Seed germination is a key stage in a plant's life cycle, influencing regeneration from seed by determining the post-germination environment, plant fitness and evolutionary potential. Therefore, seed germination traits are expected to play a fundamental role in the naturalization of alien seed plants; yet broad-scale empirical evidence of this remains limited. Using seed germination data for 1146 native temperate European herbaceous species, we tested whether species that have become naturalized outside their native range differ from non-naturalized species in overall germinability (final germination proportion) and in their germination responses to six environmental cues across temperate, tropical dry and tropical humid macroclimatic zones of naturalization. We also assessed whether germinability and responses to these cues are associated with the geographic extent of naturalization, using a phylogenetically informed meta-analysis that integrates 18,596 standardized laboratory germination records with global naturalization data. Naturalization was a common phenomenon, with 60% of species having naturalized in temperate regions and over 30% having naturalized in tropical regions. Naturalized species showed consistently higher overall germinability, germination at lower temperatures and higher requirements for seed scarification compared to non-naturalized species, while other germination traits varied with the macroclimatic zone of naturalization. The extent of naturalization was also positively, though weakly, related to higher germinability and to the same germination traits that distinguished naturalized from non-naturalized species. Synthesis. This study provides global-scale evidence that the naturalization of European herbaceous species is related to specific germination traits acquired in the native range. Our findings indicate that traits such as high germinability, low stratification requirements and responsiveness to scarification act as preadaptations that facilitate naturalization by increasing opportunities for establishment. They also show that standardized laboratory germination tests using seeds sourced from native populations represent a cost-effective tool for improving global risk assessments and for predicting naturalization potential under climate change through alterations in regeneration from seed.
1. This account presents information on all aspects of the biology of Geranium sylvaticum L. (Wood Crane's-Bill) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of Britain and Ireland: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, conservation and management. 2. Geranium sylvaticum is a perennial forb of woodland, semi-natural grassland, tall-herb vegetation, boreal dwarf shrub heaths and subalpine and subarctic scrub. In Britain and Ireland, it occurs in cool and moist northern-montane climates, in upland hay meadows, road verges, riverbanks, fens and mires, mountain rock ledges, crags and ravines and upland mixed ash forests. 3. Geranium sylvaticum is widespread in Scotland and northern England, with scattered native occurrences in Wales, central England and at the coast of County Antrim, Ireland. It has an extensive native range in Europe and Asia. At the northeastern end of this range, G. sylvaticum can occur down to sea level, whereas in more southern range parts, it is limited to mountain habitats. 4. In Britain and Ireland, Geranium sylvaticum is a species mainly of neutral to moderately calcareous soils of intermediate fertility. In its continental Eurasian range, it also occurs on more acidic soils. 5. Geranium sylvaticum is gynodioecious, that is individual plants are typically female or hermaphrodite. Occasionally, individuals are gynomonoecious, producing both female and hermaphrodite flowers. Female flowers are usually smaller than the protrandrous hermaphrodite flowers. Flowers are visited by insects of the orders Hymenoptera, Diptera and Lepidoptera, as well as Coleoptera and Hemiptera. 6. Primary seed dispersal of G. sylvaticum is ballistic, that is seeds are ejected from fruits. The species has a transient soil seed bank persisting for less than 12 months. The seeds have physical dormancy, that is their seed coat is initially impermeable to water. The species has little capacity for vegetative spread. 7. In Britain and Ireland, G. sylvaticum underwent long-term distributional decline mostly before 1987. A marked recent increase in records has been observed in northern Scotland, due to either a slight northerly shift in its distribution and/or increased recording in previously underrecorded areas.
