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Forest development following agricultural abandonment concerns extensive areas including the Massif Central region of France where this study was undertaken. This land-use and land-cover change is expected to have effects on biodiversity and ecosystem services, including an increase of carbon sequestration—a major concern in the face of climate change. Nevertheless, uncertainties about carbon stock changes during successions are remaining, especially as to the total stock and the contribution of the different carbon pools. Our work contributes to this field by studying carbon stocks in multiple plots of different successional stages. We measured and estimated carbon stocks in aboveground and belowground vegetation, deadwood, litter and superficial soil, and surveyed plant communities and plot conditions (slope, aspect, soil characteristics). The average total carbon stock increased along the succession from 70.60 at stage 0 to 314.19 tC ha−1 at stage 5. However, the total carbon stocks at the young forest stage (abandoned for 74 years maximum) and the older forest stage (forested for at least 74 years) were not significantly different, and probably reflected strong local heterogeneity in the older forest stage. An increase of the carbon stock was found in all pools, except the soil pool that did not vary significantly between the successional stages. The aboveground carbon stock was found strongly related to the woody species cover, especially the macrophanerophyte cover. This case study supports the view that the succession dynamics of former agricultural plots participates in carbon sequestration, sometimes with great local variations. [ABSTRACT FROM AUTHOR]

The transition zone between the upper forest boundary and the treeless alpine vegetation (i.e., the treeline ecotone) is expected to shift upward in elevation with global warming. Multiple factors in addition to climate are influencing tree establishment, but it is uncertain to what degree. In this study, we took advantage of a unique dataset with field measurements of mountain birch trees acquired from 32 boreal–alpine treeline ecotone sites situated along a 1100‐km latitudinal gradient in Norway to investigate the role of climate, herbivory, topography, and vegetation on the establishment success of trees. To represent tree establishment, we recorded occurrence, survival, and height growth of short juvenile birch trees (stem height ≤1 m) as response variables at each site in 2008, 2012, and 2018. We used already available climate and herbivory data, and airborne laser scanning (ALS) and unmanned aerial vehicle (UAV) surveyed imagery together with field measurements to compute topography and vegetation explanatory variables per site on microsite scale (approx. 1 m2). We observed a clear decrease in short juvenile birch tree establishment due to livestock herbivory, evidenced by lower occurrence, reduced survival rate, and diminished height growth in treeline ecotones with higher livestock densities. Winter precipitation and the two land cover classes, tree‐covered area and lee side vegetation, were also important for tree establishment. However, the direction and magnitude of the relationships depended on the stage of establishment. While winter precipitation can lead to higher tree occurrence, long‐term survival is not necessarily ensured, reflecting diverse requirements for optimal conditions of tree establishment. Thus, our results show that occurrence, survival, and height growth of short juvenile birch trees differ in their requirements to climate, topography, and vegetation, but tree establishment is consistently low with livestock herbivory. Overall, our results suggest that treeline ecotones will shift toward higher elevations in areas with little or no livestock herbivory and close to already established trees and in lee sides. Regarding management and conservation issues, our results suggest that free‐roaming livestock can reduce tree establishment and hinder treeline ecotone shifts into threatened alpine ecosystems, at least for birch‐dominated treelines. [ABSTRACT FROM AUTHOR]

As one of the important ecological responses of ecosystem to global climate change, forest expansion can alter land surface energy budget and local microclimate. Land surface temperature (LST) and soil temperature (ST) indicate the above‐ and below‐ground thermal state, respectively. However, the lack of studies on the relationships between LST and ST changes after forest expansion hinders our understanding of the vegetation‐microclimate interactions, especially during the dormant season. We quantified the change of LST (∆LST) and ST (∆ST) after forest expansion in the dormant season on the Qinghai‐Tibet Plateau (QTP), and then explored their differences and linkages. The results showed that forest expansion significantly decreased LST by 0.75 ± 0.20°C, while significantly increased ST in three layers (0–7, 7–28, and 28–100 cm) by 0.31 ± 0.06, 0.29 ± 0.05, and 0.20 ± 0.04°C, respectively. The decreased LST was conducive to the preservation of snow, leading to larger snow depth, larger fractional snow cover and more snow cover days in forests than grasslands, which further promoted the increased ST through enhanced thermal insulation. Furthermore, it is suggested that the cooling impact of forest expansion on LST and warming impact on ST would both be stronger at humid sites than at dry sites. These findings will contribute to understand the vegetation‐microclimate‐snow interactions and the decoupling phenomenon between LST and ST in the dormant season influenced by vegetation change. Plain Language Summary: Forest expansion is happening almost all over the world, altering land surface energy cycle. However, it is unclear that whether the temperature above ground and below ground are changing similarly or divergently. Land surface temperature (LST) and soil temperature (ST) indicate the above‐ and below‐ground thermal state, respectively. In this work, we quantified the change of these two temperatures after forest expansion in the dormant season on the Qinghai‐Tibet Plateau, and then explored their relationships. The results showed that forest expansion significantly decreased LST by 0.75 ± 0.20°C, while significantly increased ST in three layers (0–7, 7–28, and 28–100 cm) by 0.31 ± 0.06, 0.29 ± 0.05, and 0.20 ± 0.04°C, respectively. Cooler land surface was conducive to the preservation of snow, leading to deeper, wider, and longer lasting snow cover in forests than grasslands, which further promoted the warmer soil through enhanced thermal insulation. Furthermore, it is suggested that humid environmental conditions would cause stronger contrasting temperature responses above and below ground after forest expansion. These findings will contribute to understand the temperature decoupling phenomenon influenced by vegetation change. Key Points: Land surface temperature (LST) and soil temperature (ST) were decoupled after forest expansion in the dormant seasonThe decrease of LST and increase of ST were associated through snow cover changeThe contrasting temperature responses were more prominent at humid sites than at dry sites [ABSTRACT FROM AUTHOR]

