Sand Grassland Research Articles

Low replicability of testing the stress–dominance hypothesis using a trait convergence/divergence pattern

AbstractAimsEcological theories predict that assembly processes are driven by two deterministic forces: environmental filtering and limiting similarity. Their relative importance under different environmental conditions is still not completely obvious. Therefore, in this paper the predictions of the stress–dominance hypothesis (SDH) are tested in several sites.LocationKiskunság in Hungary, and Deliblato Sands in Serbia, Central Europe.MethodsWe studied a productivity gradient from open sand grasslands to meadows. The cover of species was estimated visually in plots with a size of 2 m × 2 m, resulting in 344 vegetation plots. Four trait values (height, seed mass, specific leaf area, and leaf size) were collected from field measurements and databases. The weighted median of interspecies distances in traits (a robust alternative to Rao's quadratic entropy) was used to determine functional diversity. The convergence and divergence of each trait in communities were evaluated by randomization tests, and effect sizes were calculated for each plot. We used hierarchical general additive models (HGAM) to determine whether the trend of effect sizes along the productivity gradient is the same in different sites.ResultsThe HGAM approach indicated that trait variations follow global trends but are influenced by site‐specific effects. The exception is seed mass, whose variation did not have any trend. Both environmental filtering and limiting similarity exist in the communities, and mainly a shift from trait convergence to a divergence pattern along the productivity gradient was observed.ConclusionThe results are mainly congruent with theoretical expectations, but the results from the different sites did not lead to the same conclusion. Although traits follow a global trend, the site effect is not negligible. Critical evaluation of SDH using trait convergence/divergence patterns for exploring rules of community assembly points out the weaknesses of this hypothesis. Therefore, alternative ways of studying trait patterns should be found to better understand community organization.

Exploring the effects of habitat management on grassland biodiversity: A case study from northern Serbia.

Grasslands represent a biodiversity hotspot in the European agricultural landscape, their restoration is necessary and offers a great opportunity to mitigate or halt harmful processes. These measures require a comprehensive knowledge of historical landscape changes, but also adequate management strategies. The required data was gathered from the sand grasslands of northern Serbia, as this habitat is of high conservation priority. This area also has a long history of different habitat management approaches (grazing and mowing versus unmanaged), which has been documented over of the last two decades. This dataset enabled us to quantify the effects of different measures across multiple taxa (plants, insect pollinators, and birds). We linked the gathered data on plants, pollinators, and birds with habitat management measures. Our results show that, at the taxon level, the adopted management strategies were beneficial for species richness, abundance, and composition, as the highest diversity of plant, insect pollinator, and bird species was found in managed areas. Thus, an innovative modelling approach was adopted in this work to identify and explain the effects of management practices on changes in habitat communities. The findings yielded can be used in the decision making as well as development of new management programmes. We thus posit that, when restoring and establishing particular communities, priority needs to be given to species with a broad ecological response. We recommend using the decision tree as a suitable machine learning model for this purpose.

A case study on the early stage of Pinus nigra invasion and its impact on species composition and pattern in Pannonic sand grassland

Alien woody species are successful invaders, frequently used for afforestation in regions like semi-arid lands. Shrubs and trees create important microhabitats in arid areas. Understorey vegetation in these habitats has unique species composition and coexistence. However, the impact of solitary woody species on understorey vegetation is less understood. This study evaluated the effect of native (Juniperus communis) and invasive solitary conifers (Pinus nigra) on surrounding vegetation, where individuals were relatively isolated (referred to as solitary conifers). The field study conducted in Pannonic dry sand grassland in 2018 recorded plant and lichen species presence around six selected solitary conifers. Composition and pattern of understorey vegetation were assessed using 26 m belt transects with 520 units of 5 cm × 5 cm contiguous microquadrats. Compositional diversity (CD) and the number of realized species combinations (NRC) were calculated from the circular transects. Results showed native conifer J. communis created more complex, organized microhabitats compared to alien P. nigra. CD and NRC values were significantly higher under native conifers than invasive ones (p = 0.045 and p = 0.026, respectively). Native species also had more species with a homogeneous pattern than the alien species. Alien conifers negatively affected understorey vegetation composition and pattern: some species exhibited significant gaps and clusters of occurrences along the transects under P. nigra. Based on our study, the removal of invasive woody species is necessary to sustain habitat diversity.

