Mown Grassland Research Articles

Restored legume acts as a “nurse” to facilitate plant compensatory growth and biomass production in mown grasslands

Restored legume acts as a “nurse” to facilitate plant compensatory growth and biomass production in mown grasslands

Testing of UV fluorescence marking with daily recaptures of a low-mobile bush-cricket species

The primary goal of developing new mark–release–recapture (MRR) methods is to make MMR more cost-effective and able to provide more information. To test the effectiveness of UV fluorescence marking, a case study was carried out on an Isophya costata population occurring in a mown grassland with a heterogeneous vegetation pattern. The marked individuals were examined daily, from the emergence of imagos until the mowing of the habitat. The 40 marked insects (20 males and 20 females) were recaptured in 206 cases over 16 days (32.2% of the potential maximal recaptures). The finding of males was 26.2% successful, and the finding of females was 38.1% successful. Females released in shorter and sparse vegetation were recaptured more than those released in dense vegetation or than males. Recaptures showed a significant decrease during the study period in almost all groups based on Mann–Kendall trend tests. Detections were made on the upper third of the vertical structure of the vegetation in 88% of cases. In most of the detections (males: 70%, females: 62%), the axis of the insect’s body was more likely to be located vertically. The results showed that the chance of detection is significantly reduced when the position of the insect’s body is facing the axis of UV illumination. Thus, the visibility of individuals can be greatly increased by marking all sides of the body.

Effect of mowing versus abandonment of mesic grasslands in Central Europe on biomass use for biogas production: Implications for semi-natural ecosystem conservation

The economic management of lignocellulosic biomass from semi-natural grasslands is now a challenge across Europe. The abandonment of mowing these grasslands leads to the gradual degradation of these ecosystems. This study investigates how chemical and biological factors affect the suitability of biomass from abandoned grasslands for biogas production. We sampled 30 mown and 30 abandoned grassland sites in the Sudetes Mountains (Poland and Czechia). The cover contribution of short herbs was found to be significantly higher in mown grasslands (p < 0.001), while that of tall herbs was more prevalent in abandoned grasslands (p < 0.01). The specific biogas yield (SBY, NL kg−1 volatile solids) is negatively affected by an increased percentage of herbs in the biomass of mown and abandoned grasslands. This is due to the inhibitory effect of herbs on biodegradation, the increase in lignin content and the decrease in cellulose. This study highlights the importance of individual plant species in assessing grassland biomass for area biogas yield (ABY, m3 ha−1) and provides new insights into a field that has not yet been extensively investigated. In mown grasslands, ABY was most positively correlated with grass species (Arrhenatherum elatius, Trisetum flavescens and Festuca pratensis). In abandoned grasslands, the ABY was most correlated with herbaceous species (Galium aparine, Urtica dioica and Chaerophyllum aromaticum) and grasses (A. elatius and Elymus repens). Mown grasslands had significantly higher species richness (p < 0.001) compared to abandoned grasslands, but the number of species sampled did not correlate with SBY and ABY. This study contributes to the development of a sustainable bio-economy by highlighting the need for efficient use of grassland biomass. This approach helps protect semi-natural ecosystems and facilitates sustainable management of renewable resources.

Soil and Vegetation Characteristics of Grassland have a Greater Influence on the Abundance and Diversity of Earthworms than the Mowing Intensity in a Managed Nature Reserve

Effects of mowing on vegetation parameters have been well studied. However, less is known about mowing effects on soil fauna and if soil properties alter this. We investigated earthworm communities in a long-term experiment 14 years after its establishment in 5 dry, fresh and moist grassland plots located in the Natura 2000 site Lainzer Tiergarten near Vienna, Austria (238–402 m a.s.l., 48°10′ N, 16°12′ E). The grasslands were either mowed once a year or every second year, or not mowed since being established. Earthworms were assessed using the non-destructive octet electro-shocking method. Additionally, vegetation composition, soil conductivity, temperature and moisture were assessed. We found 13 earthworm species across all treatments, although their abundance was generally low with 6.1 ± 4.7 worms m−2. The total earthworm abundance and species diversity was higher in dry compared to fresh and moist grasslands but was not affected by mowing frequency. Endogeic earthworms (Aporrectodea caliginosa, Aporrectodea rosea) and epigeics (Lumbricus rubellus) were more tolerant to mowing than anecics (Lumbricus terrestris, Allolobophora longa). Since plant species richness was highest in annually mown grasslands and earthworm species richness was positively related to plant species numbers, we recommend regular, low-input management to promote above- and belowground biodiversity in these grasslands.