BACKGROUND AND AIMS:Plant functional traits link environmental conditions to plant performance and adaptation. Growing evidence suggests that intraspecific trait variation can be as important as differences between species, yet large intraspecific studies of in-situ variation remain rare. While most studies have focused on plant morphological traits, the concentrations of elemental nutrients in seeds have received much less attention so far. METHODS:We conducted a large-scale in-situ study of the widespread annual ruderal grass Hordeum murinum. We sampled 2070 individuals from 207 populations across a large part of its native range in Europe and North Africa. We measured seed ripening phenology and growth-related traits in-situ and analyzed concentrations of elemental nutrients in the seeds. KEY RESULTS:We found that Hordeum murinum grew larger, produced seeds later, and had heavier seeds in colder and wetter regions. Plants growing in denser vegetation were taller and produced heavier seeds but formed fewer spikes. Concentrations of elemental nutrients in the seed generally declined with seed weight and were primarily driven by climatic variables, whereas soil conditions had only minor effects on plant traits and seed nutrients. Population identity explained a substantial proportion of trait variation, indicating a possible genetic component. CONCLUSIONS:Our findings provide a comprehensive view of how Hordeum murinum responds to environmental gradients across its European distribution. Climatic variables, particularly temperature, are key drivers of reproductive timing and concentrations of elemental nutrients in the seed, whereas local environmental conditions, such as biotic pressures, are more critical for growth-related traits. Together, these patterns indicate that Hordeum murinum modulates its growth and reproductive investment along environmental gradients, balancing phenology, stress tolerance, and limited competitive capacity.
Questions Seeds of many plant species are programmed not to germinate under various environmental scenarios. Thus, delayed seed germination is widespread, despite the higher fitness expected for earlier germinating seeds. We explore delayed germination by testing the hypothesis that it is a mechanism to cope with stress and disturbance during regeneration.Location Europe.Methods We retrieved 14,357 records representing 997 species from SeedArc, a global seed germination database. We classified species into four stress groups (low, drought, cold, and wetlands) and two disturbance groups (low and high) using their ecological preferences for temperature, moisture, and disturbance. We tested the likelihood of delayed germination as a function of stress-disturbance using phylogenetically informed meta-analysis.Results Delayed germination is more likely in species adapted to cold stress and wetlands and less likely in species adapted to disturbance. Species adapted to low stress and low disturbance present some degree of delayed germination. Different stress-disturbance groups respond differently to germination cues.Conclusions Delayed germination is widespread in temperate flowering plants and works as a mechanism to cope with stress, disturbance, and competition. The regeneration niche of the angiosperms shows a fundamental divide between those adapted to cold and those adapted to drought.
One hundred percent pasture-fed beef production has been suggested as a promising approach for sustainable ruminant farming, due to the potential benefits that can accrue across a range of sustainability domains. This study aimed to investigate the impacts across the four domains of sustainability of a wholesale switch from conventional to 100% pasture-fed beef production in the UK. We used fuzzy cognitive mapping (FCM) as a method for extracting knowledge from multiple stakeholders to create representative systems models of both conventional and pasture-based beef production systems. We then conducted a scenario analysis to assess how a switch to a pasture-fed system could affect components of sustainability in the UK beef sector. The FCMs indicated that vegetation quality, grass use efficiency, and soil health were central components of the pasture-fed approach, while economic and regulatory aspects, and climate change targets were more central to mainstream production approaches. The most marked changes under the 100% conversion scenario were an increase in income from subsidies (27.3%) in line with 'public money for public goods', a decrease in ability to export beef (unless advice to reduce consumption of animal protein is followed) (23.5%), a decrease in land used for farming vs other uses (e.g., natural capital) (11.23%), and a decrease in the use of feed from agricultural co/byproducts (7.5%), freeing up these feed sources for more sustainable monogastric production. Therefore, the mapping and scenario analysis suggests that while upscaling the pasture-fed approach may reduce productivity, it would likely increase public goods provision and reduce feed-food competition in the UK.
The distinction often made between active and passive restoration approaches is a false dichotomy that persists in much research, policy, and financial structures today. We explore the contradictions imposed by this terminology and the merits of replacing this dichotomy with a continuum-based intervention framework. In practice, the main distinction between "passive" and "active" restoration lies primarily in the timing and extent of human interventions. We apply the intervention continuum framework to forest, grassland, stream, and peatland ecosystems, emphasizing that a range of restoration approaches within the scope of ecological or ecosystem restoration are typically employed in most projects, and all can contribute to the recovery of native ecosystems and prevention of further degradation. As restoration is fundamentally about the recovery of ecosystems, eliminating human sources of degradation is essential to enable ecosystem recovery processes, regardless of subsequent interventions that may be needed to assist recovery. Our review of restoration practices involving different levels of intervention highlights the benefits of recognizing a broader suite of restoration interventions in the financial and policy frameworks that currently underpin restoration activity. Effective restoration interventions emerge from an understanding of nature's intrinsic recovery potential and overcoming specific obstacles that limit this potential.
