Typical Grassland Species Research Articles

Participation of grassland species in various successional series in a temperate European region and implications for habitat management

Restoration strategies of semi-natural grasslands at various disturbed sites require an understanding of the resilience of these habitats and knowledge of their specific successional dynamics. Here, we assess (i) to what extent and under what circumstances grassland species can spontaneously establish and survive in various successional series, and (ii) whether some successional stages may provide surrogate habitats for typical grassland species. Besides grassland species, we evaluated the participation of other species groups, namely woodland, synanthropic and open wetland species, to demonstrate general successional trends. We studied 12 different successional series ca 60 years long in the Czech Republic, central Europe, and evaluated changes in species numbers and cover of species groups. Our results showed grassland species participated not only temporarily but also continuously during the first six decades of succession, as we had expected. Their decline in the late successional stages was only slightly visible despite the formation of woodland in most successional series. In some cases, the woodland was not completely closed and still allowed some grassland species to survive in the understorey. However, we found clear negative correlations between the participation of grassland and woodland species in the late successional stages. Woodland species generally increased, while synanthropic species clearly decreased during succession. Open wetland species slightly decreased, probably due to increasing site terrestrialisation in several successional series. The number and cover of dry grassland species decreased with increasing altitude, while those of mesic grassland species increased, indicating a decisive role of climate for their participation in succession. Successional trends discussed here represent general patterns but cannot be automatically applied in restoration without considering the specificity of each successional series. The establishment of grasslands in most successional series can be prevailingly maintained by management to reduce the establishment and expansion of woody species, otherwise grasslands only rarely persist in habitats under extreme site conditions or certain natural disturbances.

Is Shrub Encroachment Driving the Decline of Small Mammal Diversity in Pyrenean Grasslands? A Preliminary Study

The Pyrenean highlands hold the southernmost populations of some endemic and rare arvicoline species associated with grasslands. This area, as well as many other areas in the Mediterranean basin, has suffered from land abandonment due to socio-economic changes during the last decades. Those changes represented a reduction of the traditional livestock grazing by goats and sheep which naturally controlled the process of shrub encroachment. Today, maintenance of open habitats such as pasture grasslands needs to be performed by mechanical actions aimed at removing shrubs and woody vegetation. We document a case study on a plot sampled for five consecutive years (2017–2021) in which clear-cutting increased the cover of herbaceous vegetation by removing shrubs, potentially improving pasture quality. Also, changes in the small mammal community were detected, such as an increase in the species density and diversity (Shannon index) after clear-cutting, with the occurrence of typical grassland species (Microtus arvalis, M. lavernedii). Nonetheless, the effects were short-term (lasting two years), and then the community returned to the pre-treatment situation. Prior to intervention, the community was dominated by two generalist and widespread species (A. sylvaticus and C. russula), and the situation was similar two years after the intervention. Small increases in shrub cover produced relevant community changes by decreasing diversity and increasing dominance of the two most common species. These results suggested that shrub encroachment produced the banalization of small mammal communities dominated by generalist species.

Molecular and morphological diversity in the /Rhombisporum clade of the genus Entoloma with a note on E. cocles

A combined morphological and molecular genetic study of the European species within the /Rhombisporum clade of the genus Entoloma reveals a high species diversity. This group comprises typical grassland species with pronounced and well-differentiated cheilocystidia, and a wide range of spore shapes varying from rhomboid to five-angled. To fix the concept of the classical species E. rhombisporum, a neotype is designated. Nine species are described as new to science based on the result of nrDNA ITS phylogeny with additional gap coding, and morphological characterization: E. caulocystidiatum, E. lunare, E. pararhombisporum, E. pentagonale, E. perrhombisporum, E. rhombiibericum, E. rhombisporoides, E. sororpratulense, and E. subcuboideum. The ITS sequences of the holotypes of previously described species belonging to the /Rhombisporum clade, viz., E. laurisilvae and E. pratulense have also been generated and are published here for the first time. Since many of the above-mentioned species have been misidentified as E. cocles, it seemed opportune to also study this species and to designate a neotype to fix its current concept. A key including European species is presented. As most of the species are potentially important indicators for threatened grassland communities, the 130 ITS barcodes newly generated for this study may be useful as a reference in conservation and metabarcoding projects.