Independent biodiversity mechanisms regulate ecosystem multifunctionality and its temporal stability under resource enrichment in a mown grassland

AbstractQuestionsAlthough the relationships between biodiversity and individual ecosystem functions under resource enrichment have been extensively studied, there is limited understanding of how resource‐induced changes affect ecosystem multifunctionality and its temporal stability, along with the underlying biological mechanisms.LocationInner Mongolia, China.MethodsWe investigated the impact of biodiversity mechanisms on ecosystem multifunctionality and its temporal stability through a 3‐year field experiment. This experiment involved augmenting growing season precipitation and nitrogen deposition, conducted in a typical steppe ecosystem of Inner Mongolia alongside regular mowing.ResultsOur findings revealed that the addition of water (W) and nitrogen (N) had varying effects on ecosystem multifunctionality and its temporal stability. The combination of N and W additions enhanced ecosystem multifunctionality, whereas both W and N + W additions promoted the temporal stability of ecosystem multifunctionality. Structural equation modeling demonstrated that the community‐weighted mean height, in response to nitrogen addition, played a key role in enhancing ecosystem multifunctionality. By contrast, increased species asynchrony because of water addition and greater functional diversity in terms of leaf area contributed to heightened temporal stability of ecosystem multifunctionality. Furthermore, the positive effects of community‐weighted mean height on ecosystem multifunctionality exhibited a gradual increase with rising threshold levels.ConclusionsOur study provides the first evidence of the independent effects of selection, exemplified by community‐weighted mean and complementarity, represented by factors such as species richness, functional diversity and species asynchrony on both ecosystem multifunctionality and its temporal stability. This underscores how global change factors can directly influence ecosystem multifunctionality and its temporal stability while also indirectly modulating biodiversity effects in the short term. Overall, our findings underscore the vital role of biodiversity conservation in enhancing grassland management and the delivery of ecosystem services in the context of global change, particularly in regions subject to extensive mowing.

Both management practices and landscape influence plant communities in urban grasslands

The development of urban areas now requires the integration of biodiversity issues, and this leads to better consideration of their seminatural habitats. Among these habitats, urban grasslands subjected to mowing management practices are commonly promoted over lawns to enhance biodiversity in cities. Despite their ecological value, relatively little attention has been paid to the effects of urban grassland management regimes or the landscape contexts of these habitats in terms of biodiversity. This study aims to investigate the effects of mowing practices and the landscape context of urban grasslands on species diversity and composition and the ecological strategies of plant communities. In this study, 66 sites (mown grasslands) were selected in the Angers and Rennes conurbations of western France according to their management practices (regarding mowing) and landscape gradient (more or less urbanized). The results show that mowing practices and landscape composition did not affect the richness or diversity of plant species but significantly influenced the composition of communities. Partitioning analysis showed that landscape composition explained twice as much of the variance in plant species composition as mowing practices did. Landscape composition favors plant species according to their strategies, preferential habitats, and life spans. Furthermore, diversification of management practices limits the establishment of nonnative species and induces a wider range of functional strategies, as late mowing favors competitors and disfavors stress-tolerant species. Nevertheless, management practices need to be put into perspective in the context of urban grasslands. Thus, this research brings new perspectives to recommendations for the management of urban green spaces.