Responses to climate change have often been found to lag behind the rate of warming that has occurred. In addition to dispersal limitation potentially restricting spread at leading range margins, the persistence of species in new and unsuitable conditions is thought to be responsible for apparent time‐lags. Soil seed banks can allow plant communities to temporarily buffer unsuitable environmental conditions, but their potential to slow responses to long‐term climate change is largely unknown. As local forest cover can also buffer the effects of a warming climate, it is important to understand how seed banks might interact with land cover to mediate community responses to climate change. We first related species‐level seed bank persistence and distribution‐derived climatic niches for 840 plant species. We then used a database of plant community data from grasslands, forests and intermediate successional habitats from across Europe to investigate relationships between seed banks and their corresponding herb layers in 2763 plots in the context of climate and land cover. We found that species from warmer climates and with broader distributions are more likely to have a higher seed bank persistence, resulting in seed banks that are composed of species with warmer and broader climatic distributions than their corresponding herb layers. This was consistent across our climatic extent, with larger differences (seed banks from even warmer climates relative to vegetation) found in grasslands. Synthesis . Seed banks have been shown to buffer plant communities through periods of environmental variability, and in a period of climate change might be expected to contain species reflecting past, cooler conditions. Here, we show that persistent seed banks often contain species with relatively warm climatic niches and those with wide climatic ranges. Although these patterns may not be primarily driven by species' climatic adaptations, the prominence of such species in seed banks might still facilitate climate‐driven community shifts. Additionally, seed banks may be related to ongoing trends regarding the spread of widespread generalist species into natural habitats, while cool‐associated species may be at risk from both short‐ and long‐term climatic variability and change.
This account presents information on all aspects of the biology of Geranium pratense L. (Meadow Crane's‐Bill). The main topics are presented within the standard framework of the Biological Flora of Britain and Ireland : distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. Geranium pratense is a perennial gynodioecious forb of neutral grassland. In Britain and Ireland, it is particularly abundant on roadside verges, railway embankments, the margins of watercourses and woodland rides. It is generally intolerant of grazing and is absent or scarce in livestock‐grazed grassland. Geranium pratense is widespread in England, Wales and Scotland but is scarce in Ireland. It has an extensive native range in Europe and Asia, extending eastwards to Russia, north‐western China and Mongolia. It has been widely introduced to new sites within its native range and has been introduced to Canada, the USA and New Zealand. Geranium pratense usually occurs on free‐draining soils but also infrequently where drainage is impeded. The soils are often nutrient‐rich and weakly acidic to weakly alkaline. The underlying geology is usually non‐acidic sedimentary rocks or superficial deposits. Geranium pratense is protandrous and is pollinated by various insects of the orders Hymenoptera, Diptera and Lepidoptera, particularly bumblebees, solitary bees, hoverflies and butterflies. Eleven species of phytophagous insect have been recorded on G. pratense in Britain and Ireland. Geranium pratense has little or no capacity for vegetative spread. Primary seed dispersal is ballistic and seeds may be flung over distances of up to several metres. The species has a transient seed bank, that is germination typically takes place in the winter and spring after seed production, after the physically dormant seeds have become permeable. Seedling establishment is higher in vegetation‐free gaps than in undisturbed grassland vegetation. There has been no significant change in its distribution between the late 1950s and 2019, although since 2000, it has expanded its range, mainly via introductions, in northern and western Scotland, west Wales and in Ireland. Alien sites have increased markedly since the 1960s due to introductions from wildflower seed sowing and spread from gardens.
