Motivation 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. Main types of variable contained 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. Spatial location and grain Global, 0.01–40,000 m². Time period and grain 1888–2015, recording dates. Major taxa and level of measurement 42,677 vascular plant taxa, plot‐level records. Software format Three main matrices (.csv), relationally linked.

AimsTo develop forest vegetation classification at the level of alliances and associations across the Hyrcanian ecoregion, Northern Iran, and to explore the effects of main environmental and geographic gradients on their distribution.LocationHyrcanian ecoregion, Northern Iran.MethodsA database of 1,597 vegetation plots of mostly 400 m2 in size with a total of 802 vascular plant taxa was established, covering the whole geographic range of the Hyrcanian forests at altitudes ranging from −22 to 2,850 m a. s. l. An expert system was developed for automatic classification of vegetation plots into alliances and associations. Detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to determine the most important environmental and geographic gradients affecting species composition.ResultsTwenty‐one associations and seven alliances of these forests, belonging to five orders and four classes, were defined. Among them, eleven associations and five alliances were described as new syntaxa. Alnion glutinosae and Smilaco excelsae‐Alnion barbatae, both distributed in the lowland belt, include swamp and wet forests, respectively. Parrotio persicae‐Carpinion betuli and Alnion subcordatae are respectively mesic and wet forests of the submontane belt. Solano kieseritzkii‐Fagion orientalis is a mesic beech forest in the montane belt, and finally, Quercion macrantherae, an open oak forest, and Centaureo hyrcanicae‐Carpinion orientalis, a dry hornbeam forest, occur in the upper‐montane belt. DCA and CCA analyses showed that the distribution of these alliances and associations is mainly related to altitude and mean annual temperature.ConclusionsBased on our results and comparison between the Hyrcanian and European forests, we propose a new, comprehensive syntaxonomic scheme for the Hyrcanian forests, supported by a classification expert system. Unlike previous studies, we linked the classification system to that of EuroVegChecklist because, though this area is outside of Europe, its vegetation is very similar to that of the European temperate forest vegetation.

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Aim To analyse the biogeographic patterns of Temperate Deciduous Forests (TDFs) in Western Eurasia based on different life‐forms and forests layers and explore their relationships with the current climate, Last Glacial Maximum (LGM) climate and topography. Location Western Eurasia. Taxon Vascular plants. Methods We delimited nine regions encompassing the variability of TDFs in Western Eurasia and collected 1000 vegetation plots from each. We deconstructed the plant communities into three layers, tree, shrub and floor. We used (i) generalized linear mixed models (GLMM) to analyse the influence of current climate, historical climate and topography on species richness by accounting for regional effects and (ii) redundancy analysis (RDA) with variance partitioning to describe the variation in life forms along abiotic gradients. The three forest layers were analysed jointly and separately. Results The Balkans, Alps and Carpathians appeared to be the richest in plant species, whereas the British Isles and the Hyrcanian region were the poorest. Annual temperature range and annual mean temperature were the best predictors of species richness for the whole dataset and for the shrub layer. The tree layer richness was mainly explained by the annual temperature range and by elevation, whereas the forest floor richness was more related to the annual temperature range and the annual mean temperature differences between the LGM and current climate. The current climate was the main predictor of the composition of the whole community, the tree layer and the floor layer, while the shrub layer was also influenced by historical climate. Main conclusions Our overview of the diversity of temperate deciduous forests in Western Eurasia demonstrates different patterns and drivers across life‐forms and forest layers. While the diversity of trees is mainly linked to current climatic conditions, the shrub layer is also driven by postglacial‐glacial climatic stability, suggesting a different origin from forest trees.