Biology subjects

Sonkoly, J.

Publications and source records attributed to Sonkoly, J..

14 recordsLinked to original sources

bioRxiv2026

The 'false transience' hypothesis: Do we need to reconsider the seed persistence classifications of soil seed bank studies?

Background and Aims Seed bank persistence data is typically indirect, inferred from the presence and distribution of seeds in the soil. However, this approach frequently underestimates seed longevity, because dormant and low-abundance seeds can remain undetected. Here, we introduce and test the 'false transience' hypothesis which proposes that a subset of species classified as having transient seeds based on soil seed bank (SSB) studies actually possess the capacity for long-term persistence. Their perceived transience stems from methodological limitations and ecological filters, rather than physiological constraints. We also aimed to assess how the seed mass and seed production of 'false transient' species compare to the full range of tested species. Methods We focused on species considered to have transient seeds based on SSB studies. We conducted a germination experiment with 103 species using dry-stored seeds aged 10-29 years. We then assessed how the seed mass and seed number of germinating species relate to the full range of tested species. Key Results From the 103 tested species, eight species (~8%) germinated. The majority of species germinating after >10 years had large seeds and low seed numbers compared to the full range of species, and all germinating species had seed numbers below the median of the tested species. Conclusions Our results provide partial support for the proposed 'false transience' hypothesis, showing that nearly 10% of supposedly transient species can persist after more than a decade of ex situ storage. Our results also suggest that 'false transients' are frequently large-seeded with low seed production, therefore being more likely to be missed in SSB studies and erroneously classified as transient. We can conclude that relying solely on field SSB data to infer seed persistence can be misleading, suggesting that the widely observed negative relationship between seed size and persistence may also require reconsideration.

ecology↗

bioRxiv2026

High-intensity sheep grazing impoverishes soil seed banks in sand grasslands

The effects of the selection of livestock type (e.g., sheep or cattle) and grazing intensity on the soil seed bank of sand grasslands of conservation interest were studied. 25 grazed grassland sites classified into four grazing intensity categories were studied. The soil seed bank was analysed by seedling emergence; germinated seedlings were classified into morpho-functional, social behaviour type (SBT) and CSR strategy groups. The following hypotheses were tested: i) Diversity and density of soil seed banks are lower in sheep-grazed sites than in cattle-grazed ones. ii) The species composition, diversity, and density of the soil seed banks are more strongly affected by grazing intensity than by the livestock type. iii) Leaf traits, SBT and CSR strategy composition are highly affected both by livestock type and grazing intensity. The main effect of livestock type only affected seed bank density, while that of grazing intensity had a significant effect on most of the variables. Most of the studied variables were affected by the interaction of grazing intensity and livestock type. Total seed bank density was lower at all grazing intensity levels in sheep-grazed sites than in cattle-grazed ones, especially close to frequently visited places. We found that sheep grazing sustained a much lower total seed bank density and lower density of species of natural and semi-natural habitats regardless to the grazing intensity. Thus, livestock type must be carefully selected and high-intensity sheep grazing should be avoided in the long-run when managing sand grasslands. HighlightsO_LIThe soil seed banks of sheep and cattle grazed sand grassland were studied C_LIO_LIEffect of grazing intensity found the most important driver of seed bank diversity and density C_LIO_LIThe total soil seed bank density was higher in cattle than sheep grazed sites C_LIO_LIBoth intensity and livestock type must be considered in the grassland management planning C_LIO_LIHigh intensity sheep grazing should be avoided in sand grassland management C_LI

ecology↗

bioRxiv2025

Unintentional seed dispersal via container-grown garden plants: Seed density and composition vary among exporter countries

