Studies comparing species’ distribution range at different time periods provide valuable information about temporal trends, and may help to identify the factors responsible for these changes. This ...knowledge is vital for setting conservation priorities and applying suitable management strategies and practices focused on species’ conservation. We examined records produced before and after December 31, 1985 for determining possible changes in the distribution range of 195 orchid species recorded in Greece, using a 10 × 10 km grid as the recording unit. We used regression techniques to explore the association of species richness with environmental and spatial variables. Species richness was calculated by using the orchid records made (a) before December 31, 1985, (b) after January 1, 1986, and (c) in both time periods. Generalized linear models (GLM) were used for identifying the most significant factors associated with the distribution of the threatened orchids of Greece. Most Greek orchids showed an increasing trend in distribution from the first to the second period, with the exception of a few Critically Endangered species, whose distribution was larger in the first than in the second period. The spatial distribution of the threatened orchids was mostly explained by land area and the area of the calcareous substrates at each grid cell, whereas all variables that were used in the GLM analysis accounted for about 32% of the variance. The observed increasing trend in orchid distribution should be attributed to the extensive research efforts during the second period, especially in areas of high altitude and towards the northern parts of Greece. Our results did not support the findings of other studies, mainly from northern Europe, which showed a significant decline in the distribution range of their orchid flora. These differences in distribution trends could be attributed to the complex orographic configuration of Greece, which renders large parts of the country rather unsuitable for agricultural use or for extensive urban development.
Land abandonment is one of the main drivers of land use/land cover (LULC) change across Europe, which has already led to a significant loss of open habitats, threatening species hosted in them. We ...investigated LULC changes for a period of 70 years in a mountainous area of central Greece (Mt Agrafa) by mapping its land cover for the years 1945, 1996 and 2015, calculating transition matrices of land cover classes and performing intensity analysis at different levels. Subareas of the study area, with different population trends, were compared in regard to their LULC change trends. Possible drivers of LULC changes were explored by means of Random Forest modeling, and landscape metrics were calculated to assess their trends. Our results showed great changes in LULC class cover, significant shrinkage of open habitats, accelerated rates of change in the recent period and no differences in LULC change patterns in relation to different population trends. Variables expressing favorability of ecological conditions for forest establishment or probability of farmland abandonment were found as more important drivers of the spatiotemporal distribution of LULC classes, while landscape metrics revealed certain trends. Our main conclusion is that land abandonment and the subsequent vegetation succession are going through a semifinal stage, before their completeness and the almost absolute dominance of the forest, and repopulation of the countryside cannot unconditionally ensure any halting effect on the land abandonment process.
•Empirical test of functional differentiation of forests at a regional scale.•Functional identity but not diversity differentiates forest community types.•Decoupled functional diversity and identity ...patterns highlight their complementarity.
We studied the differentiation among plant communities of deciduous broadleaved and mountain coniferous forests in terms of functional diversity and identity at a regional scale (northern and central Greece). We asked if patterns of functional differentiation among communities are consistent between the overstorey and understorey layers and if they can be influenced by deep past environmental conditions. Functional Richness (FRic) and Functional Dispersion (FDis), as well as their standardized effect sizes, were employed to assess the multivariate functional diversity of the community types. In contrast, single-trait Community Weighted Means (CWMs) were used as surrogates of functional identity. The aforementioned indices were calculated for three datasets, namely all the vascular plant taxa found in individual vegetation plots (total community), all phanerophyte (tree and shrub) taxa (overstorey) and all non-phanerophyte vascular plant taxa (understorey). We found that community types and especially four broad forest types (beech, ravine, pine and oak forests) are well differentiated in terms of functional composition (identity), as indicated by Non-Metric Multidimensional Scaling (NMDS). After conducting an NMDS for the three datasets, functional identity based on the total floristic composition was found to be the best discriminator of the studied communities. However, contrasting patterns were found for some specific traits or their categories between overstorey and understorey layers. The patterns of functional diversity of the community types (based on multivariate indices), revealed by calculating the standardized effect sizes of FRic and FDis based on the richness null model, did not differ substantially from random expectations for most of the studied community types when the dataset of all the vascular plant taxa was analyzed. However, the patterns revealed for the overstorey layer differed from those for the understorey layer. For the latter layer, the clustered structure was revealed in many community types based on the ses.FDis metric. Indications of deep past influence on the functional composition were found for certain community types (i.e. ravine forests) based on single-trait metrics, but no indication of such influence was found based on multivariate indices. Our findings highlight the complementarity and the additive explanatory value of the simultaneous use of single- and multi-trait approaches and their application to different layers in forests.
Alien plant invasions in European woodlands Wagner, Viktoria; Chytrý, Milan; Jiménez-Alfaro, Borja ...
