub, and ruderal phytocenoses. The syntaxonomic scheme, including 10 classes, 13 orders, 15 alliances, and 28 associations with their characteristics, is presented. The class Phragmito-Magnocaricetea occupies about 65-70 % of mire area and has the largest number of syntaxa and cenoflora species (15 associations and 81 species). The class Alnetea glutinosae covering about 15-20 % of mire territory is the second the most widespread syntaxon of plant communities. The habitats of plant communities within the territory of the mire are protected by the European Union Council Directive 92/43/EEC (N3150, N 3270, N 6430, andN 7140). The communities of the associations Lemnetum minoris, Lemno-Spirrodeletum, Lemnetum trisulcae, Calletum palustris, Lysimachio vulgaris-Filipenduletum, and Bidentetum cernuae are registered in these biotopes. Calla palustris, Veratrum lobelianum, and Menyanthes trifoliate are rare species for the city of Kyiv and the Kyiv region. Ostericum palustre is listed in the Appendix 1 of the Bern Convention.
The steppe zone covers the southern part of Chelyabinsk region (38 % of territory). Arable land occupies the main part of the steppe zone, virgin steppes form small scattered patches under grazing and regular fires. Until now There was no enough information on the diversity of steppe vegetation in this region, whereas the steppe syntaxonomy of adjacent regions is rather well developed (Zhirnova, Saitov, 1993; Dubravnaya ..., 1994; Flora..., 2010; Korolyuk, 2014, 2017; Unikalnye..., 2014; Yusupova, Yamalov, 2016; Yusupova et al., 2018; Golovanov et al., 2021). The purpose of present study is to reveal the diversity of the steppes in the Southern Trans-Urals within the steppe zone and to present their classification according to Braun-Blanquet approach.
The investigated area is a high foothill plain, settling on the Trans-Ural peneplain. Its western border frames the foot of the Urals eastern ridges, and the eastern one adjoins the western limit of marine tertiary sediments of the West Siberian Plain. Igneous, sedimentary and metamorphic rocks of the Paleozoic prevail in geological structure, granite intrusions are widespread. Dominant soils are typical, southern and saline chernozem. The steppe zone forms latitudinal stripe of 2 degrees wide with its northern border along 54 10' N. From the north to the south the climate becomes warmer and drier. A peculiarity of this area are numerous tiny pine, birch and aspen-birch forests forming a landscape of "false forest-steppe".
The article is based on the analysis of 286 geobotanical relevés made by authors in 2006–2021 in the southern part of Chelyabinsk region. The classification was carried out using a modified TWINSPAN algorithm (Roleček et al., 2009) in the JUICE 7.0 package (Tichý, 2002). There are 7 associations, 1 subassociations, 5 variants and 1 community, belonging to orders Brachypodietalia pinnati (meadow steppes) and Helictotricho-Stipetalia (typical steppes) within the class Festuco-Brometea. Associations Artemisio nitrosae–Festucetum valesiacae ass. nov. and Carici supinae–Aizopsietum hybridae ass. nov., subass. Diantho acicularis–Orostachyetum spinosae inops subass. nov. and community Nepeta ucranica–Stipa lessingiana, as well as 5 variants were described for the first time. Ass. Diantho acicularis–Orostachyetum spinosae Schubert, Jäger et Mahn ex Yamalov, Zolotareva, Korolyuk, Makunina, Lebedeva ass. nov. and subass. Poo angustifoliae–Stipetum pennatae Yamalov, Bayanov, Muldashev et Averinova 2013 typicum subass. nov. were validated. Most of syntaxa forming the basis of steppe vegetation belong to the order Helictotricho-Stipetalia.
The zonal herb-bunchgrass steppes of the ass. Helictotricho desertorum–Stipetum rubentis occur on flat surfaces (placors) and gentle slopes, prevailing on hilly plain. Previuosly the such steppes dominated in the northern part of the steppe zone in the West Siberian Plain and Northern Kazakhstan, but now most of these have been replaced by arable land. The unplowed steppes which are strongly used as pastures now are assigned to the ass. Artemisio austriacae–Stipetum capillatae.
