ABSTRACT Afforestation of formerly open, water‐limited habitats is a globally widespread form of land conversion, driven by the need for timber and non‐timber forest products, and capturing atmospheric carbon. However, increased tree cover can adversely affect hydrological cycles by increasing evapotranspiration and reducing downslope water yield, threatening agricultural production and water‐dependent habitats. Here, we assessed the effect of afforestation with the non‐native Robinia pseudoacacia in dry sandy upland areas of Hungary on the water supply of adjacent wetlands, and experimentally tested whether forest thinning can restore the hydrologic regime. We found that little moisture seeped down to the subsoil of plantations due to increased precipitation interception and transpiration, compared with grassy uplands. The lack of deep infiltration precluded lateral moisture seepage across the upland–wetland ecotone during the growing season. Conversely, we detected no notable interruption of lateral flows from grassy upland areas. Forest thinning (approx. 40% of the basal area) did not meaningfully improve water availability, probably because the effects of lower interception and transpiration were offset by the disruption of the understorey microclimate and the quick recovery of the canopy cover. We conclude that the afforestation of upland areas is an important contributor to wetland loss in the region and partial solutions are of limited effectiveness. We recommend a landscape‐wide reconsideration of forestry strategies on uplands and planning alternative land use types to support soil moisture infiltration. One possible approach is to restore the original open ecosystems, but supporting solar developments in these marginal areas is also a viable option.

The rapid global expansion of ground-mounted photovoltaic solar farms creates a growing land-use conflict between renewable energy production and biodiversity conservation. Ecovoltaics—ecologically informed solar farm design and management—has been proposed as a promising reconciliation, yet empirical evidence remains scarce. We evaluated the success rate of high-diversity grassland restoration in three solar farms in Hungary. In half of each farm, we sowed a 50-species native seed mixture in the gaps between panel rows, and gradually reduced management intensity. The remaining parts of the farms served as conventional management controls; nearby semi-natural grasslands provided reference conditions. Within three years, sown solar farm parts converged toward reference grasslands in plant species richness and cover of grassland specialists, while remaining consistently more diverse than controls. The potential availability of floral resources was substantially higher in sown parts than in the controls and mostly matched that of the references. Pollinator responses were strong and consistent: species richness and abundance of wild bees and hoverflies were higher in sown solar farm parts than in reference grasslands in all years, even after accounting for non-habitat areas under the panels. Control solar farm parts showed intermediate levels. Our findings demonstrate that sowing high-diversity seed mixtures and reducing management intensity can rapidly transform solar farms from biodiversity-poor habitats into flower-rich grasslands that support diverse pollinator communities. Ecovoltaic grassland restoration therefore offers a practical pathway to reconcile renewable energy expansion with biodiversity enhancement within short timeframes.

Hemiparasitic plants are known to be able to diversify degraded grasslands by lowering the competitive power of dominant grasses. Recent research indicates that hemiparasites may also be used against invasive alien plants. Here, we tested the effects of Odontites luteus, a native European hemiparasite, on Sporobolus cryptandrus, a recently established and rapidly spreading C4 grass of North-American origin. We found that Odontites considers Sporobolus a suitable host and reduces its biomass production (and potentially its competitive ability) by approx. 50%, equaling the effect on its major native host, Festuca vaginata. However, Festuca showed severe metabolic impairment (reduced photosynthetic capacity and increased physiological stress) under hemiparasite pressure. So, the application of hemiparasites is a promising biocontrol tool against Sporobolus (and potentially other invasive C4 grasses), but it is not a silver bullet. We cannot expect a full eradication of the invasive species and a recovery of the native community but thinning monodominant Sporobolus stands to allow certain populations of native species, particularly those resistant to Odontites, to come back is a more realistic goal. This could lead to a partial recovery of the former species composition and an improvement of ecosystem functions, such as providing food for pollinators.

