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Overview of the four reviewed global change drivers (warming, drought, air pollution and biological invasions), their interaction with forest canopies, key‐canopy characteristics and sub‐canopy environmental conditions addressed in this paper. Forest elements by macrovector on Freepik.
Source publication
Via sheltering, decoupling and buffering mechanisms, tree canopies have the capacity to mitigate impacts of multiple global‐change drivers on below‐canopy processes and organisms in forests. As a result, canopies have an important potential as nature‐based solution.
The optimal combinations of forest canopy structural attributes to jointly mitigate...
Citations
... Canopy closure is a decisive stage of forest development. The development of the canopy stabilizes the microclimatic conditions, decreases light availability, and alters nutrient inputs on the forest floor (Figure 1b, arrow 3) (Verheyen et al. 2024). At this stage, soil inoculations may be less targeted at the introduction of tree microbial symbionts but can be used to promote the establishment of larger soil organisms augmenting the restoration potential, in particular for those that need specific abiotic conditions different from the harsh environment of bare cropland soil. ...
Afforestation is increasingly recognized as a critical strategy to restore ecosystems and enhance biodiversity on post‐agricultural landscapes. However, agricultural legacies, such as altered soil structure, nutrient imbalances, and depleted microbial diversity, can slow down forest establishment or cause ecosystems to deviate from expected successional trajectories. In this opinion paper, we explore the potential of soil inoculations as a tool to overcome these challenges by introducing beneficial microbial communities that can accelerate ecosystem recovery and forest development. Restoring soil biodiversity is a crucial aspect of this process that drives broader ecosystem functionality and resilience. We highlight the need to carefully consider the type and timing of inoculations and to ensure compatibility between the inoculum and recipient site characteristics to optimize the establishment of introduced species. While tree productivity is often a central focus of afforestation efforts, the restoration of soil biodiversity, which will also contribute to increased ecosystem‐level functions, should also be a priority for long‐term forest resilience. Agricultural legacies add complexities to the restoration process, creating unique challenges that need to be addressed in restoration planning. Thus, successful inoculation strategies require a thorough understanding of both donor and recipient site characteristics, also in relation to potential mismatches related to soil physiochemical properties to avoid unintended consequences such as the non‐establishment of introduced species. Additionally, we call for the re‐evaluation of afforestation targets and the development of standardized monitoring protocols that track the success of inoculation efforts, particularly regarding soil health, microbial community establishment, and biodiversity recovery. By integrating inoculation practices within a broader restoration framework, we can enhance the resilience, biodiversity, and ecosystem functionality of newly afforested landscapes. Ultimately, this approach may play a critical role in ensuring the success of large‐scale afforestation projects.
... Forests are increasingly being recognized as a nature-based solution in addressing the climate crisis [1][2][3]. Forests absorb carbon dioxide (CO 2 ) through photosynthesis, storing it in above-or below-ground biomass, with additional carbon deposited in soil, leaf litter, and deadwood. However, when forests are degraded or deforested, the stored carbon is released back into the atmosphere. ...
The REDD+ framework (Reducing Emissions from Deforestation and Forest Degradation, along with sustainable forest management and the conservation and enhancement of forest carbon stocks in developing countries) incentivizes developing countries to reduce greenhouse gas emissions and enhance carbon storage by mitigating deforestation and forest degradation. To receive results-based payments, participating countries must meet United Nations Framework Convention on Climate Change (UNFCCC) requirements for Measurement, Reporting, and Verification (MRV) capacities. This study categorizes developing countries into three phases based on MRV implementation levels: phase 1 (readiness), phase 2 (demonstration), and phase 3 (implementation). Unlike the higher implementation levels observed in phase 2 and phase 3 countries, phase 1 countries have received limited attention due to their early stages of REDD+ implementation. However, assessing the potential of these countries for future REDD+ engagement and Internationally Transferred Mitigation Outcome (ITMO) collaboration is crucial for achieving REDD+ goals. Thus, this study quantitatively assessed MRV capacity among phase 1 countries using an MRV capacity assessment tool, with the goal of identifying high-potential candidates for REDD+ advancement. We applied an MRV capacity assessment tool to 48 phase 1 countries out of the 71 developing countries registered on the REDD+ web platform as of September 2024. The results reveal that (1) the countries with the highest MRV scores were Ghana, India, Guatemala, Liberia, and Mongolia, with Ghana demonstrating strong potential for progression to the implementation phase due to its robust performance in both Measurement and Reporting components. In contrast, Chad scored the lowest, followed by Uruguay, Namibia, Mali, Cuba, and Benin. (2) Overall, phase 1 countries scored lower in the Reporting (R) component, which emphasizes administrative capacity, compared to the Measurement (M) component, which is technically oriented, highlighting the need for improved administrative capacity, particularly in developing and submitting the National Strategy/Action Plan and Safeguard Information System report to meet Cancun Agreement standards. While this study evaluates REDD+ implementation potential in phase 1 countries based on MRV capacity, future research should explore the effectiveness of strengthening MRV capacity through Official Development Assistance (ODA), assessing potential emissions reduction and ITMO potential.
