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European dry thin-soil calcareous grasslands (alvars) are species-rich semi-natural habitats. Cessation of traditional management, such as mowing and grazing, leads to shrub and tree encroachment and the local extinction of characteristic alvar species. While soil microbes are known to play a critical role in driving vegetation and ecosystem dynamics, more information is needed about their composition and function in grasslands of different dynamic stages. Here we assess the composition of soil fungal, prokaryotic, and plant communities using soil environmental DNA from restored alvar grasslands in Estonia. The study areas included grasslands that had experienced different degrees of woody encroachment prior to restoration (woody plant removal and grazing), as well as unmanaged open grasslands. We found that, in general, different taxonomic groups exhibited correlated patterns of between-community variation. Previous forest sites, which had prior to restoration experienced a high degree of woody encroachment by ectomycorrhizal Scots pine, were compositionally most distinct from managed open grasslands, which had little woody vegetation even prior to restoration. The functional structure of plant and fungal communities varied in ways that were consistent with the representation of mycorrhizal types in the ecosystems prior to restoration. Compositional differences between managed and unmanaged open grasslands reflecting the implementation of grazing without further management interventions were clearer among fungal, and to an extent prokaryotic, communities than among plant communities. While previous studies have shown that during woody encroachment of alvar grassland, plant communities change first and fungal communities follow, our DNA-based results suggest that microbial communities reacted faster than plant communities during the restoration of grazing management in alvar grassland. We conclude that while the plant community responds faster to cessation of management, the fungal community responds faster to restoration of management. This may indicate hysteresis, where the eventual pathway back to the original state (grazed ecosystem) differs from the pathway taken towards the alternative state (abandoned semi-natural grassland ecosystem). [ABSTRACT FROM AUTHOR]

Semi-natural grasslands and their diverse biota are threatened by changes in land-use like afforestation, abandonment of traditional practices, urban development or conversion into intensive agricultural land. Extensive loss and fragmentation of semi-natural grasslands consequently affects ecosystem functioning inherit to open landscapes and the sustainable provision of ecosystem services. Ecological restoration of grasslands has potential to halt further decline and hopefully reverse some of the damage done to the grasslands and vital ecosystem services they provide. By assessing grasslands before and after the restoration, we evaluated how restoring overgrown and forested semi-natural grasslands to open grasslands impacts nine ecosystem services: habitat maintenance, soil condition maintenance, soil carbon storage, pollination, pest regulation, provision of wild food and medicinal herbs, forage production, wood production and recreation. We also analyzed the relationship between ecosystem multifunctionality and species richness of multiple organism groups. We found that already few years after restoration, restored grasslands exhibited rapidly increasing biodiversity and ecosystem service provision. Similarly, the overall ecosystem multifunctionality increased significantly after restoration in previously overgrown and afforested grasslands. However, while a robust and strong positive relationship between multitrophic diversity and ecosystem multifunctionality existed before restoration, this relationship was somewhat weakened after restoration. We propose two potential explanations: first, the previously distinct condition classes became more similar, starting to resemble open grassland habitats in their species richness and composition. Second, the relationship may have been weakened by the temporarily disrupted and transitional nature of the ecosystem post-restoration, due to varying recovery rates among different species groups and ecosystem services. Notably, soil-related services (carbon storage and soil maintenance) take longer to respond to restoration, compared to other services. In addition, we detected significant negative impact of prolonged drought on pest regulation and forage production service in both restored and unrestored areas. Semi-natural grasslands are both biodiversity and ecosystem service "hotspots" in European landscapes and restoring these habitats significantly increases the provision potential of important ecosystem services. However, restoration planning must consider landscape history, regional characteristics and the importance of long-term monitoring for getting the most accurate results. • Grassland restoration raised multitrophic diversity and ecosystem multifunctionality. • We detected rapid positive impacts of restoration on several ecosystem services. • No effect on soil condition or soil carbon storage was detected. • Prolonged drought severely impacts ecosystem service provision and grassland recovery. • Long-term monitoring of the sites is essential to measure restoration success and grassland recovery. [ABSTRACT FROM AUTHOR]