Bird communities are facing heavy declines, especially in agricultural landscapes. An exponentially spreading landscape feature, photovoltaic solar farms, may offer an opportunity for their conservation. Compared to croplands and other disturbed areas, solar farms may provide stable food and nesting sources, but also pose challenges due to intensive vegetation management and the presence of artificial structures. We know little about how bird communities respond to these novel habitat characteristics, preventing the formulation of evidence-based guidelines to benefit birds in solar farms. Here, we aimed to unravel drivers of bird community patterns in solar farms embedded in transformed, agricultural landscapes. Using data from 32 farms and surrounding landscapes, we found that birds in the farms form distinct communities compared to the surrounding landscape, and the bigger the farm, the more distinct the community. Indicator species of solar farms include urban and open-habitat species, while forest species only spill over to the farms from adjacent woody habitats. Although some open-habitat species regularly occur in solar farms, those that require a clean skyline avoid the farms. In addition, if better-quality grasslands are available around, open-habitat birds do not enter in higher numbers but tend to lower their preference on the farms. Birds showed seasonal variation in solar farm use; they were more common during the breeding season than in the fall. These findings highlight the potential (e.g., for open-habitat bird conservation) and the limitations (e.g. unfavourable off-season conditions) of solar farms, which we could strategically exploit and should navigate with targeted interventions, respectively.

Microrefugia play a key role in facilitating the persistence of biodiversity during climate change. Many occur in topographically complex landscapes shaped by various disturbances, but we know little about how the combined effects of topography and disturbance affect the capacity of refugia to support biodiversity. To better understand this, we inventoried taxonomic richness across four biological groups (soil microbiota, vascular plants, terrestrial snails, and ants), as well as climatic and soil conditions, in different microhabitats (south-facing slopes, north-facing slopes, and bottoms) of topographic depressions (dolines) and on the surrounding plateaus. Unique species assemblages and cooler, moister microclimatic conditions in dolines supported their importance as biodiversity hotspots and microrefugia. Relationships between indicators of disturbances (anthropogenic: historical logging; natural: canopy gaps) and species richness differed, depending on the biological group and microhabitat. While most biological groups seemingly recovered within 50 years following clear-felling, plants did not, highlighting the persistent impact of anthropogenic disturbances on refugial capacity. Plants were also the only group that displayed a significant response to the presence of small canopy gaps at doline bottoms, which promoted the occurrence of specific plant species. All biological groups displayed some response to microhabitats, although these responses differed among taxa. Therefore, high environmental heterogeneity appears to help facilitate the role of dolines as biodiversity hotspots and microrefugia. We conclude that the direction and magnitude of the effects of disturbances and topography are taxon-specific, due to species-specific responses to microenvironmental conditions. Disturbance history is an important consideration when identifying refugia for climate change management.

Topographic depressions in karst landscapes, called dolines, serve as important microrefugia for biodiversity. However, they may be strongly affected by various anthropogenic disturbances, including forest management, waste dumping, and livestock grazing. Although the effects of grazing on doline vegetation are well documented, far less is known about how grazing intensity influences arthropod communities within these landforms. To study the effects of grazing intensity on arthropods, we applied a multi-taxa approach including spiders (Araneae), true bugs (Hemiptera: Heteroptera), and ants (Hymenoptera: Formicidae) as bioindicators. We selected 18 doline bottoms and their adjacent plateaus in the Aggtelek Karst, Hungary, and sampled them over two consecutive years - with grazing present in one year and excluded in the other, the latter serving as a control. We used structural equation models (SEMs) to assess how habitat type (doline vs. plateau) - which reflects associated differences in microclimate and vegetation characteristics - together with grazing intensity influenced arthropod abundance and diversity. The SEMs showed that in the control year, habitat-related differences between dolines and plateaus were clearly reflected in the diversity patterns of all three arthropod groups, with higher species richness and abundance in dolines. Grazing partially overrode this pattern through both direct and indirect pathways, although the extent and underlying mechanisms differed among taxa. Our results demonstrate that habitat type, vegetation height, and grazing intensity interactively shape arthropod diversity in karst landscapes. Appropriately managed grazing may help maintain the arthropod biodiversity of these microrefugia and should therefore be considered in future conservation planning.

