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Shrubs and trees are assumed less likely to lose genetic variation in response to habitat fragmentation because they have certain life-history characteristics such as long lifespans and extensive pollen flow. To test this assumption, we conducted a meta-analysis with data on 97 woody plant species derived from 98 studies of habitat fragmentation. We measured the weighted response of four different measures of population-level genetic diversity to habitat fragmentation with Hedge's d and Spearman rank correlation.We tested whether the genetic response to habitat fragmentation was mediated by life-history traits (longevity, pollination mode, and seed dispersal vector) and study characteristics (genetic marker and plant material used). For both tests of effect size habitat fragmentation was associated with a substantial decrease in expected heterozygosity, number of alleles, and percentage of polymorphic loci, whereas the population inbreeding coefficient was not associated with these measures. The largest proportion of variation among effect sizes was explained by pollination mechanism and by the age of the tissue (progeny or adult) that was genotyped. Our primary finding was that wind-pollinated trees and shrubs appeared to be as likely to lose genetic variation as insect-pollinated species, indicating that severe habitat fragmentation may lead to pollen limitation and limited gene flow. In comparison with results of previous meta-analyses on mainly herbaceous species, we found trees and shrubs were as likely to have negative genetic responses to habitat fragmentation as herbaceous species. We also found that the genetic variation in offspring was generally less than that of adult trees, which is evidence of a genetic extinction debt and probably reflects the genetic diversity of the historical, less-fragmented landscape. Se asume que los arbustos y hierbas tienen menos probabilidad de perder variación genética como respuesta a la fragmentación del habitat porque su historia de vida tiene ciertas características como longevidad y flujo extensivo de polen. Para probar esta suposición, realizamos un meta-análisis con datos de 97 especies de plantas leñosas derivados de 97 estudios de fragmentación del habitat. Medimos la respuesta ponderada de cuatro medidas diferentes de diversidad genética a nivel población con fragmentación de habitat mediante correlación d de Hedge y de rangos de Spearman. Probamos si la respuesta genética a la fragmentación del habitat estaba mediada por los atributos de la historia de vida (longevidad, forma de polinización y vector dispersor de semillas) y características de estudio (marcador genético y material vegetal utilizado). Para ambas pruebas del efecto del tamaño, la fragmentación del hábitat se asoció con un decremento sustancial de la heterocigosidad esperada, el número de alelosy el porcentaje de loci polimórfico, mientras que el coeficiente de endogamia no se asoció con esas medidas. La mayor proporción de variación entre los tamaños de efecto se explicó por el mecanismo de polinización y por la edad del tejido (progenie o adulto) que fue genotipado. Nuestro hallazgo primario fue que los árboles y arbustos polinizados por viento aparentemente tuvieron la misma probabilidad de perder variación genética que las especies polinizadas por insectos, lo que indica que la fragmentación de hábitat severa puede llevar a una limitación de polen y en el flujo de genes. En comparación con resultados de meta-análisis previos, principalmente de especies herbáceas, encontramos que árboles y arbustos tenían la misma probabilidad que las especies herbáceas de tener respuestas genéticas negativas a la fragmentación del habitat. También encontramos que la variación genética de la descendencia generalmente fue menor que la de árboles adultos, lo cual es evidencia de una deuda de extinción genética y probablemente refleja la diversidad genética del paisaje histórico, menos fragmentado.

As of 2020, the world has an estimated 290 million ha of planted forests and this number is continuously increasing. Of these, 131 million ha are monospecific planted forests under intensive management. Although monospecific planted forests are important in providing timber, they harbor less biodiversity and are potentially more susceptible to disturbances than natural or diverse planted forests. Here, we point out the increasing scientific evidence for increased resilience and ecosystem service provision of functionally and species diverse planted forests (hereafter referred to as diverse planted forests) compared to monospecific ones. Furthermore, we propose five concrete steps to foster the adoption of diverse planted forests: (1) improve awareness of benefits and practical options of diverse planted forests among land‐owners, managers, and investors; (2) incentivize tree species diversity in public funding of afforestation and programs to diversify current maladapted planted forests of low diversity; (3) develop new wood‐based products that can be derived from many different tree species not yet in use; (4) invest in research to assess landscape benefits of diverse planted forests for functional connectivity and resilience to global‐change threats; and (5) improve the evidence base on diverse planted forests, in particular in currently under‐represented regions, where new options could be tested.