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, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 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/datab ases/Grass landD ivers ityEx plorer) 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. [ABSTRACT FROM AUTHOR]

Temperate calcareous grasslands are characterized by high levels of species richness at small spatial scales. Nevertheless, many species from a habitat-specific regional species pool may be absent from local communities and represent the 'dark diversity' of these sites. Here we investigate dry calcareous grasslands in northern Europe to determine what proportion of the habitat-specific species pool is realized at small scales (i.e. how the community completeness varies) and which mechanisms may be contributing to the relative sizes of the observed and dark diversity. We test whether the absence of particular species in potentially suitable grassland sites is a consequence of dispersal limitation and/or a low ability to tolerate stress (e.g. drought and grazing). We analysed a total of 1223 vegetation plots (1 × 1 m) from dry calcareous grasslands in Sweden, Estonia and western Russia. The species co-occurrence approach was used to estimate the dark diversity for each plot. We calculated the maximum dispersal distance for each of the 291 species in our dataset by using simple plant traits (dispersal syndrome, growth form and seed characteristics). Large seed size was used as proxy for small seed number; tall plant height and low S-strategy type scores were used to characterise low stress-tolerance. Levels of small-scale community completeness were relatively low (more species were absent than present) and varied between the grasslands in different geographic areas. Species in the dark diversity were generally characterized by shorter dispersal distances and greater seed weight (fewer seeds) than species in the observed diversity. Species within the dark diversity were generally taller and had a lower tolerance of stressful conditions. We conclude that, even if temperate grasslands have high levels of small-scale plant diversity, the majority of potentially suitable species in the regional species pool may be absent as a result of dispersal limitation and low stress-tolerance. [ABSTRACT FROM AUTHOR]

We used an extensive dataset (1220 vegetation plots of 1m2) to study vegetation gradients and fine-scale plant diversity in dry calcareous grasslands (including alvar grasslands) in the Baltic Sea region. The study area covers the entire European distributional range of alvar habitats: Sweden (Öland, Gotland, Götaland), Estonia (Saaremaa, Hiiumaa, north Estonia, west Estonia), and western Russia (Izhora, Izborsk). Fine-scale plant diversity was characterized by species richness and standardized phylogenetic diversity (comparing the observed mean pairwise phylogenetic distance (MPD) with MPD values from random communities). Ordination techniques (DCA) were used to characterize the main vegetation gradient. Variables describing local environment, climate, the biogeographic composition of the plant communities, and geographic location were related to fine-scale species richness and phylogenetic diversity using variation partitioning techniques and linear mixed models. The main vegetation gradient in the dry calcareous grasslands in the Baltic Sea region had a strong geographic component, was associated with soil depth, species’ stress- and disturbance-tolerance and the age of the grassland habitat. Fine-scale phylogenetic diversity and species richness were negatively associated suggesting that these two diversity components are influenced by different sets of environmental and historical parameters. Fine-scale species richness was unimodally associated with the main vegetation gradient, and the highest levels of species richness were found under intermediate environmental (disturbance, light conditions and temperature) conditions where there was a mixture of species from different biogeographic regions. In contrast to species richness, fine-scale phylogenetic diversity was negatively associated with the main vegetation gradient. The highest phylogenetic diversity was found in the extremely thin-soiled alvar grasslands in Götaland and on the Baltic islands (especially on Öland) where the high phylogenetic diversity is likely to be a reflection of a long history of continuous openness that has allowed time for the “collection” of phylogenetically different species within these unique habitats. [ABSTRACT FROM AUTHOR]

