Search

International audience; Grasslands, which constitute almost 40% of the terrestrial biosphere, provide habitat for a great diversity of animals and plants and contribute to the livelihoods of more than 1 billion people worldwide. Whereas the destruction and degradation of grasslands can occur rapidly, recent work indicates that complete recovery of biodiversity and essential functions occurs slowly or not at all. Grassland restoration—interventions to speed or guide this recovery—has received less attention than restoration of forested ecosystems, often due to the prevailing assumption that grasslands are recently formed habitats that can reassemble quickly. Viewing grassland restoration as long-term assembly toward old-growth endpoints, with appreciation of feedbacks and threshold shifts, will be crucial for recognizing when and how restoration can guide recovery of this globally important ecosystem.

To achieve the ambitious goals of the UN Decade on Ecosystem Restoration, restoration frameworks should embrace the diversity of ecosystems found on Earth, including open-canopy ecosystems, which have been largely overlooked. Considering the paucity of scientific foundations promoting restoration science, policy, and practice for open tropical ecosystems, we provide overarching guidelines to restore the campo rupestre, a Neotropical, open megadiverse grassland that has been increasingly threatened by multiple human activities, especially mining. Restoration techniques for tropical grasslands are still at its infancy, and attempts to restore campo rupestre have had, so far, low to moderate success, highlighting the need for a tailored restoration framework. In a scenario of increasing degradation and scarcity of on-site restoration experiments, we propose 10 principles to improve our ability to plan, implement, and monitor restoration in campo rupestre: (1) include socioeconomic dimensions, (2) implement active restoration, (3) keep low soil fertility, (4) restore disturbance regimes, (5) address genetic structure and adaptation potential, (6) restore geographically restricted and specialized ecological interactions, (7) incorporate functional approaches, (8) use seed-based restoration strategies to enhance biodiversity, (9) translocation is inevitable, and (10) long-term monitoring is mandatory. Our principles represent the best available evidence to support better science and practice for the restoration of campo rupestre and, to some extent, can be useful for other megadiverse, fire-prone, and nutrient-poor ecosystems.

International audience; Native plants of the Sahara are remarkably resistant to prolonged droughts and are important sources of forage, food, and medicine. Their regeneration from seeds after strong anthropogenic disturbances is a challenging step toward their conservation and to mitigate desertification. We studied the germination responses of 43 dominant native species of the Sahara desert that could be propagated from seeds for future ecological restoration projects, exploring the effects of cold stratification and temperatures on seed germination. Seeds were stratified at 4°C for 3 days and then tested for germination at 5, 10, 15, 20, 25, 30, 35, and 40°C. While cold stratification negatively affected four species, it improved the germination of 36 species. Five of these species required cold stratification to germinate. Temperatures during the germination trial significantly influenced seed germinability. Twenty-three species (54%) germinated to higher percentages at intermediate temperatures (20 to 30°C) similar to the maximum temperatures of the rainiest months, when germination in the field is high. Thirteen species (30%) also germinated at a higher temperature (40°C). Seven species (16%) germinated best at low temperatures (5 to 10°C). Our results suggest that cold stratification is an efficient and easy treatment to apply prior to sowing seeds in the field for restoration.

International audience; With the advent of the Anthropocene, biological invasions have reached an unprecedented level, and the number of species introductions is still increasing in an ever-changing world. Despite major advances in invasion science, significant debate and lack of clarity remain surrounding the determinants of success of introduced species, the magnitude and dimensions of their impact, and the mechanisms sustaining successful invasions. Empirical studies show divergent impacts of alien populations on ecosystems and contrasting effects of biotic and abiotic factors on the dynamics of alien populations, which hinders the creation of a unified theory of biological invasions. Compounding these issues is the plethora of hypotheses that aim to explain invasion success, which can be unclear and contradictory. We propose a synthesis that categorizes hypotheses along a timeline of invasion. We sorted invasion hypotheses along the invasion timeline, and considered population, community and ecosystem levels. This temporal sorting of invasion concepts shows that each is relevant at a specific stage of the invasion. Although concepts and empirical findings on alien species may appear contradictory, when mapped onto an invasion timeline, they may be combined in a complementary way. An overall scheme is proposed to summarise the theoretical dynamics of ecosystems subjected to invasions. For any given case study, this framework provides a guide through the maze of theories and should help choose the appropriate concepts according to the stage of invasion.

11 páginas, 5 figuras, 1 tabla, Many degraded ecosystems need active restoration to conserve biodiversity and re-establish ecosystem function, both highlighted targets of the UN Decade on Ecosystem Restoration and the proposed EU Nature restoration law. Soil translocation, where both plant propagules and their associated soil biota are co-introduced, has increasingly been proposed as a powerful restoration technique for terrestrial ecosystems. However, a synthesis of the effectiveness of this method across ecosystems is lacking. To address how soil translocation affects restoration success, we performed a meta-analysis synthesizing data from 46 field experiments and their respective reference ecosystems in 17 countries across four continents. In each experiment, vegetation composition was recorded in response to soil translocation treatments and the resultant vegetational changes (diversity and composition) were quantified. We found that soil translocation leads to plant community development further away from the control and more towards the reference plant communities compared with treatments where only plant propagules were introduced. However, the variability of effect sizes among experiments was large, suggesting strong dependence of restoration success on restoration context. We found that restoration success was more likely on loamy soils and when translocation treatments were implemented over larger spatial areas (>180 m2). Furthermore, we found that restoration success either consistently increased or decreased over time depending on the experiment. Not only is this congruent with positive feedbacks between plant and soil communities driving plant community development, but it also suggests that the composition of the translocated plant and soil communities, and initial starting conditions, are critical for long-term restoration success. Synthesis and applications. Our analysis highlights soil translocation can be a successful restoration method across a broad range of ecosystems. However, its implementation needs to depend on a thorough evaluation of local conditions and the potential added value. Further refinement of soil translocation techniques is needed to increase success rates.