Genetic diversity assessment of Helichrysum arenarium (Asteraceae) for the genetic restoration of declining populations.

Helichrysum arenarium (L.) Moench (Asteraceae) is a self-compatible, insect-pollinated herb occurring in sand grasslands, and is declining and endangered in many parts of its European distribution range. A recovery plan of H. arenarium has been conducted in southern Belgium, involving plant translocations. We developed multiplex genotyping protocol for nine microsatellite markers previously published for Helichrysum italicum and two newly developed microsatellite markers for H. arenarium. Eleven polymorphic loci were associated (pooled) in two multiplex panels, to assess the genetic status of the only small remaining population in Belgium and of three large German populations used as seed source for propagating transplants. The small Belgian population was characterized by high clonality, with only two, however heterozygous, genets detected. The three large German populations showed high genetic diversity (H e ranging from 0.635 to 0.670) and no significant inbreeding coefficient values, despite expectations of geitonogamous selfing. Management practices (grazing livestock) increasing seed dispersal distances, inbreeding depression at early stages of development, and mechanisms preventing or delaying selfing might be hypothesized to explain the observed patterns. The two Belgian genotypes remained within genetic variation range of German populations so that the high genetic differentiation between Belgian and German populations (F ST values ranging from 0.186 to 0.206) likely resulted from genetic drift effects and small sample size. Transplants obtained from seeds sampled from the three large source populations from Germany constitute a highly diverse, noninbred gene pool, and are thus of high genetic quality for plant translocations.

Microhabitat selection of meadow and steppe vipers enlightened by digital photography and image processing to describe grassland vegetation structure

AbstractUnderstanding animals' selection of microhabitats is important in both ecology and biodiversity conservation. However, there is no generally accepted methodology for the characterization of microhabitats, especially for vegetation structure. We studied microhabitat selection of three Vipera snakes by comparing grassland vegetation structure between viper occurrence points and random points in three grassland ecosystems: V. graeca in mountain meadows of Albania, V. renardi in loess steppes of Ukraine and V. ursinii in sand grasslands in Hungary. We quantified vegetation structure in an objective manner by automated processing of images taken of the vegetation against a vegetation profile board under standardized conditions. We developed an R script for automatic calculation of four vegetation structure variables derived from raster data obtained in the images: leaf area (LA), height of closed vegetation (HCV), maximum height of vegetation (MHV) and foliage height diversity (FHD). Generalized linear mixed models revealed that snake occurrence was positively related to HCV in V. graeca, to LA in V. renardi and to LA and MHV in V. ursinii, and negatively to HCV in V. ursinii. Our results demonstrate that vegetation structure variables derived from automated image processing significantly relate to viper microhabitat selection. Our method minimizes the risk of subjectivity in measuring vegetation structure, enables the aggregation of adjacent pixel data and is suitable for comparison of or extrapolation across different vegetation types or ecosystems.

The role of drought, disturbance, and seed dispersal in dominance shifts in a temperate grassland

AbstractAimsMore intense and frequent droughts predicted for the future will heavily affect grasslands worldwide and, along with various other disturbances, possibly trigger major vegetation shifts. Therefore, documenting these changes and understanding the mechanisms behind them is essential. Our study aimed to investigate how dominant species in a semiarid grassland respond to a combination of small‐scale experimental disturbances and naturally occurring droughts and uncover the underlying mechanisms.LocationCentral Hungary.MethodsWe conducted a small‐scale disturbance experiment in a semiarid temperate grassland and followed recovery for 18 years, including severe drought events. In 1999, we established 16 sites, eight dominated by Festuca vaginata and another eight by Stipa borysthenica, the two dominant species of sand grasslands in the region. At each site, three permanent plots were marked that received either a cutting or digging treatment or remained as controls. We monitored the cover and density changes of Festuca and Stipa annually.ResultsIn the early years following the disturbance, Festuca recovered at a similar rate under both disturbance treatments, while Stipa recovered faster in cut than in dug plots. When natural drought events caused major diebacks of both species, Stipa recovered very quickly and regained dominance in initially Stipa‐dominated plots, and it also took over in initially Festuca‐dominated control and cut plots. However, digging at Festuca‐dominated sites delayed drought‐induced Stipa colonisation and thus favoured Festuca recovery. We found that the poor performance of Stipa in dug plots was related to sharply reduced seedling establishment, which resulted from the low number of seeds captured by the bare soil surface after digging.ConclusionsOur results demonstrate that recurring drought events may induce dominance shifts in temperate grasslands, but small‐scale disturbances can modulate vegetation responses. Our findings emphasise the importance of post‐disturbance regeneration patterns in drought‐induced vegetation shifts and show that seed dispersal strategy may have a major effect on vegetation dynamics.