Purpose of Review Forests provide multiple ecosystem services (ES) to society, and the demand for ES is growing at the global level. However, how to manage forests for the provision of multiple and sometimes conflicting services is a complex and still unresolved issue. In this study, we reviewed the scientific literature for the period 2010–2020 dealing with forest management and multiple ES in Mediterranean forests, with the aim of (1) outlining the progress in research, (2) identifying knowledge gaps and research needs, and (3) discussing management approaches considering multiple ES. The selected literature was analyzed considering different aspects of multiple ES (e.g., drivers of changes, modeling approaches, trade-offs, and synergies). Recent Findings Our results show that wood production is still one of the main management objectives, with an increasing attention toward non wood forest products. Carbon sequestration and biodiversity were the most investigated regulating functions, but also specific aspects are gaining attention (e.g., lichens for microclimate regulation). Changes in stand structure and density, the impact of coppice vs. high forest, and the effect of management practices vs. abandonment were considered as drivers of change at the stand/management unit scale, while the impact of climate changes and disturbances were considered at the landscape/regional scale using modeling. Summary Despite the progress made in the last decade, our review highlights that further research is needed to fill the gaps in the scientific literature regarding how forest management influences the provision of multiple ES in the Mediterranean region. From a conceptual point of view, there is the need for a shift to a new paradigm based on an adaptable, flexible management, and planning approach to sustain self-organization, adaptive capacity, and overall resilience of Mediterranean forests, overcoming the ecosystem “service” approach; operatively, research should move toward a transdisciplinary approach, which considers problems from a diversity of points of view and involves extended peer communities not only in the dissemination of research results, but also in the research process itself.

The use of wood products is often promoted as a climate change mitigation option to reduce atmospheric carbon dioxide concentrations. In previous literature, we identified longevity and recycling rate as two determining factors that influence the carbon stock in wood products, but no studies have predicted the effect of improved wood use on carbon storage over time. In this study, we aimed at evaluating changes in the lifespan and the recycling rate as two options for enhancing carbon stock in wood products for different time horizons. We first explored the behaviour over time of both factors in a theoretical simulation, and then calculated their effect for the European wood sector of the future. The theoretical simulation shows that the carbon stock in wood products increases linearly when increasing the average lifespan of wood products and exponentially when improving the recycling rate. The emissions savings under the current use of wood products in Europe in 2030 were estimated at 57.65 Mt carbon dioxide (CO 2 ) per year. This amount could be increased 5 Mt CO 2 if average lifespan increased 19.54 % or if recycling rate increased 20.92 % in 2017. However, the combination of both strategies could increase the emissions saving almost 5 Mt CO 2 more by 2030. Incrementing recycling rate of paper and paperboard is the best short-term strategy (2030) to reduce emissions, but elongating average lifespan of wood-based panels is a better strategy for longer term periods (2046).

Eastern Rwanda consists of a mosaic of different land cover types, with agroforestry, forest patches, and shrubland all containing tree cover. Mapping and monitoring the landscape is costly and time-intensive, creating a need for automated methods using openly available satellite imagery. Google Earth Engine and the random forests algorithm offer the potential to use such imagery to map tree cover types in the study area. Sentinel-2 satellite imagery, along with vegetation indices, texture metrics, principal components, and non-spectral layers were combined over the dry and rainy seasons. Different combinations of input bands were used to classify land cover types in the study area. Recursive feature elimination was used to select the most important input features for accurate classification, with three final models selected for classification. The highest classification accuracies were obtained for the forest class (85–92%) followed by shrubland (77–81%) and agroforestry (68–77%). Agroforestry cover was predicted for 36% of the study area, forest cover was predicted for 14% of the study area, and shrubland cover was predicted for 18% of the study area. Non-spectral layers and texture metrics were among the most important features for accurate classification. Mixed pixels and fragmented tree patches presented challenges for the accurate delineation of some tree cover types, resulting in some discrepancies with other studies. Nonetheless, the methods used in this study were capable of delivering accurate results across the study area using freely available satellite imagery and methods that are not costly and are easy to apply in future studies.

