Biology subjects

Valko, O.

Publications and source records attributed to Valko, O..

8 recordsLinked to original sources

bioRxiv2025

On the edge of extinction: Delayed plant genetic response to forest edge dynamics

Understanding genetic responses to forest dynamics is essential for predicting the long-term viability of understory plant populations and for developing effective conservation strategies. This study investigates genetic extinction debt and colonization credit in Circaea lutetiana, a clonal forest understory species, across its European range. Using pooled genotype-by-sequencing data from 40 forest edge and core populations, we examined to what extent population size, latitude and historical changes in forest configuration predict genetic diversity. Our findings reveal that the historical forest configuration profoundly shapes present-day genetic diversity. Long-established forest edge populations exhibit significantly reduced allelic richness (-9%) compared to core populations, indicating the partial pay-off of a genetic extinction debt. In contrast, populations from recently established forest edges maintain comparable allelic richness to core populations, suggesting delayed population genetic responses to land use changes. Finally, populations established in areas that were afforested during the past 250 years exhibit lower genetic diversity than historical forest core populations, indicating a delay in genetic recovery and thus a potential genetic colonization credit. Our results highlight that C. lutetiana populations are not at equilibrium with the current forest configuration, underscoring the role of lagged genetic responses across very long time scales. Connectivity and population size further moderate genetic diversity, with smaller, isolated populations particularly vulnerable to genetic erosion. Given the limited research on delayed evolution in forest understory species, our results improve the understanding of extinction risk dynamics and underscore the need for history-informed restoration efforts.

ecology↗

bioRxiv2025

Small grassland patches are hotspots for medicinal plants and associated phytochemical diversity in European agricultural landscapes

O_LIMedicinal plants are threatened by overcollection and habitat loss due to human activities. In this study, we aimed to reveal how ancient earthen burial mounds covered with successional grasslands of different ages can contribute to conservation of medicinal plants and related phytochemical diversity in European agricultural landscapes. C_LIO_LIUsing vegetation data collected from 166 mounds in Hungary, we identified the medicinal plant species present at these sites, and based on multiple literature sources, provided the secondary metabolite profiles of the medicinal plants and plant communities. By using generalized linear mixed models and redundancy analysis we investigated how the age of the vegetation, percentage of croplands around the sites, site area, and soil properties influence the diversity of medicinal plants and associated phytochemicals. C_LIO_LIWe found that mounds provide safe havens for a wide range of medicinal plants and secondary metabolites. Our results showed that grassland-related medicinal plants producing iridoids and diterpenes were typical on mounds with older grasslands. A large proportion of croplands in the neighboring landscape and high soil pH supported generalist medicinal plants producing nitrogen-containing and sesquiterpene related secondary metabolites. Higher soil nitrogen, phosphorus, and potassium content favored medicinal plants producing lignans, glycosides, and organic acids. C_LIO_LIOur results suggest that the high phytochemical diversity is supported by the occurrence of various compounds facilitating the adaptation of medicinal plants to the various environmental stressors and biotic factors, such as competition, herbivory and pathogens, present in sites embedded in agricultural landscapes. C_LI Societal Impact StatementBesides being important components of landscape-level biodiversity, medicinal plants are essential resources for traditional and modern healthcare. However, in parallel with biodiversity loss driven by human activities, populations of medicinal plants have also declined. By maintaining connections between nature, culture, and people, sacred natural sites can help counteract this trend. We studied the potential of ancient burial mounds to maintain populations of medicinal plants and related phytochemical diversity in European agricultural landscapes. Our findings highlight the importance of conserving grassland vegetation and associated biodiversity at these sites, which is crucial for preserving a key ecosystem service in intensively managed landscapes.

ecology↗

bioRxiv2024

Effect of pre-germination temperature conditions on germination characteristics of temperate grassland species

Germination characteristics of target species used for grassland restoration are often unknown, despite such information would be essential for designing restoration interventions. Filling this knowledge gap and improving our understanding about germination responses of grassland species to varying cold and warm treatments could be especially important in the face of climate change. Here we studied the effect of three different durations of warm dry stratification and three different durations of cold wet stratification, and their combinations in a full factorial design (in total 15 different pre-germination treatments), on the germination capacity of 48 grassland species native to Central Europe. Stratification treatments modelled present and forecasted summer (1-3 months warm period) and winter (1-3 months cold period) temperature conditions, while the study of the combined effect of these treatments is especially important in spring-germinating species. As response variables, we calculated relative response indexes and germination uncertainties of each species separately and applied general linear models to study the effect of treatments on these variables. We found clear effect of warm- or cold stratification on relative response indexes only in four species: strong positive response to warm stratification was found in Silene conica, while strong positive response to cold stratification was found in Agrimonia eupatoria, Echium vulgare, and Plantago lanceolata. The responses to treatment combinations were contradictory or lacked clear trends in most of the species. Germination uncertainty in general was high for all species, supporting the fact that Central European grassland species often rely on bet hedging as risk spreading strategy, to avoid unfavourable conditions during seedling establishment.

plant biology↗

bioRxiv2022

Heritage of ancient cultures supports conservation: a continent-wide perspective from the Eurasian steppes

Civilisations including ancient ones, have shaped the global ecosystems in many ways through a co-evolution of landscapes and humans. However, the cultural legacies of ancient and lost civilisations are seldom considered in conservation. Here using a continental-scale dataset containing over 1,000 data records on the localities, land cover, protection status and cultural values related to ancient steppic burial mounds (so-called kurgans), we evaluated how these iconic and widespread landmarks can contribute to grassland conservation in the Eurasian steppes, which is one of the most endangered biomes on Earth. By using Bayesian logistic generalized regressions and proportional odds logistic regressions, we aimed to reveal the potential of mounds in preserving grasslands considering landscapes with different levels of land use transformation. We also compared the conservation potential of mounds situated inside and outside protected areas and assessed whether the presence of cultural, historical or spiritual values support the maintenance of grasslands on them. We revealed that kurgans have enormous importance in preserving grasslands in transformed landscapes outside protected areas, where they can act as habitat islands, and provide an additional pillar for conservation by contributing to habitat conservation and improvement of habitat connectivity. We found that besides their steep slopes hindering ploughing, the existence of cultural, historical or religious values could almost double the chance for grassland occurrence on kurgans due to the related extensive land use and the respect of local communities. As the estimated number of steppic mounds is about 600,000 and also similar historical features exist in all continents, our results can be upscaled to a global level. Our results also suggest that an integrative socio-ecological approach in conservation might support the positive synergistic effects of conservational, landscape and cultural values.

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↗