Differences in grassland sward biodiversity and management regime lead to mixed effects on ecosystem services

Species rich grasslands provide ecosystem services such as floral and faunal diversity, livestock forage, carbon sequestration and water regulation. However, the best combinations of sward diversity and management intensity to achieve the above-mentioned ecosystem services are not fully known. To address this, we established experimental grasslands with three sward types with varying diversity levels: productive monoculture (PM; perennial ryegrass (Lolium perenne)), biodiverse (BD) and productive biodiverse (PBD; i.e., diverse sward with species selected to increase forage quantity and quality) and with a management gradient ranging from extensive (i.e., low input, late mowing) to intensive (i.e., high input, early mowing). After three years, we found successful establishment of biodiverse swards with high forb cover, particularly under extensive management, but changes to meadow bird habitat parameters (i.e., sward height and vertical vegetation density) were negative. Forage dry matter yield was highest in BD and intensively managed swards in 2019 and 2020, but intensively managed swards had higher dry matter yield regardless of sward type in 2020. Forage N concentration was highest in PBD swards and digestible organic matter was highest in PM and PBD swards, indicating the productive plants species added to the PBD swards improved forage quality. Improvements in carbon sequestration and water regulation were minimal. Collectively, diverse swards, different management regimes and their interactions benefit certain ecosystem services, but not all. Taken together, these findings pull focus on the need for careful consideration of sward species composition, management and their interactions in order to maximise specific ecosystem services in young, mown grasslands.

Grassland cut detection based on Sentinel-2 time series to respond to the environmental and technical challenges of the Austrian fodder production for livestock feeding

The relationship between yield and quality of grassland fodder is an important factor for livestock farmers to consider when deciding the timing of grassland cuts. Even for experienced farmers, estimating this relationship is difficult because external factors such as weather can affect the growth rate of plants. Satellite remote sensing techniques have good potential for the modelling of fodder biomass and quality. However, more accurate grassland cut dates are needed. Unfortunately, current cut detection methods vary in both form, function and accuracy and a common framework for cut detection does not yet exist, especially for in-season cut estimation. The aim of this study is to develop an improved methodology for Austrian fodder production systems that can be used for both post-season and in-season cut detection. In the first case, cuts are detected at the end of the vegetation period and used for post-season assessment at national and regional levels. In the second case, cuts are detected in near-real-time during the season, and they can be used to model yield and quality. The approach is tested across the Austrian landscape on mown grasslands using freely available Copernicus Sentinel-2 imagery on the Google Earth Engine (GEE). The method uses a fitted NDVI curve obtained by iteratively smoothing the upper envelope of the actual observations using the Whittaker smoother. Cuts are detected by meeting a threshold in the difference between the fitted NDVI curve and the actual observed NDVI values. Additional innovative steps were developed to reduce the impact of cloud cover on the results for timely and accurate cut detection, including a gradient boosting algorithm to detect false positive cuts due to missed clouds. A set of rules for the method was trained on 97 plots and validated on a further 502 plots over three years (2020, 2021 and 2022). The method performed well in plots with two to four cuts per season, but occasionally struggled in more intensively managed systems, most likely due to a rule preventing two cuts within 27 days. A pooled post-season cut date detection f-score of 0.79 suggests that the method can accurately detect cuts, with absolute detection errors of <5 days. The main misclassifications were the results of (thin and semi-transparent) clouds being erroneously detected as cuts. With an f-score of 0.80 and total absolute delayed detection of approximately 6 days, the in-season cut date detection performs similarly to the post-season configuration. This indicates a high potential for near-real-time applications. Our results moreover indicate a general improvement of existing methodologies despite performing the cut detection across the fragmented, mountainous and diverse Austrian landscape. Future work will include grazed pastures and natural grassland with less intensive human activity.

Improved soil surface nitrogen balance method for assessing nutrient use efficiency and potential environmental impacts within an alpine meadow dominated region

The soil surface nitrogen balance (SSNB) method is commonly used to assess the nutrient use efficiency (NUE) of agricultural systems and any associated potential environmental impacts. However, the nitrogen flow of wide natural grasslands and other natural areas differ from that of artificial croplands and mown grasslands. In this study, we integrated root growth and the important nutrient resorption process into the SSNB model and used the improved model to clarify the nitrogen (N) flow and balance in the Three Rivers Headwater Region (TRHR)—an area dominated by alpine meadows—from 2012–2019. In the grassland system, the N surplus (ΔN) was 0.274 g m−2 year−1, and root return (BLD) dominated the N input, accounting for 67% of the total input (3.924 g m−2 year−1). N resorption was the main internal N flow in the grassland system (1.079 g m−2 year−1), and 30% of grassland uptake (NUP−grass). The ΔN of the agricultural system was 1.097 g m−2 year−1, which was four times that of the grassland, and chemical fertilizer was the largest input, accounting for 84% of the total input. The NUE in grassland was 93%, which suggests a risk of soil mining and degradation, while that of cropland was 76% and within an ideal range. The ΔN provides a robust measure of river N export, the TRHR was divided into three catchments, and the export coefficient was 16.14%–55.68%. The results of this study show that the improved SSNB model can be applied to a wide range of natural grasslands that have high root biomass and resorption characteristics.