Microrefugia are small areas that allow species to persist in changing environments. Dolines in karst landscapes may function as such safe havens. By analysing vegetation data from 270 plots collected within nine large dolines and on the surrounding plateau in Northern Hungary, we found that topographic complexity in dolines has the potential to support a wide array of plant species with diverse biogeographic affinities. To safeguard the large number of endangered plant species and the high biodiversity associated with dolines, conservation management should take into account the complex interactions among topographic complexity, environmental conditions, and species distributions in karstic microrefugia and their surrounding areas.

Topographic complexity supports the maintenance of a high diversity of microhabitats, which may act as important 'safe havens' - or microrefugia - for biodiversity. Microrefugia are sites with specific environmental conditions that facilitate the persistence of species during environmental changes and exhibit unique ecoevolutionary dynamics. However, our knowledge about how topographic complexity and related ecoevolutionary selective forces influence the functional and phylogenetic signatures of species assemblages in microrefugia is very limited. Although the conceptual framework on the systematic integration of plant functional traits into the study of refugia is well established, more empirical studies on functional trait composition and functional diversity in refugia are urgently needed for more effective conservation. Here we analyzed the distribution of various plant functional traits and phylogenetic patterns in microhabitats (south- and north-facing slopes, and bottoms) of 30 large topographic depressions (i.e. doline microrefugia) and microhabitats of the surrounding plateaus in two distant forested karst regions. We found that plant assemblages in the understory of dolines and their surroundings are characterized by unique functional values and combinations of traits. Doline bottoms had the highest functional diversity among doline microhabitats and supported plant assemblages with considerably different trait compositions from the plateaus. Bottoms also had the highest phylogenetic diversity. These results suggest that topographic complexity in forested dolines has a significant effect on the distribution of plant functional traits in the understory. High functional and phylogenetic diversity in doline bottoms can have important consequences for the long-term survival of plant populations, highlighting that these microhabitats may provide a higher resilience and support an adaptive community-level response to natural and anthropogenic stressors. Understanding mechanisms that drive the survival of species within microrefugia is required to determine the best conservation and management strategies.

Solar energy is the most rapidly growing renewable globally. However, ground-mounted solar panels have a high land requirement, leading to extensive, low-nature-value photovoltaic parks. This may be alleviated by considering ecological aspects during their planning, construction and mainetnance. The resulting ecovoltaic park can bring various benefits for the owners if ecosystem services related to the imporved ecological conditions are recognized and wisely utilized. A major step in developing ecovoltaic parks is the creation of a short but species-rich grassland ecosystem. There is little empirical evidence on how to achieve this; therefore, we set up an experimental sowing experiment in three formerly conventional photovoltaic parks located in the forest-steppe zone of Hungary. From the regional native grassland species pool, we selected short but competitive ones (two graminoids and 50 forbs that are often visited by pollinators), and sowed them in half of the parks (between panel rows) in October, 2022, while the other half was left as control. In 2023, we surveyed the vegetation of the sown and control parts of the parks and adjacent old-growth grasslands (as references), and found that total plant species richness and the species richness of grassland specialists increased compared to the control sites, but remained below the references. In contrast, the cumulative cover of grassland specialist species in the sown sites could reach the references. We also surveyed pollinator assemblages (hoverflies and wild bees), and found higher species richness and Shannon diversity in the sown parts then in the reference grasslands, while control parts of the parks showed intermediate values. This might have been caused by spillover from the sown parts, although flying pollinators might have also taken advantage of the permanent windshade among the panel rows of control parts, despite the low food supply compared to the reference grasslands. Our findings suggest a rapid improvement of plant and pollinator assemblages after sowing native seed mixtures in solar parks. The resulting high-nature-value grassland ecosystem can have many co-benefits for the owners, as (i) it requires lower management intensity due to the short vegetation, (ii) has the potential to offer high-quality forage for livestock or honey-bees, and (iii) lowers the widespread “not-in-my-backyard” syndrome of local inhabitants due to its attractive, flower-rich appearance.