The mechanisms driving nonrandom assembly patterns in plant communities have long been of interest in ecological research. Competing ecological theories predict that coexisting species may either be more functionally dissimilar than expected by chance (with functional 'divergence' mainly reflecting niche differentiation) or be functionally more similar than expected (with functional 'convergence' reflecting either the outcome of environmental filtering or weaker-competitor exclusion effects). Assembly patterns are usually assessed at a single scale and disturbance regime, whereas considering different spatial scales and disturbance regimes may clarify the underlying assembly mechanisms., We tested the prediction that convergence and divergence are scale- and disturbance- dependent in grazed and abandoned species-rich dry grasslands within a 22 km2 landscape in south-eastern Sweden. Convergence and divergence were tested for plant species' traits and phylogenetic relationships at three nested spatial scales: within 412 plots (50 × 50 cm, divided into 10 × 10 cm subplots), within 117 grassland patches (from 0.02 to 11.63 ha) and within the whole landscape (across patches)., At the finest scale (10 × 10 cm subplots within plots), coexisting species were more different than expected by chance (divergence), both functionally and phylogenetically, suggesting niche differentiation. At the intermediate scale (50 × 50 cm plots within patches), coexisting species showed convergence, suggesting environmental filtering. No significant deviations from random expectations were detected at the broadest scale (patches within the 22 km2 landscape) - suggesting the prevalence of dispersal limitation at this scale. The fact that nonrandom patterns were particularly evident under grazed conditions is consistent with the prediction that assembly patterns are disturbance dependent., Synthesis. This study shows that multiple trait-based assembly processes operate simultaneously in species-rich communities, across spatial scales and disturbance regimes. The results support earlier theoretical predictions that divergence between coexisting species may be an important driver of community assembly, particularly at finer spatial scales, where species compete for the same local resources. In contrast, environmental filtering is expected at broader spatial scales, where species growing in particular environmental conditions share traits that are adaptive under those conditions. Within given habitat types, dispersal limitation may, however, override environmental filtering at increasing spatial scales of observation. [ABSTRACT FROM AUTHOR]

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Questions To what extent is species richness in semi-natural grasslands related to local environmental factors and (present/past) surrounding landscape structure? Do responses of species richness depend on degree of habitat specialization (specialists vs generalists) and/or scale of the study? Location Öland, Sweden. Methods Richness of herbaceous vascular plants (subdivided into richness of grassland specialists and generalists) was recorded within 50 × 50 cm plots and 0.1-4.8 ha grassland polygons. Generalized linear models and hierarchical partitioning were used to identify local factors (habitat area and heterogeneity, grazing intensity, habitat continuity) and landscape factors (proportion of surrounding grassland in 2004, 1938 and 1800, and landscape diversity in 2004) associated with the richness estimates. Results At the polygon scale, both specialist and generalist richness was positively associated with local habitat area and heterogeneity and, independently of area and heterogeneity, with grazing intensity, habitat continuity and amount of surrounding grassland in 1800. At the plot scale, specialist species richness was positively associated with habitat heterogeneity, amount of surrounding grassland in 2004 and landscape diversity. Plot-scale generalist richness was negatively associated with surrounding grassland in 1938 and positively associated with local grazing intensity. Conclusions Because both habitat specialization and study scale influence conclusions about relationships between species richness and local and landscape factors, the study highlights the need to consider species diversity at multiple spatial scales when making decisions about grassland management. Large-scale (polygon) species richness is influenced by immigration processes, with both specialists and generalists accumulating in old grasslands over centuries of grazing management. Habitat heterogeneity increased specialist species richness at both scales, suggesting that management policies should favour maintenance of a heterogeneous mosaic of open areas, trees and shrubs in temperate grazed grasslands. Although grassland specialists are sensitive to grassland isolation, in extensively managed landscapes with high landscape diversity input of grassland species from the landscape matrix may buffer negative effects of habitat fragmentation on grassland communities. [ABSTRACT FROM AUTHOR]