Effects of Grazing Sheep and Mowing on Grassland Vegetation Community and Soil Microbial Activity under Different Levels of Nitrogen Deposition

Increasing nitrogen deposition plays a critical role in the material circulation of grassland. Mowing and grazing sheep are important means of utilizing grassland. This study investigated the effects of nitrogen deposition, sheep grazing and mowing on the soil, vegetation and soil microorganisms of grassland. N deposition increased soil inorganic nitrogen, SOM and microbial activity, and decreased soil pH, while grazing sheep and mowing had opposing effects. Compared with mowing, grazing sheep decreased the range of grass groups in the community. N deposition increased the proportion of Leymus chinensis in the community and decreased community diversity. N deposition enhanced the contribution rate of soil to the vegetation community, and reduced the effect of microorganisms on the vegetation community. In addition, N deposition significantly interacted with mowing and grazing sheep in terms of effects on soil inorganic nitrogen, soil organic matter (SOM), microbial respiration (Q), microbial mass carbon (MBC), and vegetation diversity. Therefore, appropriate N deposition in sheep grazing and mown grasslands could enhance inorganic N and organic matter, increase microbial activity, offset the adverse effects of grazing sheep and mowing, and contribute to maintaining community diversity and grassland productivity.

Impact of mowing frequency and temperature on the production of temperate grasslands: explanations received by an individual‐based model

Grasslands represent an important ecosystem type as they provide numerous ecosystem services. Field studies have shown that temperate grasslands with high diversity can be highly productive. Management and changing environmental conditions can impact the diversity–production relationship. However, the specific mechanisms and role of biodiversity, environmental factors or anthropogenic interventions that lead to changes in production are not well understood. Here, we used the individual‐based grassland model GRASSMIND parameterized for a field biodiversity experiment to analyze changes in the diversity–production relationship when varying the mowing frequency and increasing air temperature. Our results revealed that the positive diversity–production relationship persists with varied mowing frequency and temperature increase, with an increased proportion of herbs in more frequently mown grasslands (from 78% to 85%). Using the model, we further investigated quantitatively how different processes (e.g. plant shading) affect grassland dynamics and production under varied mowing frequencies and air temperature. Although aboveground net primary production (ANPP) decreased in more frequently mown grasslands (20% less ANPP), biomass yields increased due to an even stronger decrease in space‐dependent plant mortality (30% less crowding). Plant mortality (intrinsic and by crowding) caused more biomass losses than caused by shading between plants or by a reduced production due to temperature increase. This study revealed how models, complementary to field experiments, can be used to analyze and quantify the importance of mechanisms and the role of environmental factors in grassland dynamics.

Mapping grassland mowing events across Germany based on combined Sentinel-2 and Landsat 8 time series