The global ornamental plant trade is well-known as an important source of alien plants, but the unintentional dispersal of seeds as contaminants of this trade is rarely considered and largely understudied. We sampled the substrate of imported container-grown plants in several garden centres in Hungary to answer the following questions: (i) What species seeds are present in the substrate of imported garden plants and in what quantity? (ii) Do the substrates of plants imported from different countries contain seeds in different density and composition? (iii) Do characteristics of the host garden plants affect the number and diversity of seeds found in their substrate? We detected altogether 2,181 seeds of 80 taxa in the substrates. On average, 1 litre of substrate contained 36 seeds of five species. Most species were alien in Hungary and considered invasive in Europe. The majority of samples contained at least one seed of a species invasive in Europe. We found that the substrate of plants imported from different countries contained seeds in different number, diversity, and composition. Thus, the structure of the horticultural trade network can shape the alien flora of importing countries. Furthermore, the substrate of needle-leaved ornamental species contained more seeds than the substrate of broad-leaved ornamentals. Our findings demonstrate that the ornamental plant trade can disperse a large number of seeds of numerous species and introduce alien species into the importing countries. We conclude that this introduction pathway deserves greater attention in invasion biology and more studies of this phenomenon are urgently needed.

ecology↗

bioRxiv2025

Inconsistent relationships detected between seed size, shape, and persistence for different plant functional groups in the Pannonian flora

Background and AimsKnowledge on seed persistence is vital from both theoretical and practical considerations but directly collecting seed persistence data for many species is rather unfeasible. Therefore, there is a need to identify traits that can predict seed persistence, but studies about the effects of seed size and shape on persistence yielded results varying across regions. We studied 392 species of the Pannonian flora (Central Europe) to asses (i) how seed mass and shape affect seed persistence, (ii) whether this effect is consistent across plant functional groups, and (iii) whether seed mass and shape are correlated in different functional groups? MethodsWe collected data on the seed mass and persistence of species and we performed measurements to calculate their Seed Shape Index, which quantifies deviation from sphericity. We analysed how seed mass and Seed Shape Index affect persistence in all herbaceous species and separately in four plant functional groups. We also tested whether and how seed mass and shape are related to each other in these groups. Key ResultsAcross all species, both seed mass and Seed Shape Index negatively affected seed persistence. The same relationship was observed separately for perennials, short-lived species, and forbs, but only seed shape affected persistence in the graminoid group. Larger seeds also tended to be less spherical in graminoid species, in contrast to all studied species and to other functional groups, where we observed inverse or no relationship between seed mass and shape. ConclusionsConsistent with many studies in other floras, both seed mass and shape negatively affected seed persistence in the Pannonian flora. However, only seed shape influenced persistence in graminoid species, suggesting that different factors may be at play in forbs and graminoids. Therefore, future studies of this relationship may need to treat and analyse graminoids separately.

ecology↗

bioRxiv2024

Origin of plant trait data matters: Shared species of Northwestern Europe and the Pannonian Ecoregion have different trait values in the two regions

Trait-based ecology considerably increased our comprehension of various fields related to ecology and evolution. As measuring traits can be time-consuming and costly, analyses regularly gather trait data from databases instead of carrying out new measurements. However, intraspecific trait variability can cause considerable differences between the trait values of different population and regions. Here we evaluated whether intraspecific trait variability causes considerable differences in trait values measured in two different regions of Europe. We tested whether regionally measured trait data from the Pannonian Ecoregion differ from trait data of the same species originating from Northwestern Europe, by comparing data from the Pannonian Database of Plant Traits (PADAPT) and the LEDA Traitbase. We evaluated six traits of the same set of species: thousand-seed mass (TSM), seed bank persistence index (SBPI), leaf area (LA), leaf dry matter content (LDMC), specific leaf area (SLA), and leaf dry mass. We found that trait data from the two databases significantly differed for TSM, SBPI, SLA, and LDMC. Our results indicate that the markedly different climate of the two regions can cause substantial intraspecific trait variation, therefore, the geographical origin of trait data matters in trait-based analyses. The findings corroborate the assumption that regionally measured trait data and building regional databases are essential for reliable regional-scale trait-based studies. We conclude that for studies analysing traits in the Pannonian Ecoregion (and possibly in Easter and Central Europe in general), it is advisable to use PADAPT instead of databases compiling data from regions with markedly different climatic conditions.

