Species-rich Semi-natural Grasslands Research Articles

Using the old-growth concept to identify old species-rich semi-natural grasslands

The concept of ‘old growth’, originally developed for forests, was recently extended to grassland to distinguish old natural grasslands (NG) from semi-natural grassland (SNG). Comparing mesophile SNGs of different ages, we show that the concept is also able to distinguish old SNGs from young SNGs and also that assembly time plays a determining role in the ecology and evolution of SNG. As expected from the old-growth concept and like NG, old SNGs have an unique floristic composition with a higher greater proportion of long-lived species with underground storage, clonal growth organs and bud banks, higher species richness, diversity and evenness. Furthermore, they have much greater floral abundances and contain sedge species not found in younger SNGs such as Carex caryophyllea which is a reliable indicator of old unimproved species-rich grasslands. Comparison with other old grassland systems suggests that the old SNGs are probably remnants of the rich biodiversity of the grassland vegetation that was once widespread in the Atlantic biogeographic region. Given their ecological, cultural and aesthetic values and their role in essential ecosystem services, these threatened old SNGs deserve urgent protection.

A single application of fertilizer can affect semi-natural grassland vegetation over half a century.

Restoration of species-rich semi-natural grassland requires not only a seed source but also appropriate soil properties. In Europe, approximately 10 years are required for the properties of fertilized soils to reach suitable conditions and be considered successfully restored. However, restoration may require additional time in Japan because heavier precipitation causes leaching of basic cations from soils, resulting in soil acidification; volcanic ejecta also forms active Al and Fe hydroxides with high phosphate sorption. Within this context, we aimed to answer the following questions: i) whether and how the impacts of fertilization remain in the soil properties after half a century in Japan; and ii) how fertilization affects the restoration of semi-natural grasslands in Japan. We investigated the vegetation and soil properties of a Zoysia japonica pasture improved half a century ago with a single application of fertilizer and an adjacent semi-natural grassland (native pasture) in Japan, and found the following: (1) the two pastures had similar dominance of Z. japonica, but differed in the species composition; (2) the improved pasture exhibited lower species richness than the native pasture; (3) soil nutrients, including N, P, K, Mg, and Ca, were higher in the improved pasture than in the native pasture; and (4) many chemical properties of the soils were associated with species composition; namely, the vegetation on nutrient-rich soil had more alien species and fewer native species. We conclude that a single dose of fertilization can affect soil properties in semi-natural grasslands over half a century in Japan, leading to species loss and changing the species composition. We suggest that fertilized soils under grazing in Japan may require more than half a century to restore the nutrients to suitable levels for the establishment of a species-diverse grassland.

Grassland legacy remaining in vegetation and seedbank species diversity: Evaluation in abandoned grasslands and plantation forests

Species-rich semi-natural grasslands have been drastically transformed into agricultural areas, plantation forests, and abandoned grasslands worldwide. Grassland legacy—the impacts of a past grassland-use history on biological communities—is often detected in clear-cut forests that were formerly grasslands. This study assessed whether grassland plant species remain in the standing vegetation and soil seedbanks in transformed former grasslands. We surveyed standing vegetation and soil seedbanks in four land-use types with a grassland history (i.e., managed grassland, abandoned grassland, evergreen plantation, and deciduous plantation) and compared plant species richness and species composition among them. Grassland species remained but had lower species richness in abandoned grasslands and plantations, particularly of evergreen trees, than in standing vegetation in managed grasslands. The grassland species richness of seedbanks was significantly lower in abandoned grasslands than in managed grasslands. There were no differences in grassland species richness or the number of individuals in seedbanks among the other land-use types. The grassland species composition differed between standing vegetation and seedbanks regardless of land use, and the grassland species composition of standing vegetation in managed grasslands clearly differed from that of the other land-use types. Additionally, exotic species appeared in both the standing vegetation and seedbanks of managed and abandoned grasslands but not in those of plantations. Thus, our study detected grassland legacy in both standing vegetation and soil seedbanks, with variations depending on diversely transformed land uses, although the presence of grassland specialist species seemed to be limited. These results highlight the potential importance of plantation forest management for grassland restoration and the risk of exotic plant establishment associated with abandoned grassland restoration. • Grassland species were present but low species richness in standing vegetation of abandoned grasslands and plantation forests. • Grassland species richness declined in seedbanks of abandoned grasslands. • Grassland species’ seeds remained in soils of evergreen and deciduous plantations. • Forest management can help secure sites and seed sources for grassland restoration.

