Bioclimatic perspectives in the distribution of Quercus ithaburensis Decne. subspecies in Turkey and in the Levant

Aim To define the bioclimatic tolerance ranges of the two Tabor oak subspecies. Prior to this definition, and considering the confusion in the literature regarding the Tabor oak subspecies geography, a reassessment of their present distribution is proposed. Location Turkey and the Levant. Methods The bioclimatic tolerance range of each subspecies was characterized by four parameters: (1) the humidity category (Q₂), (2) the winter variant (m) – the two basic variables used in Emberger's method for the definition of Mediterranean bioclimates, (3) the length of the dry season (LDS) and (4) its severity, expressed by the dry season water deficit (DSWD). The reference to the last two variables in the definition of bioclimatic tolerance ranges of Mediterranean species has so far never been considered. The concept of bioclimatic niche, based on the reference to these four parameters, is proposed and discussed. Results The reassessment of the Tabor oak subspecies distribution shows that their extents of occurrence do not overlap and are significantly distant. The comparison between the characteristics of each subspecies bioclimatic niche has highlighted three major differences: (1) The bioclimatic niche of the subspecies macrolepis is characterized by a great heterogeneity as it includes up to 10 distinct bioclimate types, whereas only four types have been found in the bioclimatic niche of the subspecies ithaburensis. (2) A 10 °C gap has been found between the winter variants of both bioclimatic niches. (3) The third major difference relates to the dry season characteristics: the bioclimatic niche of the subspecies ithaburensis is characterized by an LDS 40–75% longer than it is in the bioclimatic niche of the subspecies macrolepis. Moreover, and surprisingly, although the most arid humidity categories are found in the bioclimatic niche of the subspecies macrolepis, the bioclimatic niche of the subspecies ithaburensis is characterized by a significantly more severe dry season as the DSWD is 36–180% greater than in the bioclimatic niche of the subspecies macrolepis. It is suggested that the duration and the severity of the dry season is a major limiting factor in the spatial distribution of the subspecies macrolepis. Main conclusions The reference to the duration (LDS) and severity (DSWS) of the dry season is essential when defining the bioclimatic niche of Mediterranean species.     

Distribution,bioclimatic niche and sympatry of two Erinaceidae in Tunisia

Numerous mammalian species of North Africa have an enigmatic distribution between the Mediterranean and Saharan area. In order to study the distribution of hedgehogs in Tunisia, field data were collected from several protected areas and various natural and peri-urban environments during 4 years 2015–2018 covering the all bioclimatic zones present in the country. The present work provides a detailed geographical and ecological distribution of hedgehogs with a total of 168 occurrence data of Atelerix algirus and Paraechinus aethiopicus. Atelerix algirus showed a wide distribution range from north to south being absent only in the extreme Saharan environment. Paraechinus aethiopicus has been recorded in the centre and the south with a specialisation in the arid and Saharan environment. A parapatry distribution is also shown with a sympatric area between arid and Saharan bioclimates. Our results improve knowledge of the bioclimatic niche and habitat characteristic of these taxa not clearly defined in previous research. The presence of the two hedgehogs on Djerba Island (A. algirus and P. aethiopicus) is also confirmed.     

Spatial variation of climatic and non-climatic controls on species distribution: the range limit of Tsuga heterophylla