Native species can reduce the establishment of invasive alien species if sown in high density and using competitive species

Invasion of alien species is one of the main drivers of land degradation threatening both natural and managed ecosystems. Ecological restoration is crucial in controlling invasion to improve biotic resistance and avoid further land degradation. We investigated the possibility of controlling the establishment of invasive alien species (IAS) by native seed addition. We tested if trait similarity or increased propagule pressure of native species results in the suppression of IAS at the early stage of development. We set up a sowing experiment with three widespread IAS in Hungary of different life forms and functional groups (Asclepias syriaca, Conyza canadensis, Tragus racemosus) and four Pannonic sand grassland species (Festuca vaginata, Galium verum, Gypsophila paniculata, Saponaria officinalis). We found no significant differences in germination ability and seedling emergence between native species and IAS, despite the differences in thousand‐seed weight. Using univariate general linear models, we found that the seedling establishment of IAS can be reduced by adding native species at high densities but also depending on the species identity. Instead of species of similar traits, the seeding of a competitor perennial grass of sand grasslands (F. vaginata) reduced the seedling emergence of all studied IAS the most. Our results confirm that IAS can be effectively controlled by native seed addition in the early establishment stage, especially applying higher densities and competitive species. We conclude that invasion‐resistant restoration can be achieved by the combination of several factors, including high‐density sowing of native species that match IAS in the early stage of development.

Intensity‐dependent effects of cattle and sheep grazing in sand grasslands — Does livestock type really matter?

AbstractAimsBy analysing cattle‐ and sheep‐grazed sand grasslands, we tested the following hypotheses: (i) livestock type has a stronger effect on the vegetation characteristics than grazing intensity; (ii) sheep grazing results in lower biomass and species and functional diversity than cattle grazing, regardless of intensity; and (iii) increased grazing intensity causes a shift of the trait composition in grasslands.LocationSand grasslands in the Nyírség region, East Hungary.MethodsWe selected 26 sand grassland sites grazed by cattle or sheep and classified them into four intensity levels. Vegetation composition was surveyed in 2 m × 2 m plots. We harvested the above‐ground biomass from 20 cm × 20 cm plots; then dried and sorted it to live biomass, litter, moss, and lichen. We compared Rao dissimilarity index, species richness, Shannon diversity, evenness, and the community‐weighted means of nine vegetative and generative traits along a grazing intensity gradient. We calculated functional richness, evenness, and divergence for comparison.ResultsWe found that some diversity metrics and community‐weighted means of most studied traits were significantly affected by grazing intensity. Several characteristics were also affected by the interaction of grazing intensity and livestock type, but none of the studied characteristics was affected by livestock type in itself. Increasing Rao dissimilarity index peaking at the fourth grazing intensity level was detected, but for other multitrait indices, no such changes were proven, except for functional divergence, which was the lowest at the first intensity level. Graminoid, forb, and litter biomass were significantly affected by intensity, but none of the biomass fractions was affected by livestock type.ConclusionsWe suggest that for the management of sand grasslands, grazing intensity should be carefully adjusted, considering not only livestock units per hectare. For practical recommendations, well‐defined, long‐term experiments studying different livestock and habitat types along an intensity gradient would be essential.