Macroecological drivers of vascular plant species composition in semi-natural grasslands: A regional study from Lower Silesia (Poland)

In agricultural landscapes of Europe, species-rich semi-natural grasslands provide numerous ecosystem services, such as forage production, ground and surface water regulation, and carbon sequestration. In the face of the declining area of grasslands, information about the macroecological drivers of grasslands diversity is an important element of studies on their ecology and management. Here, we tested the effect of factors representing environmental gradients, landscape structure, human pressure, habitat continuity in time, and spatial structure on species composition of vascular plants in semi-natural grasslands. The analysis was performed using a multivariate approach for 689 vegetation plots distributed across ~20,000 km2 in the Lower Silesia region (Poland, Central Europe). We found that species composition was significantly influenced by factors representing all studied groups. The most influential factors were temperature, long-term habitat continuity, and topography. Moreover, we captured the correlation between habitat conditions and habitat continuity. Old grasslands (existing since the 1940s) usually occurred in wet habitats, and medium grasslands (existing since the 1980s) existed in highlands in most cases. We highlighted the potential of freely available environmental databases, as well as historical topographic maps, in the exploration of patterns of species composition at a large spatial extent. The result show also the usefulness of vegetation databases in recognition of grassland complexes contributing the regional biodiversity.

Grazing in temporary paddocks with hardy breed horses (Konik polski) improved species-rich grasslands restoration in artificial embankments of the Rhône river (Southern France)

Extensive horse grazing with hardy breeds is largely used in conservation management for restoring species-rich semi-natural grasslands in Europe. As an example, the Donzère-Mondragon Rhône river embankments (south-eastern France) where horse grazing with Konik polski succeeded to maintain high species richness in patches of open and short grassland, but failed for patches of tall grassland dominated by the grass tussock species Brachypodium phoenicoides . In response, an increase of herd density by the creation of temporary paddocks was applied in tall grassland patches. Grazing pressure over time between patches was estimated via GPS fixed to mares, biomass, plant species richness measurements and from multispectral photographs, the normalized Difference Vegetation Index (NDVI) was calculated. Finally, telemetric data were collected. We wondered if the use of extensive horse grazing with temporary paddocks occupation, increase plant species richness. After three years, our results show that the increase in stocking rate enabled a significant increase of plant species richness in the tall grassland patches, with a significant decline of B. phoenicoides in all paddocks. The NDVI was strongly correlated with herbaceous biomass and plant species richness, while the number of GPS points indicating the position of the mares was higher in areas where the NDVI was high. These results are discussed for improving horse grazing conservation systems efficiency on grasslands established in anthropized sites such as embankments and the use of the NDVI as an appropriate tool to help decision-making for large-scale applications.

Novel pollen analogue technique shows bumblebees display low floral constancy and prefer sites with high floral diversity

ContextThere have been dramatic global declines in pollinating insects. A common land management intervention to support wild pollinators is to plant non-crop flowering plants (‘pollinator planting’). However, there are limited data on which species or spatial arrangement of planting provide maximum benefit to wild pollinators.ObjectivesHere we investigate which flowering species and locations are visited by free-foraging Bombus terrestris (buff-tailed bumblebees) in species-rich semi-natural grassland and woodland.MethodsTwo study nests of buff-tailed bumblebees were established in Wytham Woods, UK. Pollen analogue pigments were sprayed on open flowers in the study area over a period of two months, with unique colours used to identify separate sections of the study area. Pollen load analysis was used to identify forage species and foraging locations.ResultsBumblebees showed low flower constancy, visiting five flower species per trip on average, and as a group the sampled bumblebees visited 36 of the 49 plant species identified in study area surveys. Many individuals foraged in multiple, spatially-discrete locations during single trips.ConclusionsThe positive relationship between floral diversity and pollen load species diversity, and the positive relationship between site floral diversity and frequency of visitation, suggest behavioural strategies that maximize the diversity of flower species visited, in line with the energetic costs and benefits hypothesis. This supports recommendations for pollinator plantings with high species diversity, potentially spread across many small forage areas across the landscape.