Mob grazing is a nature-based solution to boost sustainable livestock productivity by optimising pasture management. It is already used widely in North America, and is now also receiving increased attention in the United Kingdom. In spite of this, its implementation by British farmers has so far remained largely unexplored. To close this gap, we studied how and why mob grazing is being adopted by British pasture-fed beef farmers. Field-level grazing management information was collected on 15 farms and analysed using cluster analysis and ordination analysis, showing the diversity of practices and establishing a gradient of mob grazing implementation. Farmer interviews explored general farming context, and rationale and motivations underpinning each farmer's grazing approach. Four main rotational approaches were identified at the field level: (1) conventional non-mob stocking by farmers still in the initial stages of discovering mob grazing; (2) mob stocking, involving reduced grazing duration at increased stocking densities, with pasture rest periods similar to those used in rotational non-mob stocking; (3) mob grazing, involving similar stocking densities as in mob stocking, but allowing for longer rest periods; and based on one early adopter of mob grazing practices in our sample (4) intensive mob grazing using very high stocking densities and frequent cattle movement, allowing for even longer rest periods. Interviews revealed the shift to mob grazing as a gradual process of farmer adaptation, involving the need to overcome constraints such as fencing and water access. Some early adopters amongst our sample of farmers observed various benefits to sustainability of livestock production, soil and ecosystem health, and animal health. We found much variation across farms, partly due to farmers adopting mob grazing gradually. Also, many farmers in our sample, in varying degree, were influenced by holistic grazing approaches. The ‘systems’ basis underlying such approaches, and variation in mob grazing implementation, mean that interdisciplinary and longer-term investigations may be most appropriate for exploring mob grazing effects. This is also illustrated by a case study involving long-term data from one intensively mob grazed farm.
The updated ClimPlant database (v.1.2) contains information on the distribution of monthly, growing-season, and annual mean, minimum and maximum temperature and total precipitation within the distribution range of 1168 European plants, mostly associated with temperate forests.Data in 56 csv-files with 1000 values for monthly, growing season and annual observations of mean, minimum, maximum temperature and precipitation in the distribution range for every species. One summary csv-file with summary statistics (mean, median, 5th and 95th percentile) for every species, of each climatic variable, together with seven key geographical descriptors: area of the distribution range, latitude and longitude of the centroid, and northern, eastern, western and southern range limit within the study area.More info in Vangansbeke et al., 2021, Global Ecology and Biogeography, 30(6), 1183–1190. https://doi.org/10.1111/geb.13303The database is freely available, but please cite both the database (https://figshare.com/s/1587e048803042bd4c07) and the methodological paper (https://doi.org/10.1111/geb.13303).ClimPlant: realized climatic niches of vascular plants in European forest understoreysPieter Vangansbeke a, František Máliš b, Radim Hédl c, Markéta Chudomelová c, Ondřej Vild c, Monika Wulf d, Ute Jahn d, Erik Welk e, Francisco Rodríguez-Sánchez f,g Alistair G. Auffret h, Inger Auestad i, Sofía Basto j, Ulf Grandin k, Hans Jacquemyn l, Anna Jakobsson m, Rein Kalamees n, Marcus A. Koch o, Rob Marrs p, Bryndis Marteinsdottir q, Jan Plue r, Markus Wagner s & Pieter De Frenne aa Forest & Nature Lab, Department of Environment, Ghent University, Geraardsbergsesteenweg 267, 9090 Melle-Gontrode, Belgium. b Faculty of Forestry, Technical University in Zvolen, T. G. Masaryka 24, SK-960 01 Zvolen, Slovakia c Institute of Botany, Czech Academy of Sciences, Lidická 25/27, 60200 Brno, Czech Republic. d Research Area 2, Leibniz - Centre for Agricultural Landscape Research (ZALF), Eberswalder Straße 84, D-15374 Müncheberg, Germany e Institute for Biology/Geobotany and Botanical Garden, Martin-Luther-University Halle-Wittenberg, Große Steinstrasse 79/80, D-06108 Halle, Germany f Department of Plant Sciences, University of Cambridge. Cambridge CB2 3EA, United Kingdom. g Departamento de Biología Vegetal y Ecología, Universidad de Sevilla. Avda. Reina Mercedes s/n, 41012 Sevilla (Spain). h Department of Ecology, Swedish University of Agricultural Sciences, 75 007 Uppsala, Sweden i Department of Environmental Sciences, Western Norway University of Applied