Climate change and anthropogenic pressures are increasingly driving abrupt regime shifts (RSs) in natural ecosystems, leading to biodiversity loss and disruptions in their functioning. In systems with alternative stable states maintained by feedback mechanisms, such shifts are difficult to reverse due to hysteresis. These systems may show early warning signals (EWSs) (e.g. critical slowing down (CSD)), indicating ecological resilience loss prior to an RS. CSD manifests as a reduced rate of recovery from disturbances and can be detected through increasing temporal autocorrelation at-lag-1 (AC1) in vegetation indicator time series. While studies increasingly use remote sensing data (e.g. the Normalized Difference Vegetation Index) to evaluate CSD in natural ecosystems, most lack in-field validation and are conducted at broad spatial scales, limiting real-world applicability. Here, we assess whether EWSs precede RSs in Zambian wet Miombo woodlands by combining field-based vegetation data with remote sensing time series. We investigate (i) whether RSs in the Miombo woodlands can be detected using field data on vegetation structure and remote sensing data, (ii) the relationship between fire frequency and RSs, and (iii) if increasing AC1 precedes an RS. Our findings demonstrate the occurrence of RSs in Miombo woodlands and provide empirical evidence supporting the use of CSD as a predictive tool. Spatial models showed that both a high fire frequency and an increasing AC1 preceding the shift are significantly (p < 0.05) linked to RS occurrence. This study highlights the importance of integrating field and remote sensing data to monitor ecosystem transitions. By identifying resilience loss and RS occurrence, our approach offers valuable insights for conservation and restoration planning, emphasizing the need for adaptive fire management strategies to mitigate degradation and promote ecosystem recovery.

Both increasing and decreasing 20th century growth trends have been reported in forests throughout Europe, but only for few species and areas suitable modelling techniques have been used to distinguish individual tree growth (operating on a local scale) from growth change due to exogenous factors (operating on a broad geographical scale). This study relates for the first time observed growth changes, in terms of basal area increment (BAI) of dominant trees of pedunculate oak, common beech and Scots pine, in north-west European temperate lowland forests (Flanders) to climate, atmospheric CO 2 and tropospheric O 3 concentrations, N deposition, site quality and forest structure for more than a century (the period 1901–2008), applying mixed models. Growth change during the 20th century is observed for oak (increasing growth) and beech (increasing growth until the 1960s, growth decline afterwards), but not for pine. It was possible to relate growth change of oak and beech to climate time series and N deposition trends. Adding time series for CO 2 and O 3 concentration did not significantly improve model results. For oak and beech a switch from positive to negative growth response with increasing nitrogen deposition throughout time is observed. Growth increase for oak is mainly determined by the interaction between growing season temperature and soil water recharge. It is reasonable to assume that the observed growth trend for oak will continue for as long as early season water availability is not compromised. The decreasing trend in summer relative air humidity observed since the 1960s in the study area can be a main cause of recent beech BAI decrease. A further growth decline of beech can be expected, independent of site quality.