Aim To assess which climatic variables control the distribution of western hemlock (Tsuga heterophylla), how climatic controls vary over latitude and between disjunct coastal and interior sub‐distributions, and whether non‐climatic factors, such as dispersal limitation and interspecific competition, affect range limits in areas of low climatic control. Location North‐western North America. Methods We compared four bioclimatic variables [actual evapotranspiration (AET), water deficit (DEF), mean temperature of the coldest month (MTCO), and growing degree‐days (GDD5)] with the distribution of T. heterophylla at a 2‐km grid cell resolution. The distribution is based on a zonal ecosystem classification where T. heterophylla is the dominant late‐successional species. For each bioclimatic variable and at each degree of latitude, we calculated the threshold that best defines the T. heterophylla distribution and assessed the extent to which T. heterophylla was segregated to one end of the bioclimatic gradient. We also fitted two forms of multivariate bioclimatic models to predict the T. heterophylla distribution: a simple threshold model and a complex Gaussian mixture model. Each model was trained separately on the coastal and interior distributions, and predicted areas outside of the T. heterophylla distribution (overprediction) were evaluated with respect to known outlier populations. Results Actual evapotranspiration was the most accurate predictor across the T. heterophylla distribution; other variables were important only in certain areas. There was strong latitudinal variation in the thresholds of all variables except AET, and the interior distribution had wider bioclimatic thresholds than the coastal distribution. The coastal distribution was predicted accurately by both bioclimatic models; areas of overprediction rarely occurred > 10 km from the observed distribution and generally matched small outlier populations. In contrast, the interior distribution was poorly predicted by both models; areas of overprediction occurred up to 140 km from the observed distribution and did not match outlier populations. The greatest overprediction occurred in Idaho and Montana in areas supporting species that typically co‐exist with T. heterophylla. Main conclusions The high predictive capacity of AET is consistent with this species’ physiological requirements for a mild and humid climate. Spatial variation of MTCO, GDD5 and DEF thresholds probably reflects both the correlation of these variables with AET and ecotypic variation. The level of overprediction in portions of the interior suggests that T. heterophylla has not completely expanded into its potential habitat. Tsuga heterophylla became common in the interior 2000–3500 years ago, compared with > 9000 years ago in the coastal region. The limited time for dispersal, coupled with frequent fires at the margins of the distribution and competition with disturbance‐adapted species, may have retarded range expansion in the interior. This study demonstrates that bioclimatic modelling can help identify various climatic and non‐climatic controls on species distributions.     

Nanism and ephemerism as reasons for a hidden abundance in vernal pool plants: The example of Lepuropetalon spathulatum in Chile

Minute size (nanism) and short live cycle (ephemerism) are characteristic features of many plants living in seasonal wetlands in Mediterranean biomes. Lepuropetalon (Celastraceae) is a monotypic genus with an antitropical distribution (disjunct in temperate regions of both Americas). L. spathulatum is the smallest vascular plant of Chile, not recorded in herbaria for decades. Its distribution, ecology and phytosociology were studied based on herbarium vouchers and field observations. L. spathulatum occurs in the fringes of vernal pools, on oligotrophic sandy soils and in grazed Acacia caven pseudo‐savannas. Its distribution is linked to the Mediterranean and Submediterranean bioclimates. Associated species are other dwarfish annuals, many of them originating from the Western Palearctic subkingdom and characteristic for the class Isoëto‐Nanojuncetea. Other floristic elements are Chilean endemics and species with a disjunction to California (character species of the Nanojuncetea australis). L. spathulatum is not a rare plant in Chile, but is often overlooked because of its dwarfish and ephemeral habit. Although most populations occurred in secondary habitats and the species can tolerate disturbance, intensification of agriculture, forest plantations and modification of the hydrological conditions may threaten the species in the long term. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Morphological and genetic variation in Aegilops geniculata from Algeria

Aegilops geniculata Roth is an annual grass relative to cultivated wheats and is widely distributed in North Africa. In order to understand the diversity of this species, 14 populations collected in different bioclimatic areas in northern Algeria were analyzed using morphological and biochemical characters. Principal component analyses (PCA) based on the inflorescence characters and ecological parameters allowed the separation of populations in two mainly bioclimatic clusters characterized by different morphological patterns. Populations originated from humid and sub-humid coastal areas were characterized by vigorous spikes. Samples collected from intermediate and high mountains with humid and semi-arid conditions had long and lanceolate spikes. Individuals with small and narrow spikes were characteristics of steppic highlands in semi-arid conditions and high mountains with humid bioclimate. Individuals were distinguished successively by spike width, spike length, rachis length and awns number. Electrophoretic analyses of high molecular weight glutenin subunits (HMW-GS) based on the phenotypic variability and genetic distances revealed a significant variation within and between populations associated with bioclimatic conditions, in particular winter temperature. Genetic diversity was higher in populations growing under warm bioclimates than in those from cold bioclimates. These results suggest that a part of the variation for HMW glutenin variability is adaptive.     

Precipitation of the warmest quarter and temperature of the warmest month are key to understanding the effect of climate change on plant species diversity in Southern African savannah

In this study, we test for the key bioclimatic variables that significantly explain the current distribution of plant species richness in a southern African ecosystem as a preamble to predicting plant species richness under a changed climate. We used 54,000 records of georeferenced plant species data to calculate species richness and spatially interpolated climate data to derive nineteen bioclimatic variables. Next, we determined the key bioclimatic variables explaining variation in species richness across Zimbabwe using regression analysis. Our results show that two bioclimatic variables, that is, precipitation of the warmest quarter (R² = 0.92, P < 0.001) and temperature of the warmest month (R² = 0.67, P < 0.001) significantly explain variation in plant species richness. In addition, results of bioclimatic modelling using future climate change projections show a reduction in the current bio‐climatically suitable area that supports high plant species richness. However, in high‐altitude areas, plant richness is less sensitive to climate change while low‐altitude areas show high sensitivity. Our results have important implications to biodiversity conservation in areas sensitive to climate change; for example, high‐altitude areas are likely to continue being biodiversity hotspots, as such future conservation efforts should be concentrated in these areas.     