Due to their heterogeneous landscape structure, extensively managed temperate silvopastoral systems provide multiple ecosystem services such as climate-resilient livestock production and carbon sequestration. Main habitat types within these landscapes (open pastures, solitary trees, shrubby patches, and adjacent second-growth forests) form an interconnected dynamic network with state transitions driven by secondary succession (towards woody states) and disturbance (towards open states), and the balance between the drivers is key to preserve their exceptionally rich herbaceous flora. To understand how soil seed bank may contribute to the dynamics of the herb layer in silvopastoral systems, we assessed its composition and richness in the above-mentioned habitats and compared these to the herb layer using non-metric multidimensional scaling, generalized linear mixed-effects models and indicator species analyses. We found that each habitat showed distinct compositional patterns, explained by strong environmental filters. Conversely, soil seed bank was more similar among habitats due to legacy seeds from previous vegetation states. This ecological memory in a particular location may assist future compositional transitions of the herb layer by reducing dispersal limitation and can be a useful asset in ecosystem restoration. Furthermore, our study showed that solitary trees with grassy or shrubby undergrowth have key roles in the herb layer dynamics of silvopastoral systems by being the main locations of soil seed bank build-up and transitional hotspots of herb layer diversity during early forest succession. Therefore, conservation strategies should pay extra attention to these small but important landscape features.

Anthropogenic biodiversity decline threatens the functioning of ecosystems and the many benefits they provide to humanity1. As well as causing species losses in directly affected locations, human influence might also reduce biodiversity in relatively unmodified vegetation if far-reaching anthropogenic effects trigger local extinctions and hinder recolonization. Here we show that local plant diversity is globally negatively related to the level of anthropogenic activity in the surrounding region. Impoverishment of natural vegetation was evident only when we considered community completeness: the proportion of all suitable species in the region that are present at a site. To estimate community completeness, we compared the number of recorded species with the dark diversity-ecologically suitable species that are absent from a site but present in the surrounding region2. In the sampled regions with a minimal human footprint index, an average of 35% of suitable plant species were present locally, compared with less than 20% in highly affected regions. Besides having the potential to uncover overlooked threats to biodiversity, dark diversity also provides guidance for nature conservation. Species in the dark diversity remain regionally present, and their local populations might be restored through measures that improve connectivity between natural vegetation fragments and reduce threats to population persistence.

Rapid urban growth leads to an extension of artificial surfaces and inefficient energy management, an increase in urban heat islands, and local climate change. This has increased the need for green infrastructure and urban trees are playing an important role. It is important to ensure that tree groups can withstand climate warming and disturbances. This study investigated the physiological parameters of Tilia tomentosa ‘Seleste’ trees situated in a medium-sized Hungarian city, examining their relationship with microclimatic differences observed on opposing sides of a street. Instruments placed on 10 trees recorded air temperature and humidity, revealing a significant difference in total insolation, which resulted in higher maximum daily temperatures on the sunny side. These microclimatic variations were found to significantly affect physiological attributes, particularly pigment content. Trees on the sunny side exhibited a higher relative water content and a higher ratio of chlorophyll a/b, indicative of light acclimatisation. Trees on the sunny side exhibited a higher relative water content and a higher ratio of chlorophyll a/b, indicating an acclimatisation to light. Furthermore, a positive correlation was observed between pigment content, total insolation, and growing degree days. The findings demonstrate how fine-scale microclimate differences influence tree physiology, providing crucial physiological indicators that inform the capacity of urban trees to provide vital ecosystem services, such as local climate regulation. This emphasises the importance of climate-conscious urban planning, as even small-scale climate change can have a broader impact.