Drone-Based Identification and Monitoring of Two Invasive Alien Plant Species in Open Sand Grasslands by Six RGB Vegetation Indices

Today, invasive alien species cause serious trouble for biodiversity and ecosystem services, which are essential for human survival. In order to effectively manage invasive species, it is important to know their current distribution and the dynamics of their spread. Unmanned aerial vehicle (UAV) monitoring is one of the best tools for gathering this information from large areas. Vegetation indices for multispectral camera images are often used for this, but RGB colour-based vegetation indices can provide a simpler and less expensive solution. The goal was to examine whether six RGB indices are suitable for identifying invasive plant species in the QGIS environment on UAV images. To examine this, we determined the shoot area and number of common milkweed (Asclepias syriaca) and the inflorescence area and number of blanket flowers (Gaillardia pulchella) as two typical invasive species in open sandy grasslands. According to the results, the cover area of common milkweed was best identified with the TGI and SSI indices. The producers’ accuracy was 76.38% (TGI) and 67.02% (SSI), while the user’s accuracy was 75.42% (TGI) and 75.12% (SSI), respectively. For the cover area of blanket flower, the IF index proved to be the most suitable index. In spite of this, it gave a low producer’s accuracy of 43.74% and user’s accuracy of 51.4%. The used methods were not suitable for the determination of milkweed shoot and the blanket flower inflorescence number, due to significant overestimation. With the methods presented here, the data of large populations of invasive species can be processed in a simple, fast, and cost-effective manner, which can ensure the precise planning of treatments for nature conservation practitioners.

Short‐term effects of the control of the invasive plant Asclepias syriaca: Secondary invasion of other neophytes instead of recovery of the native species

AbstractQuestionThis study aimed to assess the impact of the invasion of Asclepias syriaca, a perennial non‐native herbaceous species, on basic soil attributes and vegetation composition, and to study the effect of mechanical control, namely the cutting of Asclepias, on target and other plant species.LocationSandy region of Kiskunság National Park, Hungary, Central Europe.MethodsIn ten old‐fields, four 4 m × 4 m plots were established (n = 40), of which three were invaded by Asclepias, and one was uninvaded. The invaded plots were treated as: (1) all Asclepias shoots removed, (2) half of the Asclepias shoots removed, or (3) untreated. The treatment was conducted twice a year in summer during the period 2019–2021. Before the first treatment, soil and vegetation were sampled. Afterwards, vegetation monitoring was performed twice a year: the cover of each vascular plant species and the number of Asclepias shoots were recorded in each plot.ResultThere were no differences in the studied soil attributes between the uninvaded and invaded plots. However, there were differences in vegetation composition, namely, the cover of sand grassland specialists was higher in uninvaded plots. Short‐term cutting negatively affected Asclepias after two years. The cover of specialists did not change in response to treatments, but the cover of other neophyte plant species increased.ConclusionsBased on our results, the invasion of Asclepias changes the vegetation composition, but not the soil. Although short‐term mowing can reduce the cover of Asclepias, but the grassland specialist plants do not regenerate; instead, secondary invasion occurs. We conclude that more time or additional treatment is required for native plant recovery.

Early sowing is more effective in the long-term for restoring sandy grassland than six years of mowing or carbon amendment

In order to find the best and most reliable practices for ecological restoration of degraded lands, longer time scales should be considered when evaluating restoration efforts. We assessed the long-term (16 years) effects of different grassland restoration treatments – seeding, mowing, and carbon amendment – in the Pannonian sand grasslands. After re-plowing in 1 m × 1 m plots, treatments were carried out in two abandoned croplands. Seeding was applied only initially (2002) while mowing and carbon amendment were carried out for six years (2003–2008). Vegetation was surveyed yearly from 2003 to 2008 and re-sampled in 2019 in each permanent treatment plot. We used principal coordinates analysis to describe the trajectories of vegetation development and linear mixed-effects models to test changes in the relative cover of native sand grassland (target) and invasive (neophyte) species with time and treatments. Relative cover of target species increased while neophyte species decreased with time in both sites. There was a higher relative cover of target species from the first or third year on and a lower relative cover of neophyte species from the third year on in one site in seeded plots compared to other treatments. Seeded species also spread into non-seeded plots by 2019, obscuring the differences between treatments 16 years after sowing. Carbon amendment proved to be beneficial in the early and mowing in the later phases of restoration. Based on the long-term results, initial seeding is the best method for restoring sand grasslands in old fields by favoring the establishment of target species and controlling non-native invasion. As a supplement to seeding, carbon amendment can be suggested in the initial phases and/or low-intensity mowing in the later phases of the restoration after land abandonment. Although the spread from seeded plots obscured the long-term differences between treatments, it optimized the restoration process, suggesting that the use of small seed introduction units can be enough to restore the whole degraded area.