International audience; Mountain grassland restoration success may be hampered by limited seed dispersal and poor soil seed banks of many grassland species. These constraints can be overcome by actively introducing propagules from nearby non-degraded communities. We tested different restoration techniques in order to understand the mechanisms favouring target species seedling recruitment and establishment. In five degraded mountain grasslands, we analysed (i) the effect of two techniques increasingly used in ecological restoration to overcome low seed dispersal: transfer of brush-harvested seed material and hay transfer, and (ii) the potentially facilitative effect of a temporary plant cover (common wheat) on the recruitment of transferred brush-harvested propagules. We found that both propagule transfer techniques were successful in establishing plant species of the donor community with an increase of plant species richness, cover and abundance of transferred species. Hay transfer was more efficient in transferring species of the donor grassland than brush-harvested material transfer. Brush-harvested material transfer only increased abundance and cover of donor grassland species when sown together with wheat. The results indicated that hay mulch favoured seedling recruitment of target species, and that propagule transfer without hay mulch needs to be compensated by additional temporary plant cover in order to create favourable conditions for seedling recruitment. A comparison with best reference communities for each restoration grassland confirmed that hay transfer and brush material transfer with wheat sowing were successful in driving plant community composition towards the desired reference state. In conclusion, restoration of mountain grasslands with shallow and stony soils clearly benefits from a facilitative effect of dead (hay) or living (wheat) vegetation cover.

Made available in DSpace on 2022-04-28T19:46:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 We introduce the concept of Biome Awareness Disparity (BAD)—defined as a failure to appreciate the significance of all biomes in conservation and restoration policy—and quantify disparities in (a) attention and interest, (b) action and (c) knowledge among biomes in tropical restoration science, practice and policy. By analysing 50,000 tweets from all Partner Institutions of the UN Decade of Ecosystem Restoration, and 45,000 tweets from the main science and environmental news media world-wide, we found strong disparities in attention and interest relative to biome extent and diversity. Tweets largely focused on forests, whereas open biomes (such as grasslands, savannas and shrublands) received less attention in relation to their area. In contrast to these differences in attention, there were equivalent likes and retweets between forest versus open biomes, suggesting the disparities may not reflect the views of the general public. Through a literature review, we found that restoration experiments are disproportionately concentrated in rainforests, dry forests and mangroves. More than half of the studies conducted in open biomes reported tree planting as the main restoration action, suggesting inappropriate application of forest-oriented techniques. Policy implications. We urge scientists, policymakers and land managers to recognise the value of open biomes for protecting biodiversity, securing ecosystem services, mitigating climate change and enhancing human livelihoods. Fixing Biome Awareness Disparity will increase the likelihood of the United Nations Decade on Ecosystem Restoration successfully delivering its promises. Department of Genetics Ecology and Evolution Federal University of Minas Gerais Institute Society Population and Nature Department of Ecology University of Brasília Research Institute for the Environment and Livelihoods Charles Darwin University Department of Biological Sciences University of Cape Town Institut Méditerranéen de Biodiversité et d'Ecologie CNRS IRD Aix Marseille Université Avignon Université IUT d'Avignon Instituto de Pesquisas Ambientais Lab of Vegetation Ecology Universidade Estadual Paulista (UNESP) Department of Plant Biology University of Campinas School of Environmental Sciences University of Liverpool Department of Zoology & Entomology University of Pretoria School of Animal Plant & Environmental Sciences University of the Witwatersrand Department of Geography College of Life and Environmental Sciences University of Exeter Department of Ecology and Conservation Biology Texas A&M University Royal Botanic Garden Edinburgh Lab of Vegetation Ecology Universidade Estadual Paulista (UNESP)

Le colloque REVER 10 « Restaurer ou reconquérir » organisé en mars 2019 par le MNHN et l’association REVER, a été l’occasion de faire un point d’étape sur le développement de l’écologie de la restauration et de la restauration écologique, au moment où débute la « décennie de la restauration des écosystèmes » décrétée par l’ONU. En France, le développement de la restauration écologique a été accompagnée par le réseau REVER créé en 2008 sur le modèle de la SER (Society for Ecological Restoration) qui favorise, notamment par l’organisation de colloques annuels, les échanges entre acteurs techniques et scientifiques ainsi que la circulation des connaissances, des concepts et des pratiques. Ces échanges ont été particulièrement importants au moment où, sur la même période, la recherche et les retours d’expériences ont conduit à une évolution et à un confortement des concepts par de nombreux débats scientifiques autour notamment des notions d’écosystèmes de référence, de nouveaux écosystèmes et de restauration passive. Aujourd’hui plus que jamais, même si la préservation doit rester une priorité, les enjeux de la restauration rendent indispensable le renforcement tant de l’acquisition de connaissances que de l’action. Ainsi la diffusion scientifique, la construction d’outils d’évaluation et d’aide à la décision et les échanges autour de retours d’expériences restent primordiaux et le réseau REVER, en lien avec les structures internationales, a un rôle indéniable à jouer.

Species from OCBILs (old, climatically buffered, infertile landscapes) are expected to exhibit reduced dispersability, linked to long-term stable environmental conditions. We tested the prediction of limited dispersability in plant communities in campo rupestre, a megadiverse OCBIL grassland. In a field experiment, we sampled sticky and funnel traps for 12 months along paired preserved and disturbed plots to estimate and compare annual seed density and richness. Our community-level seed rain assessment suggested widespread seed limitation in both preserved and disturbed areas, expressed by the low seed density in traps (average of 2.6 seeds/m2/day) and remarkably low seed density found for 90% of the morphospecies. Although seed density in campo rupestre was much lower than for other grasslands, species richness (92 seed morphospecies) was the highest reported in the literature. Higher seed density and species richness were captured in funnel traps, especially during the rainy season. Approximately 32% of morphospecies were registered exclusively in disturbed plots and 25% exclusively in preserved plots. This limited seed dispersability is of particular relevance for a better understanding of seed ecology and resilience in campo rupestre and may partially explain the poor recovery of these disturbed areas after soil removal.