Context: Multifunctional rural landscapes are social-ecological systems that represent a link between nature and culture. They are characterized by the conservation and protection of ecological processes, natural resources and biocultural diversity. The conservation of these landscapes is mainly based on the establishment of Protected Natural Areas (PAs) whose regulatory schemes have often promoted their degradation. Objectives: We evaluate the effectiveness of the conservation strategies of the Natural Park category in the protection and maintenance of rural cultural landscapes. We analyse at a regional and local scale both the dynamics of land-uses and the socioeconomic structure of the local populations involved, identifying the main social-ecological indicators of change in the protected landscape. Methods: We apply a methodological approach, based on geoprocessing tools and multivariate analysis, to examine social-ecological changes in rural cultural landscapes after the establishment of a network of PAs. The designed method allows us to infer the ecological and socioeconomic resilience of protected landscapes. Results: Conservation efforts have tended to underestimate rural landscapes in favour of natural ones, mainly forest systems, and have not been able to prevent the processes of abandonment and degradation of protected landscapes. A simplification of the land-use systems dependent on traditional farming practices is observed. This implies the loss of both the multifunctionality of rural landscapes and their resilience to environmental changes. The key socioeconomic indicators identified highlight the deterioration of the rurality of protected landscapes. Conclusions: Our social-ecological approach is a useful tool to evaluate the effectiveness of PAs. Protection of landscape is related to the decline of traditional agricultural systems and rewilding through land abandonment. Culturalness is necessary to promote the management and conservation of rural landscapes from a holistic perspective. [ABSTRACT FROM AUTHOR]

Abstract The transition zone between the upper forest boundary and the treeless alpine vegetation (i.e., the treeline ecotone) is expected to shift upward in elevation with global warming. Multiple factors in addition to climate are influencing tree establishment, but it is uncertain to what degree. In this study, we took advantage of a unique dataset with field measurements of mountain birch trees acquired from 32 boreal–alpine treeline ecotone sites situated along a 1100‐km latitudinal gradient in Norway to investigate the role of climate, herbivory, topography, and vegetation on the establishment success of trees. To represent tree establishment, we recorded occurrence, survival, and height growth of short juvenile birch trees (stem height ≤1 m) as response variables at each site in 2008, 2012, and 2018. We used already available climate and herbivory data, and airborne laser scanning (ALS) and unmanned aerial vehicle (UAV) surveyed imagery together with field measurements to compute topography and vegetation explanatory variables per site on microsite scale (approx. 1 m2). We observed a clear decrease in short juvenile birch tree establishment due to livestock herbivory, evidenced by lower occurrence, reduced survival rate, and diminished height growth in treeline ecotones with higher livestock densities. Winter precipitation and the two land cover classes, tree‐covered area and lee side vegetation, were also important for tree establishment. However, the direction and magnitude of the relationships depended on the stage of establishment. While winter precipitation can lead to higher tree occurrence, long‐term survival is not necessarily ensured, reflecting diverse requirements for optimal conditions of tree establishment. Thus, our results show that occurrence, survival, and height growth of short juvenile birch trees differ in their requirements to climate, topography, and vegetation, but tree establishment is consistently low with livestock herbivory. Overall, our results suggest that treeline ecotones will shift toward higher elevations in areas with little or no livestock herbivory and close to already established trees and in lee sides. Regarding management and conservation issues, our results suggest that free‐roaming livestock can reduce tree establishment and hinder treeline ecotone shifts into threatened alpine ecosystems, at least for birch‐dominated treelines.