Potential distribution of semi-deciduous forests in Castile and Leon (Spain) in relation to climatic variations

About 45% of the total surface area of the Castile and Leon region today can potentially be occupied by semi-deciduous forests, chiefly dominated by Quercus faginea Willd. and Quercus pyrenaica Lam. On the basis of extrapolated trends in annual mean temperature and precipitation in Castile and Leon observed over the 37-year period from 1961 to 1997 [del Río et al. 2005], predicted changes in the areas covered by Q. faginea and Q. pyrenaica forests in 2025, 2050 and 2075 were made. A decrease in Q. faginea forests may occur if observed trends in temperature and precipitation continue. With respect to Q. pyrenaica forests, they may increase in present Mediterranean areas and decreases in Temperate Submediterranean areas. In some cases, both types of forests could be replaced by deciduous forests. The predicted results in the natural distribution of vegetation types by the bioclimatic models can be used to establish policies for improved future nature conservation and land management.     

Creating individual accessible area hypotheses improves stacked species distribution model performance

Aim

Stacked species distribution models (SDMs) are an important step towards estimating species richness, but frequently overpredict this metric and therefore erroneously predict which species comprise a given community. We test the idea that developing hypotheses about accessible area a priori can greatly improve model performance. By integrating dispersal ability via accessible area into SDM creation, we address an often‐overlooked facet of ecological niche modelling.

Innovation

By limiting the training and transference areas to theoretically accessible areas, we are creating more accurate SDMs on the basis of a taxon's explorable environments. This limitation of space and environment is a more accurate reflection of a taxon's true dispersal properties and more accurately reflects the geographical and environmental space to which a taxon is exposed. Here, we compare the predictive performance of stacked SDMs derived from spatially constrained and unconstrained training areas.

Main conclusions

Restricting a species’ training and transference areas to a theoretically accessible area greatly improves model performance. Stacked SDMs drawn from spatially restricted training areas predicted species richness and community composition more accurately than non‐restricted stacked SDMs. These accessible area‐based restrictions mimic true dispersal barriers to species and limit training areas to the suite of environments to those which a species is exposed to in nature. Furthermore, these restrictions serve to ‘clip’ predictions in geographical space, thus removing overpredictions in adjacent geographical regions where the species is known to be absent.     

Chemical Diversity among the Essential Oils of Wild Populations of Stachys lavandulifolia Vahl (Lamiaceae) from Iran

The variation of the essential‐oil composition among ten wild populations of Stachys lavandulifolia Vahl (Lamiaceae), collected from different geographical regions of Iran, was assessed by GC‐FID and GC/MS analyses, and their intraspecific chemical variability was determined. Altogether, 49 compounds were identified in the oils, and a relatively high variation in their contents was found. The major compounds of the essential oils were myrcene (0.0–26.2%), limonene (0.0–24.5%), germacrene D (4.2–19.3%), bicyclogermacrene (1.6–18.0%), δ‐cadinene (6.5–16.0%), pulegone (0.0–15.1%), (Z)‐hex‐3‐enyl tiglate (0.0–15.1%), (E)‐caryophyllene (0.0–12.9), α‐zingiberene (0.2–12.2%), and spathulenol (1.6–11.1%). For the determination of the chemotypes and the chemical variability, the essential‐oil components were subjected to cluster analysis (CA). The five different chemotypes characterized were Chemotype I (germacrene D/bicyclogermacrene), Chemotype II (germacrene D/spathulenol), Chemotype III (limonene/δ‐cadinene), Chemotype IV (pulegone), and Chemotype V (α‐zingiberene). The high chemical variation among the populations according to their geographical and bioclimatic distribution imposes that conservation strategies of populations should be made appropriately, taking into account these factors. The in situ and ex situ conservation strategies should concern all populations representing the different chemotypes.     