International audience; Invasive plant species, such as Carpobrotus species, threaten the biodiversity of Mediterranean islands. Ecological restoration can include the control of invasive plants, but the effect of Carpobrotus removal on arthropods is understudied. Here, we evaluated the influence of Carpobrotus removal on beetle assemblages, on a Mediterranean island. Between November 2011 and February 2012, we manually removed Carpobrotus and its litter. A site composed of native shrubland vegetation located in the vicinity was studied to estimate the beetle assemblage natural variations. Two years before removal (2010‐2011), and every two years following removal (2013, 2015, 2017, 2019), we sampled beetles with pitfall traps. Vegetation did not change at the shrubland site and beetle assemblages stayed relatively stable. After the removal of Carpobrotus at the Carpobrotus site, a diverse halophilic grassland vegetation colonized as well as some chamaephytes. The taxonomic and functional richness of beetle species increased significantly following removal. Assemblage composition changed significantly between pre‐ and post‐removal years with a high taxonomic turnover rate. Predators (e.g. Staphylinidae, Carabidae) and detritivores (Tenebrionidae) most likely benefited from the vegetation opening, while the diversification of microhabitats led to the availability of a wider variety of prey. Large floricolous beetles (Scarabaeidae) were the most reduced by Carpobrotus removal along with small non‐flying beetles. This rapid change in beetle assemblages occurred within seven years. Future studies should be carried out in areas where reference ecosystems are available to meet the requirements of a Before‐After‐Control‐Impact approach.

Herbivory is ubiquitous. Despite being a potential driver of plant distribution and performance, herbivory remains largely undocumented. Some early attempts have been made to review, globally, how much leaf area is removed through insect feeding. Kozlov et al., in one of the most comprehensive reviews regarding global patterns of herbivory, have compiled published studies regarding foliar removal and sampled data on global herbivory levels using a standardized protocol. However, in the review by Kozlov et al., only 15 sampling sites, comprising 33 plant species, were evaluated in tropical areas around the globe. In Brazil, which ranks first in terms of plant biodiversity, with a total of 46,097 species, almost half (43%) being endemic, a single data point was sampled, covering only two plant species. In an attempt to increase knowledge regarding herbivory in tropical plant species and to provide the raw data needed to test general hypotheses related to plant–herbivore interactions across large spatial scales, we proposed a joint, collaborative network to evaluate tropical herbivory. This network allowed us to update and expand the data on insect herbivory in tropical and temperate plant species. Our data set, collected with a standardized protocol, covers 45 sampling sites from nine countries and includes leaf herbivory measurements of 57,239 leaves from 209 species of vascular plants belonging to 65 families from tropical and temperate regions. They expand previous data sets by including a total of 32 sampling sites from tropical areas around the globe, comprising 152 species, 146 of them being sampled in Brazil. For temperate areas, it includes 13 sampling sites, comprising 59 species. Thus, when compared to the most recent comprehensive review of insect herbivory (Kozlov et al.), our data set has increased the base of available data for the tropical plants more than 460% (from 33 to 152 species) and the Brazilian sampling was increased 7,300% (from 2 to 146 species). Data on precise levels of herbivory are presented for more than 57,000 leaves worldwide. There are no copyright restrictions. Please cite this paper when using the current data in publications; the authors request to be informed how the data is used in the publications.

Dry grasslands of the Northwestern Mediterranean Basin are seminatural species‐rich ecosystems, composed of many annual species and some structuring perennial species. As these grasslands have been used as rangelands for centuries, human management (grazing; fire regimes) is one of their main ecological and evolutionary drivers, along with the Mediterranean climate. Despite EU conservation policy, damage to such grasslands still occurs and efficient ecological restoration is needed. This article reviews restoration constraints, effective techniques, and research perspectives for restoring them in the light of their ecological characteristics. Major restoration constraints specifically include (1) a poor contribution of the internal (seed bank) and external (seed rain) species pools, and (2) low establishment of some perennial species. The latter may be the result of the low seed quantity or quality of perennial species, stochastic or extended droughts, high soil nutrient content that may lead to competition (e.g. between weed and target species), inappropriate grazing management or fire regimes leading to shrub encroachment, or the death of target species seedlings in early stages of restoration. Successful restoration techniques include seeding, transplanting, hay transfer, and timely soil transfer, all of which have to be adapted to regional plant phenology and to local Mediterranean climate. They must be combined with appropriate grazing or fire management. Their success may depend on years with particular rainfall amounts or patterns or on particular target plant species. We discuss research perspectives contributing to a better understanding of seed dispersal, seedling recruitment, and soil processes and suggest the benefits of using ecosystem engineer species.

International audience; Mediterranean island biodiversity is threatened by invasive plants, especially by Carpobrotus species. Invasive plant control is a major management tool for the restoration of invaded areas, but the effect of Carpobrotus removal on arthropods is poorly understood. In this study, we evaluate how spider assemblages are influenced by Carpobrotus removal on a Mediterranean island. A Carpobrotus patch was manually uprooted, followed by litter removal between November 2011 and February 2012. A nearby site with native matorral vegetation and no management was also studied. Spider communities were sampled using pitfall traps two years before removal (2010–2011), and then every two years after, between 2013 and 2019. Vegetation at the Carpobrotus site changed from a dense mat of Carpobrotus to a diverse halophilous grassland with some chamaephytes, while it remained stable in the matorral. Spider species richness increased significantly after removal and significant changes in assemblage composition were observed between pre- and post-removal years with a high turnover rate, while spider assemblages remained relatively stable in the matorral. Litter-dwelling spiders with trap strategies like Oecobius navus were the most reduced by Carpobrotus removal, while foliage-dwelling spiders which forage on plants like Xysticus benefited the most, likely due to vegetation opening and diversification of microhabitats. The increase in bare ground cover favoured Aelurillus v-insignatus, Nomisia celerima and Zodarion elegans, which are characterized by an affinity for dry sunny environments. Invasive Carpobrotus removal induced a rapid change (7 years) in spider assemblages as well as an enrichment in taxonomic and functional diversities.