The Eucalyptus genus is extensively planted in Brazil for industrial use, and with the expansion of forest frontiers and climate changes, studies are needed on how these changes affect wood density (WD). The aim of this study was to evaluate the effect of some climate variables on WD of an Eucalyptus urophylla clone for a 4–5 year period. WD from trees collected in 12 sites were evaluated. Five growth rings were identified using a magnifying glass, X-ray densitometry, and forest inventory. WD was correlated with temperature (T), precipitation (P), soil water deficit, ring width, and current annual increment. There was no variation in WD in the first 20 months among sites. From that age on, WD was mainly correlated with T (r > 0.6). The 1 °C increase in T resulted in a WD reduction of 0.014 g cm−1, and increases of 10 m³ ha−1 in the final volume were related to an increase of 0.004 g cm−1 in WD. Researchers and managers should continue to put efforts into broad experimental networks to assess the effects of climate change on the adaptation and wood quality of Eucalyptus clones. Highlights The influence of climate on E. urophylla wood density was greater after the third year of growth. The mean air temperature was the best correlated climatic variable with E. urophylla wood density. The cross-site climatic gradient was more important in wood density variation of E. urophylla than the variability among the years. [ABSTRACT FROM AUTHOR]

Forest expansion after rural abandonment is changing landscapes, bringing new challenges and opportunities. Juvenile performance has an effect in the establishment of new forests and the subsequent acclimation of adult trees. However, most studies have focused on the performance of adult trees. Here, we analysed differences in the phenotypic trait space of juveniles across gradients of Juniperus thurifera woodland expansion and explored which traits shape juveniles' performance, seeking specific drivers of such differentiation and the role of the ontogeny. Thus, we surveyed functional leaf and plant-size traits in 180 juveniles growing in 18 plots at three different tree density stages (mature woodland, recently established area and a transition zone between both) and recorded local environmental conditions around each individual. We also estimated their radial growth and resilience to drought (in terms of resistance, recovery and resilience) as performance indicators. We found no relevant effects of the study environmental variables, but we did find a shift in the phenotypic space among juveniles across the gradient, with taller crowns and higher amount of leaf N and δ13C at the expanding edge. This trait differentiation across the gradient implied higher performance of young trees growing in old agricultural fields, both in growth rate and drought resilience terms. Our results showed a relevant land-use legacy on early trait differentiation that shapes more efficient phenotypes in the expanding edge compared to those in mature woodlands, suggesting that the future of these new forests is not compromised under current conditions. [ABSTRACT FROM AUTHOR]

Numerous evapotranspiration (ET) products have been produced using various approaches and diverse forcing data even as the magnitude and trends of ET show divergence. We simulated ET using updated land use and cover change (LUCC) data in China from 1900 to 2020. We found that China’s ET increased slightly from 1900 to 1980, but it increased rapidly after 1980 due to LUCC characterized by forest expansion (2.05 mm yr ^−1 , P < 0.01). We also found that the ET trends derived from our simulation were significantly higher than other ET products (−0.70–1.47 mm yr ^−1 , P < 0.01), implying that existing, long-term ET products might have underestimated ET trends in China during the post-1980 period because of underrepresented LUCC. These underestimated ET trends could introduce biases in the regional water budget and water resources management. We advocate for future studies to take into account the impacts of LUCC in global ET simulations.

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Spatiotemporal changes over previous decades in grazed Mediterranean landscapes have taken the form of woody plant encroachment in open areas (e.g., grasslands, open shrublands, silvopastoral areas), altering its structure and diversity. Demographic and socioeconomic changes have played a significant role in landscape transformations, mainly by causing the abandonment of traditional management practices such as pastoral activities, wood harvesting, and agricultural practices in marginal lands. This study aimed to quantify and evaluate the spatiotemporal changes in a typical grazed Mediterranean landscape of Mount Zireia during 1945–2020, and to investigate the effect of these changes on the future development (2020–2040) of land use/land cover (LULC) types. Cartographic materials such as aerial orthophotos from 1945, land use maps of 1960, Corine Land Cover of 2018, and recent satellite images were processed with ArcGIS software. To estimate the future projection trends of LULC types, logistic regression analyses were considered in the framework of CLUE modeling. The results indicated that the strongest trend of spatiotemporal changes were forest expansion in open areas, and grasslands reduction, suggesting that the LULC types that were mainly affected were forest, grasslands, and silvopastoral areas. Future development prediction showed that forests will most probably continue to expand over grassland and silvopastoral areas, holding a high dynamic of expansion into abandoned areas. The reduction in grasslands and silvopastoral areas, independent of environment and biodiversity implications, represents a major threat to sustainable livestock husbandry based on natural grazing resources. [ABSTRACT FROM AUTHOR]