Modelling species distributions to predict areas at risk of invasion by the exotic aquatic New Zealand mudsnail Potamopyrgus antipodarum (Gray 1843)

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Another example of cryptic diversity in lichen-forming fungi: the new species <Emphasis Type="Italic">Parmelia mayi</Emphasis> (Ascomycota: Parmeliaceae)

In the last decade, a number of cryptic species have been discovered in lichenized fungi, especially in species with a cosmopolitan or disjunctive distribution. Parmelia saxatilis is one of the most common and widely distributed species. Recent molecular studies have detected two species, P. ernstiae and P. serrana, within P. saxatilis s. lat., suggesting the existence of considerable genetic diversity that may not yet be expressed at the phenotypic level. Due to the complexity in the P. saxatilis s. lat. group, we used this as a model to study the species boundary and identify cryptic lineages. We used Phylogenetic (Bayes, ML and MP) and genetic distance approaches to analyze ITS and β-tubulin sequences. Our results confirm the existence of another cryptic lineage within P. saxatilis s. lat. This lineage is described herein as a new species, P. mayi. It forms an independent, strongly supported, monophyletic lineage, distantly related to the morphologically similar species P. ernstiae, P. saxatilis and P. serrana. Morphologically, it is indistinguishable from P. saxatilis but the new species is separated by molecular, bioclimatic, biogeographic and chemical characters. At present, P. mayi appears to have a restricted distribution in the northern Appalachian mountain territories of North America. It is found in climatic conditions ranging from hemiboreal and orotemperate to cryorotemperate ultrahyperhumid bioclimates.     

Environment‐Related Variations of the Composition of the Essential Oils of Rosemary (Rosmarinus officinalis L.) in the Balkan Penninsula

Composition of the essential oils of Rosmarinus officinalis of ten populations from the Balkan Peninsula were determined by GC/FID and GC/MS. The main constituents were 1,8‐cineole, camphor, α‐pinene, and borneol. Multivariate statistical analysis (UPGMA cluster analysis and principal‐component analysis (PCA)) revealed two major types of rosemary oil, i.e., 1,8‐cineole and camphor‐type, and two intermediate types, i.e., camphor/1,8‐cineole/borneol type and 1,8‐cineole/camphor type. The regression analyses (simple linear regression and stepwise multiple regression) have shown that, with respect to basic geographic, orographic, and 19 bioclimatic characteristics of each population, bioclimatic factor temperature of habitat represented the dominant abiogenetic factor, which, in chemical sense, led to differentiation of populations in the studied region. Also, the regression analysis have shown that some constituents of essential oils are independent of any single bioclimatic factors. However, some constituents display statistically significant correlations with some abiotic factors.     

Ecology and biogeography in 3D: The case of the Australian Proteaceae

The key biophysical pressures shaping the ecology and evolution of species can be broadly aggregated into three dimensions: environmental conditions, disturbance regimes and biotic interactions. The relative importance of each dimension varies over time and space, and in most cases multiple dimensions need to be addressed to adequately understand the habitat and functional traits of species at broad spatial and phylogenetic scales. However, it is currently common to consider only one or two selective pressures even when studying large clades. We illustrate the importance of the all‐inclusive multidimensional approach with reference to the large and iconic plant family, Proteaceae: we review life‐history traits related to these three dimensions for the 46 genera occurring in Australia and show that this family can be considered the product of a long history of harsh environments, recurrent fires and strong faunal interactions. Because most Proteaceae species occur in fire‐prone ecosystems and possess fire‐adaptive traits that are both ancient and essential for their survival, disturbance by fire is likely to explain much of this family's ecology, evolution and distribution. Approaches that only examine prevailing environmental variables may fail to identify the mechanisms that drive a taxon's biogeography; they need to consider the likely mechanisms of adaptation and accept or reject plausible alternative hypotheses as the evidence allows. As multidisciplinary teams that consider all aspects of a taxon's ecology are assembled, and databases and numerical tools become increasingly available, studies on the ecology, biogeography and diversity of organisms at broader spatial and phylogenetic scales will arrive at more realistic conclusions.     