Ecological restoration (ER) of terrestrial ecosystems has become widespread in past decades. However, assessing its success is complex mainly due to the diversity of objectives pursued, actions undertaken but also statistical methods for treating data. We demonstrate here that, due to the heterogeneity of collected data, the success of restoration actions can be overestimated in meta-analyses. We advocate analyzing distinctly two types of actions in ER, those aiming at increasing an ecosystem attribute (e.g. species richness of a native plant species, ER+), and those aiming at decreasing it (e.g. invasive species cover, ER-). We also suggest that only one index for assessing the success of a restoration action is not enough. We propose here to complete RR (Remaining Recovery) by a novel index informing on 'what has been restored by comparison to what should have been recovered': the 'Achieved Restoration' index (AR)., EU´s Seventh Framework Program, REMEDINAL

International audience; Species of the genus Carpobrotus, or iceplant, are succulent mat‐forming perennial herbs often introduced for soil stabilization. They are common in coastal environments and may thus threaten island biodiversity. While their effects are well known on soils, plant communities and associated fauna, the effects of Carpobrotus control on vegetation recovery is poorly documented. The aim of the paper is to describe plant community trajectories after Carpobrotus removal.

International audience

The prevailing nature-based solution to tackle climate change is tree planting. However, there is growing evidence that it has serious contraindications in many regions. The main shortcoming of global tree planting is its awareness disparity to alternative ecosystem types, mainly grasslands. Grasslands, where they constitute the natural vegetation, may support higher biodiversity and a safer, soil-locked carbon stock than plantations and other forests. We suggest replacing “tree planting” by “restore native vegetation.” This improved action terminology reduces the risks of inappropriate afforestation and, by diversifying target ecosystem types, does not reduce but increases potential land area for nature-based climate mitigation.

International audience; Questions Seedling recruitment is a key step in any seed-based ecological restoration project. There is a controversial discussion (a) whether soil preparation is required to reduce competition of pre-existing vegetation, or whether vegetation cover facilitate seedling recruitment, and (b) whether grazing should be excluded in initial stages of grassland restoration to protect seedlings, because grazing exclusion may also favour competitive ruderal species. We set up a combined soil preparation and grazing experiment to evaluate the effect of both factors on seedling recruitment of seeds transferred from a species-rich donor site.Location Upper Durance valley, Hautes-Alpes, France.Methods The experiment was set up using a full factorial split-plot design with five replicate sites. The treatments included soil preparation (harrowed or not) and grazing (excluded or not). Seeds were transferred using plant material brushed in a non-degraded reference grassland. The individuals of all occurring species were counted on the restoration sites, and the survival and reproduction of two focal species, Bromopsis erecta and Rhinanthus alectorolophus, were recorded for three months.Results Soil preparation by harrowing reduced the density of spontaneously emerging species and increased the seedling density of species transferred from the donor site. Grazing had only a weak negative effect on the recruitment of transferred species. The main effect of both treatments on seedling survival was not significant, but a significant interaction indicated that the grazing effect depended on soil preparation, with a negative effect of grazing only in non-harrowed plots.Conclusions The reduction of competition by soil preparation before seed addition of brush material had a positive effect on the seedling recruitment of transferred species and can thus clearly be recommended in our study system. The weak negative effect of grazing may not always justify fencing costs.

Seed dispersal has key implications for community dynamics and restoration ecology. However, estimating seed rain (the number and diversity of seeds arriving in a given area) is challenging, and the lack of standardization in measurement prevents cross-site comparisons. Seed trap effectiveness and accuracy of seed sorting methods are key components of seed rain estimates in need of standardization. We propose and describe a standardized protocol for evaluating the effectiveness of two seed trap types (sticky and funnel traps) and the accuracy of a seed sorting method. We used widely available seeds (arugula, quinoa, sesame and sunflower) to produce a gradient of seed size, weight and colour. Proof-of-concept was tested in a tropical grassland, where traps were set for 30 days. Our results suggest that we underestimate dispersal of seeds with less than 2 mm width that can be easily mistaken for debris and soil particles or that fail to adhere to sticky traps. Seeds on sticky traps may be more vulnerable to removal by wind and rain, whereas seeds in funnel traps are more susceptible to decay. We found no evidence of observer bias on seed sorting for funnel trap samples. However, accuracy on seed sorting for funnel trap samples tended to decline for seeds with less than 2 mm width, suggesting a size-dependence in seed retrieval success. Our standardized protocol addressing trap effectiveness and seed sorting methods will increase the reliability of data obtained in seed rain studies and allow more reliable comparisons between datasets.

International audience; In restoration ecology, the reference ecosystem represents a key concept which is well defined from a theoretical point of view. In practice, however, selecting reference systems, such as reference plant communities, often lacks clear methodology. In order to facilitate this selection, we provide a framework based on ecological theory, and more precisely on relationships between vegetation and environmental factors, to identify reference plant communities. The four major steps are: (1) the delimitation of a geographical zone in which habitat types similar to restoration sites occur; (2) the identification of environmental factors structuring non-degraded plant communities within this geographical zone; (3) the comparison of the environmental factors between non-degraded and degraded sites; and (4) the selection of the non-degraded sites most similar to restoration sites in terms of environmental factors to use them as references. We concept-proved our approach by identifying reference communities using environmental factor combinations for five mountain grassland sites degraded by the construction of a high-voltage line. In a multivariate analysis of 18 non-degraded sites, we identified six major environmental factors explaining plant species compositions. A second multivariate analysis including degraded sites provided environmental distances of the 18 non-degraded to each of the degraded sites. The results demonstrated that the environmentally most similar sites were not necessarily the geographically closest ones. In conclusion, the analysis of regional plant-environment interactions provides an important tool to identify reference communities or source sites for seed transfer if not available adjacent to degraded habitats.