ecology↗

bioRxiv2024

Nurseries and garden centres as hubs of alien plant invasions

The growing global horticultural trade is having a steadily increasing impact on the rate at which alien species are introduced into new areas, partly because horticultural trade also entails the unintentional dispersal of many contaminant species. Although there are reports about noteworthy occurrences of alien plant species in garden centres, this phenomenon has hardly been studied systematically. To bridge this knowledge gap, we conducted systematic field surveys in 12 garden centres in Hungary to assess their alien flora. We hypothesised that (i) the number of alien species inhabiting a garden centre is positively correlated with its size, (ii) relative to their size, garden centres host a disproportionately large proportion of the local alien flora, and (iii) alien species inhabiting garden centres differ from the regional alien flora in their traits. We recorded altogether 93,788 individuals of 67 introduced species, seven of which have not yet been reported from the country. There was considerable variability in the number of species and individuals found in each garden centre, but there was no correlation between the size of the garden centres and the number of species they host. Despite their relatively small size, the studied garden centres hosted a considerable proportion of the local alien flora, indicating that they strongly accumulate alien species and that they can act as invasion hubs for several alien species. Alien species inhabiting garden centres differed from the regional alien flora in some of their trait values, indicating that the species that are most successful at establishing populations inside garden centres are both good dispersers and possess an effective resource-acquisitive strategy. We conclude that established alien plant populations in garden centres may induce local invasions, and in the meantime, individuals and seeds inside the containers of ornamental plants are regularly transported to distant areas by the customers. Therefore, plant species dispersed as contaminants of horticultural stock need to be better considered in invasion biology to reduce the threat they may present.

ecology↗

bioRxiv2023

Alkaline and loess grasslands with contrasting richness and biomass patterns are not separated on the CSR strategy spectrum.

Studying the relationship between biodiversity patterns and processes in vegetation has been at the centre of interest in vegetation ecology for several decades. By studying the biomass of loess and alkaline grasslands along a water and salinity gradient, we aimed to analyse species diversity and CSR functional type patterns. We aimed to test the following hypotheses: i) The biomass and species richness scores and the species composition are significantly different between the sampled grassland community types. ii) The sampled communities are well separated based on the CSR strategy spectrum. iii) The amount of green biomass and litter are positively correlated with competitiveness and negatively with stress tolerance. The biomass and species richness scores and the species composition of the sampled communities along the sampled gradients were significantly different; the highest species richness, evenness and Shannon diversity values were found in loess grasslands. The highest level of litter accumulation was found in alkaline meadows. The communities were well separated in the ordinations but surprisingly, calculation of coordinates for CSR strategy types have not shown clear separation of the grassland community types. Based on the results we can conclude that the current CSR classification is too robust to delineate grassland communities in alkaline landscapes which are markedly different in composition. We point out that the CSR classification is based on the magnitude of stress, and it is not able to differentiate between the various forms of stress which might be responsible for the marked compositional differences. Therefore, developing an index focusing specifically on the functional characterisation of stressed communities and able to differentiate between different forms of stress (e.g., water and/or salinity stress) would be highly beneficial for future studies.

ecology↗

bioRxiv2022

PADAPT 1.0 - the Pannonian Database of Plant Traits

We present PADAPT 1.0, the Pannonian Database of Plant Traits which relies on regional data sources and integrates existing data and new measurements on a wide range of traits and attributes of the plant species of the Pannonian Biogeographical Region and makes it freely accessible at www.padapt.eu. The current version covers the species of the region occurring in Hungary (cc. 90% of the regions flora) and consists of 126,337 records on 2745 taxa. There are 53 plant attributes in PADAPT 1.0 organised in six major groups: (i) Habitus and strategy, (ii) Reproduction, (iii) Kariology, (iv) Distribution and conservation, (v) Ecological indicator values, and (vi) Leaf traits. By including species of the eastern part of Europe not covered by other databases, PADAPT can facilitate studying the flora and vegetation of the eastern part of the continent. Data collection will continue in the future and the PADAPT team welcomes researchers interested in contributing with data. The main task before an updated version of the database is to include species of the Pannonian region not covered by the current version. In conclusion, although data coverage is far from complete, PADAPT meets the longstanding need for a regional database of the Pannonian flora.