Purpose of review A rapidly changing climate is weakening the resilience of forest ecosystems through vitality loss of major native tree species, which reduces the ability of forests to deliver ecosystem services. Established invasive tree species (EITS) may take over the vacant space potentially preventing the regeneration of the preferred native tree species. This paper aims to investigate how expansion of these invasive non-native tree species can be addressed in a context of climate-smart forest management, considering alternatives to costly and often ineffective EITS control measures. Recent findings We found that forest ecologists increasingly recognize that climate-smart forest management, in particular tree species diversification and close-to-nature forest management, can strengthen the resilience of forests against negative impacts by EITS. In the resulting resilient forest ecosystems, a more closed canopy may deprive EITS of their invasive nature, and EITS may contribute to climate change adaptation. Summary This review proposes new pathways for forest management transcending the apparent incompatibility between the dominance of EITS and the adaptation capacity of forests and forest management to climate change. Adaptive measures to increase the resilience of forests to climate change may prevent the dominance of EITS. Under such conditions, useful functional traits of these tree species may even contribute to maintenance or enhancement of biodiversity, provisioning of ecosystem services and adaptation to climate change.

Aims The aim of the study was to explore whether the encroachment of an East-African savannah ecosystem by the invasive shrub Dichrostachys cinerea L. Wight & Arn has resulted in changes in the Arbuscular Mycorrhizal Fungus (AMF) communities which are associated with roots of the extant herbaceous plant communities. We hypothesized that this could happen either through introducing new AMF taxa, or through inducing changes in the savannah soil environment or plant community composition. Methods We selected five blocks in the savannah plains of the Nech Sar National Park, southern Ethiopia, and in each block, we established nine vegetation plots along a gradient of D. cinerea encroachment. We sampled roots from the encroaching shrub D. cinerea and from three dominant graminoids ( Brachiaria deflexa , Chrysopogon plumulosus, Lintonia nutans ) and two forbs ( Commelina forskaolii , Ruellia prostrata ), and used a metagenomics approach to identify the AMF taxa associated with their roots. Results D. cinerea exhibited higher AMF richness and diversity, and a significantly different AMF community composition, compared with the sampled herbaceous plants in the unencroached plots. Herbaceous plants in sparsely encroached plots harbored a higher AMF diversity as compared to the control plots, while those in densely encroached plots exhibited an intermediate AMF diversity. D. cinerea encroachment, host plant lifeform, soil characteristics and extant herbaceous plant species diversity all affected AMF community composition associated with the herbaceous plant roots. Conclusions Woody encroachment might have affected AMF communities of the extant herbaceous vegetation in savannah ecosystems both directly, through introducing novel AMF taxa associated with the encroaching shrub species, and indirectly, through encroachment effects on the environment. Restoration of encroached savannahs should therefore take into account the legacy effects of the invader on the microbial communities.

Key messageBeech trees growing in biodiverse patches in Belgium have higher radial growth and are less physiologically sensitive to drought than those in monocultures. Forest diversification therefore alleviates the negative effects of drought on beech.Common beech, a widespread and economically important tree species in Europe, is known to be drought sensitive. For ensuring its survival under increasing future drought conditions, we need to advance our understanding on the relationships between drought and its growth performance. Diversifying forests has been proposed as a management strategy to mitigate the effects of drought, because a more complete use of the available water is expected. We made use of a tree species diversity gradient in Belgium to study if beech trees growing in diverse forest patches are more resistant and resilient to drought than beech trees in monocultures. Combining dendrochronological and stable carbon (δ13C) and oxygen isotope (δ18O) data allowed for studying the effect of tree species diversity on the response of beech growth to drought regarding stem radial growth and physiological performance. Up to 62% enhanced stem radial growth strongly increased growth stability, and higher resistance to drought was observed for beech trees in diverse forest patches. Beech performs best in three-species mixtures, particularly those with oak and maple. In drought years, beech growth is more reduced in monocultures than mixtures. During these drought years, δ13C values increased, and the increase was weaker in beech trees of diverse stands compared to monospecific stands, indicating enhanced stomatal conductance and growth continuation in mixtures. δ18O patterns did not indicate a clear effect of diversity or the response of beech trees to drought. Overall, our results indicate that until now, still the positive effects of diversity on beech growth outperform the negative effects induced by drought.