Potential and Limitations of Grasslands α-Diversity Prediction Using Fine-Scale Hyperspectral Imagery

Plant biodiversity is an important feature of grassland ecosystems, as it is related to the provision of many ecosystem services crucial for the human economy and well-being. Given the importance of grasslands, research has been carried out in recent years on the potential to monitor them with novel remote sensing techniques. In this study, the optical diversity (also called spectral diversity) approach was adopted to check the potential of using high-resolution hyperspectral images to estimate α-diversity in grassland ecosystems. In 2018 and 2019, grassland species composition was surveyed and canopy hyperspectral data were acquired at two grassland sites: Monte Bondone (IT-MBo; species-rich semi-natural grasslands) and an experimental farm of the University of Padova, Legnaro, Padua, Italy (IT-PD; artificially established grassland plots with a species-poor mixture). The relationship between biodiversity (species richness, Shannon’s, species evenness, and Simpson’s indices) and optical diversity metrics (coefficient of variation-CV and standard deviation-SD) was not consistent across the investigated grassland plant communities. Species richness could be estimated by optical diversity metrics with an R = 0.87 at the IT-PD species-poor site. In the more complex and species-rich grasslands at IT-MBo, the estimation of biodiversity indices was more difficult and the optical diversity metrics failed to estimate biodiversity as accurately as in IT-PD probably due to the higher number of species and the strong canopy spatial heterogeneity. Therefore, the results of the study confirmed the ability of spectral proxies to detect grassland α-diversity in man-made grassland ecosystems but highlighted the limitations of the spectral diversity approach to estimate biodiversity when natural grasslands are observed. Nevertheless, at IT-MBo, the optical diversity metric SD calculated from post-processed hyperspectral images and transformed spectra showed, in the red part of the spectrum, a significant correlation (up to R = 0.56, p = 0.004) with biodiversity indices. Spatial resampling highlighted that for the IT-PD sward the optimal optical pixel size was 1 cm, while for the IT-MBo natural grassland it was 1 mm. The random pixel extraction did not improve the performance of the optical diversity metrics at both study sites. Further research is needed to fully understand the links between α-diversity and spectral and biochemical heterogeneity in complex heterogeneous ecosystems, and to assess whether the optical diversity approach can be adopted at the spatial scale to detect β-diversity. Such insights will provide more robust information on the mechanisms linking grassland diversity and optical heterogeneity.

Altered rhizoctonia assemblages in grasslands on ex-arable land support germination of mycorrhizal generalist, not specialist orchids.

Species-rich seminatural grasslands in Central Europe have suffered a dramatic loss of biodiversity due to conversion to arable land, but vast areas are being restored. Population recovery oforchids, which depend on mycorrhizal fungi for germination, is however limited. We hypothesised that ploughing and fertilisation caused shifts in orchid mycorrhizal communities in soil and restricted orchid germination. We examined edaphic conditions in 60 restored and seminatural grasslands, and germination success in 10 restored grasslands. Using a newly designed primer, we screened the composition of rhizoctonias in soil, seedlings and roots of seven orchid species. Seminatural and restored grasslands differed significantly in nutrient amounts and rhizoctonia assemblages in soil. While Serendipitaceae prevailed in seminatural grasslands with a higher organic matter content, Ceratobasidiaceae were more frequent in phosphorus-rich restored grasslands with increased abundance on younger restored sites. Tulasnellaceae displayed no preference. Germination success in restored grasslands differed significantly between orchid species; two mycorrhizal generalist species germinated with a broad range of rhizoctonias at most restored grasslands, while germination success of specialists was low. Past agricultural practices have a long-lasting effect on soil conditions and orchid mycorrhizal communities. Altered mycorrhizal availability may be the main reason for low germination success of specialist orchid species.

