In this study, I analyzed the natural recovery of grasslands on abandoned agricultural fields in the Transylvanian Lowland (Câmpia Transilvaniei), Romania. I examined fields that were abandoned 1–40 ...years ago and considered how successful they have been in recovering spontaneously as compared to reference grassland, especially in relation to species composition and dominance structure. Diverse, nondegraded seminatural grasslands from the surroundings were chosen as targets for the recovery. Five such grasslands were analyzed in order to have multiple references that accounted for site heterogeneity and different land use history. This study found that the number of natural and seminatural habitat species increased, whereas the number of weeds and aliens decreased with age. Old‐fields had become very similar in species composition and dominance structure to reference grasslands over a 14‐ to 20‐year time interval, with the only failure being the unsuccessful or slow colonization of a few grassland species. Because spontaneous succession is efficient, human interventions are not needed to restore target communities on the old‐fields. Propagule pressure expressed by the area of potential seed source in a 500‐m‐radius buffer was found to have a strong influence on recovery success of old‐fields. The success of grassland species in colonizing postagricultural fields was not affected by their dispersal mode but by their frequency in the landscape, this being another evidence for the importance of propagule availability in the course of recovery. In order to maintain the potential for recovery of this landscape, we need to protect those close to natural habitats that contain a high amount of native flora.
Aims
: To develop a consistent ecological indicator value system for Europe for five of the main plant niche dimensions: soil moisture (M), soil nitrogen (N), soil reaction (R), light (L) and ...temperature (T).
Study area
: Europe (and closely adjacent regions).
Methods
: We identified 31 indicator value systems for vascular plants in Europe that contained assessments on at least one of the five aforementioned niche dimensions. We rescaled the indicator values of each dimension to a continuous scale, in which 0 represents the minimum and 10 the maximum value present in Europe. Taxon names were harmonised to the Euro+Med Plantbase. For each of the five dimensions, we calculated European values for niche position and niche width by combining the values from the individual EIV systems. Using T values as an example, we externally validated our European indicator values against the median of bioclimatic conditions for global occurrence data of the taxa.
Results
: In total, we derived European indicator values of niche position and niche width for 14,835 taxa (14,714 for M, 13,748 for N, 14,254 for R, 14,054 for L, 14,496 for T). Relating the obtained values for temperature niche position to the bioclimatic data of species yielded a higher correlation than any of the original EIV systems (
r
= 0.859).
The database
: The newly developed Ecological Indicator Values for Europe (EIVE) 1.0, together with all source systems, is available in a flexible, harmonised open access database.
Conclusions
: EIVE is the most comprehensive ecological indicator value system for European vascular plants to date. The uniform interval scales for niche position and niche width provide new possibilities for ecological and macroecological analyses of vegetation patterns. The developed workflow and documentation will facilitate the future release of updated and expanded versions of EIVE, which may for example include the addition of further taxonomic groups, additional niche dimensions, external validation or regionalisation.
Abbreviations
: EIV = Ecological indicator value; EIVE = Ecological Indicator Values for Europe; EVA = European Vegetation Archive; GBIF = Global Biodiversity Information Facility;
i
= index for taxa;
j
= index for EIV systems; L = ecological indicator for light; M = ecological indicator for moisture; N = ecological indicator for nitrogen availability; R = ecological indicator for reaction; T = ecological indicator for temperature.
The importance of environmental difference among sites and dispersal limitations of species to the explanation of diversity differs among biological systems and geographical regions. We hypothesized ...that climate and then dispersal limitation will predominantly explain the similarity of alpine vegetation at increasing distances between pairs of regions at subcontinental extent. We computed the similarity of all pairs of 23 European mountain regions below 50° N after dividing the species lists of each region by calcareous or siliceous substrates. Distance decay in similarity was better fitted by a cubic polynomial than a negative exponential function, and the fit was better on calcareous than on siliceous substrate. Commonality analysis revealed that the proportion of explanation of beta diversity by climatic difference had unimodal patterns on a gradient of increasing distance between regions, while explanation by dispersal limitation had consistently rising patterns on both substrates. On siliceous substrate, dispersal limitation explained more of the variation in beta diversity only at longer distances, but it was predominant at all distances on calcareous substrate. The steeper response to distance at <1600 km and >2600 km may indicate dispersal limitation at different temporal scales, and the uptick in the response to distance at the longest distances may reflect how isolated some regions have been before and since the last glacial maximum.