Topographic complexity creates fine-scale variability in microclimatic conditions and supports biodiversity in forests. While much is known about the effects of various levels of natural and anthropogenic disturbances on forest biodiversity, less is understood about how small changes in canopy structure (e.g., canopy gaps) influence certain environmental conditions and biodiversity components at different topographic positions. In this study, we compared the environmental factors, trait composition, as well as species and functional diversity of understorey plant communities in habitats of topographic depressions (i.e., dolines) and the surrounding plateaus. The habitat types were as follows: doline bottoms with closed canopies, doline bottoms with a small canopy gap, plateaus with closed canopies, and plateaus with a small canopy gap. We used both species-based and functional trait-based approaches. Our findings indicate that topographic complexity and the presence of small canopy gaps play a significant role in driving vegetation dynamics and functionality, thus supporting taxonomic and functional diversity in dolines and their surroundings. Small canopy gaps in doline bottoms increased the refugial capacity of this habitat and maintained species and functional traits that were less frequent in the other habitats. On the plateaus, small canopy gaps played a key role in the recruitment of the climate-change-vulnerable tree species Fagus sylvatica. Therefore, creating small canopy gaps in different habitats within topographically complex landscapes may support forest biodiversity by enhancing the capacity of these habitats to serve as ‘safe havens’ during periods of anthropogenic climate change.

Complex landscapes (i.e., those harboring multiple habitat types at immediate spatial proximity) are highly relevant to both applied and theoretical ecological research, yet the mechanisms shaping functional trait distributions and diversity metrics across trophic levels in these systems remain poorly understood. To address this knowledge gap, we used wood-pastures as a model system and focused on two prominent groups occupying different trophic levels: plants and ants. We sampled three Central-European wood-pastures, with all four encompassed habitat types (grasslands, solitary trees, forest edges, and forests; 48 sites in total). Our results revealed significant differences in taxonomic and functional composition for both groups among the different habitat types of wood-pastures. However, the underlying mechanisms driving these patterns differed between plants and ants. Based on RLQ and fourth-corner analyses, heterogeneity in environmental conditions mainly influenced plant functional trait distributions. In contrast, ant diversity metrics and trait distributions were strongly linked to vegetation characteristics and habitat structure, and were only indirectly influenced by local microclimate, as shown by path analyses. These highlight that while mapping the increased environmental heterogeneity of complex landscapes, the main mechanisms shaping functional composition and diversity metrics might differ for organisms at different trophic levels (i.e., predominantly environmental filtering for plants and interspecific competition for ants). Consequently, the patterns and peaks of taxonomic and functional diversity do not necessarily coincide for different organisms in complex landscapes, emphasizing that conservation initiatives should focus on the system as a whole, rather than individual habitat types, to maximize biodiversity conservation.

Ecosystem restoration is increasingly recognized as a means of climate change mitigation. Recent global-scale studies have suggested that ecosystem restoration could offset a substantial fraction of human carbon emissions since the Industrial Revolution. However, global carbon sequestration potential remains uncertain due to the tree-centric view of some models and difficulties in modelling restoration across different ecosystem types. Here we applied a model-based prediction workflow to estimate the carbon capture potential of restoring forest, shrubland, grassland and wetland ecosystems until 2100. We found that the maximum sequestration potential is 96.9 Gt of carbon, equivalent to 17.6