ecology↗

bioRxiv2021

Trade of commercial potting substrates: A largely overlooked means of the long-distance dispersal of plants

Although long-distance dispersal (LDD) events are considered to be rare and highly stochastic, they are disproportionately important and drive several large-scale ecological processes. The realisation of the disproportionate importance of LDD has led to an upsurge in studies of this phenomenon; yet, we still have a very limited understanding of its frequency, extent and consequences. Humanity intentionally spreads a high number of species, but a less obvious issue is that it is associated with the accidental dispersal of other plant species. Although the global trade of potted plants and horticultural substrates is capable of dispersing large quantities of propagules, this issue has hardly been studied from an ecological point of view. We used the seedling emergence method to assess the viable seed content of different types of commercial potting substrates to answer the following questions: (i) In what richness and density do substrates contain viable seeds? (ii) Does the composition of substrates influence their viable seed content? and (iii) Are there common characteristics of the species dispersed this way? We detected altogether 438 seedlings of 66 taxa and found that 1 litre of potting substrate contains an average of 13.27 seeds of 6.24 species, so an average 20-litre bag of substrate contains 265 viable seeds. There was a high variability in the seed content of the substrates, as substrates containing cattle manure contained a substantially higher number of species and seeds than substrates without manure. Based on this, this pathway of LDD is an interplay between endozoochory by grazing livestock and accidental human-vectored dispersal, implying that the diet preference of grazing animals largely determines the ability of a plant species to be dispersed this way. According to our results, potting substrates can disperse large quantities of seeds of a wide range of plant species, moreover, these dispersal events occur on very long distances in almost all cases. We conclude that this kind of human-vectored LDD may have complex effects on plant populations and communities; however, as this dispersal pathway is largely understudied and has hardly been considered as a type of LDD, its consequences are still largely unknown and further studies of the issue are of great importance.

ecology↗

bioRxiv2021

Sand dropseed (Sporobolus cryptandrus) - A new pest in Eurasian sand areas?

For the effective control of an invasive species, gathering as much information as possible on its ecology, establishment and persistence in the subjected communities is of utmost importance. We aimed to review the current distribution and characteristics of Sporobolus cryptandrus (sand dropseed), an invasive C4 grass species of North American origin recently discovered in Hungary. We aimed to provide information on (i) its current distribution paying special attention to its invasion in Eurasia; (ii) the characteristics of the invaded habitats in Central Europe; (iii) seed bank formation and germination characteristics, crucial factors in early establishment; and (iv) the effects of its increasing cover on vegetation composition. Finally, we aimed to (v) point out further research directions that could enable us to understand the invasion success of this potential invasive species. Field surveys uncovered large stands of the species in Central and Eastern Hungary with most of the locations in the former, especially the Kiskunsag region. The species invaded disturbed stands of dry and open sand grasslands, closed dune slack grasslands and it also penetrates into natural open sand grasslands from neighbouring disturbed habitats. Increasing cover of Sporobolus cryptandrus caused a decline in species richness and abundance of subordinate species both in the vegetation and seed banks, but a low density of Sporobolus cryptandrus can even have a weak positive effect on these characteristics. Viable seeds of Sporobolus were detected from all soil layers (2.5 cm layers measured from the surface to 10 cm in depth), which indicates that the species is able to form a persistent seed bank (1,114 to 3,077 seeds/m2 with increasing scores towards higher abundance of the species in vegetation). Germination of Sporobolus cryptandrus was negatively affected by both litter cover and 1 cm deep soil burial. To sum up, Sporobolus cryptandrus can be considered as a transformer invasive species, whose spread forms a high risk for dry sand and steppe grasslands in Eurasia. We can conclude that for the effective suppression of the species it is necessary: (i) to clarify the origin of the detected populations; (ii) to assess its competitive ability including its potential allelopathic effects; (iii) to assess its seed bank formation potential in habitats with different abiotic conditions; and (iv) to assess the possibility of its suppression by natural enemies and management techniques such as mowing or livestock grazing.