Soil and Plant Characteristics in a Restored Area under Mid-Term Site Management

Mid- and long-term monitoring of restoration projects have to be performed, as short-term evaluations do not give comprehensive information about their outcomes. In this study, we assessed the results of a forest restoration project, implemented in former road builder’s yards. We evaluated the recovery of the soil’s physical and chemical properties, the effectiveness and naturalness of sward restoration, and the success of woody species planting. Our hypotheses were that soil–plant interaction strongly influenced the restoration dynamics. The areas were restored in 2016. In 2014, we collected data from 28 restored areas. Eight years after the restoration, the physical and chemical properties of the soil indicated good quality. Suitable soil conditions were reflected in the herbaceous vegetation cover, which was higher than 60% in all the areas. The sown mixture successfully contained spontaneous species, and perennials prevailed over annuals, indicating stability in the composition of the sward. Alien species cover (generally < 10%) was controlled by sown species. Sown species also outcompeted ruderal and typical grassland species, reducing the naturalness of the herbaceous layer. Tree and shrub growth was low, and soil properties did not affect their height. Our results underline the importance of sowing an herbaceous species mixture in degraded areas in order to efficiently restore the soil cover and to reduce the colonization of alien species. Moreover, in our study, we showed how soil properties differently affected plant species groups.

Seeding and Overseeding Native Hayseed Support Plant and Soil Arthropod Communities in Agriculture Areas.

Using native seed mixtures to create or recover grassland habitats in rotation to crops or in strips surrounding fields is considered a cost-effective practice to enhance ecosystem resilience and agro-biodiversity. The aim of this research was to assess the effects of native hayseed mixtures on plant and microarthropod communities in an agricultural area of Northern Italy. Three different experimental treatments were set up. The first was a control (C) (i.e., non-seeded plots left to spontaneous vegetation succession after ploughing no deeper than 15 cm). The second, hayseed seeded (Hs) after ploughing no deeper than 15 cm. The third experimental treatment was hayseed overseeded (Ov) on the resident plant community after only a superficial harrowing. Ov plots exhibited the preeminent positive effects on the total productivity and quality of the grassland in terms of total vegetation cover, cover and richness of typical grassland species (i.e., Molinio-Arrhenatheretea species), and cover of legumes, grasses and perennial species. Moreover, Ov sites exhibited the highest abundance of microarthropod taxa and soil biological quality (QBS-ar) but only in spring, when the disturbance of ploughing negatively affected Hs and C plots. On the other hand, Hs sites showed a great reduction of invasive alien (i.e., Ambrosia artemisiifolia and Artemisia verlotiorum) and segetal weed species (i.e., Capsella bursa-pastoris and Spergula arvensis) in terms of cover. This study provides valuable indication on using hayseed mixtures to create grassland habitats as reservoir of native flora and soil biodiversity in agriculture areas.

Establishment rate of regional provenances mirrors relative share and germination rate in a climate change experiment

AbstractClimate change and land‐use changes are among the major threats to biodiversity as they alter global and local environmental conditions in unprecedented dimensions. Therefore, the investigation of the ability of species and communities to cope with rapidly changing environments as well as the comprehensive understanding of possible evolutionary adaptation processes is urgently needed for their sustainable management and the maintenance of associated ecosystem processes. Here, seminatural grasslands receive special attention, because they are among the most species‐rich ecosystems in Central Europe, which are threatened by global change and land‐use intensification already since the beginning of the twentieth century. Hence, understanding their potential to respond to rapidly changing environments is important for future management. Here, the Global Change Experimental Facility (GCEF) is an opportunity to investigate the role of microevolution in response to climate change. Two of the land‐use regimes in the GCEF are seminatural, extensively used species‐rich meadow and pasture grasslands established by sowing common, native, and regionally typical grassland species in 2014. In view of ecological restoration, for each species a seed mixture of up to seven source populations was sown aiming to establish high levels of intraspecific variation from the regional gene pool. Here, we present the first evaluation of genetic and trait variation of source populations and of their establishment in the GCEF two years after sowing for six grassland species. Using AFLP markers, we assessed genetic variation of source populations and tested whether the source gene pools have established in the experiment. Additionally, we investigated phenotypic variation of source populations and performed PST‐FST comparisons to test whether trait differentiation is adaptive. Our study revealed that genetic and phenotypic differentiation of source populations is widespread in the grassland species studied, even on small geographic scales. The GCEF populations are highly diverse due to the mixture of the different, often genetically and phenotypically differentiated source populations. They represent a genetically diverse source for both selection among existing and evolution of new genotypes. Thus, the GCEF can be used as experiment to study evolutionary processes in response to the climate change and land‐use scenarios.