This study aimed to examine the vertical stratification of the soil seed bank in wet grasslands, with a special emphasis on seeds in deeper soil layers that are generally not considered in seed bank studies. We studied the soil seed bank at four depths: 0–10 cm, 10–30 cm, 30–50 cm, 50–70 cm in five study sites in Central Hungary. The seedling emergence method was used to detect viable seeds. The relationship between the vertical stratification of the seed bank and species traits was studied using generalized linear mixed models. We also sampled the aboveground vegetation and applied non-metric multidimensional scaling to evaluate the species composition of the seed bank and vegetation. The species richness and the seed density of different layers were significantly different; both decreasing with increasing depth. Although most viable seeds were found in 0–10 cm depth (22,632 seeds/m2), an unexpected large number of seeds germinated also from the deepest soil layer (50–70 cm; 4170 seeds/m2). Species without morphological specializations for spatial seed dispersal (i.e., Allium dispersal type), lower water requirements, and heavier seeds occurred in great abundance in the deeper soil layers. The dominance of species without specialized spatial dispersal suggests that they invest more in temporal dispersal by the soil seed bank. Forbs and perennial species dominated both the seed bank and the aboveground vegetation; however, the dominant species in the seed bank did not correspond to the dominant species in the aboveground vegetation. Our results suggest that the seed bank of wet grasslands does not contain the full habitat-specific species pool despite its high seed density and species richness. The restoration of the studied wet grasslands cannot rely solely on the local seed banks.

Aims: Ecological strategies can provide information about plant community assembly and its main drivers. Our aim was to reveal the dominant strategies of the vegetation types of forest-grassland mosaics and to deduce the assembly processes responsible for their species composition.LocationHungary.Methods: We investigated eight vegetation types of Hungarian forest-steppes. The trade-off between three key traits related to leaf size and economics was used to calculate Grime's competitive-stress tolerance-ruderal (CSR) value for each species, based on which the mean value for each vegetation type was determined. Detrended correspondence analysis (DCA) ordination was used to reveal the compositional differences among the vegetation types under study. To analyze how ecological strategies correlate with the compositional gradient, we used linear regression between plot ordination scores (the first DCA scores) and each strategy (C, S, and R). Linear mixed-effect models were used to evaluate the differences between the vegetation types regarding each strategy (C, S, and R).Results: Each vegetation type was dominated by the stress-tolerator strategy, indicating the prominent role of environmental filtering in community assembly. However, ecological strategies differed significantly among the communities. The importance of the stress-tolerator strategy decreased toward the less harsh end of the gradient (i.e., from grasslands to forests), while the competitor strategy showed a reverse pattern. The ruderal strategy was weakly correlated with the gradient, although its proportion increased toward the harsh end of the gradient.Conclusions: With ongoing climate change, an increasing importance of environmental filtering is expected in the assembly of the vegetation types in the studied forest-grassland mosaics. We suggest that CSR strategies offer a useful tool for studying plant-community assembly rules along environmental gradients.

Common milkweed (Asclepias syriaca L.) is a widespread invasive alien forb in dry sandy habitats of Central Europe. It adversely affects native plant and animal communities, but its ecosystem-level effects, particularly on hydrology, are little known. Since milkweed has an extensive, deep root system and large, broad leaves, we assumed a negative effect on the soil moisture content of the hosting ecosystem. Following the before-after control-impact protocol, we first compared the soil moisture content of the top 120 cm of the soil under seven milkweed stands to that of non-invaded reference sites. We then treated half of the stands by mechanically removing all aboveground milkweed biomass and repeated the comparative soil moisture measurements. We found that milkweed stands had significantly drier soils than reference grasslands during the growing season, but the soil under milkweed stands recharged to the level of the references in autumn and winter. However, the amount of moisture needed for this recharge was lost from deeper percolation to groundwater. Milkweed treatment prevented the depletion of moisture during the growing season, saving 21.6 l m−2 of water on average. Treatment did not affect non-milkweed plant biomass, thus, moisture patterns could fully be attributed to the milkweed stands. Our results reinforce the importance of milkweed suppression in invaded grasslands, as, besides enabling the recovery of the native grassland ecosystem, it promotes groundwater recharge, which is particularly important in the dry regions of Central Europe, currently facing severe aridification due to climate change and unfavourable land use trends.