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Question: How many vegetation plot observations (relevés) are available in electronic databases, how are they geographically distributed, what are their properties and how might they be discovered and located for research and application? Location: Global. Methods: We compiled the Global Index of Vegetation-Plot Databases (GIVD; http://www.givd.info), an Internet resource aimed at registering metadata on existing vegetation databases. For inclusion, databases need to (i) contain temporally and spatially explicit species co-occurrence data and (ii) be accessible to the scientific public. This paper summarizes structure and data quality of databases registered in GIVD as of 30 December 2010. Results: On the given date, 132 databases containing more than 2.4 million non-overlapping plots had been registered in GIVD. The majority of these data were in European databases (83 databases, 1.6 million plots), whereas other continents were represented by substantially less (North America 15, Asia 13, Africa nine, South America seven, Australasia two, multi-continental three). The oldest plot observation was 1864, but most plots were recorded after 1970. Most plots reported vegetation on areas of 1 to 1000 m2; some also stored time-series and nested-plot data. Apart from geographic reference (required for inclusion), most frequent information was on altitude (71%), slope aspect and inclination (58%) and land use (38%), but rarely soil properties (

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... VegItaly (see http://www.vegitaly.it) is a long-term project coordinated by the Italian Society for Vegetation Science (SISV) and the Italian Botanical Society (SBI). It is registered in the GIVD (Dengler et al., 2011) with the ID: EU-IT-001 (see http://www.givd.info/ID/EU-IT-001) (Venanzoni et al., 2012). ...
... It allows the compilation of data collected by researchers using a variety of approaches. Following the definition of 'vegetation database' suggested by the GIVD Dengler et al., 2011) and the Eco-informatics working group of the International Association of Vegetation Science, it provides certified support for scientific research. ...
... Further key steps have now been taken by many EVS members to locate and capture additional plots, and to centralise data storage of such plots. The Global Index of Vegetation-Plot Databases (GIVD) platform (Dengler et al., 2011) was developed to provide a meta-resource of electronic databases whose hosts are willing in principle to share the captured data. Already, 83 European databases covering more than 1.6 million relevés have been registered. ...
Book
All maps of vegetation or habitats are based on a system of classification. For vegetation, this has usually been based on phytosociological synsystems, while classifications of habitats, being more recent, have been produced at national, regional and international levels (e.g. Czech biotopes, Nordic vegetation types and Corine biotopes). This chapter discusses the classification systems in use for mapping vegetation and habitats in different countries, and also the work towards harmonisation at European scale. It introduces the EUNIS habitat classification, proposed as a European standard under the EU INSPIRE Directive (Directive 2007/2/EC), and its crosswalks to and from other typologies. Finally, it presents the habitat typologies used for monitoring, statistical and distribution modelling approaches as developed by the BioHab and EBONE projects.
... VegItaly (see http://www.vegitaly.it) is a long-term project coordinated by the Italian Society for Vegetation Science (SISV) and the Italian Botanical Society (SBI). It is registered in the GIVD (Dengler et al., 2011) with the ID: EU-IT-001 (see http://www.givd.info/ID/EU-IT-001) (Venanzoni et al., 2012). ...
... It allows the compilation of data collected by researchers using a variety of approaches. Following the definition of 'vegetation database' suggested by the GIVD Dengler et al., 2011) and the Eco-informatics working group of the International Association of Vegetation Science, it provides certified support for scientific research. ...
... Further key steps have now been taken by many EVS members to locate and capture additional plots, and to centralise data storage of such plots. The Global Index of Vegetation-Plot Databases (GIVD) platform (Dengler et al., 2011) was developed to provide a meta-resource of electronic databases whose hosts are willing in principle to share the captured data. Already, 83 European databases covering more than 1.6 million relevés have been registered. ...
Technical Report
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Chapter 3 summary All maps of vegetation or habitats are based on a system of classification. For vegetation, this has usually been based on phytosociological synsystems, while classifications of habitats, being more recent, have been produced at national, regional and international levels (e.g. Czech biotopes, Nordic vegetation types and Corine biotopes). This chapter discusses the classification systems in use for mapping vegetation and habitats in different countries, and also the work towards harmonisation at European scale. It introduces the EUNIS habitat classification, proposed as a European standard under the EU INSPIRE Directive (Directive 2007/2/EC), and its crosswalks to and from other typologies. Finally, it presents the habitat typologies used for monitoring, statistical and distribution modelling approaches as developed by the BioHab and EBONE projects.
... For instance, the data from New Zealand only include plots collected in non-forest ecosystems, while data from Chile only refer to forests. We urge potential users to carefully read the section 'Usage notes' below and the description of each individual dataset in GIVD (Dengler et al., 2011), and to contact the custodians of each dataset for further information. ...
... The authors are grateful to the thousands of vegetation scientists who sampled vegetation plots in the field or digitized them into regional, national or international databases. The authors also Dengler et al. (2011). Biomes refer to Schultz (2005), modified to include also the world mountain regions (Körner et al., 2017 ...
Article
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Assessing biodiversity status and trends in plant communities is critical for understanding, quantifying and predicting the effects of global change on ecosystems. Vegetation plots record the occurrence or abundance of all plant species co‐occurring within delimited local areas. This allows species absences to be inferred, information seldom provided by existing global plant datasets. Although many vegetation plots have been recorded, most are not available to the global research community. A recent initiative, called ‘sPlot’, compiled the first global vegetation plot database, and continues to grow and curate it. The sPlot database, however, is extremely unbalanced spatially and environmentally, and is not open‐access. Here, we address both these issues by (a) resampling the vegetation plots using several environmental variables as sampling strata and (b) securing permission from data holders of 105 local‐to‐regional datasets to openly release data. We thus present sPlotOpen, the largest open‐access dataset of vegetation plots ever released. sPlotOpen can be used to explore global diversity at the plant community level, as ground truth data in remote sensing applications, or as a baseline for biodiversity monitoring. Vegetation plots (n = 95,104) recording cover or abundance of naturally co‐occurring vascular plant species within delimited areas. sPlotOpen contains three partially overlapping resampled datasets (c. 50,000 plots each), to be used as replicates in global analyses. Besides geographical location, date, plot size, biome, elevation, slope, aspect, vegetation type, naturalness, coverage of various vegetation layers, and source dataset, plot‐level data also include community‐weighted means and variances of 18 plant functional traits from the TRY Plant Trait Database. Global, 0.01–40,000 m². 1888–2015, recording dates. 42,677 vascular plant taxa, plot‐level records. Three main matrices (.csv), relationally linked.
... This approach has great potential for macroecology as it combines fine-grain sizes with large spatial extents, a combination that could contribute to a more mechanistic understanding of patterns, but for a long time was underrepresented in macroecology (Beck et al., 2012). Moreover, vegetation-plot data allow for a much wider range of macroecological analyses than species occurrence databases do (Dengler et al., 2011;Bruelheide et al., 2019). Most of such plot-based macroecological papers take the information in the underlying databases as unquestioned facts. ...
... delimited plots. Large vegetation-plot databases at regional and national (seeDengler et al., 2011 for an overview), continental(Chytrý et al., 2016) or global(Bruelheide et al., 2019) scales are naturally less selective as their main aim is to get as many vegetation-plot records as possible. They include, to a large extent, traditional phytosociological relevés, in which the plot borders were often not precisely delimited in the field. ...
Article
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Aims Understanding fine-grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine-grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups). Location Palaearctic biogeographic realm. Methods We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001 m², 0.001 m², 0.01 m², 0.1 m², 1 m², 10 m², 100 m² and 1000 m² and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class. Results Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi-natural) grasslands and natural grasslands are the richest vegetation type. The open-access file ”GrassPlot Diversity Benchmarks” and the web tool “GrassPlot Diversity Explorer” are now available online (https://edgg.org/databases/GrasslandDiversityExplorer) and provide more insights into species richness patterns in the Palaearctic open habitats. Conclusions The GrassPlot Diversity Benchmarks provide high-quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, , biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation-plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology.
... At the same time, knowledge accumulated in past research programs can also provide the basis for constructive research into vegetation history, biogeography and conservation. Database structures such as vegetation-plot databases may serve as important repositories for data curation and ensure research repeatability and meta-analysis in the context of macroecological and biogeographical studies (Dengler et al. 2011;Bruelheide et al. 2019). ...
... In addition to inclusion in the Global Index of Vegetation-Plot Databases (Dengler et al. 2011;Alvarez et al. 2012b), this database also contributed to the sPlot initiative (Bruelheide et al. 2019). ...
Article
SWEA-Dataveg is a vegetation-plot database collecting observations mainly in sub-Saharan Africa but also open to the rest of the African continent. To date this database contains more than 5,500 plot observations provided by 47 sources (projects, monographs, and articles). While the database is stored in PostgreSQL (including the PostGIS extension), the R-package "vegtable" implements a suitable exchange format. In this article we assess the current content of SWEA-Database and introduce its history and future as a repository of data for syntaxonomic assessments and macroecological research.
... Digital ground photographs of vegetation microplots can be used to infer localized knowledge across broader landscapes, such as large-scale vegetation patterns and plant classifications [7]. These photographs have ultra-high spatial resolution (mm) by nature, and allow scientists or artificial intelligence to classify plant species in the survey location with high accuracy [7]. ...
... Digital ground photographs of vegetation microplots can be used to infer localized knowledge across broader landscapes, such as large-scale vegetation patterns and plant classifications [7]. These photographs have ultra-high spatial resolution (mm) by nature, and allow scientists or artificial intelligence to classify plant species in the survey location with high accuracy [7]. This information can be used to inform classification models operating at lower resolution over the same area, such as aerial or satellite imagery. ...
Article
Relating ground photographs to UAV orthomosaics is a key linkage required for accurate multi-scaled lichen mapping. Conventional methods of multi-scaled lichen mapping, such as random forest models and convolutional neural networks, heavily rely on pixel DN values for classification.However, the limited spectral range of ground photos requires additional characteristics to differentiate lichen from spectrally similar objects, such as bright logs. By applying a neural network to tiles of a UAV orthomosaics, additional characteristics, such as surface texture and spatial patterns, can be used for inferences. Our methodology used a neural network (UAV LiCNN) trained on ground photo mosaics to predict lichen in UAV orthomosaic tiles. The UAV LiCNN achieved mean user and producer accuracies of 85.84% and 92.93%, respectively, in the high lichen class across eight different orthomosaics. We compared the known lichen percentages found in 77 vegetation microplots with the predicted lichen percentage calculated from the UAV LiCNN, resulting in a R2 relationship of 0.6910. This research shows that AI models trained on ground photographs effectively classify lichen in UAV orthomosaics. Limiting factors include the misclassification of spectrally similar objects to lichen in the RGB bands and dark shadows cast by vegetation.
... The data collection system is structurally stable, consistent and flexible, which makes it easy for scientists to use the data. Due to the adoption of universal format for data collection, Polish Vegetation Database already worked well with foreign databases [14,46]. This indicated that further exchange and cooperation on an international scale is now possible. ...