Meadow steppes of the order Brachypodietalia pinnati are strictly related to the "false forest-steppe" landscape. In the steppe zone meadow steppes of the subass. P. a.–S. p. typicum (Fig. 4) occur at the edges of forests and in shallow depressions. Further north, in the forest-steppe zone of the Trans-Urals, this subassociation becomes typical. The mostly mesophytic meadow steppes of the "false forest-steppe" stripe belong to the subass. Galio veri–Stipetum tirsae serratuletosum coronatae.
The main factors responsinle for differentiation of vegetation of the class Festuco-Brometea in study area are moisture, salinity and rock outcrops.
The topological series along the moisture gradient is represented in the landscape of “false forest-steppe”: Galio veri–Stipetum tirsae serratuletosum coronatae (meadow steppes on the edges of forests) –> Poo angustifoliae–Stipetum pennatae typicum (meadow steppes on the edges of forests and in shallow depressions) –> Helictotricho desertorum–Stipetum rubentis (typical herb-bunchgrass steppes).
Numerous rock outcrops in the central part of the Urals are the reason for the wide distribution of petrophytic communities. However, the diversity and species richness of petrophytic steppes is small (only two associations) in the Trans-Urals peneplain where rough-skeletal and eroded soils are rare. Petrophytic steppes of the ass. Carici supinae–Aizopsietum hybridae ass. nov. (Table 11, rel. 1–12), holotypus: Table 11, rel. no. 4 (12-0173): Russian Federation, Chelyabinsk region, Chesmenskiy district, mountain Shchukina near Kalinovskiy settlement, 53.81199° N, 60.50121° E, 12.06.2012, collector — A. Yu. Korolyuk) are common on granite outcrops in the most elevated relief elements of the Ural-Tobolsk watershed. Communities of the subass. Diantho acicularis–Orostachyetum spinosae inops subass. nov. (Table 10, rel. 1–12), holotypus: Table 10, rel. no. 11 (12-0139): Russian Federation, Chelyabinsk region, Kartalinskiy district, right bank the river Karagaylyayat between the v. Varshavskay and Elizavethopol’skoe, 52.81884° N, 60.45562° E, 09.06.2012, collector — A. Yu. Korolyuk) on the various rock outcrops are the impoverished variant of petrophytic steppes of the mountainous part of the Urals.
The communities of the ass. Artemisio nitrosae–Festucetum valesiacae ass. nov. (Table 8, rel. 1–12. Holotypus hoc loco: Table 8, rel. no. 3 (12-0128): Russian Federation, Chelyabinsk region, Bredinskiy district, near Bredy settlement, 52.44794° N, 60.32095° E, 08.06.2012, collector — A. Yu. Korolyuk) occur on the slopes with saline tertiary clays in the eastern part of study area.
The steppes of the Southern Trans-Urals combine the characteristic features of the steppe vegetation of adjacent territories. Herb-bunchgrass steppes of the Southern Trans-Urals are closely related to the West Siberian and Kazakhstan ones, while meadow steppes are associated with the Southern Urals syntaxa; the last ones include a number of European meadow-steppe species. There are some Ural endemics in syntaxa of petrophytic steppes, that make them closer to the Southern Urals syntaxa.
This paper presents a new and simple method to find indicator species and species assemblages characterizing groups of sites. The novelty of our approach lies in the way we combine a species relative abundance with its relative frequency of occurrence in the various groups of sites. This index is maximum when all individuals of a species are found in a single group of sites and when the species occurs in all sites of that group; it is a symmetric indicator. The statistical significance of the species indicator values is evaluated using a randomization procedure. Contrary to TWINSPAN, our indicator index for a given species is independent of the other species relative abundances, and there is no need to use pseudospecies. The new method identifies indicator species for typologies of species releves obtained by any hierarchical or nonhierarchical classification procedure; its use is independent of the classification method. Because indicator species give ecological meaning to groups of sites, this method provides criteria to compare typologies, to identify where to stop dividing clusters into subsets, and to point out the main levels in a hierarchical classification of sites. Species can be grouped on the basis of their indicator values for each clustering level, the heterogeneous nature of species assemblages observed in any one site being well preserved. Such assemblages are usually a mixture of eurytopic (higher level) and stenotopic species (characteristic of lower level clusters). The species assemblage approach demonstrates the importance of the 'sampled patch size,' i.e., the diversity of sampled ecological combinations, when we compare the frequencies of core and Satellite species. A new way to present species-site tables, accounting for the hierarchical relationships among species, is proposed. A large data set of carabid beetle distributions in open habitats of Belgium is used as a case study to illustrate the new method.