Spatially explicit knowledge on grassland extent and management is critical to understand and monitor the impact of grassland use intensity on ecosystem services and biodiversity. While regional studies allow detailed insights into land use and ecosystem service interactions, information on a national scale can aid biodiversity assessments. However, for most European countries this information is not yet widely available. We used an analysis-ready-data cube that contains dense time series of co-registered Sentinel-2 and Landsat 8 data, covering the extent of Germany. We propose an algorithm that detects mowing events in the time series based on residuals from an assumed undisturbed phenology, as an indicator of grassland use intensity. A self-adaptive ruleset enabled to account for regional variations in land surface phenology and non-stationary time series on a pixel-basis. We mapped mowing events for the years from 2017 to 2020 for permanent grassland areas in Germany. The results were validated on a pixel level in four of the main natural regions in Germany based on reported mowing events for a total of 92 (2018) and 78 (2019) grassland parcels. Results for 2020 were evaluated with combined time series of Landsat, Sentinel-2 and PlanetScope data. The mean absolute percentage error between detected and reported mowing events was on average 40% (2018), 36% (2019) and 35% (2020). Mowing events were on average detected 11 days (2018), 7 days (2019) and 6 days (2020) after the reported mowing. Performance measures varied between the different regions of Germany, and lower accuracies were found in areas that are revisited less frequently by Sentinel-2. Thus, we assessed the influence of data availability and found that the detection of mowing events was less influenced by data availability when at least 16 cloud-free observations were available in the grassland season. Still, the distribution of available observations throughout the season appeared to be critical. On a national scale our results revealed overall higher shares of less intensively mown grasslands and smaller shares of highly intensively managed grasslands. Hotspots of the latter were identified in the alpine foreland in Southern Germany as well as in the lowlands in the Northwest of Germany. While these patterns were stable throughout the years, the results revealed a tendency to lower management intensity in the extremely dry year 2018. Our results emphasize the ability of the approach to map the intensity of grassland management throughout large areas despite variations in data availability and environmental conditions.

Microarthropod communities and their ecosystem services restore when permanent grassland with mowing or low-intensity grazing is installed

The current focus on intensification and maximizing productivity in agriculture can endanger soil biota and the ecosystem services they provide in such a way that it acts counterproductive and increases the dependence on external inputs. In this study, we aimed to identify the factors that are most limiting for the restoration of soil biota and their ecosystem services on sandy soils. To this end, we assessed microarthropod communities, their relationship with the aboveground food web and their effect on organic matter decomposition, in two land-use types: grasslands with agricultural land use and grasslands with nature land use. The latter are grasslands converted from agricultural land use, for the development of the Dutch National Ecological Network. For these land-use types, we took into account two main factors of disturbance: the number of years since the last tillage (i.e., plowing event), and the current grassland management (mowing or grazing). We found that the diversity of microarthropods was higher in nature grasslands than in agricultural grasslands. The abundance of microarthropods increased with time since last tillage for grasslands that were mown, but not for grasslands that were grazed. An agricultural grassland without tillage since 39 years had a microarthropod abundance similar to reference natural grasslands reported in previous research. The number of predatory beetles increased with a higher microarthropod abundance in mown grasslands, but not so in grazed grasslands. The number of fungivorous and herbofungivorous grazer microarthropods positively influenced the decomposition of soil organic matter as measured with the Tea Bag Index. Furthermore, we found a negative effect of Difenyl and total fungicide concentrations in the soil on (herbo)fungivorous grazers. Contrary to our expectations, we found more pesticide residues in nature grasslands than in agricultural grasslands. In conclusion, to restore the soil microarthropods and the ecosystem services they contribute to, the best practice is to strive for permanent grassland (without tillage) with mowing or low-intensity grazing (without compaction of the topsoil).

Glucose amendment influences restructuring of compacted soil blocks – Results of a field experiment with varying soil-site conditions

Man-induced soil compaction is a widespread problem for soil fertility and soil usability. Negative consequences may persist for a long time. However, the burrowing activity of soil fauna (pore creation) and growth of plant roots as well as swelling and shrinking can loosen compacted soil over time. This study was focused on the question if an increased energy supply can promote the soil-loosening action of soil biota in compacted soil. We conducted an experiment where compacted soil blocks of two different substrates (different pH) with and without addition of glucose (as energy supply) were exposed to sites with contrasting potentials for restructuring (mown grassland and acidic spruce plantation). Glucose addition stimulated the burrowing activity of soil fauna in compacted soil blocks. Synergism between earthworms and plant root growth had the strongest effect on soil loosening. The site conditions (notably pore-creating biological activity) and the soil acidity of the compacted soil play a key role for the structural recovery. In soil blocks without earthworm activity glucose amendment inhibited rooting by plants, most likely because microbial metabolism led to oxygen deficit in the compacted soil block.