Article
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The phytosociological database Polish Vegetation Database collects relevés of all vegetation types in Poland. The database was established in 2007 and is located at Department of Biodiversity and Plant Cover Protection, University of Wrocław (http://synbiot.uni.wroc.pl). On March 2012, the database included 40000 relevés collected between 1927 and 2011. Most of relevés was taken from published papers and represents almost all types of habitats of Poland. Large groups of relevés represent meadows and pastures (Molinio-Arrhnehteretrea), broadleaf forests (Querco-Fagetea), arable land communities (Stellarietea), coniferous forests (Vaccinio-Piceetea) and eutrophic reed communities (Phragmitetea). In comparison to other countries in Central Europe, Polish Vegetation Database currently belongs to medium-sized databases, with full functionality and accessibility. The present article describes its development, basic operational information and how it can be used in analysis of vegetation in Poland.
... Altogether three basic sources of vegetation data have been used: (1) Our own relevés from plots for complex investigation of Cyperus fuscus (genetics, soil seed bank, vegetation; see Section 2.1). In total, 37 sites in AT, CZ, PL, and SK were sampled (31 of them also served for sampling of plant material for genetic analyses and 32 of them were analyzed for their soil seed bank), with 3 relevés for each of them, i.e., 111 relevés in total (July-October 2012; Table S1); (2) Additional relevés collected by K.G.B., K.B., K.Š., K.T., or P.K. between 2000 and 2019 in AT, CZ, or SK; 37 relevés in total, usually a single relevé per site; (3) Data with the occurrence of C. fuscus from the national phytosociological databases [43] of Austria (Austrian Vegetation Database-AVD [44]; 50 relevés), the Czech Republic (Czech National Vegetation Database-CNPD [45]; 516 relevés), Poland (Polish Vegetation Database -PVD [46]; 337 relevés), and Slovakia (Slovak Vegetation Database, also called Central Database of Phytosociological Samples-CDF [47]; 147 relevés), and from the Gravel Bar Vegetation Database (GBVD [48]; 11 relevés). The initial number of relevés from all sources was 1206. ...
Article
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The ecology and species diversity of ephemeral wetland vegetation have been fairly well studied, but the biology of its characteristic species has rarely been investigated holistically. Here we combine previous results on the genetic diversity of a suitable model species (the diploid Cyperus fuscus) with new data on its historical and recent occurrence, its ecological and climatic niche, and the associated vegetation. Analysis of phytosociological relevés from Central Europe revealed a broad ecological niche of C. fuscus with an optimum in the Isoëto-Nanojuncetea class, extending to several other vegetation types. Overall species composition in the relevés highlight C. fuscus as a potential indicator of habitat conditions suitable for a range of other threatened taxa. Analysis of historical records of C. fuscus from the Czech Republic showed an increasing trend in the number of localities since the 1990s. It seems that recent climate warming allows the thermophilous C. fuscus to expand its range into colder regions. Isoëto-Nanojuncetea and Bidentetea species are well represented in the soil seed bank in both riverine and anthropogenic habitats of C. fuscus. Vegetation diversity has a weak negative effect and anthropogenic (compared to riverine) habitats have a strong negative effect on genetic diversity in this species.
... While plot data and relevant databases are becoming increasingly available and comprehensive (e.g., Dengler et al., 2011;Bruelheide et al., 2019), they are spread thinly across a labyrinth of sources with different levels of access and are frequently reported in nonstandard formats (Wiser, 2016). Furthermore, plot databases often have a strong spatial bias. ...
Article
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Aims Trees dominate the biomass in many ecosystems and are essential for ecosystem functioning and human well‐being. They are also one of the best studied functional groups of plants, with vast amounts of biodiversity data available in scattered sources. We here aim to illustrate that an efficient integration of this data could produce a more holistic understanding of vegetation. Methods To assess the extent of potential data integration, we use key databases of plant biodiversity to 1) obtain a list of tree species and their distributions, 2) identify coverage and gaps of different aspects of tree biodiversity data, and 3) discuss large‐scale patterns of tree biodiversity in relation to vegetation. Results Our global list of trees included 58,044 species. Taxonomic coverage varies in three key databases, with data on the distribution, functional traits, and molecular sequences for about 84%, 45% and 44% of all tree species, which is > 10% greater than for plants overall. For 28% of all tree species, data are available in all three databases. However, less data are digitally accessible about the demography, ecological interactions, and socio‐economic role of tree species. Integrating and imputing existing tree biodiversity data, mobilization of non‐digitized resources and targeted data collection, especially in tropical countries, could help closing some of the remaining data gaps. Conclusions Due to their key ecosystem roles and having large amounts of accessible data, trees are a good model group for understanding vegetation patterns. Indeed, tree biodiversity data are already beginning to elucidate the community dynamics, functional diversity, evolutionary history and ecological interactions of vegetation, with great potential for future applications. An interoperable and openly accessible framework linking various databases would greatly benefit future macroecological studies, and should be linked to a platform that makes information readily accessible to end users in biodiversity conservation and management.
... The methods we have outlined here have global applications. The ever-growing volume of floristic site data (Dengler et al. 2011;Peet et al. 2013;Bruelheide et al. 2019) and large-scale syntheses of species to a growth form (Engemann et al. 2016;Oliver et al. 2019;Kattge et al. 2020) has offered opportunities to explore how site-based observations can be extended to inform spatial models. Currently, much effort and attention has been applied to using these floristic data to inventory, describe and map vegetation community types at broad scales (e.g. ...
... The methods we have outlined here have global applications. The ever-growing volume of floristic site data (Dengler et al. 2011;Peet et al. 2013;Bruelheide et al. 2019) and large-scale syntheses of species to a growth form (Engemann et al. 2016;Oliver et al. 2019;Kattge et al. 2020) has offered opportunities to explore how site-based observations can be extended to inform spatial models. Currently, much effort and attention has been applied to using these floristic data to inventory, describe and map vegetation community types at broad scales (e.g. ...
Article
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Context Ensembles of artificial neural network models can be trained to predict the continuous characteristics of vegetation such as the foliage cover and species richness of different plant functional groups. Objectives Our first objective was to synthesise existing site-based observations of native plant species to quantify summed percentage foliage cover and species richness within four functional groups and in totality. Secondly, we generated spatially-explicit, continuous, landscape-scale models of these functional groups, accompanied by maps of the model residuals to show uncertainty. Methods Using a case study from New South Wales, Australia, we aggregated floristic observations from 6806 sites into four common plant growth forms (trees, shrubs, grasses and forbs) representing four different functional groups. We coupled these response data with spatially-complete surfaces describing environmental predictors and predictors that reflect landscape-scale disturbance. We predicted the distribution of foliage cover and species richness of these four plant functional groups over 1.5 million hectares. Importantly, we display spatially explicit model residuals so that end-users have a tangible and transparent means of assessing model uncertainty. Results Models of richness generally performed well (R² 0.43–0.63), whereas models of cover were more variable (R² 0.12–0.69). RMSD ranged from 1.42 (tree richness) to 29.86 (total native cover). MAE ranged from 1.0 (tree richness) to 20.73 (total native foliage cover). Conclusions Continuous maps of vegetation attributes can add considerable value to existing maps and models of discrete vegetation classes and provide ecologically informative data to support better decisions across multiple spatial scales.
... However, despite numerous attempts, remote identification of tree species still remains very difficult, if at all possible, especially in forests with high biodiversity and complex multi-layered structures (Wäldchen et al., 2018). This is one of the reasons why forest field plots are still being maintained in many regions of the world (Dengler et al., 2011;Zhao et al., 2014;Anderson-Teixeira et al., 2015;Gadow et al., 2016). Vegetation may be classified using informal qualitative descriptions on the basis of expert knowledge or formal quantitative rules on the basis of chosen thresholds for relevant attributes (Kočí et al., 2003;De Cáceres et al., 2019;Chytrý et al., 2020). ...
Article
Aims Traditional quantitative approaches to forest classification are based on differences in species abundance or incidence among communities. In these approaches, all species are regarded as biologically equidistant regardless of the biological heterogeneity. The objective of the study is to evaluate the potential of the “Discriminating Avalanche” approach, which integrates species abundance and biological heterogeneity, as a new basis for forest classification. Location China, India, Iran, Ukraine, Germany, Italy, Mexico, Peru, and South Africa. Method We illustrate our approach using a set of 35 large tree‐mapped forest plots from various regions of the world. Our dissimilarity matrices, which integrate species abundance with biological heterogeneity, are compared with the standard Bray–Curtis and Whittaker dissimilarity indices, and provide the quantitative basis for a hierarchical cluster analysis. Results Four distinct groups of forests were identified using the proposed forest dissimilarity matrix. Afro‐montane forests from South Africa constitute a first group. A second group includes temperate deciduous broad‐leaved forests dominated by oak (Quercus) and beech (Fagus) from Europe and China. Conifer‐dominated forests constitute a third group. The remaining forests constitute the fourth group. Conclusion Biological heterogeneity provides a practical basis for vegetation classification. The results of this study, based on a variety of temperate and tropical forests, suggest that a measure of biological dissimilarity based on evolutionary and morphological differences among species is more effective than the traditional species abundance‐based approaches to classify an arbitrary set of plant communities. This approach promises greater refinement and consistency in ecological classification. In particular, it has advantage in classifying forests along large geographic scales in situations of high beta diversity and species turnover.
... We used plot data from the collaborative vegetation-plot database GrassPlot Biurrun et al., 2019; https://edgg.org/databases/GrassPlot) registered as EU-00-003 in the Global Index of Vegetation-Plot Databases (GIVD; Dengler et al., 2011). GrassPlot assembles ...
Article
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Questions: Which environmental factors influence fine-grain beta diversity of vegetation and do they vary among taxonomic groups? Location: Palaearctic biogeographic realm. Methods: We extracted 4,654 nested-plot series with at least four different grain sizes between 0.0001 m² and 1,024 m² from the GrassPlot database, covering a wide range of different grassland and other open habitat types. We derived extensive environmental and structural information for these series. For each series and four taxonomic groups (vascular plants, bryophytes, lichens, all), we calculated the slope parameter (z-value) of the power-law species–area relationship (SAR), as a beta diversity measure. We tested whether z-values differed among taxonomic groups and with respect to biogeographic gradients (latitude, elevation, macroclimate), ecological (site) characteristics (several stress-productivity, disturbance and heterogeneity measures, including land use) and alpha diversity (c-value of the power-law SAR). Results: Mean z-values were highest for lichens, intermediate for vascular plants and lowest for bryophytes. Bivariate regressions of z-values against environmental variables had rather low predictive power (mean R² = 0.07 for vascular plants, less for other taxa). For vascular plants, the strongest predictors of z-values were herb layer cover (negative), elevation (positive), rock and stone cover (positive) and the c-value (u-shaped). All tested metrics related to land use (fertilisation, livestock grazing, mowing, burning, decrease in naturalness) led to a decrease in z-values. Other predictors had little or no impact on z-values. The patterns for bryophytes, lichens and all taxa combined were similar but weaker than those for vascular plants. Main conclusions: We conclude that productivity has negative and heterogeneity positive effects on z-values, while the effect of disturbance varies depending on type and intensity. These patterns and the differences among taxonomic groups can be explained via the effects of these drivers on the mean occupancy of species, which is mathematically linked to beta diversity.