International audience; Mediterranean island biodiversity is threatened by invasive plants, especially by Carpobrotus species. Invasive plant control is a major management tool for the restoration of invaded areas, but the effect of Carpobrotus removal on arthropods has not been studied yet. In this study, we evaluate how beetle and spider assemblages are influenced by Carpobrotus removal on a Mediterranean island. A 0.5-ha Carpobrotus patch was manually uprooted followed by litter removal between November 2011 and February 2012. A nearby site with native matorral vegetation and no management was also studied. Beetle and spider communities were sampled using pitfall traps two years before removal (2010-2011), and then every two years after, between 2013 and 2019. Vegetation at the Carpobrotus site changed from a dense mat of Carpobrotus to a diverse halophilous grassland with some chamaephytes, while it remained stable in the matorral. Beetle and spider species richness increased significantly after removal and significant changes in assemblage composition were observed between pre-and post-removal years with a high turnover rate, while beetle and spider assemblages remained relatively stable in the matorral. Detritivore beetles (e.g. Asida dejeani and Arthrolips spp.) and predators (e.g. Oligota muensteri and Harpalus attenuatus) were the species most enhanced by the restoration. Netocia oblonga, a floricolous phytophage, was negatively impacted. Litter-dwelling spiders with trap strategy (e.g. Oecobius navus) were the most reduced by Carpobrotus removal, while ground-dwelling spiders with active hunting strategy (e.g. Xysticus spp.) benefited most likely from the diversification of plant microhabitats. The increase in bare ground cover favored Zodarion elegans, Nomisia celerima, and Linyphiids, which are characterized by an affinity for dry sunny environments. This rapid change in beetle and spider assemblages within seven years of invasive plant removal showed that these two groups can be useful bioindicators of restoration processes.

Made available in DSpace on 2020-12-12T01:36:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 The historical focus in research and policy on forest restoration and temperate ecosystems has created misunderstandings for the restoration of tropical and subtropical old-growth grassy biomes (TGB). Such misconceptions have detrimental consequences for biodiversity, ecosystem services, and human livelihoods in woodlands, savannas, and grasslands worldwide. Here, we demystify TGB restoration myths to promote a positive agenda to increase the likelihood of success of ambitious landscape-scale restoration goals of nonforest ecosystems. The 10 TGB restoration myths are: (1) grasslands originate from degraded forests, (2) tree cover is a reliable indicator of habitat quality, (3) planting trees is always good for biodiversity and ecosystem services, (4) grasslands are biodiversity-poor and provide few ecosystem services, (5) enhancing plant nutrition is needed in restoration, (6) disturbance is detrimental, (7) techniques used to restore temperate grasslands also work for TGB, (8) grasslands represent early stages of forest succession, (9) grassland restoration is only about grasses, and (10) grassland restoration is fast. By demystifying TGB restoration, we hope that policymakers, scientists, and restorationists come to understand and embrace the value of these ecosystems and are motivated to establish policies, standards, indicators, and techniques that enhance the success of TGB restoration. We must abandon misperceptions and misunderstandings of TGB ecology that result in ill-conceived policies and build an informed and compelling global ecosystem restoration agenda that maintains and improves the well-being of all inhabitants of grassy biomes. Departamento de Genética Ecologia e Evolução Instituto de Ciências Biológicas Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627 School of Biological Sciences University of Western Australia Department of Biological Sciences University of Cape Town Floresta Estadual de Assis Instituto Florestal do Estado de São Paulo, P.O. Box 104 Lab of Vegetation Ecology Instituto de Biociências Universidade Estadual Paulista (UNESP), Av. 24A, 1515 Centre for Functional Biodiversity School of Life Sciences University of KwaZulu-Natal Department of Plant Biology Institute of Biology University of Campinas—UNICAMP Departamento de Botânica Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500 Departamento de Ciências Ambientais (DCA) Instituto de Florestas (IF) Universidade Federal Rural do Rio de Janeiro—UFRRJ, BR 465, Km 07 Unit for Environmental Sciences and Management North-West University Department of Plant Sciences University of California Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE) Avignon Université UMR CNRS IRD Aix Marseille Université IUT Site Agroparc, BP 61207 Lab of Vegetation Ecology Instituto de Biociências Universidade Estadual Paulista (UNESP), Av. 24A, 1515

International audience; Questions: Giving a time advance to restored native plant species has recently been considered a promising way to improve their persistence and reduce invasion success (i.e., through priority effects). However, little is known about the influence of the elapsed time between seeding and invasion and its interaction with other characteristics such as species composition and density, despite the fact that it could substantially help developing effective management strategies. Methods: In a pot experiment, we simulated invasion by three major invasive species (Ambrosia artemisiifolia, Bothriochloa barbinodis, and Cortaderia selloana) in soil covered with recipient communities differing in species composition (one, three or nine species), density (700 or 2,778 seeds/m 2), and time advance (established one or five months previously). We assessed early invasion success by measuring seedling emergence and survival over six months. Results: Early invasion success was mainly explained by recipient community's time advance and composition (or their interaction), while density had limited influence. Polycultures (three or nine species) showed generally greater invasion resistance, most likely due to high above-ground biomass essentially produced by two species. Species composition interacted with time advance in two ways: (a) Bothriochloa barbinodis seedling emergence was impacted by composition only in communities having five months of advance, suggesting that the contribution of species composition to invasion resistance varies according to the age of the community, and (b) Ambrosia artemisiifolia and Cortaderia selloana survival was affected by time advance in polycultures only, which produced much more biomass than monocultures, implying that a greater head start provides a competitive advantage only if it allows a sufficient increase in biomass production. Conclusions: Implementing revegetation as soon as site clearance work is over, as well as establishing productive native species may help reduce invasion success. How much of an advantage recipient community time advance represents depends on biomass production.

