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Roughly 2 billion ha of land are degraded and in need of ecological restoration worldwide. Active restoration frequently involves revegetation, which leads to the dilemma of whether to conduct direct seeding or to plant nursery-grown seedlings. The choice of revegetation method can regulate plant survival and performance, with economic implications that ultimately feed back to our capacity to conduct restoration. We followed a peer-reviewed protocol to develop a systematic map that collates, describes and catalogues the available studies on how seeding compares to planting in achieving restoration targets. We compiled a database with the characteristics of all retrieved studies, which can be searched to identify studies of particular locations and habitats, objectives of restoration, plant material, technical aspects, and outcomes measured. The search was made in eight languages and retrieved 3355 publications, of which 178 were retained. The systematic map identifies research gaps, such as a lack of studies in the global South, in tropical rainforests, and covering a long time period, which represent opportunities to expand field-based research. Additionally, many studies overlooked reporting on important technical aspects such as seed provenance and nursery cultivation methods, and others such as watering or seedling protection were more frequently applied for planting than for seeding, which limits our capacity to learn from past research. Most studies measured outcomes related to the target plants but avoided measuring general restoration outcomes or economic aspects. This represents a relevant gap in research, as the choice of revegetation method is greatly based on economic aspects and the achievement of restoration goals goes beyond the establishment of plants. Finally, we identified a substantial volume of studies conducted in temperate regions and over short periods (0–5 y). This research cluster calls for a future in-depth synthesis, potentially through me, Ministerio de Ciencia, Innovación y Universidades, Ministerio de Universidades, Ministerio de Ciencia e Innovación (MICIN), Junta de Andalucía, Depto. de Biodiversidad, Ecología y Evolución, Fac. de Ciencias Biológicas, TRUE, pub

We define societal disturbances as discrete events that abruptly disrupt the functioning of human societies. There is a variety of such events, including hurricanes, floods, epidemics, nuclear accidents, earthquakes and wars, among others. These disturbances can interact, further increasing their impacts. The severity of disturbances does not only depend on their intrinsic properties (type, intensity and magnitude) but also greatly on human aspects (socioeconomic, historical, political and cultural aspects that define vulnerability). Very large or severe disturbances are infrequent and unpredictable. Yet societal disturbances are intrinsic to human societies; they have occurred through the entire human history and will continue to occur in the future. We can increase preparedness and recovery capacity but cannot avoid disturbances. The type, regime and scale of disturbances change with the development of societies. The increase in population density and complexity also increases the severity of many disturbances. Societal disturbances can temporarily disrupt the functioning of societies. However, when those disturbances are frequent, societies adapt to them and thus disturbances contribute to shape cultural evolution. That is, societal disturbances have a cost at short temporal scales, but they can build up resilience at mid- to long-term scales. Understanding this dynamic view of human systems is becoming more important as climate is changing, humans are overexploiting natural resources and humanity is dense and hyperconnected. We need to take advantage of frequent small disturbances, as they can build resilience and reduce the likelihood of infrequent large and severe disturbances. Our challenge is to encourage actions and policies to be prepared for unknown, unpredictable and unprecedented (infrequent) large-scale societal disturbances that will surely arrive.

Grassroots movements such as the Trillion Tree Campaign (1) and international policies such as the EU Biodiversity Strategy for 2030 (2) aim to mitigate climate change through ambitious tree planting objectives. However, tree planting targets could produce counterproductive side effects (3), including an increase in the amount and continuity of fuels, a key driver of large fires in a warming world (4, 5). Drier weather, coupled with afforestation dominated by extensive, dense, even-aged, monospecific conifer or eucalypt plantations, has already promoted megafires in places like Chile and Portugal (6), and burnt areas are more likely to reburn when postfire management includes extensive reforestation instead of natural regrowth (7). Reforestation programs should prioritize the mitigation of fire risks.