Climate change and the advancement of forestry in areas with greater water scarcity represent major challenges for Eucalyptus cultivation in Brazil. This study aimed to evaluate the productivity and wood quality of non-traditional Corymbia and Eucalyptus species in two Brazilian climatic conditions, to expand the genetic base available for breeding programs. Mean annual increment, wood density, stem biomass, heartwood and bark percentage, tangential vessel diameter, vessel frequency, fiber length, and fiber wall thickness were assessed. Four Corymbia species (Corymbia citriodora subsp. citriodora , Corymbia henryi , Corymbia torelliana , Corymbia citriodora subsp. variegata) and three Eucalyptus species (Eucalyptus amplifolia , Eucalyptus longirostrata , Eucalyptus major) were evaluated. Monthly evaluations were conducted on the mean air temperature, precipitation, and soil water deficit. Soil water deficit had a negative impact on mean annual increment, biomass, and heartwood percentage, while also resulting in higher bark percentages. However, it did not affect wood density or vessel diameter. The species showed different behaviors in response to the increase in water deficit. Eucalyptus longirostrata had the lowest impact on the environment, the highest mean annual increment (48.40 m³ ha−1 and 26.94 m³ ha−1) and heartwood percentage values (19.23 % and 16.27 %). Corymbia henryi had the most similar mean annual increment values in both locations (25.33 m³ ha−1 and 20.18 m³ ha−1), but there was a significant decrease in heartwood formation in the location with the lower soil water deficit (18.20 %). Corymbia citriodora subsp. citriodora , Corymbia henryi , Corymbia citriodora subsp. variegata , Eucalyptus major , and Corymbia torelliana displayed strong growth and wood characteristics, indicating great potential for cultivation in both locations. • Site differences had an impact on tree growth. • Productivity decreases as water deficit increases. • The climate variations across sites didn't impact the species' vessel density or diameter. • C. citriodora subsp. variegata and E. longirostrata had the highest stem biomass values in both sites. [ABSTRACT FROM AUTHOR]

The spatiotemporal changes of the grazed Greek landscapes in the last 75 years resemble those evidenced in most parts of the northern Mediterranean region, where woody vegetation encroached on open areas changing landscape structure and diversity. These landscape transitions are deeply influenced by demographic and socioeconomic changes that exacerbate the abandonment of traditional management practices including livestock farming and wood harvesting. The aim of this paper was to examine the spatiotemporal changes regarding land use/land cover (LULC) types in a typical grazed landscape of the Lagadas area in northern Greece in the period 1945–2020 and try to associate them with socioeconomic changes. Special attention was given to grassland evolution. Cartographic material in various forms, such as historic (LULC) data sets in shapefile format (1945, 1960 and 1993), recent land use maps (Corine Land Cover of 2018), and satellite images (Google Earth images from 2017 to 2020) was analyzed with Geographic Information Systems software and landscape metrics. Socioeconomic inventory data and grazing animal numbers were also collected and analyzed from diachronic census reports of Greek authorities. Spatiotemporal changes in the Lagadas landscape showed that grasslands, open shrublands and silvopastoral areas decreased during the examined period in favor of dense shrublands and forests, causing a significant reduction in landscape diversity and heterogeneity. Main demographic and socioeconomic drivers were the decrease of the local population, population aging and a significant reduction of employment in the primary economic sector over time. These changes were coupled with reductions in the number of grazing animals (sheep, goats, and cattle), firewood harvesting and charcoal production and were identified as the main reasons for landscape change. Grasslands have become increasingly fragmented and isolated over the years. Future sustainable livestock husbandry in the area is seriously threatened by the ongoing reduction of grasslands and open shrublands. [ABSTRACT FROM AUTHOR]