... Quantitative description of the vegetation of a wildlife system of interest should be the first ecological research priority. Unfortunately, the natural vegetation of the majority of African countries remains poorly described (Dengler et al. 2011). Although relatively detailed study of vegetation has been undertaken across southern (e.g. ...
Article
The vegetation of Mushingashi Conservancy in central Zambia was classified and mapped to provide a template for wildlife management. Putative vegetation types were delineated using Landsat 8 imagery, then sampled with 73 plots for vegetation composition and structure, and topo-edaphic properties. Classification followed a four-stage process. Valley dambo and floodplain grasslands were first separated as landscape units from wooded plots. Hierarchical cluster analysis was then used to identify 13 vegetation types based on woody composition and structure. Convex hull plots on a principal component analysis biplot successfully delineated the topo-edaphic environment and woody structure of each type. Linear discriminant analysis confirmed differences in topo-edaphic environment among types. The main environmental gradient was from vertic clays, supporting open Acacia woodland, to sandy soils, supporting miombo woodland, but other gradients were also important. Of a total of 193 woody species recorded, 25 occurred only on large termitaria. An influence of environmental gradients independent of plant-available moisture and nutrients is emphasised. Total woody cover decreased conspicuously on clay-rich soils with increased water availability. A functional vegetation classification of this nature is considered an essential first step towards the informed management of rangeland for large herbivores. Potential applications for management are discussed.
... Considering that most vegetation surveys in Europe have been carried out in accordance with the traditional Braun-Blanquet approach, the relatively standardized data collection protocols in European vegetation surveys should enhance consistency (Mucina et al., 2000). A notable contribution to vegetation classification is the development of vegetation-plot databases in which millions of records are stored Dengler et al., 2011). A key point is, however, to use a classification method that ensures stable, repeatable, and consistent classification outcome. ...
Article
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The goal of this study was to propose a hierarchically nested classification system comprising four principal levels of the Braun-Blanquet system for Polish grasslands of the class Molinio-Arrhenatheretea. Using the Cocktail method, we defined consistent criteria for delimitation of the class, three orders, nine alliances, and 45 associations. Formal definitions were prepared using the summed cover and presence/absence information of species groups and individual dominant species. We created an expert system with a set of assignment rules that unambiguously classify relevés to a single unit at the given abstraction level of the Braun-Blanquet system in such a way that a relevé matched by the definition of a focal vegetation unit must be matched by definitions of all superior units. Of 11,535 relevés classified to Molinio-Arrhenatheretea, 36% were recognized at the association level, and 57% and 85% at the alliance and order level, respectively. All relevés were assigned unambiguously, meaning that a single relevé could not be assigned to more than one unit within the same hierarchical level (no overlap between vegetation units). This study is the first proposal of a hierarchically nested classification system that classifies grassland vegetation at different syntaxonomical levels unequivocally. It is important to create definitions for different syntaxonomical levels because the majority of vegetation patches do not fit to the associations, but can only be assigned to high-rank units such as alliance, order, or class.
... Presently, there are no taxonomic keys or resources that facilitate the comprehensive identification of seedling pines (but see Lawson 1990 for brief notes on P. echinata Mill.). This is unfortunate considering the general importance of pines in numerous forest types and the on-going need for accurate identification of seedlings and vegetative individuals in plot-based vegetation studies (Chytry et al. 2011, Dengler et al. 2011a, 2011b, Enquist et al. 2016). In the course of a larger project analyzing vegetative response to silvicultural treatments in a remnant Piedmont savanna in North Carolina, the need presented itself to distinguish between seedlings of three pine species: P. echinata (subg. ...
... The species richness of plants and their diversity, calculated by Shannon's diversity index, were used as robust measures of possible habitat heterogeneity of sampling sites (Table 1). All data was deposited in software package TURBOVEG 2.101 (Hennekens and Schaminée, 2001) and included in the Vegetation Database of Northern Part of Serbia (AP Vojvodina) (GIVD ID EU-RS-004) (Dengler et al., 2011). ...
Article
Nestedness is currently one of the most explored structural patterns of biological communities, especially since its major application in studies on ecological networks. Research on the nested pattern, as a spatial structural descriptor of communities, was mostly focused on theoretical background in the conservation of habitat islands. Here, we explore, to what extent nested true bug communities are present in saline grassland fragments of the Pannonian ecoregion and what are the reasons for their nestedness. In 2015 and 2017, we sampled true bugs from 17 saline pastures in northern Serbia. We applied three different sampling procedures (i.e. gradient in sampling effort) for collecting true bugs: along 20 m long transect, 3 × 30 m long parallel transects and total inventory. Analyses showed significant nestedness of the true bug communities and consistency of the pattern regardless of the data type (binary vs. weighted data) and applied metrics (NODF vs. spectral radius, WNODF vs. spectral radius). However, with the decrease of sampling effort and/or the exclusion of grass feeders, all metrics gradually detect less frequently significant nestedness. The only constant factor which was found to induce nestedness in true bug communities was true bug species richness. Plant cover features showed a weak influence on the nested pattern and landscape features did not take part at all. We believe nestedness of true bugs was the result of differences in habitat complexity among sampling sites, but detailed studies are needed to reveal which abiotic and/or biotic factors are responsible for it. For further studies, priority should be given to investigating the influence of management of saline grasslands on the nestedness in true bug communities.
... Currently, interest in vegetation classification and its applications is growing . The introduction of new numerical methods and formal classification approaches (De Cáceres et al., 2015) and the availability of large vegetation-plot databases (Dengler et al., 2011;Chytrý et al., 2016;Bruelheide et al., 2019) contributed to overcoming the criticism of subjectivity of the traditional Braun-Blanquet method of vegetation classification (Braun-Blanquet, 1932). This has also paved the way for synthetic international vegetation classification studies on the European scale (e.g. ...
Article
Aim Vegetation types of Mediterranean thermophilous pine forests dominated by Pinus brutia, P. halepensis, P. pinaster, and P. pinea were studied in various areas. However, a comprehensive formal vegetation classification of these forests based on a detailed data analysis has never been developed. Our aim is to provide the first broad‐scale classification of these pine forests based on a large dataset of vegetation plots. Location Southern Europe, North Africa, Levant, Anatolia, Crimea and the Caucasus. Methods We prepared a dataset of European and Mediterranean pine‐forest vegetation plots. We selected 7277 plots dominated by the cold‐sensitive Mediterranean pine species Pinus brutia, P. halepensis, P. pinaster, and P. pinea. We classified these plots using TWINSPAN, interpreted the ecologically and biogeographically homogeneous TWINSPAN clusters as alliances, and developed an expert system for automatic vegetation classification at the class, order and alliance levels. Results We described Pinetea halepensis as a new class for the Mediterranean lowland to submontane pine forests, included in the existing Pinetalia halepensis order, and distinguished 12 alliances of native thermophilous pine forests, including four newly described, and three informal groups merging supposedly native stands and old‐established plantations. The main gradients in species composition reflect elevational vegetation belts and the west‐east, and partly north‐south, biogeographical differences. Both temperature and precipitation seasonality co‐vary with these gradients. Conclusions We provide the first formal classification at the order and alliance levels for all the Mediterranean thermophilous pine forests based on vegetation‐plot data. This classification includes traditional syntaxa, which have been critically revised, a new class and four new alliances. We also outline a methodological workflow that might be useful for other vegetation classification syntheses. The expert system, which is jointly based on pine dominance and species composition, is a tool for applying this classification in research and nature conservation survey, monitoring and management.
... These maps are full of ecological information, as they can be considered "integrated maps"; indeed, vegetation communities are correlated to environmental data such as bioclimatic features, topographic conditions, lithology, and land use. The widespread use of this approach in the botanical scientific community has meant that a large part of the world's vegetation has been studied and classified using a standard and shared methodology [6] with the production of a large amount of data collected in various databases of more or less easy access (i.e., [7,8]). ...
Article
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Phytosociology is a reference method to classify vegetation that relies on field data. Its classification in hierarchical vegetation units, from plant associations to class level, hierarchically reflects the floristic similarity between different sites on different spatial scales. The development of remotely sensed multispectral platforms as satellites enormously contributes to the detection and mapping of vegetation on all scales. However, the integration between phytosociology and remotely sensed data is rather difficult and little practiced despite being a goal for the modern science of vegetation. In this study, we demonstrate how normalized difference vegetation index (NDVI) time series with functional principal component analysis (FPCA) could support the analyses of phytosociologists. The approach supports the recognition and characterization of forest plant communities identified on the ground by the phytosociological approach by using NDVI time series that encode phenological behaviors. The methodology was evaluated in two study areas of central Italy, and it could characterize and discriminate six different forest plant associations that have similar dominant tree species but distinct specific composition: three dominated by black hornbeam (Ostrya carpinifolia) and three dominated by holm oak (Quercus ilex). The methodology was also able to optimize the ground data collection of unexplored areas (from a phytosociological point of view) by using a phenoclustering approach. The obtained results confirmed that by using remote sensing, it is possible to separate and distinguish plant communities in an objective/instrumental way, thus overcoming the subjectivity intrinsic to the phytosociological method. In particular, FPCA functional components (NDVI seasonalities) were significantly correlated with vegetation abundance data variation (Mantel r = 0.76, p < 0.001).
... All 103 relevés used in this study are stored in, and available from, the Forests Vegetation Database of Bosnia and Herzegovina, with the ID EU-BA-001 in the Global Index of Vegetation-Plot Databases (Dengler et al. 2011). ...
Article
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The paper describes two new mesophilous communities of oriental hornbeam (Carpinus orientalis) coppice from the northern Dinaric Alps in Bosnia and Herzegovina (B&H). While oriental hornbeam is mainly considered to be a part of thermophilous forests and scrub, numerical analysis of 103 relevés of C. orientalis dominated coppice from B&H has shown that two new, rather mesophilous, communities thrive on calcareous bedrock of NW B&H. They represent secondary successional stages of mesotermic forest vegetation in this region. Association Epimedio alpini-Carpinetum orientalis ass. nova hoc loco is related to Illyrian oak-hornbeam forests of Erythronio-Carpinion betuli, while Asplenio scolopendrii-Carpinetum orientalis ass. nova hoc loco is linked to Balkan submediterranean ravine forests of Ostryo-Tilion. Although these two associations were recorded only in the NW B&H, their distribution is potentially larger, as their source communities are relatively common throughout the Dinaric Alps, so the information about their distribution, vertical structure, and syndynamic relations could be very useful in a national scale forest management and nature conservation.
... Such plots typically contain a full list of vascular plant species, often also a list of bryophytes and lichens, estimates of cover abundance of each species and various additional sources of information on vegetation structure, location and environmental features in the plot (Dengler et al., 2011). These plots were extracted from the EVA database (Chytrý et al., 2016;accessed on 19 May 2020), and several other databases not included in EVA (see the full list of databases used in this study in Appendix S2). ...