Succession matters: Community shifts in moths over three decades increases multifunctionality in intermediate successional stages

Species composition strongly depends on time, place and resources. In this context, semi-natural grasslands belong to the most species-rich habitats of Europe, and succession may eventually cause local extinction of typical grassland species, but conversely increase species richness due to habitat diversification. Here, we analyse potential effects of succession of calcareous grasslands on moths. Our studied community, assessed over three decades in south-eastern Germany, comprised >1000 species. We compiled data on the ecology of each of these species, considering the larval and adult stages. We assigned Ellenberg indicator values to each main larval food plant species used by these lepidopterans. Changes in the community means of these indicators were applied to test for possible consequences of the changes in habitat structure and quality. Our data revealed increasing multifunctionality of community structure, higher variability of habitat association over time, the appearance of range expanding species, but also local extinction of various typical grassland moth species. These shifts in species composition mirror effects of succession, which frequently transform previously homogenous semi-natural grasslands into a heterogeneous habitat mosaic.

Fire increases the reproduction of the dominant grass Brachypodium retusum and Mediterranean steppe diversity in a combined burning and grazing experiment

AbstractAimsWe assessed what the effects of fire and grazing are on vegetative growth and sexual reproduction of Brachypodium retusum, the dominant species of Mediterranean Thero‐Brachypodietea grasslands (“steppes”) and on species composition of the associated plant community.Location“La Crau”, southeastern France.MethodsWe set up a split‐plot experiment testing the effects of fire season (winter, summer) and grazing on plant cover, inflorescence number, seed set and germination of Brachypodium retusum in traditionally grazed grasslands. We further analyzed plant species composition and diversity in vegetation relevés. The same fire treatments were tested in a second experiment in long‐term grazing exclosures.ResultsBrachypodium retusum showed a rapid post‐fire recovery, but other species of the associated plant community, in particular annuals, recovered as fast or even faster. Fire increased Brachypodium retusum inflorescence production and seed set per inflorescence and this effect was stronger in the summer fire treatment. At the community level, fire significantly increased species richness, evenness and Bray–Curtis dissimilarity in the second post‐fire season and again, the summer fire effect was stronger. Grazing exclusion for two seasons had only a small effect on Brachypodium retusum and the associated plant community. The effect of both fire treatments on Brachypodium retusum was similar in long‐term exclosures. In these exclosures, fire resulted in a community shift towards the species composition of traditionally grazed steppes.ConclusionsThe concomitant positive effects of experimental burning on Brachypodium retusum reproduction and on plant diversity of Mediterranean steppe vegetation suggest that the system is adapted to fire as an important driver of community composition. Annual species surviving as seeds are as successful in post‐fire recovery as perennial resprouters. Prescribed burning may be an alternative strategy to restore community structure in abandoned (ungrazed) steppes showing a decline in typical grassland species after several years of grazing abandonment.

Contribution of the soil seed bank to the restoration of temperate grasslands by mechanical sward disturbance

The restoration of grasslands is one of the primary targets of nature conservation. An easy tool to stimulate the growth of plant species currently absent from the aboveground vegetation but hidden in the “dark”, is to make use of the soil seed bank. Here, seeds of rare and endangered species may still be present. However, the potential contribution of soil seed banks to effective grasslands restoration still remains unclear, as some but not many valuable species built up a persistent seed bank. To evaluate the potential of the soil seed bank for grassland restoration, we installed an experiment in 73 differently managed grasslands in Germany, where the seed bank was activated by mechanical sward disturbance. We also determined the species richness, the density of viable seeds, and the functional composition of seed banks and monitored the regeneration of the aboveground vegetation over two seasons. Our results show that sward disturbance led to an activation of the soil seed banks, which, however, contributed only little to the revegetation after sward disturbance. In addition, the severe impoverishment of the soil seed bank indicated a restricted potential for the restoration of temperate grasslands. Nevertheless, the activation of the soil seed bank increased not only the richness of arable weeds but also slightly the richness of typical grassland species. We conclude that only in recently improved and strongly species‐impoverished grasslands, sward disturbance alone might be able to slightly increase plant species richness. To achieve a distinct increase in species richness, additional diaspore transfer is needed.