Natural forest regrowth on abandoned land represents a major land use change in some regions of Europe. This is driven by various factors related to land abandonment, particularly changing socioeconomic conditions for agriculture and rural depopulation. Little research exists about how the issue is addressed at the policy level. This paper looks into the policymaking related to natural forest regrowth in France and Spain, two countries where land abandonment and natural forest regrowth occur at significant scales. We conduct a policy discourse analysis building upon 27 interviews carried out between 2018 and 2020 with policy actors from various fields that connect with these topics. We find four competing storylines in both countries: extensive agriculture, forestry, landscape conservation, and wilderness. These storylines differ regarding the framing of natural forest regrowth as a problem or an opportunity, and the preferred policy solutions. While storylines rooted in extensive agriculture, landscape conservation and forestry tend to problematize the phenomenon, a wilderness storyline voices an opportunity perspective. In France, a few actors voice elements of an insignificance storyline. Given its spatial importance, natural forest regrowth will likely become more important for future policymaking in the EU. Engaging in further research across disciplines and policy fields is necessary to study the phenomenon and its possible management and governance options. • Policy actors narrate natural forest regrowth on abandoned land through storylines. • Interview results distinguish four storylines on natural forest regrowth. • Three storylines tend to highlight the threat of natural forest regrowth. • Natural forest regrowth has not yet received much political attention. • Shifts towards a rewilding perspective may strengthen an opportunity framing. [ABSTRACT FROM AUTHOR]

Forest expansion into savanna is a pervasive phenomenon in West and Central Africa, warranting comparative studies under diverse environmental conditions. We collected vegetation data from the woody and grassy components within 73 plots of 0.16 ha distributed along a successional gradient from humid savanna to forest in Central Africa. We associated spatially collocated edaphic parameters and fire frequency derived from remote sensing to investigate their combined influence on the vegetation. Soil texture was more influential in shaping savanna structure and species distribution than soil fertility, with clay-rich soils promoting higher grass productivity and fire frequency. Savanna featuring woody aboveground biomass surpassing 40 Mg ha -1 could escape the grass-fire feedback loop, by depressing grass biomass below 4 Mg ha -1 . This thicker woody layer also favoured the establishment of fire-tolerant forest pioneers, which synergically contributed to the expansion of forests. Conversely, savannas below this fire suppression threshold sustained a balance between trees and grasses through the grass-fire feedback mechanism. This hysteresis loop, particularly pronounced on clayey soils, suggests that the contrast between grassy savanna and young forests might represent alternative ecosystem states, although savannas with low woody biomass remained vulnerable to forest edge encroachment.

The influence of the ancient landscape configuration and the land use legacies on forest cover change has been thoroughly investigated in temperate and tropical forests while it remains barely explored at high-latitudinal regions. This study explores the landscape drivers leading forest cover changes and their influence on current forest attributes in the world’s southernmost forests (Argentina). Nothofagus antarctica forest cover changes were determined by combining multitemporal photo-interpretation of aerial photographs (1961) and satellite images (2016–2019). We analyzed changes in land covers and landscape diversity indexes. We also explored the potential relationships among descriptors of forest structure, soil or understory characteristics, and the magnitude of forest increase. Forest cover increased in 55 sites (72% of study area), and decreased in 21 sites (28% of study area). Cleared forests and forest edges decreased by half from past to the present, while woody encroachment increased. This resulted in a diversification of the current landscape by an increase in the number of land cover categories and Shannon–Wiener index. The increase in forest cover was positively influenced by land cover diversity and latitude, i.e., major increases at southern latitudes. Forests with greater recovery presented more similar understory attributes than those with lower recovery, while in other forest structures and soil properties, different magnitudes of recovery occurred. Sites with a high proportion of forest recovery evidence a reduction of past land use legacies (e.g., forage plant species introduced for livestock) at a local scale. These results expand our knowledge about the current natural dynamic of high-latitude forests, although the precise anthropic pressure changes (e.g., livestock density) leading to this process are still unclear and should be further investigated. Management practices should consider these spatial differences in the response to recovery of sub-Antarctic forests, such as the management of densely regenerated areas by thinning, or the restoration of degraded forests, as well as the monitoring of woody encroachment in natural grasslands and peatlands. Although we document an overall gain in N. antarctica forests, the results could vary when incorporating other forest types (N. pumilio, N. betuloides) and geographic zones (e.g., Andean mountains), due to the complex dynamics of these coupled human-natural systems. [ABSTRACT FROM AUTHOR]