Article
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Aim The EUNIS Habitat Classification is a widely used reference framework for European habitat types (habitats), but it lacks formal definitions of individual habitats that would enable their unequivocal identification. Our goal was to develop a tool for assigning vegetation‐plot records to the habitats of the EUNIS system, use it to classify a European vegetation‐plot database, and compile statistically‐derived characteristic species combinations and distribution maps for these habitats. Location Europe. Methods We developed the classification expert system EUNIS‐ESy, which contains definitions of individual EUNIS habitats based on their species composition and geographic location. Each habitat was formally defined as a formula in a computer language combining algebraic and set‐theoretic concepts with formal logical operators. We applied this expert system to classify 1,261,373 vegetation plots from the European Vegetation Archive (EVA) and other databases. Then we determined diagnostic, constant and dominant species for each habitat by calculating species‐to‐habitat fidelity and constancy (occurrence frequency) in the classified dataset. Finally, we mapped the plot locations for each habitat. Results Formal definitions were developed for 199 habitats at Level 3 of the EUNIS hierarchy, including 25 coastal, 18 wetland, 55 grassland, 43 shrubland, 46 forest and 12 man‐made habitats. The expert system classified 1,125,121 vegetation plots to these habitat groups and 73,188 to other habitats, while 63,064 plots remained unclassified or were classified to more than one habitat. Data on each habitat were summarized in factsheets containing habitat description, distribution map, corresponding syntaxa and characteristic species combination. Conclusions EUNIS habitats were characterized for the first time in terms of their species composition and distribution, based on a classification of a European database of vegetation plots using the newly developed electronic expert system EUNIS‐ESy. The data provided and the expert system have considerable potential for future use in European nature conservation planning, monitoring and assessment.
... Sometimes, publications find their way into the other domain. This has become much easier since the dawn of the digital era with large, easily searchable literature databases, open access and scientific networks expanding online (e.g., Dengler et al., 2011). Nevertheless, only a few research groups bridge both disciplines. ...
Article
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Two scientific disciplines, vegetation science and weed science, study arable weed vegetation, which has seen a strong diversity decrease in Europe over the last decades. We compared two collections of plot‐based vegetation records originating from these two disciplines. The aim was to check the suitability of the collections for joint analysis and for addressing research questions from the opposing domains. We asked: are these collections complementary? If so, how can they be used for joint analysis? Europe. We compared 13 311 phytosociological relevés and 13 328 records from weed science, concerning both data collection properties and the recorded species richness. To deal with bias in the data, we also analysed different subsets (i.e., crops, geographical regions, organic vs conventional fields, center vs edge plots). Records from vegetation science have an average species number of 19.0 ± 10.4. Metadata on survey methodology or agronomic practices are rare in this collection. Records from weed science have an average species number of 8.5 ± 6.4. They are accompanied by extensive methodological information. Vegetation science records and the weed science records taken at field edges or from organic fields have similar species numbers. The collections cover different parts of Europe but the results are consistent in six geographical subsets and the overall data set. The difference in species numbers may be caused by differences in methodology between the disciplines, i.e., plot positioning within fields, plot sizes, or survey timing. This comparison of arable weed data that were originally sampled with a different purpose represents a new effort in connecting research between vegetation scientists and weed scientists. Both collections show different aspects of weed vegetation, which means the joint use of the data is valuable as it can contribute to a more complete picture of weed species diversity in European arable landscapes. Vegetation of arable weeds is sampled by two rarely interacting scientific communities: phytosociologists and weed scientists from an agronomical background. We compare two data collections. Agronomical weed surveys were taken mainly in field centres and have a lower species richness than phytosociological data, taken presumably mostly in field edges. Combined use is proposed for a more accurate picture of weed vegetation.
... Another example is the Global Index of Vegetation Plot Databases that indexes the metadata of vegetation-plot data that are publicly available (Dengler et al., 2011). In contrast, DataONE has a broader scope that indexes the metadata of a large variety of biological and environmental data (Michener et al., 2012). ...
Article
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Addressing global environmental challenges requires access to biodiversity data across wide spatial, temporal and taxonomic scales. Availability of such data has increased exponentially recently with the proliferation of biodiversity databases. However, heterogeneous coverage, protocols, and standards have hampered integration among these databases. To stimulate the next stage of data integration, here we present a synthesis of major databases, and investigate (a) how the coverage of databases varies across taxonomy, space, and record type; (b) what degree of integration is present among databases; (c) how integration of databases can increase biodiversity knowledge; and (d) the barriers to database integration. Global. Contemporary. Plants and vertebrates. We reviewed 12 established biodiversity databases that mainly focus on geographic distributions and functional traits at global scale. We synthesized information from these databases to assess the status of their integration and major knowledge gaps and barriers to full integration. We estimated how improved integration can increase the data coverage for terrestrial plants and vertebrates. Every database reviewed had a unique focus of data coverage. Exchanges of biodiversity information were common among databases, although not always clearly documented. Functional trait databases were more isolated than those pertaining to species distributions. Variation and potential incompatibility of taxonomic systems used by different databases posed a major barrier to data integration. We found that integration of distribution databases could lead to increased taxonomic coverage that corresponds to 23 years’ advancement in data accumulation, and improvement in taxonomic coverage could be as high as 22.4% for trait databases. Rapid increases in biodiversity knowledge can be achieved through the integration of databases, providing the data necessary to address critical environmental challenges. Full integration across databases will require tackling the major impediments to data integration: taxonomic incompatibility, lags in data exchange, barriers to effective data synchronization, and isolation of individual initiatives.
... Analysis of vegetation and habitat diversity crucially depends on the availability of vegetation-plot data (Dengler et al., 2011;Chytrý et al., 2016Chytrý et al., , 2020. Therefore, many countries have created their own national vegetation-plot databases over the last decades. ...
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Questions What are the main vegetation types of forest and shrubland vegetation at the alliance level in Mediterranean Turkey? What is their syntaxonomical position? Can we integrate them into the European vegetation classification system? Which environmental factors are the main drivers of the floristic differentiation of vegetation types? Location Southern and western Turkey. Methods We collected 4,717 vegetation plots of forest and shrubland vegetation in Mediterranean Turkey and performed an unsupervised classification of this dataset. We described vegetation types based on the classification results, expert knowledge and information from the literature. We defined diagnostic species and prepared distribution maps for each vegetation type. To support the interpretation of the vegetation types, we determined the most important environmental variables using canonical correspondence analysis. Results The studied vegetation was divided into 21 types related to three vegetation belts: 1) thermo- and meso-mediterranean, comprising coniferous (Pinus brutia, P. pinea) and sclerophyllous forests, as well as macchia, garrigue and phrygana; 2) supra-mediterranean, comprising Pinus nigra subsp. pallasiana forests, thermophilous deciduous forests dominated by various oak species and Ostrya carpinifolia, and forests dominated by temperate species like Fagus orientalis, and 3) oro-mediterranean, comprising forests and shrublands dominated by Abies cilicica, Cedrus libani, Juniperus excelsa and J. communis subsp. nana. Elevation was identified as the main environmental driver of the vegetation pattern. Among climatic variables, the most important are the mean temperatures (annual and of driest, coldest, and warmest quarters), minimum temperature of winter, precipitation of warmest and driest quarters and precipitation seasonality. These factors indicate the decreasing effect of the Mediterranean climate with increasing elevation. Conclusions The vegetation of Mediterranean Turkey is arranged along climatic gradients depending on elevation and the distance from the Mediterranean Sea. Most vegetation types in this area correspond to the syntaxa accepted in EuroVegChecklist, while others were described as new.
... Therefore, integrating vegetation inventory databases, such as the Global Index of Vegetation-Plot Databases (http://www.givd.info; accessed on 19 September 2021) with the 313 databases and 3,630,327 plots registered (date accessed: October 2021), into the GBIF database was a critical factor for broadening and refining biodiversity occurrence data [74,75]. ...
Article
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Trochodendron aralioides Siebold & Zucc. is a relic tree that is discontinuously scattered across the mountainous areas of Japan, Taiwan, and South Korea, but the origin of T. aralioides in South Korea is still unclear and debated. To confirm its distribution and explore its origins, we constructed a streamlined framework to examine potential species distribution using multiple open access data and free and open-source software, as well as employing maximum entropy principles to predict the potential distribution of T. aralioides. The results showed reasonably good discrimination and were used to examine and discuss the explicit distribution of T. aralioides. The potential distribution of T. aralioides in Japan extended from Iriomote Island to approximately 37° N in Honshu on the Pacific Ocean side. In Taiwan, the potential distribution of T. aralioides was more common than in Japan. It occurred at 1500–3000 m a.s.l. across the Central Mountain Range and decreased toward the northern and southern tips, correlating to the descending pattern of the cloud belt. Thermal and moisture conditions were important factors to determine the distribution of T. aralioides. The potential distribution indicated that Jeju island had high potential as a habitat for T. aralioides, and that may indirectly imply its existence and origins in South Korea, as some researchers have noted.
... In recent years, species occurrence data have increased in volume and accessibility. This can be ascribed to several initiatives: the digitisation of historic biological records (Page et al., 2015); the proliferation and growth of citizen science monitoring initiatives (Spear et al., 2017); the launch of online data aggregators such as GBIF and similar regional portals (Nelson & Ellis, 2019); and the compilation of more specialist databases focused on particular types of ecological community (Dengler et al., 2011), monitoring data (Dornelas et al., 2018) or other evidence types (Hudson et al., 2017). Thanks to these initiatives, it is now straightforward for ecologists to access large quantities of data, and to use them for research. ...
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1. Aggregated species occurrence and abundance data from disparate sources are increasingly accessible to ecologists for the analysis of temporal trends in biodiversity. However, sampling biases relevant to any given research question are often poorly explored and infrequently reported; this can undermine statistical inference. In other disciplines, it is common for researchers to complete “risk‐of‐bias” assessments to expose and document the potential for biases to undermine conclusions. The huge growth in available data, and recent controversies surrounding their use to infer temporal trends, indicate that similar assessments are urgently needed in ecology. 2. We introduce ROBITT, a structured tool for assessing the “Risk‐Of‐Bias In studies of Temporal Trends in ecology”. ROBITT has a similar format to its counterparts in other disciplines: it comprises signalling questions designed to elicit information on the potential for bias in key study domains. In answering these, users will define study inferential goal(s) and relevant statistical target populations. This information is used to assess potential sampling biases across domains relevant to the research question (e.g. geography, taxonomy, environment), and how these vary through time. If assessments indicate biases, then users must clearly describe them and/or explain what mitigating action will be taken. 3. Everything that users need to complete a ROBITT assessment is provided: the tool, a guidance document, and a worked example. Following other disciplines, the tool and guidance document were developed through a consensus‐forming process across experts working in relevant areas of ecology and evidence synthesis. 4. We propose that researchers should be strongly encouraged to include a ROBITT assessment when publishing studies of biodiversity trends, especially when using aggregated data. This will help researchers to structure their thinking, clearly acknowledge potential sampling issues, highlight where expert consultation is required, and provides an opportunity to describe data checks that might go unreported. ROBITT will also enable reviewers, editors, and readers to establish how well research conclusions are supported given a dataset combined with some analytical approach. In turn, it should strengthen evidence‐based policy and practice, reduce differing interpretations of data, and provide a clearer picture of the uncertainties associated with our understanding of reality.