The choice of revegetating via direct seeding or planting nursery-grown seedlings influences the potential stresses suffered by seedlings such as herbivory and drought. The outcome of the balance between both revegetation methods may ultimately depend on how species identity and traits such as seed and seedling size interact with environmental conditions. To test this, we will conduct a continental-scale experiment consisting of one mini-experiment replicated by multiple participants across Europe. Each participant will establish a site with seeded and planted individuals of one or more native, locally growing oak (Quercus) species; the selection of this genus aims to favour continental-scale participation and to allow testing the response of a widely distributed genus of broad ecological and economic relevance. At each site, participants will follow the present protocol for seed collection, seeding in the field, nursery cultivation, outplanting, protection against herbivores, site maintenance, and measurement of seedling performance and environmental variables. Each measurement on each species at each site will produce one effect size; the data will be analysed through mixed-effects meta-analysis. With this approach we will assess the main effect of revegetation method, species, plant functional traits, and the potential effect of site-specific effect moderators. Overall, we will provide a continental-scale estimate on the seeding vs. planting dilemma and analyse to what extent the differences in environmental conditions across sites, seed size, functional traits, and the phylogenetic relatedness of species can account for the differences in the effect of revegetation method on seedling performance across study sites and species., La elección del método de revegetación (siembra directa o plantación) puede delimitar el éxito de los proyectos de restauración influyendo significativamente en la resistencia de las plantas al estrés hídrico y a la herbivoría. Las diferencias de éxito entre ambos métodos dependerá de la interacción entre las características funcionales de las especies, como el tamaño de las plantas y las semillas, y las condiciones ambientales. Sin embargo, no existen hasta la fecha estudios que hayan comparado ambos métodos con metodologías estandarizadas y a lo largo de grandes gradientes ambientales. Este trabajo establece la metodología y el diseño experimental para llevar a cabo un estudio a escala paneuropea sobre el éxito de proyectos de restauración con especies de quercíneas comparando la siembra directa con la plantación. Los resultados de este estudio aportarán soluciones específicas para la restauración de distintos ambientes a escala continental y analizarán cómo las condiciones ambientales de los sitios experimentales y las propias características de las especies pueden condicionar el éxito de ambos métodos de revegetación., Ministerio de Ciencia e Innovación (MICINN)/FEDER, Depto. de Biodiversidad, Ecología y Evolución, Fac. de Ciencias Biológicas, TRUE, pub

Questions: Do burn severity and soil chemistry drive species and trait composition on recently burned clear-cuttings? Does the spatial distribution of common, easily dispersed colonizers vary with distance to fire perimeter? Location A 13,000 ha production forest landscape in boreal southern Sweden burned in a wildfire in 2014. Methods: Vascular plants and bryophytes were recorded in permanent plots on clear-cuts two and five years following fire, covering a burn severity gradient. Soil carbon content (reflecting burn severity), pH and nutrients were measured at plot level. Trait data were retrieved from the BIEN and LEDA databases and analyzed using community-weighted mean (CWM) trait values. Statistical analyses included generalized linear mixed models (GLMMs), non-metric multidimensional scaling (NMDS) and multivariate ANOVA. Results: Low burn severity resulted in higher frequency of legacy species (e.g. Vaccinium myrtillus), while high burn severity facilitated colonizing species (e.g. Senecio sylvaticus). Vegetation varied with soil chemistry, expressed through pH. Species composition changed between years and deviated from unburned clear-cuts. After five years the most common taxa on burned plots were the vascular plants Chamaenerion angustifolium, Betula spp. and Populus tremula and the bryophytes Ceratodon purpureus and Polytrichum juniperinum. CWM specific leaf area (SLA) decreased markedly with time and root buds increased with total carbon content in the soil (i.e., toward less severely burned plots), while soil pH was not associated with any studied trait. Chamaenerion angustifolium decreased with distance to the fire perimeter, while Ceratodon purpureus increased. Conclusions: Burn severity and soil pH weakly drive vegetation dynamics in the early phase following fire on clear-cuts, indicating a large influence of stochastic processes. Deciduous trees are common already after five years and their further expansion will affect light and nutrient availabi

A recent warning to humanity signed by >15 000 scientists identified global environmental threats that require urgent policy response from world leaders (Ripple et al 2017). Here, we document challenges and propose solutions related to ongoing shifts in natural disturbance regimes, which are both a cause and a consequence of major environmental perils. We propose the development of new disturbance management plans based on novel policies for land management, biodiversity conservation, and ecosystem restoration, which accommodate forecasted disturbance regime shifts and expected ecosystem responses.