Abstract Background Forest is the largest biomass carbon (C) pool in China, taking up a substantial amount of atmospheric carbon dioxide. Although it is well understood that planted forests (PFs) act as a large C sink, the contribution of human management to C storage enhancement remains obscure. Moreover, existing projections of forest C dynamics suffer from spatially inconsistent age and type information or neglected human management impacts. In this study, using developed PF age and type maps and data collected from 1371 forest plantation sites in China, we simulated biomass C stock change and quantified management impacts for the time period 2010–2050. Results Results show that future forest biomass C increment might have been overestimated by 32.5%–107.5% in former studies. We also found that age-related growth will be by far the largest contributor to PF biomass C increment from 2010 to 2050 (1.23 ± 0.002 Pg C, 1 Pg = 1015 g = 1 billion metric tons), followed by the impact of human management (0.57 ± 0.02 Pg C), while the contribution of climate is slight (0.087 ± 0.04 Pg C). Besides, an additional 0.24 ± 0.07 Pg C can be stored if current PFs are all managed by 2050, resulting in a total increase of 2.13 ± 0.05 Pg C. Conclusions Forest management and age-related growth dominate the biomass C change in PFs, while the effect of climatic factors on the accumulation is minor. To achieve the ambitious goal of forest C stock enhancement by 3.5 Pg from 2020 to 2050, we advocate to improve the management of existing forests and reduce the requests for more lands for forest expansion, which helps mitigate potential conflicts with agricultural sectors. Our results highlight that appropriate planning and management are required for sustaining and enhancing biomass C sequestration in China’s PF.

Afforestation to control soil erosion has been implemented throughout China over the past few decades. The long‐term hydrological effects, such as total water yield and baseflow, of this large‐scale anthropogenic activity remain unclear. Using six decades of hydrologic observations and remote sensing data, we explore the hydrological responses to forest expansion in four basins with contrasting climates across China. No significant change in runoff was found for the period 1970–2012 for the cold and dry Hailar River Basin in northeastern China. However, both forest expansion and reduced precipitation contributed to the runoff reduction after afforestation since the late 1990s. Similarly, afforestation and drying climate since the mid‐1990s induced a significant decrease in runoff for the Weihe River Basin in semi‐arid northwestern China. In contrast, the two wet basins in the humid southern China, Ganjiang River Basin and Dongjiang River Basin, showed insignificant changes in total runoff during their study periods. However, the baseflow in the winter dry seasons in these two watersheds significantly increased since the 1950s. Our results highlight the long‐term variable effects of forest expansion and local climatic variability on basin hydrology in different climatic regions. This study suggests that landuse change in the humid study watersheds did not cause dramatic change in river flow and that region‐specific afforestation policy should be considered to deal with forestation‐water quantity trade‐off. Conclusions from this study can help improve decision‐making for ecological restoration policies and water resource management in China and other countries where intensive afforestation efforts are taking place. Key Points: Both precipitation and afforestation explained reduction in runoff for dry basinsForest recovery did not result in significant changes in total runoff for two wet basinsDry season baseflow in two wet basins had an upward trend [ABSTRACT FROM AUTHOR]

Treelines are expected to expand into alpine ecosystems with global warming, but herbivory may delay this expansion. This study quantifies long-term effects of temporally varying sheep densities on birch recruitment and growth in the treeline ecotone. We examined treeline ecotone successional trajectories and legacy effects in a replicated experimental setup, where enclosures were present for 14 years with three different sheep densities (0, 25, 80 sheep km−2). Before and after the enclosures were present, the site had an ambient sheep density of 20–25 km−2. We sampled field data 4 years after enclosure removal and compared these to data sampled 8 and 9 years after enclosure erection. We sampled data on birch browsing pressure, birch distribution across life-stages (recruits, saplings, and mature trees), and birch annual radial growth. Fourteen years of increased or decreased sheep density had observable legacy effects depending on birch life-stage. Birch recruit prevalence decreased in areas, where sheep were reintroduced after being absent for 14 years. For the same areas, sapling and mature tree prevalence increased, indicating that these areas have entered alternative successional trajectories compared to areas, where sheep were present the whole time. Birch annual radial growth showed a lag effect of 2 years after enclosure removal, with growth decreasing in areas where sheep had been absent for 14 years and increasing where sheep densities were high. Thus, decadal-scale absences of herbivores can leave legacy effects due to increased numbers of trees that have high resistance to later-introduced herbivore browsing. [ABSTRACT FROM AUTHOR]

Given the worldwide plans for extensive tree planting, we urgently need to understand how and where implementation will contribute to goals such as those for carbon sequestration. We used a long‐term, large‐scale native reforestation project in the Scottish Highlands to assess the response of carbon storage and other ecosystem functions to reforestation and grazing exclusion. We measured aboveground carbon, topsoil carbon, topsoil nitrogen, decomposition rates, soil invertebrate feeding activity, tree regeneration, and ground‐layer and moss height at 14 sites that are in the early stages of reforestation and fenced to exclude grazing. Reforestation areas were compared to unforested and mature forest areas that are both grazed and ungrazed, using 10 × 10 m plots. Aboveground carbon in the reforestation plots (1.4 kg/m2 [95% CI: 0.6, 2.6], average age 20 years since reforestation) was c. 8% of the mature forest plots (17.1 kg/m2 [13.1, 21.8]). Topsoil carbon was lower in the reforestation plots (18.78 kg/m2 [11.79, 25.78]) than in the unforested (29.82 kg/m2 [24.34, 35.29]) or mature forest (31.39 kg/m2 [22.91, 39.88]) plots. Responses of other functions to the reforestation and grazing interventions varied. Our results suggest that reforestation may trigger carbon loss from areas with high initial soil carbon even with low disturbance establishment, at least in the short term. Our work emphasizes where we lack knowledge: on the potential for long‐term re‐accumulation of soil carbon under semi‐natural native reforestation, soil carbon sequestration in the deeper soil layers, and the response of soil carbon to natural regeneration. [ABSTRACT FROM AUTHOR]