Vegetation development after a large scale restoration of species-rich grasslands in a Central European floodplain

Large scale restoration using local high-diversity seed mixture combined with turf transfer was applied on ex-arable land in the Morava River floodplain in the western Slovakia in the years 1999–2012. The post-restoration vegetation development was recorded during 12 years after the restoration using floristic records per restored polygons with cover estimation in simple 3-degree scale. Temporal changes in species composition were evaluated by gradient analysis and number of characteristic grassland and ruderal species on restored sites was analysed by general linear models. Species composition changed gradually towards the species composition typical for species-rich floodplain grasslands, but the trajectory was not straightforward and several irregularities were observed. They were probably induced by extreme weather events (drought, floods). The decrease in ruderal species and increase in the number of typical floodplain grassland species were observed, when floodplain grassland species permanently outcompeted ruderal species since 8th year after the restoration. However the development in large scale was slower, than expected from previous small-scale experiments, it is evident, that combination of local seed mixture sowing with a turf transfer is a feasible method for the restoration of species-rich floodplain grasslands from arable land.

Genetic diversity of calcareous grassland plant species depends on historical landscape configuration

BackgroundHabitat fragmentation is considered to be a main reason for decreasing genetic diversity of plant species. However, the results of many fragmentation studies are inconsistent. This may be due to the influence of habitat conditions, having an indirect effect on genetic variation via reproduction. Consequently we took a comparative approach to analyse the impact of habitat fragmentation and habitat conditions on the genetic diversity of calcareous grassland species in this study. We selected five typical grassland species (Primula veris, Dianthus carthusianorum, Medicago falcata, Polygala comosa and Salvia pratensis) occurring in 18 fragments of calcareous grasslands in south eastern Germany. We sampled 1286 individuals in 87 populations and analysed genetic diversity using amplified fragment length polymorphisms. Additionally, we collected data concerning habitat fragmentation (historical and present landscape structure) and habitat conditions (vegetation structure, soil conditions) of the selected study sites. The whole data set was analysed using Bayesian multiple regressions.ResultsOur investigation indicated a habitat loss of nearly 80% and increasing isolation between grasslands since 1830. Bayesian analysis revealed a significant impact of the historical landscape structure, whereas habitat conditions played no important role for the present-day genetic variation of the studied plant species.ConclusionsOur study indicates that the historical landscape structure may be more important for genetic diversity than present habitat conditions. Populations persisting in abandoned grassland fragments may contribute significantly to the species’ variability even under deteriorating habitat conditions. Therefore, these populations should be included in approaches to preserve the genetic variation of calcareous grassland species.

The contribution of successional grasslands to the conservation of semi-natural grasslands species – A landscape perspective

Many species that are typical of calcareous, semi-natural grasslands (“typical grassland species”) are declining in Europe as a result of habitat-loss and -fragmentation. Whereas populations of these species are expected to be largest in old semi-natural grasslands, these species may also occur in successional grasslands on previously arable fields. We used a space-for-time approach to analyse changes in the frequencies of typical grassland species, and changes in soil properties, over a 280-year arable-to-grassland succession within a Swedish landscape. Our study revealed that a number of typical grassland species had higher frequencies in mid-successional (50–279years) than in old (≥280years) grasslands. Mid-successional grasslands also contained many of the typical grassland species that were present in old grasslands, but at lower frequencies, and had soil conditions similar to those of old grasslands. Early-successional (5–14 and 15–49years) grasslands contained few typical grassland species. In highly fragmented landscapes, mid-successional grasslands provide additional habitat for many typical grassland species, and can function as temporary refugia (“substitute habitat”) for these species until old grasslands are “restored”. The overall population sizes of some typical grassland species and red-listed species are likely to be substantially increased by the presence of mid-successional grasslands within the landscape. Our study suggests that, rather than focussing solely on old grassland fragments, conservation strategies for typical grassland species should adopt a dynamic, landscape-based perspective that recognizes the role of successional grasslands. Ensuring a continuous development of mid-successional grasslands is expected to be beneficial for populations of many typical grassland species.