Mitochondrial DNA phylogeography of Spodoptera exigua across a broad geographic area in China

The beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae), is an important agriculture pest in China that causes serious economic losses in some of the main crop‐producing areas. To monitor and manage this pest effectively, it is necessary to investigate its phylogeographic patterns in China. In this study, we used a partial sequence of mitochondrial DNA Cytb gene consisting of 724 bps to investigate the genetic diversity of the beet armyworm. A total of 765 individuals from 47 populations across the main distribution range of the species were collected, and 112 haplotypes were identified. Moderate‐to‐high levels of genetic diversity (Hd = 0.672 ± 0.017, Pi = 0.00268 ± 0.00021) for the total populations were obtained. Phylogenetic and median‐joining network analyses indicated there was no distinct geographic distribution pattern among haplotypes. Overall, the study also revealed significant differentiation among some populations (P < 0.05). The F_ST values of Shenyang population (SY2012–SY 2014), as well as Baoding (BD), Taian (TA), Lucheng (LC), Zhengzhou (ZZ) and Wuhan (WH), were significantly different from those of the populations in most other locations. Hierarchical AMOVA showed there was no significantly genetic structure between populations located in seven geographic regions and four main bioclimatic zones. Finally, unimodal mismatch distribution combined with negative Tajima's D (D = ?2.696, P < 0.001) and Fu's F_S (F_S = ?207.228, P > 0.05) indicated recent population expansion of S. exigua at large spatial scales in China.     

(Chemotaxonomic) Implications of Postharvest/Storage‐Induced Changes in Plant Volatile Profiles – the Case of Artemisia absinthium L. Essential Oil

The plant volatile profile and the essential‐oil chemical composition change during the storage of plant material. The objective of this study was to develop a mathematical model able to predict, explain, and quantify these changes. Mathematical equations, derived under the assumption that the essential oil contained within plant material could be treated as an ideal solution (Raoult's law), were applied for tracking of postharvest changes in the volatile profile of Artemisia absinthium L. (the essential oils were analyzed by GC‐FID and GC/MS). Starting from a specific chemical composition of an essential‐oil sample obtained from plant material after a short drying period (typically 5–10 d), and by using the equations derived from this model, one could easily predict evaporation‐induced changes in the volatile profile of the plant material. Based on the composition of the essential‐oil sample obtained after a given storage time t, it is possible to identify those components that were involved in chemical reactions, both as reactants and possible products. The established model even allowed the recognition of pairs of transformation, i.e., ‘daughter’ products and their ‘parent’ compounds. The obtained results highlight that the essential‐oil composition is highly dependent on the storage period of any plant material and urges caution in different types of phytochemical studies, especially chemotaxonomic ones, or practical application.     

Predicting the current distribution and potential spread of the exotic grass Eragrostis plana Nees in South America and identifying a bioclimatic niche shift during invasion

Eragrostis plana (Poaceae) is a perennial grass introduced from South Africa to the state of Rio Grande do Sul in southern Brazil. Currently, it is considered an invasive grass in several regions of the world, including South America, where it has caused negative ecological and socio‐economic impacts. Ecological niche models, using bioclimatic variables, are often used to predict the potential distribution of invasive species. In this study we prepared two bioclimatic models for E. plana using the Genetic Algorithm for Rule‐set Production, the first based on data from its native region (South Africa) and the second on data from both the native and invaded (South America) regions. We then projected each model onto South America to identify regions vulnerable to invasion by the species, and compared our results with available records of the species in South America. Finally, we explored the model's predictions for the existence of a bioclimatic niche shift during the invasion process of E. plana in South America, using multivariate statistical analysis. The model created with native distribution data was only able to predict (with highly suitable habitat) the region of introduction of E. plana in South America. However, the current distribution, as well as the region of introduction of the species, was reliably predicted by the model created with data from both native and invaded regions. Our multivariate analysis supports a hypothesis of bioclimatic niche shift during the invasion process of E. plana in South America.     

Niche-based modelling as a tool for predicting the risk of alien plant invasions at a global scale