International audience; Questions: Anthropogenic disturbances are known to be followed by extremely poor recovery in edaphic grasslands. However, the role of interactions with diaspore predators and secondary dispersers, which compose the dispersal filter and modulate plant community recovery, has been overlooked. We performed field experiments to investigate how soil disturbances affect diaspore interactions with the ground‐foraging fauna to better understand how disturbance influences regeneration potential.Location: Campo rupestre vegetation, megadiverse edaphic grasslands, southeastern Brazil.Methods: We used diaspores from five native species to compare removal rates between disturbed (top soil removal) and preserved sites; we also controlled invertebrate and vertebrate access to determine their role. In addition, we assessed differences in the diaspore removal effectiveness (DRE) and the structure of animal–diaspore interactions through network based‐approach.Results: For three species, the average diaspore removal rates was relatively high (between 30% and 70%). Invertebrates were the most common removal agents in both disturbed and preserved sites. Interactions with foraging fauna and removal rates were 20% smaller in disturbed sites. Considering all diaspore removal events in disturbed sites, 24% resulted in the displacement from disturbed to preserved sites, but no diaspore was transported from preserved to disturbed ones. The animal–diaspore network was exclusively composed by ant–diaspore interactions and was more diverse and robust in preserved sites compared with disturbed ones. Seed predator ants (Pheidole and Dorymyrmex) were more common in disturbed sites. Furthermore, significant differences were found in the DRE between ant species and site types, suggesting specificity in the provision of dispersal services.Conclusions: Topsoil removal affected removal proportions, DRE and ant–diaspore interaction network structure. The lack of diaspore dispersal towards disturbed sites indicates that soil removal affects secondary seed removal dynamics, impeding recovery potential. Disturbance negatively affected diaspore fate by reshaping interactions with ground‐foraging secondary seed dispersers and predators, constraining the development of seed bank and thus impacting upon vegetation dynamics and resilience.

Despite growing recognition of the conservation values of grassy biomes, our understanding of how to maintain and restore biodiverse tropical grasslands (including savannas and open-canopy grassy woodlands) remains limited. To incorporate grasslands into large-scale restoration efforts, we synthesised existing ecological knowledge of tropical grassland resilience and approaches to plant community restoration. Tropical grassland plant communities are resilient to, and often dependent on, the endogenous disturbances with which they evolved - frequent fires and native megafaunal herbivory. In stark contrast, tropical grasslands are extremely vulnerable to human-caused exogenous disturbances, particularly those that alter soils and destroy belowground biomass (e.g. tillage agriculture, surface mining); tropical grassland restoration after severe soil disturbances is expensive and rarely achieves management targets. Where grasslands have been degraded by altered disturbance regimes (e.g. fire exclusion), exotic plant invasions, or afforestation, restoration efforts can recreate vegetation structure (i.e. historical tree density and herbaceous ground cover), but species-diverse plant communities, including endemic species, are slow to recover. Complicating plant-community restoration efforts, many tropical grassland species, particularly those that invest in underground storage organs, are difficult to propagate and re-establish. To guide restoration decisions, we draw on the old-growth grassland concept, the novel ecosystem concept, and theory regarding tree cover along resource gradients in savannas to propose a conceptual framework that classifies tropical grasslands into three broad ecosystem states. These states are: (1) old-growth grasslands (i.e. ancient, biodiverse grassy ecosystems), where management should focus on the maintenance of disturbance regimes; (2) hybrid grasslands, where restoration should emphasise a return towards the old-growth state; and (3) novel ecosystems, where the magnitude of environmental change (i.e. a shift to an alternative ecosystem state) or the socioecological context preclude a return to historical conditions.

International audience; 1. The control of invasive species is a central topic of both applied and theoretical research. Understanding h o w a nd whi ch ecological theories can be used to improve invasion resistance of plant communities is essential, to design effective control strategies. 2. The theory of limiting similarity, stating that coexistence between species is more limited by competitive exclusion when species share niche properties, is often considered by applied ecologists as a possible approach to limiting plant invasions at the local scale. 3. The complexity of measuring ecological niche overlap between species as well as the difficulty of disentangling niche from fitness processes currently limit the demonstration and application of this theory. Limiting similarity appears to operate at a timescale that is too long for efficient impact on invasive species' early establishment. It may also be ineffective against invasions in the long term, due to environmental changes and community instability. Finally, limiting similarity is not applicable to the most common situations, where there are multiple co-occurring invasive species or no prior identification of potential invasives. 4. Synthesis and applications. Whether the theory of limiting similarity, predicting competitive exclusion when species display niche similarities, can be successfully applied to limit plant invasions-or not-is an important issue for practitioners facing invasive species. In practice, using limiting similarity to design invasion-resistant plant communities appears to be complex, ineffective and unsuitable for most common situations.

Species dispersal, establishment, and assembly are crucial stages of the life history of plants, and clear understanding of the governing forces and rules that shape species composition in a particular community is vital for successful ecological restoration. In this article, we focus on five aspects of seed dispersal and plant establishment, which should be considered during habitat restoration actions. In the first two sections, we discuss the success of spontaneous dispersal and establishment on restoration based on either spatial dispersal or local seed banks. In the third section, we assess the possibilities of species introduction and assisted dispersal. In the fourth section, we introduce some possibilities for the improvement of establishment success of spontaneously dispersed or introduced species. Finally, we highlight issues influencing long‐term persistence and sustainability of restored habitats, related to the alteration of management type and intensity, climate change, and spread of non‐native species. With the present article, we introduce the special issue entitled “Seed dispersal and soil seed banks – promising sources for ecological restoration” containing 15 papers by 62 authors from 10 countries arranged in the abovementioned five topics.