ecology↗

bioRxiv2020

Establishment gaps in species-poor grasslands: artificial biodiversity hotspots to support the colonization of target species

Sowing of grass seed mixtures is a feasible and cost-effective method for landscape-scale grassland restoration. However, sowing only grasses usually leads to species-poor and dense grass sward, where the establishment of target forbs is hampered both by microsite and propagule limitation. To overcome these limitations and increase the diversity of species-poor sown grasslands we developed a novel method by creating establishment gaps. We used tillage to open gaps of 1 m2, 4 m2 and 16 m2 size in the dense grass sward of six species-poor sown grasslands in the Great Hungarian Plain. We sowed high-diversity seed mixtures of 35 native species into all gaps. We analyzed vegetation development during the first five years after setting up the trial. We also studied the colonization dynamics of the sown species along four 20-m transects around each gap, resulting in a total of 1440 plots of 1 m2 size that were studied. Our results indicated that most of the sown species were able to establish permanently in the establishment gaps. The total cover and the cover of perennial sown species increased independently of gap size. Meanwhile the cover of short-lived sown species decreased during the five years. There was only a moderate level of weed abundance in the gaps, and weed cover decreased over the years. The sown target species started to colonize the species-poor grasslands surrounding the establishment gaps within five years. The highest number of species and individuals dispersed from the 4 m2-sized gaps, as they had a more stable development than small gaps and were exposed to lower grazing pressure than large ones. Implications for practiceO_LIEstablishment gaps are widely applicable tools to increase the diversity of species-poor grasslands. Gaps of 4 m2 represent a more feasible solution compared to larger openings also for the farmers, because there is only a moderate level of weed encroachment and smaller soil disturbance occurs during their creation. C_LIO_LIWe recommend sowing high-diversity seed mixtures containing both short-lived species that can establish in the first year and perennial species, which guarantee a high cover of target species later on. C_LIO_LIGaps sown with high-diversity seed mixture are highly resistant to unfavorable climatic conditions: increasing grass abundance in dry years does not hamper the recovery of target grassland species in the following years. C_LI

ecology↗

bioRxiv2020

Consumption rate and dietary choice of cattle in species-rich mesic grasslands

For the improvement and maintenance of the desirable ecological value of grasslands it is necessary to manage them in a way which maintains their structure and their long-term functioning. Extensive grazing plays a crucial role in the seasonal biomass removal, thereby it prevents litter accumulation and shrub encroachment. Defoliation and biomass removal are among the most important effects of grazing on the vegetation, while the sufficient quantity and quality of plant biomass is an important ecosystem service for animal husbandry. In order to maintain the long term functioning of pastures it is important to gather information about the amount of consumed biomass and the dietary choice of the grazers. Therefore, we studied the direct effects of grazing on species-rich meadow steppes in Central-Hungary and the underlying mechanisms of dietary choice of cattle using trait-based approach. We asked the following questions: (i) What are the direct effects of grazing on the main biomass fractions (litter, moss, forbs and graminoids)? (ii) Which traits distinguish the preferred and non-preferred vascular plant species? The studied pastures were divided into two adjacent units, which were managed differently in the study year: the grazed units were managed by grazing for three months before the sampling date, while the control units remained ungrazed until the sampling. We collected above-ground biomass samples, measured leaf traits and shoot nitrogen content of plants. The consumption of the litter and moss biomass was negligible, while the reduction of the live biomass of vascular plants was 65%. Grazing significantly decreased the flowering success of plants. Cattle consumed species characterized by high specific leaf area and high nitrogen content. Based on our results we emphasize that, in order to ensure the reproduction of most plant species in the long term, it is unfavourable to graze an area every year in the same period. Instead, it is recommended to use grazing in a mosaic spatial and temporal pattern. The livestock carrying capacity of an area and the long-term management of grasslands can be carefully planned based on biomass measurements and the nutritional value of plants, which is well indicated by some easily measurable plant properties such as specific leaf area and the nitrogen content of species.