The long-term effect of initial restoration intervention, landscape composition, and time on the progress of Pannonic sand grassland restoration

AbstractTo help upscale ecological restoration of degraded lands, landscape factors and longer time scales should be considered when assessing restoration efforts. We evaluated the impact of initial restoration intervention, landscape composition, and elapsed time since the restoration began on the long-term progress of Pannonic sand grassland restoration. Treatments (seeding, mowing, and carbon amendment) were implemented for 6–7 years and monitoring lasted up to 23 years after the first treatment applications in eight experimental blocks belonging to three field experiments. The abundance of target/neophyte species, and distance from primary grasslands and plantations (as major source of target/neophyte species) were estimated in 500 m landscape buffers around each block to characterize landscape composition. Restoration progress was calculated as the difference between the relative cover of target/neophyte species in treatment and control plots. Restoration intervention and neophyte abundance in the landscape had a significant effect on the restoration progress, but time did not. Seeding had the highest positive effect on target species and also prevented invasion by neophyte species. Higher abundance of neophytes in the landscape and the proximity to plantations increased the cover of neophytes in treatment plots. We conclude that restoration interventions may have a greater impact on restoration progress in the longer term than landscape factors or elapsed time. Seeding proved to be the best method in restoring sand grasslands by both favoring target species and controlling invasion. From the landscape factors, the abundance of neophyte species and distance to plantations should be considered when prioritizing areas and efforts for restoration.

Interactions Between an Apex Predator and Mesopredators Across a Landscape with Human Interference

Photo 1. In the Caldén forest region of central Argentina, we installed 16 camera traps in each of 45 10 × 10-km grid cells, covering 61,611 km2, to determine interactions between carnivores and explore contributions of habitat, biotic, and anthropic factors on co-occurrence. The carnivore guild was constituted of the puma, Puma concolor (top predator; upper center of photograph), and subordinate predators (under puma, from left to right: pampas fox, Pseudalopex gymnocercus; pampas cat, Leopardus colocolo; Geoffroy's cat, Leopardus geoffroyi; and Molina's hog-nosed skunk, Conepatus chinga). Geoffroy's cats and skunks spatially avoided pumas (negative sign), but pumas did not influence pampas fox or pampas cat space use (equal sign). Photograph credits: José H. Sarasola and Juan I. Zanón Martínez. Photo 2. The study area corresponds to the Espinal phytogeographic province, mainly occupied by the Caldén forest (left), but includes interspersed sand grasslands and salt deposits (right). This forest is a xerophilic forest ecosystem dominated by Caldén trees (Prosopis caldenia), covering from 30% to 50%, and grasslands predominating over bushes. The topography is characterized by plateaus, valleys, hills, and low-altitude plains (<200 m). Photograph credit: José H. Sarasola. These photographs illustrate the article “Assessing carnivore spatial co-occurrence and temporal overlap in the face of human interference in a semiarid forest” by Juan I. Zanón Martínez, Javier Seoane, Marcella J. Kelly, José Hernán Sarasola, and Alejandro Travaini published in Ecological Applications. https://doi.org/10.1002/eap.2482.

Invasion of the North American 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 affected 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 in the Kiskunság region. The species invaded disturbed stands of dry and open sand grasslands, closed dune slack grasslands and it also penetrates natural open sand grasslands from neighboring disturbed habitats. Increasing cover of Sporobolus cryptandrus was associated with 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 (1114 to 3077 seeds/m 2 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. • We studied the distribution and characteristics of the invasive sand dropseed. • The species invades degraded grasslands, undisturbed sand grasslands and steppes. • With increasing dropseed cover declining plant species diversity was found. • Persistent seed banks and an effective germination of the species was detected. • Spread of sand dropseed forms a high risk for dry sand grasslands in Eurasia.