... This classification is usually based on plot observations (also known as phytosociological relevés), and classification schemes have a hierarchical structure, where the association is the fundamental unit and class is the highest rank (Westhoff and van der Maarel 1978;Dengler et al. 2008). Despite criticisms regarding the common preferential sampling strategy and the heterogeneity in the use of plot sizes and abundance scales (Dengler et al. 2008;De Cáceres et al. 2015), current development of classification methods including the implementation of expert systems (Tichý et al. 2019;Bruelheide et al. 2021) and the proliferation of initiatives compiling and sharing records in vegetation-plot databases (Dengler et al. 2011;Alvarez et al. 2012), enhance the potential application of the Braun-Blanquet approach as a reference system for the summary of vegetation diversity at a national level. ...
Article
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Aims : The Braun-Blanquet approach has been widely implemented to generate classification schemes at the country level and Chile is not an exception. In spite of numerous studies, a revised system for the whole country is still missing and most of the current surveys are restricted to a small set of vegetation groups or specific study sites. To fill this gap, we established a vegetation-plot database and updated the classification into a single syntaxonomic scheme. We also performed a comparison of this scheme with the formation system following the EcoVeg approach. Study area : Continental Chile. Methods : We compiled a database of 1,582 plot observations, which are classified into 29 classes, 43 orders, 65 alliances, and 162 associations according to the Braun-Blanquet approach. Results : These observations were assigned to 7 formation classes, 10 subclasses and 19 formations in the EcoVeg approach. There are several mismatches between phytosociological classes and EcoVeg formations, which indicates some inconsistencies in the current stage of syntaxonomy in Chile. Besides a big contrast on bioclimatic conditions within the country’s territory, the occurrence of intrazonal vegetation may explain the high diversity of phytosociological associations recorded in this database. Conclusions : This work may constitute the basis for the implementation of the EcoVeg classification at the levels of alliance and association and can be extended for other countries in the South American sub-continent.
... Testolin et al. (2021) used data from the global vegetation-plot database sPlot (Bruelheide et al., 2019), and four relied on regional data compilations (Bourgeois et al., 2021;Craven et al., 2021;Kusumoto et al., 2021;Tordoni et al., 2021). This pattern highlights that community efforts of collating extensive collaborative vegetation-plot databases, such as EVA, sPlot and GrassPlot, have the potential to facilitate new research avenues (Bruelheide et al., 2019;Dengler et al., 2011;Wiser, 2016), often beyond the initial scopes imagined by the founders of these databases, not mentioning the aims of most original field workers. ...
... Despite the large amount of phytosociological data we have compiled, there is still an unsufficient cover of large with abundant presence of bog vegetation (large areas in Scandinavia, Ukraine, Belarus, and especially in Russia; Figure 1). Although there has been considerable progress in the development of vegetation-plot databases in recent decades, stimulated especially by the establishment of the Global Index of Vegetation Databases (Dengler et al., 2011) and the integration of European databases into the European Vegetation Archive (Chytrý et al., 2016), uneven coverage of Europe by vegetation-plot data with significant gaps still persists (Sporbert et al., 2019). Therefore, further efforts are needed in vegetation sampling and data digitizing in areas with poor representation in vegetation-plot databases. ...
Article
Classification of European bog vegetation (Oxycocco‐Sphagnetea class); identification of diagnostic species for the class and vegetation subgroups (orders and alliances) development of an expert system for automatic classification of vegetation plots; and production of distribution maps of the Oxycocco‐Sphagnetea class and its alliances. Europe A dataset of vegetation‐plot records was compiled to cover most of the European continent by various bog types. An unsupervised classification (beta‐flexible linkage method, Sørensen distance measure) and DCA ordination were applied. Formal definitions of syntaxa based on species presence and covers, and respecting the results of the unsupervised classification, were developed and included in a classification expert system. The Oxycocco‐Sphagnetea class, its two orders (Sphagno‐Ericetalia tetralicis and Sphagnetalia medii) and seven compositionally distinct alliances were formally defined. In addition to the syntaxa included in EuroVegChecklist, three new alliances were distinguished: Rubo chamaemori‐Dicranion elongati (subarctic polygon and palsa mires); Erico mackaianae‐Sphagnion papillosi (blanket bogs of the northwestern Iberian Peninsula); and Sphagno baltici‐Trichophorion cespitosi (boreal bog lawns). The latter alliance was newly described in this article. This first pan‐European formalized classification of European bog vegetation partially followed the system presented in EuroVegChecklist, but suggested three additional alliances. One covers palsa and polygon mires, one covers Iberian bogs with endemics and one fills the syntaxonomical gap for lawn microhabitats in boreal bogs. A classification expert system has been developed, which allows assignment of vegetation plots to the types described.
... In recent decades, vegetation science has benefited from the development and maintenance of large vegetation databases (Dengler et al., 2011). Historical vegetation relevés performed by early vegetation ecologists, together with recent vegetation-plot data stemming from regional, but also national or continental research and survey projects, have been carefully assembled and digitally archived in the context of centralized initiatives Chytrý et al., 2016;Sabatini et al., 2021;Wiser, 2016). ...
Article
Analysing temporal patterns in plant communities is extremely important to quantify the extent and the consequences of ecological changes, especially considering the current biodiversity crisis. Long‐term data collected through the regular sampling of permanent plots represent the most accurate resource to study ecological succession, analyse the stability of a community over time and understand the mechanisms driving vegetation change. We hereby present the LOng‐Term Vegetation Sampling (LOTVS) initiative, a global collection of vegetation time‐series derived from the regular monitoring of plant species in permanent plots. With 79 datasets from five continents and 7789 vegetation time‐series monitored for at least six years and mostly on an annual basis, LOTVS possibly represents the largest collection of temporally fine‐grained vegetation time‐series derived from permanent plots and made accessible to the research community. As such, it has an outstanding potential to support innovative research in the fields of vegetation science, plant ecology and temporal ecology.
... The EUNIS habitat classification is a comprehensive hierarchical system for habitat identification in Europe, while the fourth hierarchical level in classification of inland surface aquatic habitats is widely used habitat resolution in ecological studies (Anđelković et al., 2016;Lillebø et al., 2019). Therefore, we suggest that UMAP can be a useful tool for habitat screening, recognition, and classification (Schaminée et al., 2009;Dengler et al., 2011). Although the UMAP was previously used to process hyperspectral vegetation data (Hennessy et al., 2021), to the best of our knowledge, this is the first paper which applied this method on the plot-based vegetation data. ...
Article
The analysis of community structure in studies of freshwater ecology often requires the application of dimensionality reduction to process multivariate data. A high number of dimensions (number of taxa/environmental parameters x number of samples), nonlinear relationships, outliers, and high variability usually hinder the visualization and interpretation of multivariate datasets. Here, we proposed a new statistical design using Uniform Manifold Approximation and Projection (UMAP), and community partitioning using Louvain algorithms, to ordinate and classify the structure of aquatic biota in two-dimensional space. We present this approach with a demonstration of five previously published datasets for diatoms, macrophytes, chironomids (larval and subfossil), and fish. Principal Component Analysis (PCA) and Ward's clustering were also used to assess the comparability of the UMAP approach compared to traditional approaches for ordination and classification. The ordination of sampling sites in 2-dimensional space showed a much denser, and easier to interpret, grouping using the UMAP approach in comparison to PCA. The classification of community structure using the Louvain algorithm in UMAP ordinal space showed a high classification strength for data with a high number of dimensions than the cluster patterns obtained with the use of a Ward's algorithm in PCA. Environmental gradients, presented via heat maps, were overlapped with the ordination patterns of aquatic communities, confirming that the ordinations obtained by UMAP were ecologically meaningful. This is the first study that applies UMAP and classification using Louvain algorithms on ecological datasets. We show that the performance of local and global structures, as well as the number of clusters determined by the algorithm, make this approach more powerful over the traditional ones.
... Many countries now have some national system of forest mensuration plots in place that measure key attributes including tree heights and canopy cover, tree diameters and framework tree species (Dengler et al., 2011, Crowther et al., 2015. Typically, these were established for informing policy and strategic decision making, rather than for wood production, rather than for ecological purposes including the identification of forest condition as it relates to primary forest. ...
Technical Report
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This report has been prepared by independent experts as a discussion paper for the workshop series with the following three objectives:1.Review and assess definitions relating to primary forests;2.Collate and evaluate datasets and methods currently available for measuring the extent of primary forests; and 3.Provide options for defining, assessing and reporting on primary forests.
... As data on environmental effects on species traits become increasingly available (Dengler et al., 2011;Edwards et al., 2013;Iversen et al., 2017;Kattge et al., 2011), applying the presented theory to forecast ecological change becomes increasingly feasible. ...
Article
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Ecosystems are subject to a multitude of anthropogenic environmental changes. Experimental research in the field of multiple stressors has typically involved varying the number of stressors, here termed stressor richness, but without controlling for total stressor intensity. Mistaking stressor intensity effects for stressor richness effects can misinform management decisions when there is a trade-off between mitigating these two factors. We incorporate multiple stressors into three community models and show that, at a fixed total stressor intensity, increasing stressor richness aggravates joint stressor effects on ecosystem functioning, but reduces effects on species persistence and composition. In addition, stressor richness weakens the positive selection and negative complementarity effects on ecosystem function. We identify the among-species variation of stressor effects on traits as a key determinant of the resulting community-level stressor effects. Taken together, our results unravel the mechanisms linking multiple environmental changes to biodiversity and ecosystem function.
... Finally, previous management and human interference on these forests were recorded. All records are stored in the Hellenic Woodland Database (Fotiadis et al. 2012), with code EU-GR-006 in the Global Index of Vegetation-Plot Databases (GIVD; Dengler et al. 2011). The identification of plant taxa was based on Flora Hellenica (Strid & Tan 19972002, Flora Europaea (Tutin et al. 1968;1972;1993), Mountain Flora of Greece (Strid 1986;Strid & Tan 1991), Flora of Turkey and the East Aegean Islands (Davis 1965-85). ...
Article
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About the distribution of Quercus ithaburensis in Greece
... In recent years, the inventory of biodiversity information has been promoted through vegetation databases from various parts of the world, such as the Global Index of Vegetation-Plot Databases (Dengler et al., 2011), European Vegetation Archive (Chytrý et al., 2016), and sPlot (Bruelheide et al., 2019). To understand the diversity of vegetation and recognize vegetation distribution patterns along environmental gradients, large-scale vegetation classifications have been performed on plot data from these databases and independent data sets (Li et al., 2013;Černý et al., 2015;Willner et al., 2017;Chytrý & Tichý, 2018;Rodwell, 2018;Bonari et al., 2021). ...