Worldwide reforestation has been recommended as a landscape restoration strategy to mitigate climate change in areas where the climate can sustain forest. This approach may threaten grassland ...ecosystems of unique biodiversity as such policies are based on the false assumption that most grasslands are man-made. Here, we use multiple lines of evidence (palaeoecological, pedological, phylogenetic, palaeontological) from Central Eastern Europe and show that various types of grasslands have persisted in this area throughout the postglacial i.e., the past 11,700 years. A warm and dry climate, frequent fires, herbivore pressure and early Neolithic settlements kept forests open until widespread forest clearance beginning 4000 to 3000 years ago. Closed forest cover has been the exception for the last two million years. This long-term persistence has likely contributed to the high biodiversity of these grasslands. Consequently, we call for a more cautious prioritisation of the protection of what may be erroneously considered natural, i.e. forests, by many environmental specialists and managers. Instead we provide a new framework for a better understanding of the evolution and persistence of different grassland types and their biodiversity, so that grasslands can be better understood, valued and conserved.
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•We prove a new framework for understanding long-term dynamics of grasslands.•This framework facilitates the identification of ancient grasslands worldwide.•Evidence of the long-term grassland continuity in potential forest areas•Grassland continuity explains the high current species richness of this ecosystem.•Better classification highlights the importance of this overlooked environment.
Questions: Litter quantity in grasslands is highly affected by disturbance regime and influences seed recruitment of constituent species through different mechanisms. Does litter act as a mechanical ...barrier to burial of freshly shed seeds, and does seed morphology affect this? How is the fate and mobility of seeds affected by litter compared to that of seeds in the seed bank? Location: Transylvanian Lowland, Romania. Methods: We analysed the seed content of litter and underlying soil collected from six dry grassland sites having different disturbance histories, ranging from sites that are currently grazed to those that have been long abandoned. We related seed content of litter to the litter quantity, seed morphology and the seed content of soil, and the estimated seed production of the above-ground vegetation. Results: Grass litter represented a natural trap for seeds; we identified significant quantities of seeds of a large number of species (37) within litter samples, and there was a mass effect in the seed trapping by litter — higher litter quantities trapped more seeds. As a long-term consequence, we expected that seed bank stores would be gradually depleted in abandoned grassland due to the elimination of seeds by litter, but this was not the case. The higher seed production of the above-ground vegetation in undisturbed sites very probably compensated for seed losses through litter. Seeds retained in the litter were larger, more rounded and had appendages than those in soil. Especially for seeds meeting any of these criteria, litter represents a hazardous medium, since the seeds may fail or have delayed germination. Conclusions: The role of litter as a seed trap is more relevant in grasslands that have not been disturbed for a long time, where litter seed entrapment can exert a selective pressure on certain species, and thus drive community assembly in grasslands.
•Crataegus monogyna, C. rhipidophylla and their hybrid seedlings had similar performance.•C. rhipidophylla had shorter, more dense stems compared to C. monogyna, with the hybrid being ...intermediate.•The hybrid manifested a higher phenotypic plasticity relative to at least one of its parents in biomass allocation in response to water availability.•The “mosaic model” describes most accurately the hybrid zone of the studied taxa.
Hybridization followed by introgression is common between European Crataegus species, while hybrids of numerous sympatric taxa are abundant and widespread in several natural and seminatural environments. No study to the present day has compared the development of Crataegus species and their hybrids in their seedling stage. Our aim was to compare seedling performance, biomass allocation and phenotypic plasticity of two sympatric Crataegus species (C. monogya and C. rhipidophylla) with contrasting shade tolerance and their natural hybrid along light and water availability gradients in a controlled pot experiment. By this means we tested which of the existing models can successfully explain the field distribution and habitat preference of the hybrid. The performance of both species and their hybrid decreased in deep shade as well as under high water availability. Variation in light availability had a more pronounced effect on seedling development than that in water availability. These results evidence that habitat differentiation between the two species under natural conditions is probably mainly driven by competitive interactions. The shade tolerant forest species C. rhipidophylla had shorter, more dense stems compared to the shade intolerant C. monogyna, with the hybrid being intermediate in these characters. This suggests a steadier growth and higher resource allocation into stems in the case of the shade tolerant species. Furthermore, the hybrid was phenotypically more plastic in biomass allocation relative to at least one of its parental species under various water availabilities, suggesting an advantage on behalf of the hybrid in establishment under a wider range of environmental conditions. Our results support the “mosaic-model” that describes most accurately the hybrid zone.
Questions
Germination is a prerequisite of successful establishment in plant communities and is influenced by many factors. Therefore, seeds are under strong selective pressure to sense and integrate ...information about their environment and modulate germination based on it. In this study, we focus on interspecific seed–seed interactions under optimal and suboptimal conditions to test three hypotheses: (H1) dominant species’ seeds and emerging seedlings are most likely to be recognised by neighbouring seeds and exert a significant effect on the germination of common subordinate species; (H2) taxonomically related species are expected to exert stronger influence than unrelated species on the germination of neighbouring seeds; and (H3) facilitative interactions are more likely to occur under suboptimal conditions (drought stress) in the seed–seed interactions.