The Czech National Phytosociological Database (GIVD ID EU-CZ-001) was established in 1996 at Masaryk University in Brno. Currently it is hosted by the Department of Botany and Zoology of this university. It is an electronic archive of phytosociological relevés and related records of species composition from vegetation plots which have been sampled on the territory of the Czech Republic. The data stored in the database are used for the development of new national vegetation classification of the Czech Republic, biodiversity analyses at local, regional, national and international level, as a source of information about distribution of plant communities and species, and for developing and testing new methods in the analysis of large sets of vegetation-plot data.
An agglomerative clustering method is outlined and its application is illustrated by reference to a classification of flood-plain communities. This method operates on metric distance and uses the within-group sum of squares as the agglomeration criterion. Agglomeration is carried out in successive cycles in a manner such that the within-group sum of squares is minimized and, accordingly, the differences between the groups are maximized at each clustering cycle. The process results in the construction of a hierarchy of dichotomous branching. Two hierarchies are presented based on separate analyses of absolute distance and standard distance, utilizing data from a previous study of plant communities on the Squamish Flood-plain, British Columbia. The results indicate that the structure imposed on the sample is dependent on the distance measure by which stand relationships are defined. The hierarchies, however, are similar and at one level the classification units closely follow the major environmental divisions on the flood-plain. These units are described as vegetation types. The corresponding class centroids are ordinated in a principal components analysis.
The vegetation relevés stored electronically in the Czech National Phytosociological Database are reviewed. The database was established in 1996, with the central database located in the Department of Botany, Masaryk University, Brno (www.sci.muni.cz/botany/database.htm). On 15 November 2002 this central database contained 54,310 relevés from the Czech Republic, collected by 332 authors between 1922-2002. Ca. 54% of the relevés were taken from published papers or monographs, 21% from theses and the rest from various unpublished reports and field-books. These relevés include 1,259,008 records of individual plant species. Territorial coverage of the country by the reléves is irregular as the areas with attractive natural or semi-natural vegetation are more intensively sampled, with gaps in coverage of less attractive or poorly accessible areas. Most relevés are of broad-leaved deciduous forests (Querco-Fagetea), meadows (Molinio- Arrhenatheretea), dry grasslands (Festuco-Brometea), and marsh grasslands (Phragmito- Magnocaricetea). The quality of the data is discussed, such as researcher bias, preferential selection of sampling sites, spatial autocorrelation and missing values for some data elements.
Detrended correspondence analysis (DCA) is an improvement upon the reciprocal averaging (RA) ordination technique. RA has two main faults: the second axis is often an arch or horseshoe distortion of the first axis, and distances in the ordination space do not have a consistent meaning in terms of compositional change (in particular, distances at the ends of the first RA axis are compressed relative to the middle). DCA corrects these two faults. Tests with simulated and field data show DCA superior to RA and to nonmetric multidimensional sealing in giving clear, interpretable results. DCA has several advantages. (a) Its performance is the best of the ordination techniques tested, and both species and sample ordinations are produced simultaneously. (b) The axes are scaled in standard deviation units with a definite meaning, (c) As implemented in a FORTRAN program called DECORANA, computing time rises only linearly with the amount of data analyzed, and only positive entries in the data matrix are stored in memory, so very large data sets present no difficulty. However, DCA has limitations, making it best to remove extreme outliers and discontinuities prior to analysis. DCA consistently gives the most interpretable ordination results, but as always the interpretation of results remains a matter of ecological insight and is improved by field experience and by integration of supplementary environmental data for the vegetation sample sites.