Grassland management and land use history shape species composition and diversity in Transylvanian semi‐natural grasslands

AbstractAimsSemi‐natural grasslands are among the most biodiverse habitats in Europe, and they are of great conservation and agricultural value. However, changes in land use like grazing intensification and the cessation of traditional management have dramatic effects on the extent and biodiversity of these ecosystems. In this study we investigated how current management practices and land use history shape species composition and diversity patterns in semi‐natural grasslands of the Eastern hills of the Cluj region.LocationEastern hills of Cluj (“Dealurile Clujului de Est” ‐ ROSCI0295) Natura 2000 conservation site and close surroundings, Transylvania, Romania.MethodsWe surveyed plots in extensively and intensively grazed grasslands, grasslands mown by hand or heavy machinery, and abandoned grasslands. To quantify grassland continuity, we analysed a series of historical cadastral and more current maps ranging from the 18th to the 21st century.ResultsSpecies composition was significantly influenced by current management, grassland continuity and environmental factors. Mown and extensively grazed grasslands had more grassland and forest edge specialists than abandoned and intensively grazed grasslands. In addition, there was a positive relationship between the number of grassland specialists, forest edge species and grassland continuity, while the number of ruderal species related negatively to grassland continuity. The highest diversity values were recorded in traditionally mown grasslands. However, diversity‐related variables were poorly reflected by grassland continuity.ConclusionsThis study provides evidence that short‐term abandonment may not be as detrimental for grasslands as often suggested, and intensive grazing results in the greatest loss in species diversity. Grassland continuity tightly influences the persistence of grassland specialist species. Thus, we recommend land use history to be included in the selection and identification of high‐nature‐value grasslands by prioritizing conservation efforts for older grasslands.

Grazing by wild red deer maintains characteristic vegetation of semi‐natural open habitats: Evidence from a three‐year exclusion experiment

AbstractQuestionsConservation management of semi‐natural open habitats today has to compensate for the decline of traditional practices of agricultural land use. Can wild and free‐ranging ungulates, such as red deer, contribute to the preservation of characteristic open habitat plant communities?LocationGrafenwöhr military training area, Germany.MethodsWe set up a grazing exclusion experiment in grasslands (lowland hay meadows) and heathlands (European dry heaths) and monitored structural vegetation characteristics (sward height, bare soil, biomass contribution of Calluna vulgaris, litter height, woody species individuals) in open and fenced plots within a three‐year study period. We compared plant species richness, diversity and community composition before and after the experimental period.ResultsIn grasslands, plant species diversity was significantly reduced in fenced compared to open plots and in both habitat types, plant community composition responded to the exclusion of red deer. When fences prevented red deer grazing, increasing height of sward and litter in both habitat types as well as reduced cover of bare soil and increasing number of woody plant individuals in heathlands indicated beginning succession. In annually mown grasslands, where the regrowth provides attractive forage for red deer, the differences between open and fenced plots were most pronounced.ConclusionsOverall, our results indicate that the conservation value of the studied open habitat types started to decrease after red deer exclusion. Grazing by wild red deer can hence provide benefits to vegetation structure and diversity and could therefore enrich the set of tools available for the conservation management of semi‐natural open vegetation types.

Spatial convergence of meadow passerine territory distribution with mowing delay: an experiment in lowland grasslands

We experimentally tested the idea that meadow passerines could tend to match grassland areas consistently managed for enhancing their reproductive success. In the Saone valley (eastern France), mowing was postponed until after July 15 in stable parts (meadows with controlled mowing MCM) of three study sites for 10 years. Bird territories were defined each year with the Territory Mapping method and hatching chronology was described after a systematic survey of prey carrying by adults. We arbitrarily considered that breeding was at the utmost risk of failure when at least two thirds of a territory area was mown earlier than the hatching date + 20 days. In study site 1 where mowing outside MCM was completed by July 15, the proportion of passerine territories within MCM increased throughout the study period from 15 to 60%, whereas MCM was only 29.1% of the total area. Meanwhile, the rate of theoretical failure due to mowers dropped to ca. 20%. In the two other study sites where significant surface areas outside MCM were still not mown by July 15, territorial birds tended to avoid the earliest mown grasslands: the theoretical risk of failure by mowers was usually ≤ 10% in site 2 where 74% of total area on average was mown after July 15, < 20% after 2014 in site 3 with 53% of the total area mown after July 15. Passerine density increased above 10 territories/10 ha in each study site after MCM implementation.

The Effect of Organic Mulching and Irrigation on the Weed Species Composition and the Soil Weed Seed Bank of Tomato.