Hyperspectral Aerial Imaging for Grassland Yield Estimation

In this study, we investigated the potential of airborne imaging spectroscopy for in-season grassland yield estimation. We utilized an unmanned aerial vehicle and a hyperspectral imager to measure radiation, ranging from 455 to 780 nm. Initially, we assessed the spectral signature of five typical grassland species by principal component analysis, and identified a distinct reflectance difference, especially between the erectophil grasses and the planophil clover leaves. Then, we analyzed the reflectance of a typical Norwegian sward composition at different harvest dates. In order to estimate yields (dry matter, DM), several powered partial least squares (PPLS) regression and linear regression (LR) models were fitted to the reflectance data and prediction performance of these models were compared with that of simple LR models, based on selected vegetation indices and plant height. We achieved the highest prediction accuracies by means of PPLS, with relative errors of prediction from 9.1 to 11.8% (329 to 487 kg DM ha−1) for the individual harvest dates and 14.3% (558 kg DM ha−1) for a generalized model.

Changes in dispersal and light capturing traits explain post‐abandonment community change in semi‐natural grasslands

AbstractQuestionDoes the role of dispersal and light limitation for community assembly change in temperate semi‐natural dry grasslands (SNDGs) post‐abandonment?LocationTemperate calcareous semi‐natural dry grasslands, western Estonia (58.642 N, 23.516 E).MethodsWe compared taxonomic and functional community structure of semi‐natural dry grasslands in Estonia at two time periods: first in 1975 when traditional grazing prevailed, and again in 2013 when management had ceased for at least 30 yr. In order to assess functional community structure, we used community‐weighted mean trait values and mean pair‐wise distance as metrics of functional diversity for traits related to plant dispersal and adaptations to reduced light availability. Successional shifts in functional community structure were examined using regression and multivariate analysis.ResultsChanges in community assembly of SNDGs post‐abandonment were largely driven by more closed vegetation structure and subsequently reduced light availability, as well as altered availability of dispersal vectors. Importance of long‐distance dispersal via grazing animals decreased while importance of bird dispersal increased under abandonment. At the same time, the importance of competition for light increased under abandonment. Results indicate that typical SNDG species are especially susceptible to abandonment because they are light‐demanding and depend on dispersal by wind or epizoochory (i.e. on the fur of animals), and their decline likely leads to reduced small‐scale species richness.ConclusionsVegetation changes in abandoned SNDGs show that regular management, by creating characteristic light and dispersal conditions, is highly important for maintaining both taxonomic and functional diversity. In particular, typical grassland species might be prone to local extinction as taller vegetation develops post‐abandonment. The importance of dispersal processes for community assembly observed in grazed SNDGs thus highlights that successful grassland conservation should include maintenance of dispersal conditions. Grassland conservation should aim to preserve the whole ecosystem and account for the multiple ecosystem processes (e.g. light availability, dispersal), which simultaneously structure plant community composition.

Management intensity and temporary conversion to other land‐use types affect plant diversity and species composition of subtropical grasslands in southern Brazil

AbstractQuestionsWe investigated the effects of grassland management intensity and temporary conversion to other land uses on abiotic and biotic properties of subtropical grasslands. We used species‐rich permanent grasslands of medium management intensity (PG‐M) as a reference, and asked the following questions: (1) do permanent grasslands with low and high management intensities (PG‐L and PG‐H, respectively) have different plant diversity and species composition than reference grasslands; and (2) do secondary grasslands recovering from conversion to arable fields (SG‐A) or pine plantations (SG‐P) differ from permanent grasslands in their plant species composition and abiotic conditions?LocationHighland grasslands, Campos de Cima da Serra, Rio Grande do Sul (RS), Brazil.MethodsWe analysed variation in plant species composition and diversity among 80 grassland sites, including three types of permanent grassland and two types of secondary grassland. An indicator species analysis was used to identify characteristic species for the different land‐use types. We used a linear discriminant analysis to investigate differences in soil conditions among land‐use types.ResultsBoth PG‐L and PG‐H differed from PG‐M regarding plant species composition. Although PG‐L shared many typical grassland species with PG‐M, their communities were generally less diverse. PG‐H, on the other hand, not only had fewer species but also deviated from PG‐M in species composition. Secondary grasslands on former arable fields and plantations differed from PG‐M in species composition and showed lower diversity. Soil conditions of SG‐P were similar to those of PG‐L and PG‐M, but they were distinct from those of PG‐H and SG‐A.ConclusionsAll land‐use types showed deviations from reference grasslands (PG‐M). The decrease in the number of species in PG‐L may be reversed if traditional management intensity is re‐introduced, whereas strong compositional changes in SG‐P may require the re‐introduction of grassland species. This is also true for PG‐H and SG‐A: both showed marked deviations from reference grasslands in biotic and abiotic components. Overall, restoration of altered land‐use types to near‐natural subtropical grassland seems feasible, but suitable techniques have to be developed.