This paper discusses vegetation types and diversity patterns in relation to environment and land-use at summer farms, a characteristic
cultural landscape in the Norwegian mountains. Floristic data (189 taxa) were collected in 130 4-m2 sample plots within 12 summer farms in Røldal, western Norway. The study was designed to sample as fully as possible the
range of floristic, environmental, and land-use conditions. Vegetation types delimited by two-way indicator species analysis
were consistent with results from earlier phytosociological studies. Detrended correspondence analysis and canonical correspondence
analysis show that rather than being distinct vegetation types, the major floristic variation is structured along a spatial
gradient from summer farm to the surrounding heathland vegetation. Species richness (alpha diversity) was modelled against
environmental variables by generalized linear modelling and compositional turnover (beta diversity) by canonical correspondence
analysis. Most environmental factors made significant contributions, but the spatial distance-to-farm gradient was the best
predictor of both species richness and turnover. While summer farms reduce mean species richness at the plot scale, the compositional
heterogeneity of the upland landscapes is increased, thereby creating ‘ecological room’ for additional vegetation types and
species. Within an overall similarity across scales, soil variables (pH, base saturation, LOI, phosphate and nitrogen) differed
considerably in their explanatory power for richness and turnover. A difference between ‘productivity limiting’ factors and
‘environmental sieves’ is proposed as an explanation. Species turnover with altitude is relatively low in grasslands as compared
to heaths.
This paper presents a new and simple method to find indicator species and species assemblages characterizing groups of sites. The novelty of our approach lies in the way we combine a species relative abundance with its relative frequency of occurrence in the various groups of sites. This index is maximum when all individuals of a species are found in a single group of sites and when the species occurs in all sites of that group; it is a symmetric indicator. The statistical significance of the species indicator values is evaluated using a randomization procedure. Contrary to TWINSPAN, our indicator index for a given species is independent of the other species relative abundances, and there is no need to use pseudospecies. The new method identifies indicator species for typologies of species releves obtained by any hierarchical or nonhierarchical classification procedure; its use is independent of the classification method. Because indicator species give ecological meaning to groups of sites, this method provides criteria to compare typologies, to identify where to stop dividing clusters into subsets, and to point out the main levels in a hierarchical classification of sites. Species can be grouped on the basis of their indicator values for each clustering level, the heterogeneous nature of species assemblages observed in any one site being well preserved. Such assemblages are usually a mixture of eurytopic (higher level) and stenotopic species (characteristic of lower level clusters). The species assemblage approach demonstrates the importance of the "sampled patch size," i.e., the diversity of sampled ecological combinations, when we compare the frequencies of core and satellite species. A new way to present species-site tables, accounting for the hierarchical relationships among species, is proposed. A large data set of carabid beetle distributions in open habitats of Belgium is used as a case study to illustrate the new method.
The full text of this classic is presented in its original format, with corrections. MAVR is superseded by my “Statistical ecology. Quantitative exploration of Nature to verify the expected and to reveal the unexpected". For further detail please visit https://sites.google.com/site/statisticalecology/
Note: Online availability of the electronic file of the corrected text free of charge for review is intended to make the unauthorised mining of its contents an uninviting prospect.
Two new divisive strategies for hierarchical classification are reported. Both use a form of 'directed search' to limit the number of possible polythetic splits examined. An objective method for testing the accuracy of divisions is defined. Preliminary results of tests of the two new methods against certain existing techniques have shown the former to produce superior divisions.
(1) The application of hierarchical classification to ecological community data is examined, using a variety of classification techniques and test data sets. Problems discussed include: (a) the choice of a conceptual space in which points representing samples or species or both are located; (b) the effects of random noise and nonlinearity; (c) the degree to which clusters are natural to a data set or are imposed by the clustering technique; (d) the choice of criteria for locating divisions; (e) clustering strategies (non-hierarchical v. hierarchical, divisive v. agglomerative, and polythetic v. monothetic); (f) the presentation of results of various clustering techniques; and (g) methods for evaluating and comparing clustering techniques and their results. (2) Five hierarchical clustering techniques are compared: complete linkage clustering, the unweighted pair group method using arithmetic averages, minimization of within-group dispersion, two-way indicator species analysis, and partitioning of an ordination space (using detrended correspondence analysis, a modification of reciprocal averaging). The first three techniques are agglomerative and the last two divisive. (3) Data sets for tests include simulated data sets in 1 to 4 dimensions (some incorporating noise of three kinds), and field data varying in number of samples, noise level, and number and length of community gradients. (4) Results indicate that two-way indicator species analysis is usually the best, but there are cases in which other techniques may be complementary or superior. (5) Theoretical requirements and test results are discussed to show why clustering of ecological community data is usually best approached by a divisive strategy. This conclusion is important because the analysis may be stopped after a limited number of divisions, thus needing less computation than do agglomerative strategies. The two divisive techniques discussed here have computer requirements which rise only linearly with the amount of data, making analysis of large data sets practical.