Mulching is a management technique to control weeds in organic and integrated tomato production. Our experiment was designed to investigate the impact of organic mulch combined with irrigation on the weed species composition and weed seed bank of open-field tomato. For three consecutive years (2016–2018), treatment of microplots included mulch only, irrigation only, mulch and irrigation combined, and the untreated control. Marginal microplots (bordered by the surrounding mown grassland) were distinguished from inner microplots to check margin effect. We collected soil samples from different depths and let the weed seeds germinate in a greenhouse. Germinated weed seedlings were counted and identified. The number of weeds, and time needed for weeding was reduced by mulching, temperature, sampling date, and the succession of the study years. Irrigation, on the other hand, had no effect on weeding time. Margin effect and year had the highest influence on weed species composition. Regarding seed bank, year and mulching had the highest influence. The importance of other variables remained low, with mulching being the strongest explained variable. Regardless of treatments, weed composition of the study area was transformed during the three-year study.

Soil moisture and a legacy of prehistoric human activities have contributed to the extraordinary plant species diversity of grasslands in the White Carpathians

The factors that determine the unique species richness and composition of some temperate grasslands are poorly known. Uniqueness of the extraordinarily species-rich grasslands in the White Carpathian mountain range (Czech Republic, Slovakia), with many disjunct occurrences of species, have been previously attributed to intermittently wet deep soils, which facilitate the co-occurrence of steppe and wet-grassland species, and Holocene continuity of open land, resulted in large species pools. Based on a detailed investigation of 23 well-preserved regularly mown grasslands differing in their vegetation composition and species richness, we tested the relative importance of the hypothetical determinants of compositional variability within semi-dry grasslands. For the first time we included measurements of seasonal moisture at different soil depths and landscape differences in the intensity of the effect of prehistoric humans. Soil moisture was measured using the frequency-domain reflectometry based Profile Probe PR2 sensor at depths of 10, 20, 30, 40 and 60 cm in the soil, repeatedly every four weeks from April to November. Soil samples were taken from the same depths in order to determine soil basicity and nutrient content. As a proxy of the intensity of the effect of prehistoric human activities, mean distances between sampled localities and the five nearest Neolithic or Aeneolithic settlements were used. The species richness was best explained by mean soil moisture, which increased towards the most species-rich grasslands, whereas the distance from prehistoric settlements had no effect. Basicity, moisture and the distance from prehistoric settlements had significant conditional effects on species composition. There was a high frequency of species of intermittently wet soils, thermophilous oak forests and forest fringes in the most valuable grasslands, which are located mostly in the south-western part of the area where the soils were moister and closer to prehistoric settlements, but the seasonal variation in moisture was not high. We conclude that coexistence of species from different habitats is dependent on regular management and high soil moisture throughout the growing season. Due to intermediate moisture conditions that are tolerated by multiple ecological groups of species, many species may locally coexist and form a species-rich grassland community of unique species composition. In addition, prehistoric human activities contributed to landscape openness and helped maintain a forest-steppe species pool during the Holocene forest optimum. Our results indicate that although this historical determinant shapes predominantly the species composition pattern, the extraordinarily species-rich spots are determined rather by abiotic factors, such as intermediate moisture and biotic interactions resulting from the type and duration of management practices.

Less is more! Rapid increase in plant species richness after reduced mowing in urban grasslands

Urban lawns provide space for recreation in cities, and they are an important part of urban green infrastructures. However, most lawns are intensively managed. As only few plant species can survive frequent mowing, urban lawns typically harbor only a limited number of plant species. To improve the biodiversity of urban lawns, it is often suggested to reduce the mowing frequency. Here, we studied the plant diversity of urban grasslands that have recently undergone management changes from mowing every few weeks to mowing only once or twice per season and compared them to intensively managed lawns. Within six years after the management changes, the grasslands with reduced mowing frequency hosted 30% more plant species than intensively managed lawns, and they were more heterogeneous both within and between grasslands. Additionally, the species composition of less frequently mown grasslands shifted from common mowing-tolerant lawn species to typical meadow species. Our study thus shows that the reduction of mowing is a simple and effective tool for increasing the biodiversity in urban grasslands.