Old‐growth grasslands, including savannas and tropical grasslands, need centuries to assemble; they are therefore expected to have low resilience to anthropogenic activities that disturb the soil (e.g. cultivation, quarrying, mining, etc.). Understanding which parameters restrict the natural recovery of degraded ecosystems is a major prerequisite for planning an effective restoration program. This study was designed to evaluate the recovery of an old‐growth grassland, the campo rupestre, after a major disturbance: gravel extraction. In 2010 (i.e. 8 years after the degradation), we analyzed soil characteristics, seed bank, and vegetation composition in degraded sites consisting of sandy or gravel substrates, as well as in reference sites of sandy and gravel grasslands. At degraded sites, soils contained lower concentrations of the main nutrients, and seed banks consisted mainly of nontarget species. Seed banks of reference grasslands were poor in species and in seeds. Eight years after the degradation, plant communities at degraded sites were still very different from those at the reference sites, with ruderals and almost no target species. Altered soil conditions, low capacity of campo rupestre species to form seed banks, and the probable restriction of seed dispersal from the target species in nearby campo rupestre considerably limited the establishment of campo rupestre plant communities in degraded areas. Time is essential for old‐growth grassland assemblage and, even with the presence of a propagule source in the surroundings, the assembly of campo rupestre plant communities in degraded sites will take centuries. Therefore, human intervention is necessary to rapidly reestablish the main species.

Restoration success of species-rich grasslands is often limited by low seed dispersal. To reintroduce target species of local provenances, bulk topsoil transfer is performed by excavating soil and vegetation from donor sites and spreading these on receptor sites. Our first objective was to determine the most advantageous season for transferring topsoil in Mediterranean grasslands. The second objective was to assess which treatmentcombination of season (spring or autumn) and transfer ratio (1:1 or 1:3)-performed best in restoring a Mediterranean grassland through bulk topsoil transfer after two large restoration projects. Just-in-time soil transfer (i.e. with no stockpiling) was implemented: (1) on a former 3ha orchard where topsoil was spread after removing trees and leveling soil; and (2) after a 5ha oil pipeline leak where polluted soil was removed prior to treatment (soil horizons were reconstituted). A seed bank study showed that the summer seed bank contained higher seed densities, species richness, and similarity to the reference site than the spring seed bank. Spring transfers gave better results than autumn transfers in terms of species richness and composition similarity with the reference site, while transfer ratios gave similar results. Long-term success was not driven by season or transfer ratio but by the underlying seed bank at receptor sites: the former orchard's weed-containing seed bank hampered topsoil transfer success. This study also suggests that restoration success cannot be deduced from seed bank studies alone, as species establishment is highly dependent on differences in growing conditions (including competition at receptor sites).

A microwave‐based process to control invasive species (seeds and adult stages) in the field prior to plant community restoration is currently under development. We investigated the effect of four microwave treatment pairings of Power × Duration (2kW4min, 4kW2min, 2kW8min, and 4kW4min) on seedling emergence of (1) an abandoned field seed bank used as a model for various plant species and (2) seeds of three species invasive in Europe: Datura stramonium (Jimson weed), Reynoutria × bohemica (Bohemian knotweed), and Solidago gigantea (Giant goldenrod). In addition, we assessed whether nontreated seeds of these three invasive species could germinate on microwave‐treated soils. As microwave soil heating usually leads to nonhomogeneous temperatures within a sample, we also assessed whether the position of seeds in the soil during microwave treatment (center vs. edges) impacted seedling emergence. Results show that the most intensive microwave treatments (2kW8min and 4kW4min), enabling the soil to reach 85°C, are highly effective in inhibiting seedling emergence of invasive species and the seed bank. The 2kW8min treatment, combining lowest power and longest exposure, is the most effective, reducing seed bank seedling emergence by 98% compared to control. The results also reveal a species‐specific response to heat, and lower microwave effectiveness on seeds located at the soil surface, which may explain the incomplete effectiveness of intensive treatments. Our results also suggest that prior microwave soil treatment does not prevent a considerable proportion of newly arrived invasive species seeds from germinating, suggesting that this method should be followed by restoration of native plant cover.

Ecological restoration has developed greatly over recent decades. Promoting harmonious relationships between scientists and practitioners, between restoration ecology and ecological restoration, is essential to improving restoration projects. These relationships are difficult to achieve at a global scale, although international action remains essential. Therefore, regional and national networks are attempting to take up the challenge. With several European countries planning to create their own network in the coming years, insights from current practice are helpful. Here, we (1) describe the context in which ecological restoration is developing in France and (2) present the French restoration network, Reseau d'Echanges et de Valorisation en Ecologie de la Restauration (REVER). Most public policies related to restoration in France are derived from European Union (EU) directives, such as those on water, ecological networks, biodiversity, and protected species and natural habitat. Restoration can also be undertaken through Environmental Impact Assessment (EIA) or subsequent to damage. Following the model of the International Society for Ecological Restoration, the French network for ecological restoration (REVER) aims at accompanying and promoting restoration by facilitating relationships between the various stakeholders: practitioners, scientists, site managers, etc. To encourage exchange of knowledge and experience, REVER manages a website, organizes workshops, and provides links with SER‐Europe and Society for Ecological Restoration International (SERI). This article provides information that will be of interest to other countries trying to meet the Aichi targets of the convention on biological diversity: the restoration of 15% of degraded ecosystems by 2020.

Invasive species management (eradication or control) can be used to promote native plant restoration. The objective of this study is to evaluate different treatments to guide the selection of future modalities for the eradication (i.e. elimination of all individuals in a population) of Carpobrotus sp. from a strict nature reserve. Two removal methods were tested: (1) living Carpobrotus removal; (2) living Carpobrotus and litter removal. To assess the effectiveness of each treatment, we studied the recolonization of native vegetation, the recolonization of Carpobrotus, and soil erosion and compared these metrics to those taken in native vegetation and in patches of intact Carpobrotus. We also tested the capacity of a 50-cm-wide Carpobrotus strip to retain soil. The removal of Carpobrotus together with its litter led to high rates of soil erosion. The Carpobrotus strips were found to retain the soil rather well. Removing live Carpobrotus while leaving its litter in place reduced soil erosion and led to higher native plant species recolonization. The composition of the vegetation 10 months after applying the treatments was biased in favor of native pioneer species. These are typically the first species to establish (Aetheoriza bulbosa and Arisarum vulgare resprouted, Frankenia hirsuta and Lotus cytisoides germinated, and Sonchus sp. benefited from long-distance dispersal). Few weedy species were recorded (e.g. Sonchus asper asper). Whatever the treatment, the risk of reinvasion from the seed bank or from resprouting stems is nonnegligible, so long-term monitoring is vital to the ultimate success of the eradication program.