Diversity & distributions,
September 2017, Volume:
23, Issue:
9/10
Journal Article
Peer reviewed
Open access
Aim: Woodlands make up a third of European territory and carry out important ecosystem functions, yet a comprehensive overview of their invasion by alien plants has never been undertaken across this ...continent. Location: Europe. Methods: We extracted data from 251,740 vegetation plots stored in the recently compiled European Vegetation Archive. After filtering (resulting in 83,396 plots; 39 regions; 1970-2015 time period), we analysed the species pool and frequency of alien vascular plants with respect to geographic origin and life-forms, and the levels of invasion across the European Nature Information System (EUNIS) woodland habitats. Results: We found a total of 386 alien plant species (comprising 7% of all recorded vascular plants). Aliens originating from outside of and from within Europe were almost equally represented in the species pool (192 vs. 181 species) but relative frequency was skewed towards the former group (77% vs. 22%) due, to some extent, to the frequent occurrence of impatiens parviflora (21% frequency among alien plants). Phanerophytes were the most species-rich life-form (148 species) and had the highest representation in terms of relative frequency (39%) among aliens in the dataset Apart from Europe (181 species), North America was the most important source of alien plants (109 species). At the local scale, temperate and boreal softwood riparian woodland (5%) and mire and mountain coniferous woodland (<1%) had the highest and lowest mean relative alien species richness (percentage of alien species per plot), respectively. Main conclusions: Our results indicate that European woodlands are prone to alien plant invasions especially when exposed to disturbance, fragmentation, alien propagule pressure and high soil nutrient levels. Given the persistence of these factors in the landscape, competitive alien plant species with a broad niche, including alien trees and shrubs, are likely to persist and spread further into European woodlands.
A central hypothesis of ecology states that regional diversity influences local diversity through species-pool effects. Species pools are supposedly shaped by large-scale factors and then filtered ...into ecological communities, but understanding these processes requires the analysis of large datasets across several regions. Here, we use a framework of community assembly at a continental scale to test the relative influence of historical and environmental drivers, in combination with regional or local species pools, on community species richness and community completeness. Using 42,173 vegetation plots sampled across European beech forests, we found that large-scale factors largely accounted for species pool sizes. At the regional scale, main predictors reflected historical contingencies related to post-glacial dispersal routes, whereas at the local scale, the influence of environmental filters was predominant. Proximity to Quaternary refugia and high precipitation were the main factors supporting community species richness, especially among beech forest specialist plants. Models for community completeness indicate the influence of large-scale factors, further suggesting community saturation as a result of dispersal limitation or biotic interactions. Our results empirically demonstrate how historical factors complement environmental gradients to provide a better understanding of biodiversity patterns across multiple regions.
The distribution of vascular plant species and assemblages existing in beech (Fagus sylvatica L.) forests was compared with the distribution of beech chloroplast DNA (cpDNA) haplotypes, aiming to ...identify possible interpretable trends of co-occurrence, on a small geographical scale, and to infer the relevant historical factors. Vegetation and genetic (cpSSR) data were collected from 60 plots on Mt. Menikio (northeastern Greece). Classification and ordination analyses were applied on the vegetation data, while on the cpSSR data, diversity measures and genetic structure analyses were employed. A probabilistic co-occurrence analysis was performed on haplotypes and taxa. The results show that a plant biogeographical border exists on Mt. Menikio which, in addition, has acted both as a refugium and as a meeting point of lineages for more than one glacial cycle. Significant associations of co-occurrence between haplotypes and vascular taxa were found but no common distribution patterns between the former and species assemblages were identified. The combined consideration of the distribution profiles of species assemblages, plant species and cpDNA haplotypes (corresponding to the three levels of biodiversity) provides concrete information on historical events, leading to a comprehensive understanding of the evolutionary and biogeographical processes that have shaped specific spatial patterns of biodiversity.