Annual burning of semi‐natural grasslands for conservation: winners and losers among plant species

Species‐rich semi‐natural grasslands in Europe are a main target for conservation efforts, and alternative methods to the traditional management of mowing or grazing would be welcome due to the difficulties in maintaining traditional management practices. One such method proposed is burning of grassland vegetation during late winter or spring. To evaluate the effects of annual spring burning vs annual mowing on semi‐natural grassland vegetation, we compared the frequency of species in eleven field experiments in southern Sweden after ca 14 years. Out of the 88 species analyzed, five were more frequent in burnt plots compared with mowed plots (Vicia cracca, Cirsium arvense, Urtica dioica, Galium verum, Convallaria majalis). In contrast, 37 species were significantly less frequent in burnt plots compared with mowed ones, those with the largest differences being Ranunculus acris, Briza media, Veronica chamaedrys, Festuca ovina, Plantago lanceolata and Anthoxanthum odoratum. Tall‐grown species and those with preferences for N‐rich soils increased in frequency under an annual spring‐burn regime, compared with annual mowing, as did species producing larger amounts of nectar. Hence, although vegetation composition becomes more trivial with annual spring burns, there might be long‐term benefits for nectar‐feeding insects.

Localized Agri-Food Systems and Biodiversity

Interest in localized agri-food systems has grown significantly in recent years. They are associated with several benefits and are seen as important for rural development. An important share of the academic debate addresses the contribution of localized food systems to the current and/or future sustainability of agriculture. Sustainability is defined in several ways, but many scholars recognize that sustainability can only be achieved by a combination of socio-economic, cultural, and environmental aspects. However, the attributes and indicators used for sustainability analyses also differ. Biodiversity is, for instance, often not included in analyses of environmental sustainability even if biodiversity is of crucial importance for longer-term ecological sustainability. To contribute to the debate about the importance of localized food production for sustainability from the environmental point of view, specifically with regard to biodiversity, this is therefore discussed based on the results of several studies presented in this paper. The studies focus on Nordic low-intensity livestock systems related to species-rich semi-natural grasslands. All the studies show that low-intensive agriculture and use of semi-natural grasslands may play an important role in maintaining biodiversity on both small and large scales. They also show that milk and dairy products from free-ranging livestock in heterogeneous landscapes with semi-natural grasslands may have a unique quality associated with local grazing resources. Thus, producers can combine production of food of documented high nutritional and gastronomic value with maintenance of biodiversity, i.e., localized agri-food production based on low-intensive agriculture systems and semi-natural grasslands may be a win-win recipe for both farmers and the society.

The biodiversity cost of reducing management intensity in species-rich grasslands: Mowing annually vs. every third year

Mowing is an important management method for species-rich semi-natural grasslands in Europe. Since mowing is costly, it is important to find a balance between mowing frequency and conservation benefits. We compared vegetation data from eleven field trials situated in southern Sweden that involved two mowing regimes, annually and every third year, as well as a no-management control. After approximately 14 years, mowing every third year showed (i) a drop in species richness and Shannon and Gini–Simpson diversity indices, (ii) an increase in woody species, and (iii) increases in tall-grown species. However, there were no apparent changes in (iv) species that were indicative of poor management, nor (v) those indicating good management. For one of the trials, data after 38 years were also evaluated. Compared with annual mowing, there were strong negative changes in the number of species in the untreated control, while the results were conflicting for mowing every third year. In conclusion, the expected loss of conservation values from reduced mowing intensity was 50–60% of the loss after abandonment. The outcomes, however, varied among the eleven sites.