The study explores whether small-scale species diversity, species evenness and species richness in semi-natural grassland communities are similarly associated with present management regime and/or present and historical landscape context (percentage of different land-cover types in the surroundings). Species diversity, evenness and richness were recorded within 441 50×50cm grassland plots in 4.5×4.5km agricultural landscape on Öland, Sweden. Recent and historical land-cover maps (years 2004, 1959, 1938, 1835, and 1800) were used to characterize the present and past landscape context of the sampled vegetation plots. Partial regression and simultaneous autoregressive models were used to explore the relationships between species diversity measures (Shannon diversity, richness and evenness) and different explanatory variables while accounting for spatial autocorrelation in the data. The results indicated that species richness was relatively sensitive to grassland isolation, while the response of species evenness to isolation was characterized by a degree of inertia. Because the richness and evenness components of species diversity may respond differently to habitat fragmentation, we suggest that monitoring projects and empirical studies that focus on changes in biodiversity in semi-natural grasslands should include the assessment of species evenness – as a complement to the assessment of species richness. In addition, our results indicated that the development and persistence of a species-rich and even grassland vegetation was favoured in areas that have historically (in the 19th century) been surrounded by grasslands. Information on landscape history should, whenever possible, be incorporated into the planning of strategies for grassland conservation. [Copyright &y& Elsevier]

Abstract: The study characterizes historical land-use change and the development of semi-natural grassland habitats, over 274 years, within a mosaic agricultural landscape (22km2) on the island of Öland (Sweden). We also explore the relationship between previous land-use, habitat continuity and present-day vascular plant species richness in grassland patches. Land-cover maps, based on cadastral maps and aerial photographs, were produced for six time-periods between 1723/1733 and 1994/1997. In 1723/1733, the landscape was dominated by grasslands, with arable land surrounding the villages. The grassland area decreased throughout the study period and grassland patches became progressively more fragmented. Present-day grasslands represent 18% of the grassland area in 1723/1733. The land-use structure of the early 18th century is still evident in the modern landscape. The majority of the present-day grasslands are situated on former common grazing land and have had a continuity of at least 274 years: the remaining grasslands are younger and developed during the 20th century on arable or forested land. The proportion of plant species that depend on grazing and are characteristic of semi-natural grasslands significantly reflects the continuity and previous land-use of grassland sites. The study illustrates the way in which information on historical land-use and habitat continuity can help to explain the structuring of plant assemblages in semi-natural grasslands within the modern landscape. [Copyright &y& Elsevier]

1 Species-rich semi-natural grasslands in Europe developed during prehistoric times and have endured due to human activity. At the same time, intensive grassland management or changes in land use may result in species extinction. As a consequence, plant diversity in semi-natural calcareous grasslands may be related to both historical and current human population density. 2 We hypothesize that current vascular plant diversity in semi-natural calcareous grasslands is positively correlated with the Late Iron Age ( c. 800–1000 years ago) density of human settlements (indicated by Late Iron Age fortresses and villages) due to enhancement of grassland extent and species dispersal, and negatively correlated with current human population density due to habitat loss and deterioration. 3 We described the size of the community vascular plant species pool, species richness per 1 m2 and the relative richness (richness divided by the size of the species pool) in 45 thin soil, calcareous (alvar) grasslands in Estonia. In addition to historical and current human population density we considered simultaneously the effects of grassland area, connectivity to other alvar grasslands, elevation above sea level (indicating grassland age), soil pH, soil N, soil P, soil depth, soil depth heterogeneity, geographical east–west gradient, precipitation and spatial autocorrelation. 4 Both the size of the community species pool and the species richness are significantly correlated with the Late Iron Age human population density. In addition, species richness was unimodally related to the current human population density. The relative richness (species ‘packing density’) was highest in the intermediate current human population densities, indicative of moderate land-use intensity. 5 Community species pool size decreased non-linearly with increasing soil N, and was highest at intermediate elevation. Small-scale richness was greater when sites were well connected and when the elevation was intermediate. Spatial autocorrelation was also significant for both species pool size and small-scale richness. 6 In summary, human land-use legacy from prehistoric times is an important aspect in plant ecology, which could be an important contributor to the current variation in biodiversity. [ABSTRACT FROM AUTHOR]