Sciences, P.O. Box 133, N-6851 Sogndal, Norway j Unidad de Ecología y Sistemática, Departamento de Biología, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 No. 43-82 Ed. Jesús Emilio Ramírez (53), Bogotá, Colombia. k Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences,Box 7050, 750 07 Uppsala, Sweden l Plant Conservation and Population Biology, Biology Department, KU Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium m Division of Educational Science and Languages, University West, Trollhättan, Sweden n Institute of Ecology and Earth Sciences, University of 27 Tartu, Juhan Liivi 2, 50409 Tartu, Estonia and Tallinn Botanic Garden, Kloostrimetsa 52, 11913 Tallinn, Estonia o Centre for Organismal Studies (COS) Heidelberg, D epartment of Biodiversity and Plant Systematics, Heidelberg University, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany p School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, UK q The Soil Conservation Service of Iceland, Gunnarsholt, 851 Hella, Iceland r Swedish Biodiversity Centre, Swedish University of Agricultural 52 Sciences, 75 007 Uppsala, Sweden s UK Centre for Ecology & Hydrology, Benson Lane, Wallingford, Oxfordshire, OX10 8BB UKCorresponding author: Pieter Vangansbeke pieter.vangansbeke@ugent.be
There is an urgent need for transformational change in agriculture to address current and future issues caused by climate change, biodiversity loss and socio-ecological disruption. But change is slow to come and is hindered by a lack of transdisciplinary evidence on potential approaches which take a systems approach. The research described here was co-developed with the Pasture Fed Livestock Association in the UK to objectively evidence their practices. These include producing pasture-based meat from livestock fed on pasture and pasture-based forages alone. This approach sits alongside wider aims of fitting their practices with the ecological conditions on each individual farm to facilitate optimal production and working collaboratively through a forum for sharing knowledge. The research provides strong indications that the PFLA approach to livestock production is resilient and viable, as well as contributing to wider public goods delivery, despite variability within and between farms. It also reveals that learning and adaption of practice (through farmer experience) is central to farming using agro-ecological approaches. This fluidity of practice presents challenges for reductionist approaches to “measuring” agricultural innovations.
Abstract Livestock farming in Great Britain (GB) faces multiple pressures. Yet, grassland managed for livestock is the most extensive habitat in GB and is key to cultural landscapes and their biodiversity and soil health. This study analysed a nationally representative dataset of over 940 large (200 m2) Neutral (agriculturally semi‐improved) and (agriculturally) Improved Grassland plots from the GB Countryside Survey (CS) to assess relationships between key grassland sward and soil variables. Analysis also looked at how these variables changed over time as plots switched between these grassland types. Data from grassland plots managed by Pasture‐Fed Livestock Association (PFLA) farmers were compared to CS plot data to assess the impacts of their practices on these variables. Plant species richness in Neutral grassland types in CS plots was positively associated with total soil invertebrate abundance (total taxa) and soil N and C and negatively associated with soil P. There were negative relationships between the covers of Lolium sp. (Neutral only), legumes and forbs and soil C and moisture variables. Grassland swards on PFLA member farms were characteristic of Neutral grassland. PFLA plots were more species rich and contained more legume and forb species and lower proportions of Lolium perenne than those on Improved Grassland. Vegetation height was greater in PFLA plots than in CS plots of either Improved or Neutral Grassland. Unlike CS Neutral Grassland plots, soil properties in PFLA plots were not significantly different from those for Improved Grassland for any measured variable (soil carbon concentration [C], bulk density, pH, nitrogen [N], phosphorus [P]). Higher species richness in grasslands is associated with positive measures of soil health. PFLA plant communities contain relatively high species richness and tall vegetation, which is positive for biodiversity. Lack of positive measures of soil health associated with higher species richness recorded in PFLA grassland (as opposed to CS grassland) may reflect time lags in soil responses to management, as evidenced through an analysis of the impacts of land‐use change over time on CS plot characteristics. Our findings indicate that pasture‐fed livestock approaches may be beneficial for grassland and wider ecosystems.