... NbS is the high degree of context dependency in ecological systems (Catford et al., 2022;Dee et al., 2023). to climatic stressors, and their relative importance, trade-offs and synergies, is urgently needed so that site specific advice for locally effective solutions can be provided (Verheyen et al., 2024). ...
... As exemplified in this Special Feature, current knowledge on the impact of some plant functional traits on microclimate can be used to create plant communities that are more resistant and resilient to climate change(Wright & Francia, 2024). Similarly, knowledge on forest canopy attributes that determine the microclimate experienced by organisms in the understory can also mitigate impacts of global change(Verheyen et al., 2024).There is now strong empirical and theoretical support that plant functional traits mechanistically underpin the ecosystem services that NbS aim to enhance. Yet, as emphasized by Ramachandranet al. (2024), functional traits are rarely considered in the design of NbS. ...
... reproductive traits of trees). The optimal forest structure and composition for mitigation of extreme droughts depends on the relative importance of different drivers of drought stress(Verheyen et al., 2024). A better understanding of the mechanistic drivers of plant responses ...
Integrated solutions to the climate and biodiversity crises—together with other global sustainability challenges—include the identification, design and implementation of nature‐based solutions (NbS). Living organisms mediate biogeochemical cycles and greenhouse gas fluxes from land and sea, and provide NbS to both climate change mitigation and adaptation. Plants, as the primary producers in ecosystems, lie at the heart of NbS.
Plant ecology provides the foundation for developing and evaluating NbS based on an understanding of the ecological processes that underlie ecosystem service flow to people. In this Special Feature, we provide a collection of mini‐reviews that presents concise and focused analysis of the plant ecology of NbS. The mini‐reviews highlight key insights, challenges and opportunities for future research.
The development of NbS that target specific ecosystem functions (e.g. carbon storage), or aim at increasing ecosystem resilience against perturbations (e.g. those associated with climate change), requires unification of ecological theory from areas such as biodiversity‐ecosystem function, plant–animal interactions, resilience and functional traits of organisms.
Synthesis. Plant ecology and nature‐based solutions (NbS) research are complementary. Plant ecology can inform the design and management of effective NbS, and provide insights for the creation of novel ecosystems that provide NbS; while learning from the implementation of NbS can progress theory. To deploy NbS at the speed and scale needed to mitigate and adapt to climate change, we must rapidly integrate ecological concepts into the design of NbS. At the same time, the design and deployment of NbS in different ecological contexts provides an unprecedented opportunity to learn how performances of individual NbS sites can be explained in an integrated way, leading to the development of general concepts. Ultimately, a mechanistic understanding of how plants and their functional traits contribute to ecosystem function and service provision is critical for the design, verification of benefits from and avoidance of adverse effects of NbS.
... Urban trees are important for the sustainable development of cities by providing a broad range of ecosystem services within urban areas which often also extend to non-urban matrices (Endreny, 2018;Nowak et al., 2018;Verheyen et al., 2024). For instance, urban trees are excellent filters for fine particles and pollutants such as nitrogen dioxide, sulphur dioxide and ozone (Hamin and Gurran, 2009; Barwise and Kumar, 2020;Diener and Mudu, 2021), and are important carbon sinks that contribute to mitigate effects of urbanization on climate warming (Nowak et al., 2013;Churkina, 2016). ...
... The two most in uential and independent forest characteristics were forest canopy density and tree diversity. Canopies are key drivers of ecosystem functioning 18 , creating a physical, chemical and biological lter to ambient conditions 37 . Tree diversity is also a recognised determinant of ecosystem function, ecosystem service provision and non-tree biodiversity 18,38 . ...
Forest risks and benefits to human health are widely recognised. Yet, variation across forest types and their ecological characteristics driving health effects remain underexplored. Based on empirical data from an interdisciplinary European forest network, we developed a Bayesian Belief Network to quantify seven causal pathways relating different forest types to physical and mental health. Results show that forests always generate net health benefits regardless of their ecological characteristics. Forest canopy density and tree species diversity emerge as key drivers, but their effect size and directionality are strongly pathway-dependent. Changes in forest canopy density can generate trade-offs. For example, forests optimised for heat buffering and air pollution mitigation may compromise medicinal plant yield and enhance Lyme disease prevalence. Tree diversity effects were weaker but more consistently positive. Forest management should therefore account for such trade-offs to tailor forest biodiversity and functioning to local public health needs of priority.
... However, there is a lack of knowledge on how the temperate fruit tree would behave when grown in the shade of other trees (called shade trees) in a multistrata agroforestry system, although such knowledge is crucial for the promotion of fruit tree-based agroforestry systems (Lauri, 2021). The effects of shade trees on subcanopy environmental conditions are well documented moderating microclimatic conditions by shading from direct sunlight, reducing vapor pressure deficit (VPD) and thus limiting evapotranspiration, and reducing wind speed (Verheyen et al., 2024). However, the effects on soil moisture are more variable and less well understood (Verheyen at al., 2024). ...