Efficiency of mechanical seed harvesting for grassland restoration

Maintaining and re-creating species-rich semi-natural grasslands are important issues in current agricultural policy in Europe. The seed that is required for their establishment can be obtained through direct harvesting from semi-natural herbaceous vegetation. To test the efficiency of mechanical seed harvesting on donor Arrhenatherion elatioris grasslands, experiments were performed in northern Italy and eastern Czech Republic. Trials were organized with a randomized block design and involved harvesting as green hay (grass mowing and immediate collection), dry hay (grass mowing and collection after drying on the field), direct combining (grass cutting and threshing at the same combine passage) and seed stripping with pull-type equipment (seed removal without grass cutting with a brush harvester pulled by a tractor). Harvesting was carried out at the time of maximum ripe standing seed yield (SSY) in the first and second regrowth. The harvested materials were analysed for seed number and weight and compared with the SSY. The species composition and phenology were also surveyed. In all methods, the seed mixture obtained contained the species present as seed at harvest time and was correlated with SSY. However, with regard to the seed number collected, the harvesting efficiency changed in relation to species group (grasses or forbs), individual species, seed maturation and regrowth. The most efficient method was harvesting as green hay (efficiency of approximately 71% of SSY and seed mixture composition that was very highly correlated with SSY). The least efficient methods were direct combining (30% of SSY and negative selectivity against light or difficult to detach seeds, producing the highest mean 1000-seeds weight) and harvesting as dry hay (39% of SSY and a high sensitivity to seed maturation level). Seed stripping, operated with downward brush rotation at the leading edge, resulted in an intermediate efficiency (60% of SSY and a seed mixture composition highly correlated with SSY). The harvesting efficiency for seed number was higher at the first regrowth than the second one for both species groups and, especially at the second regrowth, higher for forbs than for grasses. Especially forb harvesting presented a problem with regard to the species number collected. The problem was, not due to harvesting inefficiency but rather for phenological reasons, as several forbs did not produce fertile stems at the first or second regrowth and some other early flowering species had already shed the seed at the harvesting time. These results improve our understanding of factors affecting the efficiency of mechanical harvesting and will help in the preparation of efficient harvesting programs.

Successful restoration of moth abundance and species-richness in grassland created under agri-environment schemes

Restoring intensive agricultural fields to species-rich semi-natural grassland could have profound effects on biodiversity and ecosystem services. However, only a minority of European agri-environment scheme funding is currently devoted to such measures (<1% in the UK) and too few studies compare biodiversity on restored habitats with that on appropriate control and reference sites. As a result, there is a lack of advice for land managers on how to implement habitat restoration to maximise conservation outcomes, especially for insects. We present a landscape-scale field study in which we tested whether the abundance and species-occurrence of moths (Lepidoptera) differed between arable fields, fields restored to species-rich grassland, and semi-natural calcareous grassland (CG). We also tested whether moths were affected by the frequency of CG indicator wildflowers, age of restoration and habitat connectivity of restored grassland. We found that the abundance of CG-associated moths on restored grassland was almost eight times that on arable fields, and abundance and species-occurrence did not differ significantly from that on semi-natural CG. The only group of moths that was more abundant on CG than restored grassland was associated with late successional stage habitats (e.g. woodland), which shows that trees and shrubs are key features maintaining insect biodiversity on CG. CG moths were more abundant on restored grassland sites where CG indicator wildflowers had established, suggesting that active enhancement of the plant community can increase the abundance of target insect groups. Restoring arable fields to species-rich grassland benefits moths over short timescales (as little as 3years) and at great distances from semi-natural CG (up to 7km). It should play a pivotal role in future agri-environment schemes aiming to increase insect biodiversity.

Flower abundance and vegetation height as predictors for nectar-feeding insect occurrence in Swedish semi-natural grasslands

With steadily shrinking areas of species-rich semi-natural grasslands in Europe, the management of the remaining fragments becomes ever more crucial for the preservation of key elements of biodiversity in the agricultural landscape. Detailed knowledge about species-wise, as well as group-wise, relationships can provide guidelines for conservation management and a basis for predictions about different management scenarios. In the present study, we related the occurrence of species of bumblebees (N=12), butterflies (31) and day-flying moths (4) and their total richness in 424 sites in southern Sweden to three grass sward attributes, (i) flower abundance, (ii) height of the grass sward and (iii) within-site variation in height of vegetation. The abundance of nectar-bearing flowers proved overall the best predictor of richness and in most of the occurrence-based species-wise models. However, both high grass sward height and high variation in grass sward height contributed significantly to species richness and occurrence of individual species. There was a tendency for bumblebees to respond less positively to flower abundance and vegetation height than butterflies and moths. One expectation was that grassland specialists, red-listed species, or species decreasing in other part of Europe, would be more responsive to tall vegetation or flower abundance but there was no support for this in the data. Hence, management strategies that promote common species will also benefit all, or most of, the rare ones as well.