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Aims To propose a comprehensive classification framework for Japanese forest vegetation, an expert system based on a traditional system was developed, using a large-scale dataset covering the whole of Japan. Location The entire Japanese archipelago Methods A dataset of 12 720 vegetation plots from the National Vegetation Survey database was established. Then, an expert system for automatic hierarchical classification was developed, based on the traditional system. The classification effectiveness was verified using fidelity measures, the occurrence of traditional characteristic species, consistency with semi-supervised K-means, and modified-TWINSPAN, and the similarity between each unit. To investigate correspondence to the environmental variables, a detrended correspondence analysis with the 'envfit' function was used. Additionally, the occurring taxa were collated and compared with the flora lists of areas surrounding Japan. Results The Japanese forest dataset was classified into 34 alliances by the expert system, and 14 orders and six classes were distinguished. Most of these units had diagnostic taxa including existing characteristic species and the heatmap of the Bray–Curtis index showed the independence of each unit, and the similarity of the plot groups assigned to the same unit. Out of 34 alliances, clustering with semi-supervised K-means supported 21 alliances, and modified-TWINSPAN supported 16 alliances. The four classes correspond to the thermal conditions and support the existing concept of vegetation zones. The lower-level vegetation units correspond to a narrower range of environmental variables than higher-level units, and species composition varied with limited environmental variables. A floristic composition comparison emphasized the complexity of the species composition of Japanese forests. Conclusions This study proposes the first formal Japanese forest classification at the class, order, and alliance levels, reflecting traditional phytosociology systems and based on large-scale vegetation plot data. Our classification provides an important foundation for the future revision of formal phytosociological systems throughout East Asia.
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The main data on the geobotanical database – Database of antropogenic vegetation of Urals and adjacent territories registered in the Global Index of Vegetation-Plot Databases and the European Vegetation Archive are presented. The database includes more than 4,000 complete geobotanical relevés made between 1984 and 2020. The database contains the territories of 3 subjects of the Russian Federation (the Republic of Bashkortostan, Orenburg, Chelyabinsk regions) and 1 - the Republic of Kazakhstan (Aktobe region). For each relevés, a complete list of species with indication of abundance in points on the Braun-Blanquet scale. The main indicators (total cover, average height of the grass, etc.). For most descriptions, GPS coordinates and location are given. The ecological conditions were assessed with use of average values of E. Landolt scale. In the J. Braun-Blanquet classification system, all communities included in the database belong to nine vegetation classes (7 anthropogenic and 2 semi-natural), 75 associations and various types of communities. Geobotanical relevés with the dominance of such aggressive invasive species ( Acer negundo, Ambrosia psylostachya, Echinocystis lobata, Elodea canadensis, Solidago canadensis, Heracleum sosnowskyi, Hordeum jubatum, Xanthium albinum etc.) are also included in the database.
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Water resources and associated ecosystems are becoming highly endangered due to ongoing global environmental changes. Spatial ecological modelling is a promising toolbox for understanding the past, present and future distribution and diversity patterns in groundwater-dependent ecosystems, such as fens, springs, streams, reed beds or wet grasslands. Still, the lack of detailed water chemistry maps prevents the use of reasonable models to be applied on continental and global scales. Being major determinants of biological composition and diversity of groundwater-dependent ecosystems, groundwater pH and calcium are of utmost importance. Here we developed an up-to-date European map of groundwater pH and Ca, based on 7577 measurements of near-surface groundwater pH and calcium distributed across Europe. In comparison to the existing European groundwater maps, we included several times more sites, especially in the regions rich in spring and fen habitats, and filled the apparent gaps in eastern and southeastern Europe. We used random forest models and regression kriging to create continuous maps of water pH and calcium at the continental scale, which is freely available also as a raster map (Hájek et al., 2020b; https://doi.org/10.5281/zenodo.4139912). Lithology had a higher importance than climate for both pH and calcium. The previously recognised latitudinal and altitudinal gradients were rediscovered with much refined regional patterns, as associated with bedrock variation. For ecological models of distribution and diversity of many terrestrial ecosystems, our new map based on field groundwater measurements is more suitable than maps of soil pH, which mirror not only bedrock chemistry but also vegetation-dependent soil processes.
Conference Paper
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The article presents data on registering 5 species of the family Ophioglossaceae in the flora of Ukraine, compiled based on the entire archive of reports, including specimens deposited in the main herbaria, notes from literature and personal findings by other researchers and the authors. For each species, comparisons of the number of encounters before and after 1980 was made, which, with a certain degree of caution, can be viewed as an estimate of the dynamics of the number of locations. Additionally, information about probably 2 new species for Ukrainan flora presented. Please see also https://www.myslenedrevo.com.ua/en/Sci/Nature/archive-ophioglossaceae-ukraine.html
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A B S TR A C T The article presents the results of an analysis of the alien flora of the ruderal vegetation of Ukraine. A total of 325 alien species which belong to 58 families and 198 genera were identified. The total anthropogenization index of the ruderal phytocoenoses is 19.8%. It was established that the highest level of anthropogenization was found in the phytocoenoses of Polygono-Poetea annuae, Stellarietea mediae and Plantaginetea majoris. The leading families of the non-native fraction of the studied plant communities were Asteraceae, Brassicaceae and Poaceae. It has been revealed that in the biomorphological spectrum of alien plants therophytes prevailed. The ecological analysis has shown the predominance of submesophytes, acidophytes, semieutrophytes, acarbonatophytes and heminitrophytes plants. It was established that according to the arrival time the kenophytes predominate and by the degree of naturalization-the epoecophytes. Comparison of the alien species composition of the ruderal plant communities by means of Jaccard's indices showed the most similarity between the classes Polygono-Poetea annuae and Plantaginetea majoris, Robinietea and Galio-Urticetea, Stellarietea mediae and Artemisietea vulgaris. For the separate classes the indices of archaeophytization, kenophytization, modernization and fluctuation of the flora were calculated. It has been established that there are 23 highly invasive species in the ruderal vegetation of Ukraine and among these Ambrosia artemisiifolia, Anisantha tectorum, Grindelia squarrosa, Heracleum mantegazzianum, H. pubescens and Xanthium oreintale ssp. riparium are transformers.
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Research Highlights: Differentiation of Scots pine forests of the class Vaccinio-Piceetea in Poland has been the subject of numerous studies, including revisions. Despite that, the area of southwestern Poland was hitherto practically unexplored in this respect. Background and Objectives: The aim of this work was therefore (i) to present the diversity of the pine forests in the Sudetes and their foreland; (ii) to compare the ecology of studied communities. Materials and Methods: We analyzed 175 phytosociological relevés collected between 1991 and 2020 in natural and anthropogenic pine stands. To identify vegetation types, we used the modified TWINSPAN algorithm; principal coordinate analysis, distance-based redundancy analysis and permutational tests were applied to identify the variation explained and the main environmental gradients shaping the studied plant communities. Results: Five associations were distinguished: thermophilous Asplenio cuneifolii-Pinetum sylvestris Pišta ex Husová in Husová et al. 2002, which develops on shallow soils over ultrabasic substrates, Hieracio pallidi-Pinetum sylvestris Stöcker 1965, which prefers outcrops of acidic rocks; Betulo carpaticae-Pinetum sylvestris Mikyška 1970, which is relict in origin and occurs on the upper Cretaceous sandstones, the peatland pine–birch forests of the Vaccinio uliginosi-Betuletum pubescentis Libbert 1933 and the Vaccinio myrtilli-Pinetum sylvestris Juraszek 1928. Moreover, community Brachypodium sylvaticum-Pinus sylvestris with the occurrence of many thermophilous and basiphilous species was also found on limestone substratum. The analysis of the species composition of pine plantations established on deciduous and mixed forests habitats revealed that these anthropogenic communities were marked by a random combination of species in which a certain group of common forest generalists participated. The distinguished communities differed clearly among each other also in habitat characteristics. Particularly important for their differentiation were soil reaction and nutrients, supported by differences in moisture, temperature and light availability. Apart from the edaphic factors, altitude and the bedrock type proved to be equally important.
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In the article, the discovery of Ophioglossum vulgatum L. on the sands of the lower Dnieper in Kherson Region (Ukraine) is reported. We also provide here a short description of the habitat.
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Aims : Trithrinax campestris is one of the palm species with the southernmost distribution in the Neotropics. Despite that the vegetation types in which T. campestris occurs are nowadays heavily threatened by land use and land cover changes, their floristic composition and structure are still to be documented. In order to characterize T. campestris habitats, the aim of this study was to describe the floristic composition of the vegetation types in which this palm occurs and their relationships with different environmental factors. Study area : The survey was conducted in central Argentina in an area comprising the southern extreme of the distribution of T. campestris in the following phytogeographic areas: Espinal, Lowland and Mountain Chaco. Methods : Following the Braun-Blanquet approach we collected 92 floristic relevés recording a total of 601 vascular plant species. Vegetation was classified through the ISOPAM hierarchical analysis. Bioclimatic and elevation data were related to the floristic data through the ISOMAP ordination. Remote-sensed images (Landsat TM, ETM+ and OLI) were used to characterize the fire frequency in the 92 stands. Results : Four vegetation types that differed in floristic composition and in diagnostic species were discriminated: 1.1 Celtis tala / Sida rhombifolia closed forest; 1.2 Aspidosperma quebracho-blanco / Prosopis kuntzei open forest; 2.1 Jarava pseudoichu / Vachellia caven open savanna; and 2.2 Acalypha variabilis / Nassella cordobensis scrubland. The ISOMAP ordination showed that differences in floristic composition were related to elevation, topography and climatic variables.Out of the 92 stands, only 21 showed the occurrence of fires during the period 1999–2018. Conclusions : Our results evidenced that vegetation types (forests, savannas and scrublands) comprising T. campestris developed in a wide range of environmental conditions. This is the first study that focuses on all vegetation types in which T. campestris occurs in central Argentina and it is relevant for conservation and sustainable management of the only native palm species in the flora of this part of the country. Taxonomic reference : Catálogo de las Plantas Vasculares del Cono Sur (Zuloaga et al. 2008) and its online update (http://www.darwin.edu.ar). Abbreviations : ISOMAP = isometric feature mapping; ISOPAM = isometric partitioning around medoids.
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The Pladias (Plant Diversity Analysis and Synthesis) Database of the Czech Flora and Vegetation was developed by the Pladias project team in 2014-2018 and has been continuously updated since then. The flora section of the database contains critically revised information on the Czech vascular flora, including 13.6 million plant occurrence records, which are dynamically displayed in maps, and data on 120 plant characteristics (traits, environmental associations and other information), divided into the sections: (1) Habitus and growth type, (2) Leaf, (3) Flower, (4) Fruit, seed and dispersal, (5) Belowground organs and clonality, (6) Trophic mode, (7) Karyology, (8) Taxon origin, (9) Ecological indicator values, (10) Habitat and sociology, (11) Distribution and frequency, and (12) Threats and protection. The vegetation section of the database contains information on Czech vegetation types extracted from the monograph Vegetation of the Czech Republic. The data are supplemented by national botanical bibliographies, electronic versions of the standard national flora and vegetation monographs, a database of more than 19,000 pictures of plant taxa and vegetation types, and digital maps (shapefiles) with botanical information. The data from the database are available online on a public portal www.pladias.cz, which also provides download options for various datasets and online identification keys to the species and vegetation types of the Czech Republic. In this paper, we describe the general scope, structure and content of the database, and details of the data on plant characteristics. To illustrate the data and describe the main geographic patterns in selected plant characteristics, we provide maps of mean values of numerical characteristics or proportions of categories for categorical characteristics on the map of the country in a grid of 5 longitudinal × 3 latitudinal minutes (approximately 6.0 km × 5.5 km). We also summarize the main variation patterns in the functional traits in the Czech flora using the principal component analysis.