Predicting the probability of successful establishment of plant species by matching climatic variables has considerable potential for incorporation in early warning systems for the management of biological invasions. We select South Africa as a model source area of invasions worldwide because it is an important exporter of plant species to other parts of the world because of the huge international demand for indigenous flora from this biodiversity hotspot. We first mapped the five ecoregions that occur both in South Africa and other parts of the world, but the very coarse definition of the ecoregions led to unreliable results in terms of predicting invasible areas. We then determined the bioclimatic features of South Africa's major terrestrial biomes and projected the potential distribution of analogous areas throughout the world. This approach is much more powerful, but depends strongly on how particular biomes are defined in donor countries. Finally, we developed bioclimatic niche models for 96 plant taxa (species and subspecies) endemic to South Africa and invasive elsewhere, and projected these globally after successfully evaluating model projections specifically for three well‐known invasive species (Carpobrotus edulis, Senecio glastifolius, Vellereophyton dealbatum) in different target areas. Cumulative probabilities of climatic suitability show that high‐risk regions are spatially limited globally but that these closely match hotspots of plant biodiversity. These probabilities are significantly correlated with the number of recorded invasive species from South Africa in natural areas, emphasizing the pivotal role of climate in defining invasion potential. Accounting for potential transfer vectors (trade and tourism) significantly adds to the explanatory power of climate suitability as an index of invasibility. The close match that we found between the climatic component of the ecological habitat suitability and the current pattern of occurrence of South Africa alien species in other parts of the world is encouraging. If species' distribution data in the donor country are available, climatic niche modelling offers a powerful tool for efficient and unbiased first‐step screening. Given that eradication of an established invasive species is extremely difficult and expensive, areas identified as potential new sites should be monitored and quarantine measures should be adopted.     

Genetic Diversity and Population Structure of Teucrium polium (Lamiaceae) in Tunisia

Random amplified polymorphic DNA markers were used to assess the genetic diversity within and among seven Tunisian diploid and polyploid populations of Teucrium polium L. from five bioclimatic areas. Out of the 141 bands generated from eight selected primers, 124 were polymorphic. The genetic diversity within a population (Shannon’s index) was high and varied according both the ploidal levels and bioclimatic zones. The genetic differentiation among populations assessed by G _ST and Φ_ST statistics was high, suggesting a low level of gene flow among them. The major proportion of the variation was attributable to individual differences within populations. The UPGMA analysis based on Nei and Li’s coefficient showed that individuals from each population clustered together. In a dendrogram using the Φ_ST distance matrix, population grouping is concordant with bioclimates and cytotypes. Conservation strategies should take into account the level of the genetic diversity of the populations according to their bioclimate and ploidal levels.     

Biogeographic Variation of Foliar n‐Alkanes of Juniperus communis var. saxatilis Pallas from the Balkans

The composition of the epicuticular n‐alkanes isolated from the leaves of ten populations of Juniperus communis L. var. saxatilis Pallas from central (continental) and western (coastal) areas of the Balkan Peninsula was characterized by GC‐FID and GC/MS analyses. In the leaf waxes, 14 n‐alkane homologues with chain‐lengths ranging from C₂₂ to C₃₅ were identified. All samples were dominated by n‐tritriacontane (C₃₃), but differences in two other dominant n‐alkanes allowed separating the coastal from the continental populations. Several statistical methods (ANOVA, principal component, discriminant, and cluster analyses as well as the Mantel test) were deployed to analyze the diversity and variability of the epicuticular‐leaf‐n‐alkane patterns of the ten natural populations of J. communis var. saxatilis and their relation to different geographic and bioclimatic parameters. Cluster analysis showed a high correlation of the leaf‐n‐alkane patterns with the geographical distribution of the investigated samples, differentiating the coastal from the continental populations of this taxon. Several bioclimatic parameters related to aridity were highly correlated with this differentiation.     

Syntaxonomy and phytogeographical differentiation of the Fagus woods in the Southwest Balkan Peninsula

Abstract. Up to now the syntaxonomy of the Fagus woods of the southern Balkans is far less known than that of beech communities in the northwestern part of the Balkan Peninsula and in central and western Europe. A set of 607 phytosociological relevés from southeastern Serbia, the Former Yugoslav Republic of Macedonia, and northern and central Greece was subjected to numerical classification and ordination. These results were used for a syntaxonomic revision of Fagus, Fagus‐Abies and Fagus‐Acer woodland communities of the southwestern Balkans. The Doronico columnae‐Fagenion (seven associations from Serbia, the F.Y.R.O.M., and high altitudes in northern Greece) and the Doronico orientalis‐Fagenion (four associations from northern and central Greece) were distinguished. The results of ordination by Canonical Variates Analysis (CVA) showed a very distinct phytogeographical pattern of differentiation between community types. The floristic composition of Fagus woods changes markedly along the north‐south gradient. The share of Subbalkan, Balkan, Submediterranean and Mediterranean species increases significantly towards the south, while the Central‐European, European, Euro‐Siberian, Euro‐Asiatic and Circumpolar species decrease in the same direction. The syntaxonomic differentiation of the Fagus woodlands and their classification into regional suballiances reflects this gradient. With the rise in altitude, the number of Balkan, Mediterranean, Submediterranean, European and Euro‐Asiatic species declines.