Biodiversity fosters the functioning and stability of forest ecosystems and, consequently, the provision of crucial ecosystem services that support human well-being and quality of life. In particular, it has been suggested that tree species diversity buffers ecosystems against the impacts of disturbances, a relationship known as the "insurance hypothesis". Natural disturbances have increased across Europe in recent decades and climate change is expected to amplify the frequency and severity of disturbance events. In this context, mitigating disturbance impacts and increasing the resilience of forest ecosystems is of growing importance. We have tested how tree species diversity modulates the impact of disturbance on net primary production and the total carbon stored in living biomass for a temperate forest landscape in Central Europe. Using the simulation model iLand to study the effect of different disturbance regimes on landscapes with varying levels of tree species richness, we found that increasing diversity generally reduces the disturbance impact on carbon storage and uptake, but that this effect weakens or even reverses with successional development. Our simulations indicate a clear positive relationship between diversity and resilience, with more diverse systems experiencing lower disturbance-induced variability in their trajectories of ecosystem functioning. We found that positive effects of tree species diversity are mainly driven by an increase in functional diversity and a modulation of traits related to recolonization and resource usage. The results of our study suggest that increasing tree species diversity could mitigate the effects of intensifying disturbance regimes on ecosystem functioning and improve the robustness of forest carbon storage and the role of forests in climate change mitigation.

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Questions Tree species diversity is widely reported to positively influence forest productivity. Yet, a consistent attribution of productivity effects is complicated by the fact that compositional and structural diversity are often related in forest ecosystems. Here, our objective was to disentangle the effects of diversity in species and structures on forest productivity. We further assessed whether the influence of structure and composition on productivity changes over the course of forest development. Location Hainich National Park, central Germany. Methods We conducted a factorial simulation experiment in which 63 unique combinations of six different tree species were studied over 500 yr of forest development. The model used was iLand, a process‐based simulator operating at individual tree resolution. The indicators of compositional diversity considered included species richness, entropy, evenness and identity, while structural diversity was characterized by indicators describing vertical and horizontal stand structure. Net primary production (NPP) was studied as the response variable, and random forest analysis was used to synthesize simulation output. Results We found positive effects of both compositional and structural diversity on productivity, but their influence changed distinctly over the course of forest development. In early‐seral stages, diversity effects on NPP were dominated by aspects of tree species composition, and displayed a strong positive selection effect for European beech (Fagus sylvatica L.). In later stages of forest development, diversity effects on NPP were dominated by structural diversity, with productivity increasing with increased variation in tree diameter and canopy complexity. Conclusion To better understand the effects of diversity on ecosystem functioning, both the compositional and structural dimensions of diversity in forest ecosystems (and their changes over time) need to be considered. In the context of ecosystem management our results suggest that the reduction in productivity associated with the loss of a canopy tree species (e.g. due to the invasion of an alien pest species) can to some degree be compensated through increased structural diversity. Fostering both compositional and structural diversity are important means to increase the robustness of forest ecosystem functioning.

& Context Maritime Pine forests cover important mountain areas in Portugal and are known to be a particularly fireprone forest type. Understory composition plays an important role in maintaining biodiversity and ecosystem services after recurrent wildfires. & Aims This study aims to improve the knowledge on the germination ecology of understory species of Maritime Pine forests, focusing on the importance of seed provenance, including in relation to germination enhancement by heating. & Methods The selected species were Cistus ladanifer L., Erica australis L., Erica umbellata L., Pterospartum tridentatum L. (Willk), and Genista triacanthos Brot. Seeds were collected from two or three distant populations. Besides a control treatment, two heating regimes were applied, i.e., 100°C during 5 min and 80°C during 30 min. & Results Heating treatments significantly enhanced germination in four out of the five species. Differences between provenances were most evident for C. ladanifer and E. australis, especially following the heating treatments. Overall, the seeds from the southern provenances germinated better and, at the same time, were smaller. & Conclusion The present results confirmed that seed provenance should not be ignored as a key factor in germination ecology, so that further work is needed to untangle the roles of environmental and genetic factors in the observed differences between provenances.

BackgroundThe coronavirus disease 2019 outbreak has led to social isolation, with the potential to increase depressive symptoms, even at the pediatric age. Before the COVID-19 pandemic, the rate of depressive symptoms in large youth cohorts was 12.9% worldwide. AimsThis study aims to characterize the impact of the COVID-19 pandemic on the pediatric population's mental health. Materials and methodsThis was an observational, descriptive, and cross-sectional study conducted through the use of a questionnaire, including the Children's Depression Inventory (CDI), between April 5 and May 5, 2021. The study was conducted on children and adolescents aged 7 to 17 years old in a school in the geographical area of a Portuguese grade II hospital. Incomplete data were excluded. Data were statistically analyzed using the IBM SPSS® program (version 28; IBM Corp., Armonk, NY), considering statistical significance if p<0.05. ResultsA total of 228 children and adolescents were included; 113 were female (49.6%). The average age of the population was 12.2 years. Fifteen point four percent (15.4%) had depressive symptoms, of which 51,9% were female. Of the children and adolescents with depressive symptoms, 5.7% had a personal history of past COVID-19 infection and 42.9% had at least one family member with a history of past COVID-19 infection. Seventeen point one percent (17.1%) had at least one family member involved in pandemic-related work. Children and adolescents who were infected with COVID-19 had more depressive symptoms than noninfected children and adolescents (p=0.013). At the same time, children and adolescents, with at least one family member with a history of past COVID-19 infection, had more depressive symptoms than children and adolescents without a family history of past COVID-19 infection (p=0.004). Children and adolescents with a family member involved in pandemic-related work had more depressive symptoms than children and adolescents without any family member involved in pandemic-related work (p=0.004). ConclusionsCOVID-19 infection, whether personal or familiar, has an impact on mental health, even in the pediatric age, and it is imperative to know the consequences of emotional and mental changes in this population.