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Taxonomic information models The first step in the implementation of a database driven application is the definition of an appropriate information model, which has to be complex enough to meet the needs of the application and at the same time simple enough to be usable (GÜNTSCH & al., 2002). The taxonomic model has to incorporate nomenclatural rules and the traditional taxonomic relationships (synonymy, taxonomic hierarchy, etc.). In addition, it has to be capable of representing different taxonomic views in order to enable the system to express arbitrary relationships between potential taxa. The solution presented here is based on the IOPI model (BERENDSOHN, 1997), but the process of implementation has led to several changes in the overall design. Other concept-oriented models published over the past 6 years are cited by GEOFFROY & BERENDSOHN (2003a). The Berlin Model is addressing botanical data, but should serve for zoology as well, with some changes in the names section and the composition of nomenclatural reference citations. Because this is a physical model (i.e. the actual database design used in the implementation), the possibility of future changes to the design here presented cannot be excluded. These are and will be documented in the databased documentation attached to BERENDSOHN & al. (2002) on the WWW. That documentation also provides links to the different projects using the Berlin Model (among others, Euro+Med, IOPI / EuroCAT, Med-Checklist, the Dendroflora of El Salvador and AlgaTerra). The core model covers nomenclatural relationships, potential taxa and their relationships, bibliographical information, and a general structure for factual data. The core model is extensible in order to meet specific project requirements by means of adding further entities and relationships. Nomenclatural type designation, for example, is a central subject of the AlgaTerra project and is thus covered in a model extension (see KUSBER et al., 2003). For pragmatic reasons it was decided to base further specification on a relational model for the underlying database. There are clear advantages in other data models, but with the general aim of realising an implementation in the near future, the choice of using a relational model was based on the assumption that – for some time to come – relational database management systems (DBMS) will remain the standard tool for data storage. The DBMS used must be capable of processing stored procedures, functions, and triggers so that maximum integrity of taxonomic data can be achieved at database level. An MS SQL-Server 2000 database has been implemented as a documentation database, serving to store a model implementation of all core and extension tables, a reservoir for program elements related to the model (triggers, user defined functions, stored procedures), and to manage the documentation of the tables and attributes. Documentation of the core model as well as existing extensions is available on-line (BERENDSOHN & al., 2002), the list of tables and attributes being generated dynamically from the documentation database.
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Swiss forest releves were analysed in order to answer the two questions: a) which are the predominant gradients causing differences in forest vegetation all over the country and b) how does a calculated gradient system of forests fit Ellenberg's ecogram of a well defined region. Two large species data sets (6488 and 1600 releves each) were analysed with Correspondence and Canonical Correspondence Analyses (CA, CCA). Averaged Landolt's indicator values for moisture, nutrients, reaction, temperature and light served as primary environmental variables, averaged indicator values for humus and continentality, soil-, temperature- and precipitation variables served as secondary. Moisture, soil warmth, soil reaction and light turned out to be the most important factors when referring to the whole country. Soil reaction in combination with soil warmth and moisture were found to influence the submontane forests of the northern parts of the Alps predominantly. With respect to Ellenberg's ecogram, our results confirm the usefulness of the old system. In contrast, recent propositions on paralleling acidity and nutrient richness on the first ecogram axis, prove to be misleading when comparing calculated and expert-derived gradients. We consider our quantitatively derived ecogram a valuable alternative to hitherto available expert-solutions in forest classification projects.
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We present a flexible protocol for recording vegetation composition and structure that is appropriate for diverse applications, is scale transgressive, yields data compatible with those from commonly used methods, and is applicable across a broad range of terrestrial vegetation. the protocol is intended to be flexible in the intensity of use and commitment of time, and sufficiently open in architecture as to be adapatible to unanticipated applications. The standard observation unit is a 10 × 10 m (0.01 ha) quadrat or 'module'. Where the extent of homogeneous vegetation is sufficient, multiple modules are combined to form a larger, more representative sample-unit. All vascular species are recorded by cover class and in intensively sampled modules as present or absent in sets of nested quadrats. For each module, tres stems are tallied by diameter class; species with exceptionally high or low stem density can be sub- or supersampled to allow efficient collection of data and assessment of population structure. The most common plot configuration consits of 10 modules arranged in a 2 × 5 array with four modules sampled intensively; this size is often necessary to capture the complexity of a forest community. For rapid reconnaissance or inventory purposes, fewer modules are typically employed, and less information is collected.
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Question: Collaborative research efforts and synthetic vegetation analyses are often limited by difficulties in sharing or combining datasets. Can we facilitate these activities by means of an exchange standard for plot-based vegetation data? Methods: In 2003, the Ecoinformatics Working Group and the Council of the International Association for Vegetation Science endorsed the development of a standard exchange schema for vegetation-plot data. In 2007, a first workshop was held to formulate a common set of goals, concepts, and terminology for plot-based vegetation data. At a second workshop in 2008, this ontology was developed into an XML (extensible markup language) schema representation designed to be maximally compatible with existing standards and databases. Results: The exchange standard for plot-based vegetation data (Veg-X) allows for observations of vegetation at both individual plant and aggregated observation levels. It ensures that observations are fixed to physical sample plots at specific points in space and time, and makes a distinction between the entity of interest (e.g. an individual tree) and the observational act (i.e. a measurement). The standard supports repeated measurements of both individual organisms and plots, allows observations of entities to be grouped following predefined or user-defined criteria, and ensures that the connection between the entity observed and taxonomic concept associated with that observation are maintained. Conclusions: Establishment of exchange standards followed by development of ecoinformatics tools built around those standards should allow scientists to efficiently combine plot data over extensive spatial and temporal gradients in order to perform analyses and make predictions of vegetation change and dynamics at local and global scales.
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The project "Die Pflanzengesellschaften Mecklenburg-Vorpommerns und ihre Gefährdung" (The plant communities of Mecklenburg-Vorpommern and their vulnerability) is published as a two-volume series consisting of a table volume (2001) and a text volume (2004). Based on a huge vegetation-plot database and a consistent and well-documented methodology, the complete vegetation of this federal state in NE Germany was phytociolociologally classified de novo. The result are 34 phytosociological classes, 12 subclasses, 70 orders, 6 suborders, 125 alliances and 284 associations. This text volume cotains synoptic tables based on more than 50,000 vegetation plots for all taxonomic ranks from association to class. As a unique feature, the so-called “Gesamtklassentabelle” (synoptic table of all classes) is provided that shows the frequency distribution of all species across the 34 vegetation classes and the resulting assessment of sociological preferences. An Introduction and summary for English-speaking readers (M. Isermann & J. Dengler; pp. 16–21 of the text volume 2004) makes most of the content of both volumes accessible to persons not comprehending German.
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Aim The aims of this study are to resolve terminological confusion around different types of species–area relationships (SARs) and their delimitation from species sampling relationships (SSRs), to provide a comprehensive overview of models and analytical methods for SARs, to evaluate these theoretically and empirically, and to suggest a more consistent approach for the treatment of species–area data. Location Curonian Spit in north-west Russia and archipelagos world-wide. Methods First, I review various typologies for SARs and SSRs as well as mathematical models, fitting procedures and goodness-of-fit measures applied to SARs. This results in a list of 23 function types, which are applicable both for untransformed (S) and for log-transformed (log S) species richness. Then, example data sets for nested plots in continuous vegetation (n = 14) and islands (n = 6) are fitted to a selection of 12 function types (linear, power, logarithmic, saturation, sigmoid) both for S and for log S. The suitability of these models is assessed with Akaike’s information criterion for S and log S, and with a newly proposed metric that addresses extrapolation capability. Results SARs, which provide species numbers for different areas and have no upper asymptote, must be distinguished from SSRs, which approach the species richness of one single area asymptotically. Among SARs, nested plots in continuous ecosystems, non-nested plots in continuous ecosystems, and isolates can be distinguished. For the SARs of the empirical data sets, the normal and quadratic power functions as well as two of the sigmoid functions (Lomolino, cumulative beta-P) generally performed well. The normal power function (fitted for S) was particularly suitable for predicting richness values over ten-fold increases in area. Linear, logarithmic, convex saturation and logistic functions generally were inappropriate. However, the two sigmoid models produced unstable results with arbitrary parameter estimates, and the quadratic power function resulted in decreasing richness values for large areas. Main conclusions Based on theoretical considerations and empirical results, I suggest that the power law should be used to describe and compare any type of SAR while at the same time testing whether the exponent z changes with spatial scale. In addition, one should be aware that power-law parameters are significantly influenced by methodology.