The chapter introduces the idea that the relationships between natural conditions and the outcome of an observation may be deterministic, random, strategic or chaotic, and that numerical ecology addresses the second type of data; it describes the role of numerical ecology among the various phases of an ecological research. The chapter includes discussion of the following topics: spatial structure, spatial dependence, and spatial correlation (independent observations, independent descriptors, linear independence, independent variable of a model, independent samples, origin of spatial structures, tests of significance in the presence of spatial correlation, and classical sampling and spatial structure), statistical testing by permutation (classical tests of significance, permutation tests, alternative types of permutation tests), computer programs and packages, ecological descriptors (i.e. variables: mathematical types of descriptors, and intensive, extensive, additive, and non-additive descriptors), descriptor coding (linear transformation, nonlinear transformations, combining descriptors, ranging and standardization, implicit transformation in association coefficients, normalization, dummy variable coding, and treatment of missing data (delete rows or columns, accommodate algorithms to missing data, estimate missing values). The chapter ends on a description of relevant software implemented in the R language.
. The computer software package TURBOVEG (for Microsoft® Windows®) was developed in The Netherlands for the processing of phytosociological data. This package comprises an easy-to-use data base management system. The data bank to be managed can be divided into several data bases which may consist of up to 100 000 relevés each. The program provides methods for input, import, selection, and export of relevés. In 1994, TURBOVEG was accepted as the standard computer package for the European Vegetation Survey. Currently it has been installed in more than 25 countries throughout Europe and overseas.
Principal components analysis has often been used to analyse multivariate data. An alternative and rather similar method, developed in France under the title `Analyse Factorielle des Correspondances' and here termed reciprocal averaging, is advocated as being more satisfactory in ecological contexts. Its particular strength is that it simultaneously ordinates both the species and the stands. The derived stand ordinations are often similar to those obtained by principal components analysis of standardized data. The theory of the method is presented in a mathematical appendix and its relation to principal components analysis is discussed. An algorithm suitable for deriving reciprocal averaging ordinations is briefly described.
R. A. Fisher's canonical analysis of contingency tables is shown to be applicable to incidence data as well as to contingency tables, and is accordingly designated by another author's name "correspondence analysis". In a theoretical section, the method is shown to be equivalent to a special case of Hotelling's canonical correlation analysis and also to a scale-free variant of principal components analysis. A practical example is examined, and a number of practical considerations discussed.
1. Early versions of the river invertebrate prediction and classification system (RIVPACS) used TWINSPAN to classify reference sites based on the macro-invertebrate fauna, followed by multiple discriminant analysis (MDA) for prediction of the fauna to be expected at new sites from environmental variables. This paper examines some alternative methods for the initial site classification and a different technique for prediction.
2. A data set of 410 sites from RIVPACS II was used for initial screening of seventeen alternative methods of site classification. Multiple discriminant analysis was used to predict classification group from environmental variables.
3. Five of the classification–prediction systems which showed promise were developed further to facilitate prediction of taxa at species and at Biological Monitoring Working Party (BMWP) family level.
4. The predictive capability of these new systems, plus RIVPACS II, was tested on an independent data set of 101 sites from locations throughout Great Britain.
5. Differences between the methods were often marginal but two gave the most consistently reliable outputs: the original TWINSPAN method, and the ordination method semi-strong hybrid multidimensional scaling (SSH) followed by K-means clustering.