... The effects of shade trees on subcanopy environmental conditions are well documented moderating microclimatic conditions by shading from direct sunlight, reducing vapor pressure deficit (VPD) and thus limiting evapotranspiration, and reducing wind speed (Verheyen et al., 2024). However, the effects on soil moisture are more variable and less well understood (Verheyen at al., 2024). Considering that the temperature under shade trees is reduced during the day and slightly increased at night (Gosme et al., 2016), growing fruit trees in the shade of larger trees could be of interest in Mediterranean climatic regions, where excess radiation, both light and temperature, has detrimental effects on leaf function (Corelli- Grappadelli, 2003) and fruit quality (sunburn damage; Schrader, 2011). ...
Agroforestry is promoted as a way to improve the sustainability of horticultural systems through plant diversification and also to mitigate climate change through carbon sequestration. It could also alleviate excessive light and temperature in high-radiation regions of the world. However, little is known about the long-term shade adaptation of the temperate fruit tree in agroforestry systems. A study was developed to investigate apple growing under walnut trees in two shade conditions compared to a full light condition. Our aim was to quantify the plasticity of traits and the covariations between traits in these three light conditions using a multiscale approach considering different scales from whole tree to annual shoot and inflorescence. Shade did not affect the height of the apple trees, while it reduced the diameter of the trunk and branches. On the other hand, the total number of growing shoots was reduced in shade, and flowering and fruiting were fewer and more irregular than in full light. Strikingly, at the whole tree scale, covariations between vegetative traits (trunk cross-sectional area versus mean branch cross-sectional area) and between vegetative and reproductive traits (trunk cross-sectional area versus total number of inflorescences) were not altered by shade. However, at the shoot scale, return-bloom was significantly reduced by shade, whereas at the inflorescence scale shade did not affect leaf number or leaf area. We propose a shade adaptation syndrome that includes not only shade intensity but also shade dynamics during the growing season and over consecutive years.
Pedunculate oak (Quercus robur L.) is widely distributed across Europe and serves critical ecological, economic, and recreational functions. Investigating its responses to stressors such as drought, extreme temperatures, pests, and pathogens provides valuable insights into its capacity to adapt to climate change. Genetic and dendrochronological studies offer complementary perspectives on this adaptability. Tree-ring analysis (dendrochronology) reveals how Q. robur has historically responded to environmental stressors, linking growth patterns to specific conditions such as drought or temperature extremes. By examining tree-ring width, density, and dynamics, researchers can identify periods of growth suppression or enhancement and predict forest responses to future climatic events. Genetic studies further complement this by uncovering adaptive genetic diversity and inheritance patterns. Identifying genetic markers associated with stress tolerance enables forest managers to prioritize the conservation of populations with higher adaptive potential. These insights can guide reforestation efforts and support the development of climate-resilient oak populations. By integrating genetic and dendrochronological data, researchers gain a holistic understanding of Q. robur’s mechanisms of resilience. This knowledge is vital for adaptive forest management and sustainable planning in the face of environmental challenges, ultimately helping to ensure the long-term viability of oak populations and their ecosystems. The topics covered in this review are very broad. We tried to include the most relevant, important, and significant studies, but focused mainly on the relatively recent Eastern European studies because they include the most of the species’ area. However, although more than 270 published works have been cited in this review, we have, of course, missed some published studies. We apologize in advance to authors of those relevant works that have not been cited.
Questions
The long‐term response of understorey vegetation to increasing tree mortality has rarely been addressed in resurvey studies. For two Quercus ‐dominated forest types, we asked: (a) How did overstorey alterations, induced by canopy mortality, affect understorey diversity and composition? (b) Is there a signal of global change effects on understorey communities? (c) Are these assemblages experiencing a homogenization process?
Location
Five sites in Quercus robur (QR) and four sites in Q. petraea (QP) forests, Slovenia.
Methods
We studied changes in vascular plants in the understorey layer from 1992/1993 to 2023 across 45 permanent 20 m × 20 m plots in QR and QP forests, respectively. Vegetation surveys were carried out following the standard Braun‐Blanquet method. We compared original surveys with recent resurveys using multivariate analysis, ecological indicator values (EIV), plant traits and methods that quantify changes in individual species.
Results
Since the early 1990s, tree layer cover decreased from 95% to an average of 55% in QR, whereas it remained relatively high (77%) in QP plots. This resulted in denser understorey vegetation and a significant increase in plot‐level species richness in QR forests, but a slight decrease in QP forests. The extensive loss of canopy cover and disturbance effects in QR forests caused significant changes in species composition. Species turnover in QR was driven by colonization of new disturbance‐tolerant taxa characterized by ruderal traits, whereas the compositional shift in QP was to a greater extent due to species losses. We detected a process of vegetation thermophilization (increase in EIV‐temperature), suggesting an effect of rapid climatic warming. Understorey communities are now more similar to each other than 30 years ago, indicating a decrease in beta‐diversity (floristic homogenization).
Conclusions
Despite some common trends, vegetation responses were forest type‐specific. Our study presents evidence of understorey vegetation changes triggered by increased canopy mortality (a strong local driver particularly in QR plots) and also points to the signal of global change symptoms (thermophilization, homogenization), which acted rather independently from the observed decline in tree layer cover.