Effect of past agricultural use on the infectivity and composition of a community of arbuscular mycorrhizal fungi

When species-rich semi-natural grasslands undergo conversion to arable fields and back to grasslands, the effect of past intensive agricultural management may persist for decades in the form of decreased plant diversity. Arbuscular mycorrhizal fungi (AMF) are an important component of grassland ecosystems affecting the biodiversity and productivity of plant communities, but little is known about their long-term response to past agricultural management after the abandonment of fields. The aim of this study was to compare the infectivity and composition of the AMF communities of a former field, abandoned 25 years ago, and a neighboring non-disturbed grassland, and to assess whether the composition of intraradical AMF communities can be linked to the inability of some plant species to colonize the abandoned field. AMF infectivity and diversity were evaluated in soil and root samples of 12 plant species differing in their ability to colonize abandoned fields. The abandoned field hosted the same pool of AMF taxa as the undisturbed grassland but the community of AMF colonized plant roots faster from a lower number of infective propagules in the abandoned field than in the grassland. The composition of intraradical AMF communities was affected by the biotope and the plant species, but was unrelated to the ability of the plant species to colonize the abandoned field. It is therefore concluded that plants and AMF have colonized the abandoned field independently and that differences between the AMF communities of the two biotopes reflect persisting differences in soil characteristics.

Establishing a semi-natural grassland: Effects of harvesting time and sowing density on species composition and structure of a restored Arrhenatherum elatius meadow

Species-rich semi-natural grasslands play an essential role in the conservation of European biodiversity. To restore them, existing grasslands may be used as a seed source. A key factor for successful restoration is the transfer of all species of the plant community to the site being restored. This approach, however, often poses practical problems due to variations in species phenology, so that only time-staggered harvesting allows the seeds of many species to be collected. Poor harvesting methods may reduce the number of species transferred from the donor to recipient site. The effects of harvesting at various time points by various methods were evaluated here in a restoration experiment on an ex-arable field in Northern Italy. Propagation materials from the first or second regrowth (or both) of a meadow dominated by Arrhenatherum elatius were collected by four harvesting methods. The materials were spread at the sowing density between 830 and 14360 seedsm−2. Species composition and structure of the vegetation were examined during 6 years. Untransferred species were almost exclusively those not present at harvesting as mature seed. Compared with materials from one regrowth period, materials from both regrowth periods significantly increased the number of transferred species per plot (26.5 vs. 28.5, respectively) and the absolute transfer rate (64% vs. 75%). Higher sowing density yielded a greater number of positive than negative effects. It favored stable establishment of donor site species and significantly reduced the presence of weeds. Nonetheless, due to the initial dominance of species with high sowing density, evenness of the restored plots was lower than that at the donor site but increased with time, at least under low- and medium-sowing-density conditions. Multiple harvesting at time points when several species with mature seed are present increases the species transfer rate. Medium sowing density positively affects restoration development because it promotes the establishment of donor site species with lower sowing density, prevents species with the highest density from dominating the vegetation during the first few years, and reduces weed cover.