6. Logistic regression, an alternative approach to prediction which does not require the prior development of a classification system, was also examined. Although its performance fell within the range offered by the other five systems tested, it conveyed no advantages over them.
7. This study demonstrated that several different multivariate methods were suitable for developing a reliable system for predicting expected probability of occurrence of taxa. This is because the prediction system involves a weighted average smoothing across site groupings.
8. Hence, the two most promising procedures for site classification, coupled to MDA, were both used in the exploratory analyses for RIVPACS III development, which utilized over 600 reference sites.
This contribution is a comment on the paper by Belbin & McDonald (1993) on the comparison of three classification strategies for use in ecology. There are two problems in evaluating clustering methods: does the sample adequately reflect the population structure, and what is the nature of the clusters sought. First, one has to decide on the number of clusters to be obtained. Possibly the best approach of all is the Bayesian coding theory for inductive inference. This may depend on the objectives of the clustering, which can be manifold. Phytosociologists do not agree on the nature of the clusters they seek, and are reticent in providing a formal definition of their clusters. As a method for identifying gradients Correspondence Analysis has had some success, so that a classification method largely based on it, notably TWINSPAN, may better reflect what phytosociologists are intuitively seeking than alternative variance minimisation methods. Additionally, TWINSPAN incorporates the characterisation through indicator species. Maybe we are more interested in these differentiating species than in the existence of clusters per se.
Simulated vegetation data of known structure and varying complexity were analyzed with Correspondence Analysis (CA), Detrended Correspondence Analysis (DCA), and a polythetic divisive method of classification as incorporated in the computer program TWINSPAN. The CA and DCA axes were statistically compared with the original gradients. In the case of TWINSPAN, the results were visually evaluated. The analyses showed that both CA and DCA will recover the first vegetation gradient in an acceptable manner only if the variation in the vegetation due to second or higher order gradients is small. Second gradients were never recovered in a meaningful manner. The sample points along these axes were so far displaced from their original positions along the gradients that the axes could not be used to represent the gradients. In particular, when the two gradients have the same length, CA and DCA gave very poor results for both the first and the second axes. This is thought to be one of the main reasons why TWINSPAN does not perform well, especially after the first division.
Little consensus has been reached as to general features of spatial variation in beta diversity, a fundamental component of species diversity. This could reflect a genuine lack of simple gradients in beta diversity, or a lack of agreement as to just what constitutes beta diversity. Unfortunately, a large number of approaches have been applied to the investigation of variation in beta diversity, which potentially makes comparisons of the findings difficult.
We review 24 measures of beta diversity for presence/absence data (the most frequent form of data to which such measures are applied) that have been employed in the literature, express many of them for the first time in common terms, and compare some of their basic properties.
Four groups of measures are distinguished, with a fundamental distinction arising between ‘broad sense’ measures incorporating differences in composition attributable to species richness gradients, and ‘narrow sense’ measures that focus on compositional differences independent of such gradients. On a number of occasions on which the former have been employed in the literature the latter may have been more appropriate, and there are many situations in which consideration of both kinds of measures would be valuable.
We particularly recommend (i) considering beta diversity measures in terms of matching/mismatching components (usually denoted a , b and c ) and thereby identifying the contribution of different sources of variation in species composition, and (ii) the use of ternary plots to express the relationship between the values of these measures and of the components, and as a way of understanding patterns in beta diversity.
The program JUICE was designed as a Microsoft® WINDOWS® application for editing, classification and analysis of large phytosociological tables and databases. This software, with a current maximum capacity of 30 000 relevés in one table, includes many functions for easy manipulation of table and header data. Various options include classification using COCKTAIL and TWINSPAN methods, calculation of interspecific associations, fidelity measures, average Ellenberg indicator values, preparation of synoptic tables, automatic sorting of relevé tables, and export of table data into other applications (word processors, spreadsheet programs or mapping packages). JUICE is optimized for use in association with TURBOVEG which is the most widespread database program for storing phytosociological data in Europe.