Tropical grassy biomes have been widely neglected for conservation and, after unplanned land use conversion, ecological restoration becomes urgent. The majority of interventions have been based on the misapplication of forest restoration techniques, because there are no validated techniques to restore the species-rich ground layer. In search for innovative techniques to restore the herbaceous layer of the cerrado vegetation, we carried out an experiment based upon topsoil and hay transfer, in the state of Sao Paulo, Brazil. The restoration treatments were: (1) transfer of topsoil collected at the end of the dry season; (2) topsoil collected at the end of the rainy season; (3) transfer of hay collected at the end of the dry season; (4) topsoil + hay collected at the end of the dry season; and (5) control. We used an old-growth grassland as source of material and as reference ecosystem to assess the efficacy of the restoration techniques applied to an area severely degraded after invasion by African grasses. After 211 days, hay transfer apparently inhibited germination and did not contribute to grassland vegetation recovery. Topsoil transfer, however, was effective at reintroducing herbaceous plants, including target species. The season of topsoil collection mattered: material collected at the end of the rainy season provided better results in terms of density and richness of the restored community than that from the dry season. The remaining challenge is to find sources of topsoil not invaded by exotic grasses in large enough amounts to support restoration initiatives without jeopardizing the source ecosystems.

While phenology data (the timing of recurring biological events) has been used to explain and predict patterns related to global change, and to address applied environmental issues, it has not been clearly identified as pertinent for restoration. This opinion article thus aims to raise awareness of the potential of phenology to enhance the quality of restoration projects and ecological restoration theory. We based our analysis on a systematic literature survey carried out in February 2014, searching the words “phenology” or “phenological” in books dealing with restoration, the term “phenolog*” in the journal Restoration Ecology, and the terms “restoration” and “phenolog*” in the database Web of Science until February 2014. We finally selected 149 studies relevant to our goals, and first classified them according to the context in which phenology was addressed. We then analyzed them within the framework of the five key steps of restoration projects: (1) the reference ecosystem; (2) biotic resources; (3) restoration methods; (4) monitoring; and (5) adaptive management. The literature survey showed that phenological information improved decision-making in the few restoration projects in which it was incorporated. We thus advocate taking phenological data into account at all stages of restoration when appropriate: from the acquisition of baseline data on the reference ecosystem to treatment design, and from restoration action planning and timing to monitoring. Phenological data should at minimum be collected for sown, keystone, dominant, and/or rare species to improve restoration quality. Phenology studies and monitoring should be promoted in future restoration guidelines.

International audience; Biological invasions have reached an unprecedented level and the number of introduced species is still increasing worldwide. Despite major advances in invasion science, the determinants of success of introduced species, the magnitude and dimensions of their impact, and the mechanisms sustaining successful invasions are still debated. Empirical studies show divergent impacts of nonnativepopulations on ecosystems and contrasting effects of biotic and abiotic factors on the dynamics of non-native populations; this is hindering the emergence of a unified theory of biological invasions. We propose a synthesis that merges perspectives from population, community, and ecosystem levels. Along a timeline of ecosystem transformation driven by nonnative species, from historical to human-modified ecosystems, we order invasion concepts and theories to clarify their chaining and relevance during each step of the invasion process. This temporal sorting of invasion concepts shows that each concept is relevant at a specific stage of theinvasion. Concepts and empirical findings on non-native species may appear contradictory. However, we suggest that, when mapped onto an invasion timeline, they may be combined in a complementary way. An overall scheme is proposed to summarise the theoretical dynamics of ecosystems subjected to invasions. For any given case study, this framework provides a guide through the maze of theories and should help choose the appropriate concepts according to the stage of invasion.

Bastin et al.’s estimate (Reports, 5 July 2019, p. 76) that tree planting for climate change mitigation could sequester 205 gigatonnes of carbon is approximately five times too large. Their analysis inflated soil organic carbon gains, failed to safeguard against warming from trees at high latitudes and elevations, and considered afforestation of savannas, grasslands, and shrublands to be restoration., Funding: Supported by the Texas A&M Sid Kyle Global Savanna Research Initiative (T.W.B.); Swiss National Science Foundation (20FI20_173691) (N.B.); Centre National pour la Recherche Scientifique CNRS PICS 2018-2020 (RESIGRASS) (E.B.); CNPq (Brazil, 303179/2016-3) (G.D.); CNPq (Brazil) (G.W.F.); CNPq (Brazil, 303988/2018-5) (A.F.); NASA award NNX17AK14G (F.F.); NSF award 1354943 (W.A.H.); Fundação de Amparo à Pesquisa do Estado de Minas Gerais (Brazil, 2016/13232-5) (S.L.S.); the Office of the Royal Society (IC170015) (C.E.R.L.); CNPq (Brazil, 310345/2018-9) (G.E.O.); the Spanish Government (FIROTIC, PGC2018-096569-B-I00) (J.G.P.); the National Research Foundation (ACCESS, 114695) (N.S.); CNPq (Brazil, 303568/2017-8) (F.A.O.S.); NSF awards 1342703 and 1926431 (C.J.S. and D.M.G.); NSF award EAR-1253713 (C.A.E.S.); Deutsche Forschungsgemeinschaft grant 5579 POEM (V.M.T.); and USDA-NIFA Sustainable Agricultural Systems Grant 12726253 (J.W.V.)