Abstract European forests are expanding and becoming denser following the widespread abandonment of farmland and rural areas. Spontaneous forest regrowth provides a cost‐effective opportunity to restore ecosystems, enhance multifunctionality and sustainability and mitigate climate change. Yet, little is known about the goods and services that such forests provide to people. We assessed the changes in nature's contributions to people (NCP) from spontaneous forest regrowth, i.e. forest expansion and densification, in South‐West Europe. We investigated 65 forest plots in four different landscapes with contrasting ecological and societal contexts. Two landscapes are located in rural areas undergoing human exodus and forest expansion and densification; the other two, in peri‐urban areas with intense land use and forest densification but negligible expansion. For each forest plot, we estimated variables related to ten out of the 18 main NCP defined by the Intergovernmental Science‐Policy Platform on Biodiversity and Ecosystem Services (IPBES). Regulating and material NCP were addressed using variables measured in the field as proxies. Non‐material NCP were studied through stakeholder interviews. Our results show across the cases that forest expansion and densification are generally associated with greater climate regulation and energy provision. Changes in other NCP, especially in non‐material ones, were strongly context‐dependent. The social perception of spontaneous forest regrowth was primarily negative in rural areas and more positive in peri‐urban landscapes. Passive restoration through spontaneous forest expansion and densification can enhance regulating and material NCP, especially when adaptive management is applied. To optimise NCP and to increase the societal awareness of and interest in spontaneous forest regrowth, the effects of this process should be analysed in close coordination with local stakeholders to unveil and quantify the many and complex trade‐offs involved in rural or peri‐urban social perceptions. A free Plain Language Summary can be found within the Supporting Information of this article.

Key message: The dioecious tree species Juniperus thurifera L. is undergoing a spontaneous process of forest expansion in southwest Europe. We investigated how growth, climate sensitivity, and wood density varied simultaneously between sexes and among stages of expansion while accounting for the variability of forest structure. We found few sex-based differences but detected lower wood density, greater growth rates, and higher sensitivity to drought in expanding fronts compared to long-existing forests. Context: Juniperus thurifera L. (Spanish juniper) is a dioecious tree species undergoing a natural process of forest expansion in southwest Europe. Aims: To assess how radial growth and wood density are simultaneously shaped by sex-based differences, the stage of forest expansion (long-existing forests, transition zones, and expanding fronts), variability in forest structure, and climate (in the case of radial growth). Methods: We measured forest structure characteristics, tree rings, and wood density in 17 plots dominated by Spanish juniper in three stages of forest expansion in central Spain. We used linear mixed models (LMMs) to explore the main drivers of variability in radial growth and wood density and sex- and stage-based differences in climate-growth sensitivity. Results: Rather than by sex, growth and wood density were mainly shaped by the stage of forest expansion, forest structure variables that characterize these stages, and climate variables (in the case of growth). Conclusion: Sexual dimorphism had a minimal effect in growth and wood density in expanding Spanish juniper woodlands. Expanding fronts could be benefiting from land-use legacies in the abandoned fields they are colonizing, as reflected in higher growth rates and lower wood density, especially during years with less summer drought stress. However, this pattern could be reversed in the event of an increase in drought episodes. [ABSTRACT FROM AUTHOR]