Drought in maternal environment boosts offspring performance in a subordinate annual grass

Drought can induce shifts in plant species or functional group abundances, which may favor coexisting subordinate species at the expense of previous dominants. Within-generation and transgenerational phenotypic plasticity can be important mechanisms to shape species responses to drought. Although a handful of studies have already investigated transgenerational plasticity in the context of drought, they provided variable results, and usually focused on species that currently dominate communities.We performed pot experiments with Secale sylvestre, a typical subordinate species in semiarid grasslands of Central Hungary. We tested if this annual grass shows reduced growth or reproduction in response to drought, and whether drought in the maternal environment affects offspring performance.For both maternal and offspring generations, plant height, shoot biomass, flowering onset, and seed number showed no within-generation plasticity in response to drought, and drought only decreased the seed mass of mother plants. In contrast, we found strong transgenerational effects on the overall performance of progenies, which changed with offspring age. At an early life stage, shoots were shorter for the offspring of drought-treated mothers than for the progenies of control mothers. This difference turned in the opposite direction later, and tiller number was also greater for the offspring of drought-treated mothers. Furthermore, the offspring of drought-treated mothers had over two-times higher adult shoot biomass and seed production compared to the offspring of control mothers. These beneficial transgenerational effects may help S. sylvestre to gain dominance in sand grasslands following dry years that decrease the abundance of perennial grasses, a vegetation change often observed in these grasslands after droughts.Our study provides the first evidence for positive transgenerational plasticity in response to drought for a subordinate species, which may be adaptive when the suppression of dominant species in the offspring environment is predictable from drought in the maternal environment.

Monograph of invasive plants in Europe N°6: Asclepias syriaca L

ABSTRACT This work synthesizes all aspects of Asclepias syriaca L. (Apocynaceae) including the taxonomy, distribution, history of introduction and spread, ecology, biology, uses and benefits, impacts on biodiversity and agriculture, legislation, and management. Asclepias syriaca is a perennial broad-leaved species native to North America. Introduced for ornamental and various other purposes, such as a source of fibre and rubber, it has become established in many regions of Europe and it had increasingly spread in the last decades (>1980s). Its reproductive behavior is characterized by a high production of wind-dispersed seeds and by the propagation of creeping lateral rhizomes, which allows the species to proliferate rapidly. The species persists in a wide range of edaphic and climatic environments. It occurs particularly in anthropogenic and (semi-)natural habitats, such as roadsides, agricultural land, abandoned sites and grasslands, open shrubland, and forests, respectively. Studies have demonstrated negative impacts on the biodiversity and ecosystem processes in invaded regions, namely in open sand grasslands in Hungary. Asclepias syriaca occurs as a competitive weed in crop fields. Since 2017, the species is regulated by the European Union (EU) under the Regulation No. 1143/2014, which states that A. syriaca is subjected to restrictions such as a ban on importing, selling, breeding and that EU member states are required to place effective management measures. Awareness raising activities are important to inform the public, farmers and stakeholders about the risks of this invasive alien plant. Effective direct control options include mechanical control as well as herbicide application.

Changes in Soil Features and Phytomass during Vegetation Succession in Sandy Areas

This research was conducted on an area of inland sands characterised by various degrees of overgrowth by vegetation and soil stabilisation. This landscape’s origin is not natural but is connected to human industrial activities dating from early medieval times, which created a powerful centre for mining and metallurgy. This study aims to identify the changes in the above- and belowground phytomass in the initial stages of succession and their influence on the chemical properties and morphology of the soil. It was found that Salix arenaria dominated in primary phytomass production in all plots tested. The amounts of this species found in each community were as follows: 8.55 kg/400 m2 (algae–mosses), 188.97 kg/400 m2 (sand grassland–willow), 123.44 kg/400 m2 (pine–willow–mosses), 14.63 kg/400 m2 (sand grassland–mosses–willow), and 196.55 kg/400 m2 (willow–pine–sand grassland). A notable share of Koeleria glauca was found in the phytomass production of Plots IV (45.73 kg) and V (86.16 kg). Basic soil properties (pH, Corg, Nt), available plant elements (P), and plant nutrients (Ca, Mg, K, P, Fe) beneath the dominant plant species were examined. Soil acidity (pH) varied greatly, ranging from acidic (pH = 3.2) to weakly acidic (pH = 6.3). The content of organic carbon (Corg) in individual plots beneath the dominant species in the humus horizon ranged from 0.28% to 1.42%. The maximum contents of organic carbon and total nitrogen were found in organic (O) and organic-humus (OA) horizons. The highest Pavail content was found in organic and organic-humus horizons, ranging from 10.41 to 65.23 mg/kg, and in mineral horizons under K. glauca (24.10 mg/kg) and Salix acutifola (25.11 mg/kg). The soil features and phytomass were varied differently across individual sites, representing different stages of succession.