ecology↗

bioRxiv2020

Vegetation and seed bank dynamics highlight the importance of post-restoration management in sown grasslands

Sowing grass seeds generally supports the rapid development of a closed perennial vegetation, which makes the method universally suitable for fast and effective landscape-scale restoration of grasslands. However, sustaining the recovered grasslands, and increasing their diversity is a challenging task. Understanding the role of seed bank compositional changes and vegetation dynamics contributes to designating management regimes that support the establishment of target species and suppress weeds. Our aim was to reveal the effect of post-restoration management on the vegetation and seed bank dynamics in grasslands restored in one of the largest European landscape-scale restoration projects. Eight years after restoration we sampled the vegetation and seed bank in a total of 96 plots located in 12 recovered grasslands in the Great Hungarian Plain. In each recovered grassland stand we designated a mown (mown from Year 1 to Year 8) and an abandoned sample site (mown from Year 1 to Year 3 then abandoned from Year 4 to Year 8). Mown and abandoned sites showed divergent vegetation and seed bank development. Abandonment led to the decline of sown grasses and higher cover of weeds, especially in the alkaline grasslands. Our study confirmed that seed bank has a limited contribution to the maintenance of biodiversity in both grassland types. We found that five years of abandonment had a larger effect on the seed bank than on the vegetation. We stress that long-term management is crucial for controlling the emergence of the weeds from their dense seed bank in restored grasslands. Implications for practiceO_LISeed sowing of grass mixtures can be a feasible tool for restoring grasslands at large scales. However, the developed vegetation usually has low biodiversity and a high seed density of weeds is typical in the soil seed bank even several years after the restoration. Therefore, post-restoration management is necessary for suppressing weeds both aboveground and belowground. C_LIO_LIWe recommend to design the long-term management of the sites subjected to grassland restoration already in the planning phase of the restoration projects and ensure that the management plan is ecologically and economically feasible. C_LIO_LIWe recommend to complement the monitoring of vegetation with the analysis of soil seed bank for evaluating restoration success. C_LI

ecology↗

bioRxiv2020

Germination response of invasive plants to soil burial depth and litter accumulation is species specific

QuestionsPlant invasions are considered among the biggest threats to biodiversity worldwide. In a full-factorial greenhouse experiment we analysed the effect of soil burial depth and litter cover on the germination of invasive plants. We hypothesised that (i) burial depth and litter cover affect the germination of the studied species, (ii) the effects of burial and litter cover interact with each other, and (iii) the effects are species-specific, but dependent on seed size. MethodsWe tested the germination and seedling growth of 11 herbaceous invasive species in a full-factorial experiment using four levels of seed burial depths and litter cover. We analysed the effect of burial, litter cover, and their interactions on germination, seedling length and biomass across species and at the species level. ResultsSoil burial depth and litter cover had a significant effect on the germination of the studied species, but there were considerable differences between species. We observed a general trend of species with bigger seeds being not or less seriously affected by soil burial and litter cover than smaller-seeded species. Correlations between seed weight and effect sizes mostly confirmed this general trend, but not in the case of soil burial. ConclusionsOur findings confirmed that seed size is a major driver of species response to litter cover and to the combined effects of litter cover and soil burial, but there is no general trend regarding the response to soil burial depth. Despite its very small seeds the germination of Cynodon dactylon was not affected by soil burial. The germination of Ambrosia artemisiifolia was hampered by both soil burial and litter cover despite its relatively large seeds. Thus, specific information on species response to burial depth and litter accumulation is crucial when planning management or restoration in areas threatened by plant invasions.

ecology↗