Four commonly used clustering methods (UPGMA, Ward Linkage,Complete Linkage and TWINSPAN) were compared in their abilitytorecognise the structure of three river macroinvertebratesdatasetswhich were pre-determined based on habitat and biologicalcharacteristics or chemical water quality of sampling sites.DCA,NMDS and ANOSIM were applied to the same datasets to providefurther information about data structure, and nonparametrictestswere also undertaken on major chemical variables to justifythepredeterminations. The modified Rand Index was used to measuretheagreement between a particular solution and the pre-determinedclassification. The results showed that Ward Linkage performedbestwhen its use was broadened and used with the CY DissimilarityMeasure, followed by TWINSPAN and Complete Linkage with UPGMAbeingleast successful. There was evidence to suggest that theeffectiveness of some clustering methods (e.g. UPGMA) may varyatdifferent clustering levels, and simulation techniques whichhavebeen used to assess clustering methods could leave somepropertiesof clustering methods unexamined.
. We compare three common types of clustering algorithms for use with community data. TWINSPAN is divisive hierarchical, flexible-UPGMA is agglomerative and hierarchical, and ALOC is non-hierarchical. A balanced design six-factor model was used to generate 480 data sets of known characteristics. Recovery of the embedded clusters suggests that both flexible UPGMA and ALOC are significantly better than TWINSPAN. No significant difference existed between flexible UPGMA and ALOC.
The application of correspondence analysis to square asymmetric tables is often unsuccessful because of the strong role played by the diagonal entries of the matrix, obscuring the data off the diagonal. A simple modification of the centring of the matrix, coupled with the corresponding change in row and column masses and row and column metrics, allows the table to be decomposed into symmetric and skew symmetric components, which can then be analysed separately. The symmetric and skew symmetric analyses can be performed by using a simple correspondence analysis program if the data are set up in a special block format. The methodology is demonstrated on a social mobility table from the first democratically elected Parliament in Germany, the Frankfurter Nationalversammlung. The table cross-tabulates the jobs of parliamentarians when first entering the labour market and their jobs in May 1848 when the Parliament started its first session.
Numerical ecology Analysis of ecological communities. MjM Software Design PC-ORD. Multi-variate analysis of ecological data
- P Legendre
- L Legendre
- Nl Mccune
- B Grace
- Us Mccune
- B Mefford
Legendre, P. & Legendre, L. 1998. Numerical ecology. 2nd edition. Elsevier, Amsterdam, NL. McCune, B. & Grace, J.B. 2002. Analysis of ecological communities. MjM Software Design, Gleneden Beach, OR, US. McCune, B. & Mefford, M.J. 1999. PC-ORD. Multi-variate analysis of ecological data, version 4.0. MjM
TWINSPAN for Windows Version 2.3. Centre for Ecology and Hydrology & University of South Bohemia, Č eske´Bude´jovice, CZ. Jaccard, P. 1912. The distribution of the flora in the alpine zone
- M O Hill
- P Sˇmilauer
Hill, M.O. & Sˇmilauer, P. 2005. TWINSPAN for Windows
Version 2.3. Centre for Ecology and Hydrology &
University of South Bohemia, Č eske´Bude´jovice, CZ.
Jaccard, P. 1912. The distribution of the flora in the alpine
zone. New Phytologist 11: 37-50.
PC-ORD. Multivariate analysis of ecological data
- B Mccune
- M J Mefford
McCune, B. & Mefford, M.J. 1999. PC-ORD. Multivariate analysis of ecological data, version 4.0. MjM
Software Design, Gleneden Beach, OR, US.
R: a language and environment for statistical computing. R Foundation for Statistical Computing
- R Development
- Core Team
R Development Core Team 2005. R: a language and
environment for statistical computing. R Foundation for
Statistical Computing, Vienna. http://www.r-project.org.
Accessed 24 February 2007.
R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. http://www.r-project.org
- R Development
- Core Team
R Development Core Team 2005. R: a language and
environment for statistical computing. R Foundation for
Statistical Computing, Vienna. http://www.r-project.org.
Accessed 24 February 2007.
Species assemblages and indicator species
- Dufrêne M.
Reciprocal averaging
- Hill
PC-ORD. Multivariate analysis of ecological data version 4.0. MjM Software Design
- B Mccune