AbstractDue to the absence or scarcity of DNA sequence data in GenBank regarding Mediterranean, Balkan or Greek native tulip species, we performed molecular characterization of the 15 wild-growing ...Greek tulip species through analysis of the internal transcribed spacer nrDNA and the psbA/trnH and trnL/trnF cpDNA regions. To facilitate conservation and sustainable utilization efforts, the aim was to identify and complement the genetic distinctiveness of six Greek endemic and five Balkan or Aegean endemic and/or subendemic wild-growing Greek native tulips and two naturalized ones of Asiatic origin, among which seven are threatened with extinction. Molecular phylogenetic analysis of 148 DNA sequences was conducted, and 85 Tulipa taxa (species and subspecies) were aligned and compared to 40 new DNA sequences generated herein for the 15 wild-growing Greek tulips. These three molecular markers resulted in 354 single-nucleotide polymorphisms (SNPs) and 20 distinct indels for all Tulipa taxa, of which 100 SNPs and 12 indels were related to the Greek tulips. Phylogenetic dendrograms were constructed for all the above-mentioned molecular markers, and the DNA sequences were analyzed separately and jointly, leading to three distinct clusters for the 15 wild-growing Greek tulips. Group 1 included Greek members of subgenus Tulipa, that is, T. scardica, T. undulatifolia, T. rhodopea, T. agenensis and T. raddii; Group 2 included only T. clusiana (subgenus Clusianae) and Group 3 included Greek members of subgenus Eriostemones, that is, *T. bakeri, T. saxatilis, T. australis, *T. cretica, *T. goulimyi, *T. orphanidea T. bithynica, *T. hageri and *T. doerfleri (asterisks indicate single-country endemics).
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.
Neophyte invasions in European grasslands Axmanová, Irena; Kalusová, Veronika; Danihelka, Jiří ...
Journal of vegetation science,
March/April 2021, 2021-03-00, 20210301, 2021-03, Volume:
32, Issue:
2
Journal Article
Peer reviewed
Open access
Questions
The human‐related spread of alien plants has serious environmental and socioeconomic impacts. Therefore, it is important to know which habitats are most threatened by invasion and why. We ...studied a wide range of European grasslands to assess: (a) which alien species are the most successful invaders in grasslands; (b) how invasion levels differ across European regions (countries or their parts) and biogeographical regions; and (c) which habitat types are the most invaded.
Location
Europe.
Methods
We selected 97,411 grassland vegetation plots from the European Vegetation Archive (EVA) and assigned a native or alien status to each of the 8,212 vascular plant species found in these plots. We considered only neophytes (alien species introduced after 1500 AD), which we further divided according to their origin. We compared the levels of invasion using relative neophyte richness in the species pool, relative neophyte richness and cover per plot, and percentages of invaded plots among regions and habitats.
Results
Only 536 species, representing 6.5% of all grassland vascular plant species, were classified as neophytes. These were mostly therophytes or hemicryptophytes with low habitat specificity. Most of them were present in very few plots, while only three species were recorded in more than 1% of all plots (Onobrychis viciifolia, Erigeron annuus and Erigeron canadensis). Although invasion levels were generally low, we found more invaded plots in the Boreal and Continental regions. When considering only non‐European neophytes, the Pannonian region was the most invaded. Among different grassland habitats, sandy grasslands were most invaded, and alpine and oromediterranean grasslands least invaded.
Conclusions
In general, natural and semi‐natural European grasslands have relatively low levels of neophyte invasions compared with human‐made habitats or alluvial forests, as well as with grasslands on other continents. The most typical neophytes invading European grasslands are species with broad ecological niches.
We provide the first overview of neophyte invasion patterns in European grasslands based on the most comprehensive data set of vegetation plots existing to date. In general, natural and semi‐natural European grasslands have relatively low levels of neophyte invasions compared with European man‐made habitats, riparian vegetation or with grasslands on other continents. The most typical neophytes are therophytes with broad niches.
Due to the complex relationship between pollen and vegetation, it is not yet clear how pollen diagrams may be interpreted with respect to changes in floristic diversity and only a few studies have ...hitherto investigated this problem. We compare pollen assemblages from moss samples in two southeastern European forests with the surrounding vegetation to investigate (a) their compositional similarity, (b) the association between their diversity characteristics in both terms of richness and evenness, and (c) the correspondence of the main ecological gradients that can be revealed by them. Two biogeographical regions with different vegetation characteristics, the Pieria mountains (north central Greece) and the slopes of Ciomadul volcano (eastern Romania), were chosen as divergent examples of floristic regions, vegetation structure and landscape openness. Pollen assemblages are efficient in capturing the presence or absence, rather than the abundance in distribution of plants in the surrounding area and this bias increases along with landscape openness and vegetation diversity, which is higher in the Pieria mountains. Pollen assemblages and vegetation correlate better in terms of richness, that is, low order diversity indices. Relatively high correlation, in terms of evenness, could be potentially found in homogenous and species poor ecosystems as for Ciomadul. Composition and diversity of woody, rather than herb, vegetation is better reflected in pollen assemblages of both areas, especially for Pieria where a direct comparison of the two components was feasible, although this depends on the species-specific pollen production and dispersal, the openness of landscape and the overall diversity of vegetation. Gradients revealed by pollen assemblages are highly and significantly correlated with those existing in vegetation. Pollen assemblages may represent the vegetation well in terms of composition, diversity (mainly richness) and ecological gradients, but this potential depends on land use, vegetation structure, biogeographical factors and plant life forms.
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