Abandonment of crop lands leads to different recovery patterns for ant and plant communities in Eastern Europe

Significant proportion of crop lands have been abandoned as management strategies have changed in Central and Eastern Europe in the past decades. The study of insect versus plant communities in such areas could help us understand how these processes take place, and whether these communities return to a semi-natural state maintained by human activities. Amongst insects ants, as ecosystem engineers, are a perfect target group in this respect. We studied epigaeic ant and plant communities of abandoned old-fields in Romania. Contrary to our expectations, the total number of ant species did not increase with time during succession on old-fields contrary to plants, where an increase was registered in the total number. Disturbancetolerant ant species dominated the ant communities throughout the successional gradient, while in the case of plants a transition was found from weed-dominated to semi-natural communities. The diversity of both ant and plant communities increased after the 1-year stage, but the patterns were different. While a return to semi-natural state could be observed in plants during old-field succession, such a definite change did not occur in ants. This might be caused by the landscape context: the lack of connectivity of old-fields to larger natural areas. While plant propagules of semi-natural and natural habitat species can still successfully colonize the old fields even under such conditions, ant colonizers are mainly disturbance-tolerant species typical for agricultural areas, which can be hardly replaced by typical grassland species. Our findings underline the existence of important discrepancies between plant and ant community succession, mostly treated as paralleling each other. This is the first study to handle the effect of abandonment on ant and plant communities simultaneously in Eastern Europe.

Land-use changes, farm management and the decline of butterflies associated with semi-natural grasslands in southern Sweden

Currently, we are experiencing biodiversity loss on different spatial scales. One of the best studied taxonomic groups in decline is the butterflies. Here, we review evidence for such declines using five systematic studies from southern Sweden that compare old butterfly surveys with the current situation. Additionally, we provide data on butterfly and burnet moth extinctions in the region’s counties. In some local areas, half of the butterfly fauna has been lost during the last 60-100 years. In terms of extinctions, counties have lost 2-10 butterfly and burnet moth species. Land use has changed markedly with key butterfly habitats such as hay meadows disappearing at alarming rates. Grazed, mixed open woodlands have been transformed into dense coniferous forests and clear-cuts and domestic grazers have been relocated from woodlands to arable fields and semi-natural grasslands. Ley has increased rapidly and is used for bale silage repeatedly during the season. Overall, the changed and intensified land use has markedly reduced the availability of nectar resources in the landscape. Species that decline in Sweden are strongly decreasing or already extinct in other parts of Europe. Many typical grassland species that were numerous in former times have declined severely; among those Hesperia comma, Lycaena virgaureae, Lycaena hippothoe, Argynnis adippe, and Polyommatus semiargus. Also, species associated with open woodlands and wetlands such as, Colias palaeno, Boloria euphrosyne and the glade-inhabiting Leptidea sinapis have all decreased markedly. Current management practise and EU Common Agricultural Policy rules favour intensive grazing on the remaining semi-natural grasslands, with strong negative effects on butterfly diversity. Abandoned grasslands are very common in less productive areas of southern Sweden and these habitats may soon become forests. There is an urgent need for immediate action to preserve unfertilized, mown and lightly grazed grasslands. It is also crucial to encourage that management of abandoned grasslands resumes before it is too late. In order to mitigate risks of further species loss and to work towards recovery of threatened butterfly populations using best known practises, we recommend twelve types of management measures favourable for many butterflies.