「河川における生物多様性に配慮した堤防植生管理」 植物種多様性の高い河川堤防半自然草地における植生と立地特性

「河川における生物多様性に配慮した堤防植生管理」 植物種多様性の高い河川堤防半自然草地における植生と立地特性

Clear-cuts in production forests: From matrix to neo-habitat for butterflies

Butterfly conservation in Europe is mainly focused on well-defined grassland habitat patches. Such an approach ignores the impact of the surrounding landscape, which may contain complementary resources and facilitate dispersal. Here, we investigated butterfly species richness and abundance in a habitat normally regarded as unsuitable matrix: production forestry clear-cuts. Butterflies were recorded in 48 clear-cuts in southern Sweden differing with regards to the time since clear-cutting and land-use history (meadow or forest based on historical maps from the 1870s). All clear-cuts had been managed as production forests for at least 80–120 years. A total of 39 species were found in clear-cuts of both land-use histories, but clear-cuts with a history as meadow had on average 34% higher species richness and 19% higher abundance than did clear-cuts with a history as forest. No effect of the time since clear-cutting was found, irrespective of land-use history, which was likely due to the narrow timespan sampled (<8 years). The absence of temporal effect suggests that clear-cuts may provide butterflies with valuable resources for 10–15 years. Assuming a 100 year forest rotational cycle, this means that 10–15% of the total forested area are made up by clear-cuts valuable to butterflies, which corresponds to an area about four times as large as that of species-rich semi-natural grasslands. The study illustrates the importance of considering land-use legacies in ecological research and question the landscape-ecological view that clear-cuts make up an unsuitable matrix for butterflies. Moreover, forest conservation management with special attention to land-use history may increase the quality of the landscape, thus facilitating butterfly metapopulation persistence. Given their large area and assets of nectar and host plant resources, clear-cuts must be considered as a butterfly habitat in its own right. Being a man-made environment with short history, we might call it a neo-habitat.

From arable land to species-rich semi-natural grasslands: Succession in abandoned fields in a dry region of central Europe

The area of arable land has decreased considerably in Europe over the last decades. Abandoned fields are potential habitats for restoration of species-rich grasslands of high conservation value, but in specific cases it is unclear whether this can be achieved by spontaneous succession or intervention is needed. In dry areas of eastern-central Europe, spontaneous succession of species-rich steppe grasslands was observed on some abandoned fields located close to ancient grasslands. We studied spontaneous succession on ex-arable land in the warm and dry area of the SE Czech Republic using space-for-time substitution. Vegetation was sampled in 175 plots, for which the time since the abandonment (4–71 years) was determined from historical aerial photographs. All plots were close to ancient dry grasslands. Annual weeds were replaced by perennial species in less than four years after abandonment. Perennial grassland was stable over seven decades, but its species composition changed: native dry-grassland species, including Red-List species, gradually increased, and so did the total number of vascular plants, reaching on average of 30–40 species per 16m2 after 40 years. Archaeophytes, including common ruderal species, decreased, while neophytes were insignificant throughout the succession. Scattered shrubs appeared at later stages, but their spread was limited by drought and recently also by nature conservation management. This study suggests that spontaneous succession can be inexpensive yet effective means of dry grassland restoration in dry areas of eastern and central Europe if sources of target species are available in nearby remnants of ancient grasslands.

Soil amendment with biochar increases the competitive ability of legumes via increased potassium availability

Soil amendment with biochar is currently proposed as a management strategy to improve soil quality and enhance plant productivity. Relatively little is known about how biochar affects plant competition, although it has been suggested that it can increase the competitive ability of legumes. This study tested the impact of a biochar on the competitive ability of legumes through alterations to soil pH and/or nutrient availability. Biochar was produced from aboveground plant biomass from a species-rich semi-natural grassland pyrolysed at 400°C. In a greenhouse experiment, a legume (red clover, Trifolium pratense L.); a grass (red fescue, Festuca rubra L.); and a forb (plantain, Plantago lanceolata L.) were grown in (1) monocultures, (2) in a mixed culture of red fescue and red clover, and (3) in a mixture of all three species. Soil treatments included fertilisation with nitrogen (N), potassium (K), phosphorus (P), or micronutrient fertiliser in the presence or absence of biochar; a pH-adjusted control soil; and a control (i.e. with no amendment). The competitive ability of red clover was quantified as the proportion of aboveground biomass of this species within the mixtures. Both biochar amendment and K fertilisation significantly (P<0.001) increased red clover biomass, and increased the competitive ability of red clover when grown with red fescue and plantain. Application of N fertiliser, irrespective of biochar amendment, resulted in significantly (P<0.001) greater red fescue and plantain biomass and eliminated the competitive advantage of red clover. The biochar-mediated pH increase did not affect red clover biomass or its competitive ability. We conclude that biochar has a beneficial effect on red clover under N limiting conditions due to an increase in K availability. Our results suggest a potential role for biochar to maintain the proportion of forage legumes in agricultural pastures or semi-natural grasslands.