Green hay transfer from species‐rich donor sites is now commonly used in Europe to restore species‐rich semi‐natural grassland, both on ex‐arable land and on former intensive grassland. However, species transfer rates are usually well below 100%, and due to lack of further colonization by additional target species after initial restoration, continued progress toward the target plant community is often very slow. We used data from a restoration experiment aiming to reestablish species‐rich grazed meadows of the MG5 grassland type according to the British National Vegetation Classification to investigate relationships between species abundance at a donor site, species capture by green hay and its seed content, and success of species establishment on experimental plots in formerly intensively managed species‐poor grassland undergoing restoration. Our results show that species with higher abundance at the donor site were more likely captured as seed in green hay, and were more likely to establish after hay application at the recipient site. Species with low abundance at the donor site that also possessed specific germination requirements that might prevent immediate establishment after green hay transfer were particularly unlikely to get established after transfer. These findings can provide guidance for additional measures aimed at ensuring establishment of a wider range of target species. Such measures could include targeted sowing of species in addition to green hay application, and management of restored grassland swards to extend or reopen an initial window of opportunity for the establishment of green hay species that might not be germinable immediately after hay transfer.
Aim: Climate and land use are key determinants of biodiversity, with past and ongoing changes posing serious threats to global ecosystems. Unlike most other organism groups, plant species can possess dormant life-history stages such as soil seed banks, which may help plant communities to resist or at least postpone the detrimental impact of global changes. This study investigates the potential for soil seed banks to achieve this. Location: Europe. Time period: 1978–2014. Major taxa studied: Flowering plants. Methods: Using a space-for-time/warming approach, we study plant species richness and composition in the herb layer and the soil seed bank in 2,796 community plots from 54 datasets in managed grasslands, forests and intermediate, successional habitats across a climate gradient. Results: Soil seed banks held more species than the herb layer, being compositionally similar across habitats. Species richness was lower in forests and successional habitats compared to grasslands, with annual temperature range more important than mean annual temperature for determining richness. Climate and land-use effects were generally less pronounced when plant community richness included seed bank species richness, while there was no clear effect of land use and climate on compositional similarity between the seed bank and the herb layer. Main conclusions: High seed bank diversity and compositional similarity between the herb layer and seed bank plant communities may provide a potentially important functional buffer against the impact of ongoing environmental changes on plant communities. This capacity could, however, be by climate warming. Dormant life-history be of in changing potentially observed time-lags in plant community
The two most common approaches to target species introduction in European meadow restoration are green‐hay transfer from species‐rich donor sites and the use of diverse seed mixtures reflecting the chosen target community. The potential of both approaches to restore species‐rich grassland has been variously reviewed, but very few studies have experimentally compared them at one and the same site. Moreover, studies involving one or both approaches have rarely taken into account environmental gradients at a site, and measured the impacts of such gradients on restoration outcomes. Such gradients do, for example, exist during grassland restoration on former arable land in river floodplains, where gradients in the occurrence of flooding, and in associated edaphic characteristics such as nutrient availability, might affect restoration outcomes. Using a randomized complete block experimental design, based on five different indicators of restoration progress, we compared the usefulness of green‐hay application and diverse seeding to restore species‐rich grazed meadows of the MG5 grassland type according to the British National Vegetation Classification, and also investigated how restoration outcomes differed after 4 years between areas within experimental plots characterized by high flood risk and areas characterized by low flood risk. Overall, both restoration approaches yielded similar results over the course of the experiment, whereas high flood risk and associated edaphic factors such as high availability of phosphorus negatively affected restoration progress particularly in terms of floristic similarity to restoration targets. These results highlight the need to take into account environmental gradients during meadow restoration.