Location
Semi‐dry temperate grassland belonging to the Festuco‐Brometea class, Cluj‐Napoca, Romania.
Methods
We assessed the rate and speed of germination of three common subordinate Asteraceae species (target species) in a controlled germination experiment. The target species’ seeds were sown in combination with low and high densities of neighbour species: two dominant Poaceae species, two subordinate Asteraceae species and two subordinate Apiaceae species; under optimal or drought conditions.
Results
Under optimal water conditions, particularly the seeds of the two dominant Poaceae species affected the germination of target species. Under drought stress, almost all neighbouring species altered the germination of two of the target species, enhancing or reducing their germination rate. Facilitation in seed–seed interactions was proved to be species‐specific rather than general under drought conditions.
Conclusions
We found evidence that the status in a plant community (dominant or subordinate), but not the taxonomic relatedness influences the outcome of seed–seed interactions during germination. Under drought stress, the persistent competitive effect of the dominant species might considerably hinder the recruitment of subordinate grassland species.
By performing a controlled germination experiment, we provide evidence that temperate grassland species’ seeds integrate species‐specific information about seeds and seedlings in their close vicinity and respond by modifying the rate or time of their germination. Especially the seeds of dominant grass species were proved to be persistent competitive neighbours, inhibiting the emergence of subordinate species.
Aims
Semi‐natural grasslands are among the most biodiverse habitats in Europe, and they are of great conservation and agricultural value. However, changes in land use like grazing intensification and ...the cessation of traditional management have dramatic effects on the extent and biodiversity of these ecosystems. In this study we investigated how current management practices and land use history shape species composition and diversity patterns in semi‐natural grasslands of the Eastern hills of the Cluj region.
Location
Eastern hills of Cluj (“Dealurile Clujului de Est” ‐ ROSCI0295) Natura 2000 conservation site and close surroundings, Transylvania, Romania.
Methods
We surveyed plots in extensively and intensively grazed grasslands, grasslands mown by hand or heavy machinery, and abandoned grasslands. To quantify grassland continuity, we analysed a series of historical cadastral and more current maps ranging from the 18th to the 21st century.
Results
Species composition was significantly influenced by current management, grassland continuity and environmental factors. Mown and extensively grazed grasslands had more grassland and forest edge specialists than abandoned and intensively grazed grasslands. In addition, there was a positive relationship between the number of grassland specialists, forest edge species and grassland continuity, while the number of ruderal species related negatively to grassland continuity. The highest diversity values were recorded in traditionally mown grasslands. However, diversity‐related variables were poorly reflected by grassland continuity.
Conclusions
This study provides evidence that short‐term abandonment may not be as detrimental for grasslands as often suggested, and intensive grazing results in the greatest loss in species diversity. Grassland continuity tightly influences the persistence of grassland specialist species. Thus, we recommend land use history to be included in the selection and identification of high‐nature‐value grasslands by prioritizing conservation efforts for older grasslands.
We investigated how current management practices and land use history shape species composition and diversity in Transylvanian semi‐natural grasslands. Our results suggest that short‐term abandonment is not as detrimental for grasslands as often suggested, and intensive grazing results in the greatest loss in species diversity. Grassland continuity tightly influences the persistence of grassland specialist species.
Aims
Vegetation‐plot records provide information on the presence and cover or abundance of plants co‐occurring in the same community. Vegetation‐plot data are spread across research groups, ...environmental agencies and biodiversity research centers and, thus, are rarely accessible at continental or global scales. Here we present the sPlot database, which collates vegetation plots worldwide to allow for the exploration of global patterns in taxonomic, functional and phylogenetic diversity at the plant community level.
Results
sPlot version 2.1 contains records from 1,121,244 vegetation plots, which comprise 23,586,216 records of plant species and their relative cover or abundance in plots collected worldwide between 1885 and 2015. We complemented the information for each plot by retrieving climate and soil conditions and the biogeographic context (e.g., biomes) from external sources, and by calculating community‐weighted means and variances of traits using gap‐filled data from the global plant trait database TRY. Moreover, we created a phylogenetic tree for 50,167 out of the 54,519 species identified in the plots. We present the first maps of global patterns of community richness and community‐weighted means of key traits.
Conclusions
The availability of vegetation plot data in sPlot offers new avenues for vegetation analysis at the global scale.
We describe sPlot, the first global vegetation‐plot database, containing 1,121,244 plots with plant species lists combined with traits from the TRY database and a global phylogeny. The potential of sPlot is illustrated with the first maps of global patterns of community richness and community‐weighted means of key traits. Rules for data usage, expected impact and limitations of sPlot are discussed.
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