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Development and evaluation of new approaches in phytosociology with special regard to vegetation classification Phytosociology had its starting point in the beginning of the 20th century as one of several schools which deal with vegetation from a scientific point of view. Josias Braun-Blanquet, who-se textbook ‘Pflanzensoziologie’ had been published in its first edition in 1928, could be seen as the founder of this school. Basic ideas of the Braun-Blanquet approach of vegetation science are the following: • Plant stands on plots are documented in a standardised manner, the so-called vegetation relevés, which form an adequate mean between being too superficial and being too lavish. They comprise information on location, site conditions and vegetation structure as well as a complete list of the occurring plant species each of those quantified by means of a combined cover-abundance scale. • Concrete plant stands (phytocoenoses) are thought to be assignable to abstract plant communities (phytocoena), which are characterised and separated one from another with regard to their whole species combination (floristic-coenological method). Since each of its constituent species has a certain ecological optimum and a specific geographical range it should be expected that they as a whole result in a clearly limited ecological space and synareal in which the community is distributed. Therefore it is not necessary to use the accordance in site conditions and geographical range as additional classification criteria. • Phytocoena are arranged into a hierarchical system according to their floristic similarity. The principal ranks of this system are bottom to top association, alliance, order and class. Those so-called syntaxa are given scientific names deriving from one or two species names. • As means for recognition and distinction of syntaxa diagnostic species are derived from the phytosociological data: Species which are restricted to a large extent to one such syntaxon are called character species, whereas differential species only differentiate one side only. Phytosociology has undergone an enormous impetus within the last century and has integrated most of the other former schools of vegetation science step by step. By means of the Braun-Blanquet approach, millions of relevés from all continents have been collected until now. For several countries comprehensive overviews of the plant communities occurring on their territories have been published. Since the 1960s numerous attempts have been made to automate the classification process by means of computer programs (numerical syntaxonomy). Phytosociology also found its way into legislation in the field of nature conservancy as protected habitats defined by the occurrence of certain syntaxa. In spite of this quantitative success phytosociology was always exposed to intense criticism, going as far as to blame it for not being scientific. Indeed, it must be stated that consistent and generally accepted methods are missing in syntaxonomy as one of the core subjects of phytosociology – even though a huge amount of phytosociological papers have been published and also numerous textbooks. Therefore the major aim of this Ph.D thesis is to develop such methods and to back them up from a theoretical point of view. As a first step, the three major purposes of vegetation classifications are determined: (1) Naming of the research object to enable communication about them. (2) Reduction of data and making them representable. This means that instead of determining and describing the distribution of numerous species doing the same only for several plant communities will be suitable generally. (3) Framework for the ‘inductive generalisation’: The floristic-coenological delimitation of phytocoena results into a far reaching accordance of the phytocoenoses belonging to them with regard to species combination and site conditions. Phytocoena therefore are suitable reference entities especially for ecological research and nature conservation. Moreover they can be used for bioindication. These purposes lead to the requests to be made on vegetation classifications which preferably should be meat. Most important are both the inner coherence of the separated units with respect to their major properties and their simple and clear discernibility. As further criteria the following should be mentioned: (1) completeness of the system. (2) Stability of the classification. (3) Tolerance against heterogeneous data. (4) Supra-regional applicability. (5) Applicability for different purposes. (6) Hierarchical structure. (7) Equivalence of syntaxa of the same rank. (8) Adequate number of discerned entities. As a whole these criteria are already fulfilled in the ‘classical’ form of the Braun-Blanquet approach. Nevertheless some weak points remain: • Until now precise and operational definitions for major concepts are missing. Syntaxonomy therefore is often difficult to comprehend for laymen. Instead of clear and verifiable criteria for and against a certain classification authors of phytosociological papers often refer to their own ‘expert knowledge’ or quote the opinion of a renowned phytosociologist. • Even though it has been well known for a long time, that numerous phytocoenoses and phytocoena are lacking character species, there is no generally accepted and methodically sound way to include them into the phytosociological system. As a result such plant stands frequently are not documented by relevés or at least not taken into account in the final syntaxonomic treatment. • Among phytosociologists belief in minimal areas is widely distributed. These should be relevé areas, beginning with which the species number does not increase substantially any more with further enlargement of the area. But it is well known for a long time by numerous empirical data as well as via theoretical arguments that every increase in area will cause an increase in the mean species number. The only problem ist that this increase is hardly recognizable when plotting the two axes of a species-area-curve in a linear scaling. This is because the function more or less follows a power function. The assumption of the existence of minimal areas lead many phytosociologists not to draw their major attention to relevé areas in syntaxonomy as long as they approximately correspond to the assumed mimimal areas. Relevé sizes for different vegetation types suggested by various textbooks differ by 150,000. Due to the dependence of species numbers from area it is not permissible to compare relevés of different area sizes. Most of the synthetic properties of plant communities as well are influenced by area size. This especially holds true for constancy which is the percentage of occurrences of a certain species within a set of relevés. By means of a conceptual model and empirical data a function is derived which approximately describes this dependence: St (A) = 1 – (1 – St0)(A / A0)^0,42, where St is the constancy and A the area size. The classification method put forward is formulated as an axiomatic system comprising twelve suggestions of definitions: 1. Phytocoenoses are defined in a pure operational manner as the plant individuals of different species growing in a time-space unit of a certain dimension. Neither discreteness nor integration are demanded a priori. This definition includes expressively all synusiae thriving in that time-space unit as for example epiphytes. 2. The so-called ‘basic syntaxonomic axiom’ states that every phytocoenosis belongs – within a syntaxonomic system – to exactly one syntaxon of a certain rank. 3. The classical definition of fidelity degrees by SZAFER & PAWŁOWSKI (1927) is both contradictory and impractical. Therefore a new differential species criterion is presented in which it says that a species can be called differential of one syntaxon versus another syntaxon of the same rank if its constancy is at least twice as high and this difference in commonness most probably is not due to chance. This formulation goes back to BERGMEIER & al. (1990) but uses constancy percentages instead of constancy classes as otherwise there would be unreasonable changes in the minimum requirements for differential species below and above the class borders. 4. Whereas constancy at association level and below is defined as percentage of relevés in which the species occurs, a constancy reference value (short: constancy) of a higher syntaxon should be calculated as a mean of the constancy values in all associations belonging to it. This me-thod of calculation is due to the fact that associations are considered the basic units of the system and prevents the results from being influenced from different examination intensities in different associations. 5. A differential species below the vegetation class must fulfil the differential species criterion against all other syntaxa of the same rank within the syntaxon of the next higher rank. To a-void both taxa from being named differential species which nearly do not contribute to the discernibility of the syntaxa and effects due to chance a restriction has to be appended: Only those taxa should be given the status of differential species which have at least 20 % constancy within the particular syntaxon and not more than 20 % in the compared syntaxa. 6. As common differential species of a class are those taxa named which are a nowhere seen character species within the particular structural type, but fulfil the differential criterion of two or three classes against all other classes of this type. 7. Character species of a syntaxon are those taxa which meet the differential species criterion compared with all other syntaxa of the same rank within a structural type. The function of character species is twofold: (1) In the classification process the principal demand of the existence of character taxa ascertains the approximate equivalence of syntaxa of one rank, which especially holds true for associations. (2) When a classification is done on the basis of the complete species combination, character species as those taxa which have a clear sociological optimum in a particular syntaxon can be used best as a means for recognition and discrimination of the entities. If the next higher syntaxa occur nowhere together, as an exception from the general rule, one taxon could be named character species in two independent syntaxa. The major reason for restricting the character species to structural types is the dependency of constancy from area size. Since the customary relevé sizes widely differ between different vegetation types, which seems to be sensible at least to some extent, it is not acceptable to classify all of them within one system. It seems to be appropriate to discern two (vegetation types with and without phanerophytes) or three (vegetation types with phanerophytes, without phanerophytes, but with other vascular plants and those built up solely by one layer of mosses, lichens and algae) floristically defined structural types a priori. Some problems related to the practical implementation of this rule are discussed and a pragmatic approach is recommended. 8. Species which meet the character species criterion within more than one syntaxon fitted into one another, which is often the case, are called transgressive character species. 9. With regard to syntaxa not possessing character species of their own it is recommended to apply the central syntaxon concept of DIERSCHKE (1981) at all syntaxonomic levels below the class. Accordingly, at a maximum one central syntaxon not or not sufficiently characterised by character species of its own can be distinguished within a syntaxon of the next higher rank. This is named in the same manner as all other syntaxa. As compared to the ‘deductive meth-ode’ developed by KOPECKÝ & HEJNÝ (1971) and other approaches to deal with negatively characterised syntaxa the suggested method has several theoretical and practical advantages. These are discussed in detail. Most important is probably the fact that the presented approach avoids the introduction of different ways of naming syntaxa, which unavoidably gives the impression that there would be an ecological difference – which in fact does not exist. 10. Syntaxa from association to class level either must be sufficiently characterised by character species of their own or be the central syntaxon of the next higher entity. ‘Sufficiently’ in this case means a constancy sum of all character species of at least 100%. 11. The association is the lowest syntaxon that could be characterised by character species of its own and not divided further in such syntaxa or otherwise it can be regarded as the central syntaxon of a (sub-) alliance. 12. The class is the highest syntaxon characterised well by character species within one structural type. To measure the ‘quality’ of a syntaxon the sum of the constancy values of its character species seems to be appropriate. An adequate classification then would be one in which the constancy sums of all classes are as high as possible. Both the minimum and the mean of those should be maximised. Some further recommendations for syntaxonomic work are presented which do not form part of the above axiomatic system: • ‘Graduated’ hierarchies are – from an information theoretical point of view – favourable to ‘flat’ ones. In many cases they reflect the structure of syntaxonomic data better. • Below association level it seems inappropriate to prolong the linear-monohierarchical classification from above. Here a multidimensional-polyhierarchical approach in which different complexes of differentiating factors stand aside with equal importance has its advantages. • Formal syntaxonomic classification above class level is to be rejected since the class is ac-cording to the suggested definition 12 the uppermost syntaxon. The syntaxonomic concept leads to requests upon the drawing up of relevés, the most important of which are the following: • Since – as has been shown – sound syntaxonomic classification is only possible on the basis of relevés of the same (or at least a similar) size, standard sizes for relevés in different structural types are proposed. • Due to the above definition of phytocoenoses and to the often high diagnostic value of non-vascular plants it is requested to document in relevés of phytocoenoses (holocoenoses) in principle all macroscopically visual photoautotroph organisms, including all synusiae such as epiphytes. The practical application of the presented syntaxonomic concept could be understood as a problem of optimisation which has to be treated in an iterative process: The most similar relevés on a floristic basis are to be combined together until the emerging units either possess character species of their own or can be regarded as the central association of a higher unit which evolves from the further joining of these basic units (associations). The treatment continues with analyses on the question which quotients and differences of percentage constancy values accord to statistical significant differences in commonness. They lead to the recommendation to complete – in case of low numbers of relevés – the requested constancy quotient q > 2 from the differential species criterion by an minimal constancy difference of Δ = (2 ⋅ n1)-1/2, where n1 is the number of relevés in the particular syntaxon. Additionally, some recommendations concerning the adequate presentation of syntaxonomic data in form of tables arise from the presented syntaxonomic concept: • It is essential always to give the (mean) sizes of the relevé areas, also in the case of constancy tables. • Constancy values should be presented as percentages and not in form of constancy classes to allow the application of the differential species criterion. • To make the results transparent, it is advisable, to give columns for all syntaxonomic levels in constancy tables and not only for associations and their subdivisions. Nomenclature is the second indispensable part of syntaxonomy besides the classification. It is ruled by the ‘International Code of Phytosociological Nomenclature’ (ICPN), which has been published in its third edition by WEBER & al. (2000). The basic function of the ICPN is to guarantee unambiguity and stability of the scientific names of syntaxa. To achieve this, two major principles are employed, that of priority and that of nomenclatural types. Although this construction and the Code as a whole have proven to be useful, some possibilities for improvement remain, of which the following should render prominent: • It seems necessary to clearly separate the system of phytocoena and that of synusiae. It is a logical contradiction if one entity at the same time is regarded as syntaxon and synusia as it is common practice at the time being. It is therefore recommended to put the synusial system on a clear nomenclatural basis, by reserving separate endings for its ranks within the ICPN. • The demands for original diagnoses of associations should be increased, to avoid the further accumulation of nomenclatural ‘ballast’ in literature. It should be pointed out in the ICPN that the requested full species list for a description of an association has to include bryophytes and lichens as well. • The ruling of subassociations by the ICPN should be omitted, especially due to the fact that it is incompatible with multidimensional subdivisions. How the presented ideas work when practically applied is shown in detail by several examples, most of which are taken from the comprehensive treatment of the plant communities in the German state Mecklenburg-Vorpommern by BERG & al. (2001b), where they have been use in a large scale survey for the first time. In particular, it is shown how more equivalent classes could be achieved in the system and how central syntaxa could solve classificatory problems about which has been debated at length but to no avail. Distribution maps of syntaxa have been published rarely so far. One possibility to generate such synchorological maps is the superimposition of distribution maps of their diagnostic species. This results in maps of ‘potential synareals’. This method is both applicable to outline and lattice maps. How this could be done is described in detail. Examples of either case are shown and their interpretation is discussed. Finally, the presented syntaxonomic concept is examined as a whole: Due to the axiomatic construction it is consistent. It meets the above given requests for vegetation classifications better than any other known approach. It has proven its practical suitability in BERG & al. (2001b), where it enabled the establishment of a syntaxonomic classification of the extant vegetation types within a region, based on a large databank. A major strength of the approach could be seen in the fact, that clear criteria are given to evaluate different classifications with respect to which of those is conform with the method at all and – if there being more – which is the best of them. Likewise high importance has the applicability of the presented method both in manual table work and as basis for an implementation in a numerical classification algorithm. The latter will be a necessary property of any syntaxonomic approach with which the data of one of the large national and supranational vegetation-plot databases arising can be analysed one day.
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