Habitat restoration requires realistic goals. To naturally regenerate European lowland calcareous grassland, whose extent has severely declined, over a century may be required for vegetation to become indistinguishable from that of old calcareous grassland. Progress of natural regeneration can be characterized using member species of the reference vegetation as indicators of favourable site condition. Chronosequence studies have suggested that calcareous-grassland species differ predictably in their ability to colonize ex-arable land, with some usually colonizing early on, and others in later stages. If such patterns are affected by gradually-attenuating establishment limitation, this would have important implications for restoration practice and indication of progress. Particularly, late-colonizing species might be better indicators of favourable site conditions than early colonizers. To explore these aspects, we have reanalysed chronosequence data previously used to investigate causal mechanisms affecting calcareous-grassland restoration progress. We carried out an indicator species analysis to determine which species are indicative of particular stages of natural regeneration. Using correlation analyses, we tested whether species colonization patterns matched those found by previous chronosequence studies that were geographically more limited or relied on more informal approaches to determine species order of colonization. Correlation analyses were also used to test whether order of colonization could be explained by establishment limitation or by dispersal limitation, or by established plant strategies that underlie such limitations. We identified 30 species as indicative of particular stages of natural regeneration, including nine that specifically indicate old calcareous grassland. Correlation results confirmed high congruence with species order of colonization in previous chronosequence studies, and indicated that establishment limitation plays a role in shaping species order of colonization, potentially mediated through differential stress tolerance. We failed to demonstrate a role of dispersal limitation in shaping order of colonization. Based on our results, we derived three categories of indicator species for passively-restored calcareous grassland, mirroring the regeneration stage during which these species usually colonize. This includes a category labelled by us as 'old-grassland indicators' that achieve notable abundance only in old grassland. We conclude by discussing how such a categorization can benefit the measurement of restoration progress, the tentative identification of old grassland and its conservation, e.g. through linking agri-environment payments to the occurrence of old-grassland indicators, thus fostering positive change in farmer attitudes towards old grassland.
Calcareous grasslands are highly biodiverse semi-natural habitats. A particular challenge to European calcareous grassland management in recent years has been the increasing dominance of the competitive grass Brachypodium pinnatum. B. pinnatum is difficult to control by traditional means but selective herbicides offer a potential alternative. We trialled five selective herbicides on two levels of B. pinnatum cover (sparse and dense) at a UK calcareous grassland site over three years of repeated treatment. We compared the effect of herbicides with a minimal intervention treatment (cutting) and current management practices (cutting and grazing for sparse cover, broad-spectrum glyphosate application for dense cover) on the cover of B. pinnatum, key indicator species and the composition of the grassland community. Areas with initially sparse B. pinnatum showed no significant reduction under any herbicide, whilst some herbicides (propyzamide, cycloxydim) showed detrimental impacts on non-target species. Cutting and grazing showed some beneficial effects, despite no significant reduction in B. pinnatum. On areas of dense B. pinnatum cover, glyphosate application reduced cover of B. pinnatum but led to colonisation by negative indicators or species typical of agricultural situations and disturbed ground. None of the selective herbicides significantly reduced dense B. pinnatwn cover, and some (propyzamide, tepraloxydim, fluazifop-P-butyl) had significant negative impacts on non-target species. Our results suggest herbicide treatments, including glyphosate, are unlikely to offer long-term control of B. pinnatum on calcareous grasslands. A more promising approach is suggested by the effect of cutting and grazing, although further experimentation is required to determine the most effective regimes.
Soil seed banks on ex‐arable land are dominated by undesirable ruderal species that compete with “desirable” target species during grassland restoration. At the same time, for continued regeneration, the latter often functionally depend on gap colonization from the seed bank, which serves as a buffer against local extinction. Nonetheless, few studies have so far investigated the effects of restoration practices on seed bank dynamics. Using a multisite experiment investigating techniques for restoring lowland mesotrophic grassland, we studied the effects of seedbed preparation (shallow cultivation using harrows or discs vs. deep cultivation using a plow) and of seed mixtures (species‐rich grass–forb mixes vs. species‐poor grass‐only mixes vs. unseeded natural regeneration) on 7 years of post‐restoration seed bank dynamics. We assessed how these practices affected density and diversity of sown and unsown species in the seed bank. Seed bank dynamics were much more strongly affected by seed sowing than by cultivation. Grass sowing resulted in stronger seed bank decline of unsown grasses, and additional forb sowing in stronger decline of unsown forbs. Higher seed densities and species richness of sown forbs colonizing from neighboring plots sown with the grass–forb mix were observed under natural regeneration than in the grass‐only sown treatment, reflecting grass priority effects on sown forb colonization in the latter. Sowing of diverse target species mixtures was associated with the greatest shift in seed bank composition away from extant ruderal species towards sown target species. Our results illustrate the usefulness of seed bank monitoring for assessing restoration progress.