N immobilization treatment revisited: A retarded and temporary effect unfolded in old‐field restoration

AbstractAimThere is increasing recognition that plant–soil feedbacks drive species co‐existence; therefore the below‐ground compartment should be better considered in ecological restoration. Addition of carbon is a restoration measure that relies on indirect plant–soil relationships by immobilizing soil nitrogen in microbial biomass to manipulate competitive hierarchies between plant species. The aim of the present work was to evaluate the impact of six years of carbon amendment in old‐field restoration in the long term, 20 years after the first application.LocationOld‐fields and reference sand steppe on dry calcareous sandy soil in Fülöpháza, Kiskun LTER site (46°53′ N, 19°24′ E), Hungary, Pannonian biogeographic region, Europe.MethodsWe applied carbon amendment in the form of sucrose and sawdust on three abandoned agricultural fields between 1998 and 2003. Vegetation was surveyed in 1998–2006 and re‐sampled in 2008, 2010 and 2018 on permanent 2 m × 2 m coenological relevés for carbon‐amended, control and reference plots (n = 144). We used principal response curves (PRC) to describe vegetation development trajectories and linear mixed‐effects models to test changes in cover of vascular plants and cryptogams, nitrogen requirement groups and restoration species groups with time and treatment.ResultsCarbon amendment resulted in lower soil nitrogen availability, and lower cover of vascular plants and cryptogams compared to control, but these differences became visible only four to five years after the first application and disappeared three years after the cessation of treatment. Minor treatment effects on the cover of oligotrophic, mesotrophic and target species were found.ConclusionsCarbon amendment did not speed up the recovery of sand grasslands; however, the reduction of cover (vegetation and cryptogam) can be a window of opportunity for other species to colonize that can be used as a complement to other treatments. Long‐term monitoring is especially important in evaluating restoration interventions that focus on indirect above‐ground–below‐ground linkages.

Effect of seed storing duration and sowing year on the seedling establishment of grassland species in xeric environments

Theavailability of seeds of native species in many countries for grassland restoration is limited; therefore, ex situ seed banks can gain importance as a source of germplasm in the future. We tested the usability of seed accessions of the Pannon Seed Bank for reintroduction with the aim to restore sandy grassland in Hungary. Seeds of 10 native sandy grassland species were seeded in the year of collection and after one or two years of storage. The establishment was estimated by counting seedlings along seeded transects for two vegetation seasons. This study produced the first numerical estimate we know about of native sand grassland species emergence in the field. A low establishment of the tested species was found, ranging from 0.002 to 8%. Within this range, Dianthus serotinus had the highest establishment, while Festuca vaginata, which was sown as matrix species, performed only medium establishment. The short‐term storage (1 or 2 years) of seeds had no significant effect, except for F. vaginata, where seed storage had a positive effect on reintroduction success. The year of seeding had the highest influence on recruitment. Four species were found to emerge over two years instead of only the first year. Based on our results, the weak seed yield of certain years and the low supply of native seeds in the market can be mitigated by using stored seeds. It is recommended to use multi‐year, scheduled seeding to reduce the negative impacts of particularly dry years and to increase the restoration success.

Survival and regeneration ability of clonal common milkweed (Asclepias syriaca L.) after a single herbicide treatment in natural open sand grasslands

Invasive species are a major threat to biodiversity, human health, and economies worldwide. Clonal growth is a common ability of most invasive plants. The clonal common milkweed Asclepias syriaca L. is the most widespread invasive species in Pannonic sand grasslands. Despite of being an invader in disturbed semi-natural vegetation, this plant prefers agricultural fields or plantations. Herbicide treatment could be one of the most cost-effective and efficient methods for controlling the extended stands of milkweed in both agricultural and protected areas. The invasion of milkweed stand was monitored from 2011 to 2017 in a strictly protected UNESCO biosphere reserve in Hungary, and a single herbicide treatment was applied in May 2014. This single treatment was successful only in a short-term but not in a long-term period, as the number of milkweed shoots decreased following herbicide treatment. The herbicide translocation by rhizomatic roots induced the damage of dormant bud banks. The surviving buds developing shoots, growth of the milkweed stand showed a slow regeneration for a longer-term period. We concluded that the successful control of milkweed after herbicide treatment depends on repeated management of treated areas to suppress further spreading during subsequent seasons.