Temporal dispersal in fragmented landscapes

Despite a good understanding on how dispersal in space structures plant communities in fragmented landscapes, we know little about dispersal in time. Empirical evidence on temporal dispersal – the soil seed bank – is lacking, with only trait-based evidence on the seed banks’ importance for species persistence in fragmented landscapes. Therefore, seed banks of remnant grassland fragments were analyzed in how they changed compared to semi-natural grasslands following fragmentation. We studied the historical trajectories in time since fragmentation, fragment size and habitat quality of 134 grassland plots, linking these to their seed bank and plant community to understand how seed banks temporally connect grassland fragments, potentially conserving the flora of historically large semi-natural grasslands. Seed-banking grassland species were present in similar proportions in all remnant grassland fragments. The seed bank composition changed with time since fragmentation started, triggered by the deterministic loss of grassland species, generating nested subsets of the seed banks of semi-natural grasslands. The spatial heterogeneity in seed bank composition among grassland fragments limited the loss of grassland species at the landscape scale. The seed bank became an increasingly important constituent of total plant diversity with time since fragmentation started, as grassland species stored an increasingly larger proportion of their local diversity in the seed bank. Temporal dispersal enables the prolonged presence and persistence of numerous typical grassland species in fragmented landscapes. The seed banks’ storage effect of plant diversity is of considerable significance to efforts aimed at conserving and restoring plant diversity in fragmented landscapes.

Ozone effects in a drier climate: implications for stomatal fluxes of reduced stomatal sensitivity to soil drying in a typical grassland species

AbstractThe widely distributed temperate grassland species Dactylis glomerata was grown in competition with Ranunculus acris at two different watering regimes and exposed for 20 weeks to eight ozone treatments with mean concentrations ranging from 16.2 to 89.5 ppb, representing pre‐industrial to predicted post‐2100 ozone climates. Measurements of stomatal conductance were used to parameterize ozone flux models for D. glomerata. For the first time, a modification was made to the standard flux model to account for the observed decrease in sensitivity of stomatal conductance to reduced water availability with increasing ozone. Comparison of calculated cumulative ozone flux between the two versions of the model demonstrated that exclusion of the ozone effect on stomatal conductance in the standard flux model led to a large underestimation of ozone fluxes at mid‐ to high‐ozone concentrations. For example, at a mean ozone concentration of 55 ppb (as predicted for many temperate areas in the next few decades), the standard flux model underestimated ozone fluxes in D. glomerata by 30–40% under reduced water availability. Although the modified flux model does not markedly change the flux‐based critical level for D. glomerata, this study indicates that use of the standard flux model to quantify the risk of ozone damage to a widely distributed grassland species such as D. glomerata in areas where high ozone concentrations and reduced soil moisture coincide could lead to an underestimation of effects. Thus, this study has shown that under predicted future climate change and ozone scenarios, ozone effects on vegetation may be even greater than previously predicted in the drier areas of the world.

Restoration potential of the persistent soil seed bank in successional calcareous (alvar) grasslands in Estonia

AbstractQuestionsWhat is the overall restoration potential of the persistent soil seed bank of abandoned alvar grassland sites? To what degree does the share of characteristic alvar grassland species in the soil seed bank change during secondary succession from traditionally managed pasture towards stages overgrown by Corylus avellana and Juniperus communis?LocationNorthern Estonia.MethodsThe species composition of above‐ground vegetation and the persistent soil seed bank were investigated in successional alvar grasslands. Particular attention was given to typical grassland species in the persistent soil seed bank. Soil seed bank density was also recorded. General linear models and non‐metric multidimensional scaling were used to assess successional trends and the restoration potential of the soil seed bank.ResultsThe cessation of traditional management has led to a considerable decline in above‐ground plant species richness. The composition of above‐ground vegetation in different successional stages was considerably more variable than that of the seed bank. We detected large and species‐rich persistent soil seed banks in all our study sites. About 70% of species in the seed banks of overgrown sites could be classified as typical grassland species. The frequency of typical alvar grassland species, such as Arabis hirsuta, Arenaria serpyllifolia, Cerastium fontanum, Helianthemum nummularium, Poa angustifolia, Potentilla crantzii, Sedum acre and Veronica spicata in the seed bank of long‐term abandoned (25 and 50 yr) sites was unexpectedly high.ConclusionsAbandoned semi‐natural grassland sites in northern Estonia still contain a relatively large grassland community species pool, including a large and effective soil seed bank. The soil seed bank could thus play a more important role in the restoration management of abandoned dry grassland communities than could be concluded from previous studies.