Globally, there is increasing interest in tree planting, leading to many country‐level commitments to reforestation. In the UK, current commitments would achieve 17% forest cover by 2050, with the highest rates of forest expansion expected in Scotland. Forest expansion with native trees is expected to increase biodiversity, particularly woodland specialist species, and associated ecosystem services. Despite this, data on biodiversity changes over the early stages of reforestation are sparse, particularly for upland areas in Scotland where opportunities for forest expansion are greatest.We collected data on the response of plants, carabid beetles and birds to native reforestation and grazing exclusion, using sites reforested over the last 30 years in the Scottish Highlands. Biodiversity in ungrazed, reforested sites was compared to unforested controls and mature native forest, both grazed and ungrazed.Mean bird species richness in reforested plots (4.4 [95% CI: 3.2, 5.9]) was higher than in unforested plots (0.8 [0.5, 1.3]), but lower than in mature forest plots (7.0 [5.4, 8.3]). In contrast, there was no systematic difference in plant or carabid beetle species richness in reforested, unforested or mature forest plots, or between grazed and ungrazed plots for the species richness of any groups. Woodland specialist bird and plant species were found in the reforested plots, and richness of woodland specialist bird species was predicted to reach levels in mature forest c. 36 years after reforestation.Species assemblages differed across habitat categories. For birds and plants, species assemblages in reforested sites were intermediate to unforested and mature sites. For carabid beetles, the assemblages in mature and reforested sites were comparable and differed from unforested sites. Grazing did not strongly influence species assemblages.Policy implications. We show that woodland specialists colonise reforested sites and species assemblages transition towards those found in the target habitat within the first 30 years of reforestation with native species. Native forest should be prioritised in Scotland's future forest expansion targets, given that mature native forest is scarce and fragmented in the Scottish Highlands and that the ultimate gain from native forest expansion may accrue over long time‐scales. [ABSTRACT FROM AUTHOR]

Spatiotemporal changes over previous decades in grazed Mediterranean landscapes have taken the form of woody plant encroachment in open areas (e.g., grasslands, open shrublands, silvopastoral areas), altering its structure and diversity. Demographic and socioeconomic changes have played a significant role in landscape transformations, mainly by causing the abandonment of traditional management practices such as pastoral activities, wood harvesting, and agricultural practices in marginal lands. This study aimed to quantify and evaluate the spatiotemporal changes in a typical grazed Mediterranean landscape of Mount Zireia during 1945–2020, and to investigate the effect of these changes on the future development (2020–2040) of land use/land cover (LULC) types. Cartographic materials such as aerial orthophotos from 1945, land use maps of 1960, Corine Land Cover of 2018, and recent satellite images were processed with ArcGIS software. To estimate the future projection trends of LULC types, logistic regression analyses were considered in the framework of CLUE modeling. The results indicated that the strongest trend of spatiotemporal changes were forest expansion in open areas, and grasslands reduction, suggesting that the LULC types that were mainly affected were forest, grasslands, and silvopastoral areas. Future development prediction showed that forests will most probably continue to expand over grassland and silvopastoral areas, holding a high dynamic of expansion into abandoned areas. The reduction in grasslands and silvopastoral areas, independent of environment and biodiversity implications, represents a major threat to sustainable livestock husbandry based on natural grazing resources.

The spatiotemporal changes of the grazed Greek landscapes in the last 75 years resemble those evidenced in most parts of the northern Mediterranean region, where woody vegetation encroached on open areas changing landscape structure and diversity. These landscape transitions are deeply influenced by demographic and socioeconomic changes that exacerbate the abandonment of traditional management practices including livestock farming and wood harvesting. The aim of this paper was to examine the spatiotemporal changes regarding land use/land cover (LULC) types in a typical grazed landscape of the Lagadas area in northern Greece in the period 1945–2020 and try to associate them with socioeconomic changes. Special attention was given to grassland evolution. Cartographic material in various forms, such as historic (LULC) data sets in shapefile format (1945, 1960 and 1993), recent land use maps (Corine Land Cover of 2018), and satellite images (Google Earth images from 2017 to 2020) was analyzed with Geographic Information Systems software and landscape metrics. Socioeconomic inventory data and grazing animal numbers were also collected and analyzed from diachronic census reports of Greek authorities. Spatiotemporal changes in the Lagadas landscape showed that grasslands, open shrublands and silvopastoral areas decreased during the examined period in favor of dense shrublands and forests, causing a significant reduction in landscape diversity and heterogeneity. Main demographic and socioeconomic drivers were the decrease of the local population, population aging and a significant reduction of employment in the primary economic sector over time. These changes were coupled with reductions in the number of grazing animals (sheep, goats, and cattle), firewood harvesting and charcoal production and were identified as the main reasons for landscape change. Grasslands have become increasingly fragmented and isolated over the years. Future sustainable livestock husbandry in the area is seriously threatened by the ongoing reduction of grasslands and open shrublands.

Background: Forest is the largest biomass carbon (C) pool in China, taking up a substantial amount of atmospheric carbon dioxide. Although it is well understood that planted forests (PFs) act as a large C sink, the contribution of human management to C storage enhancement remains obscure. Moreover, existing projections of forest C dynamics suffer from spatially inconsistent age and type information or neglected human management impacts. In this study, using developed PF age and type maps and data collected from 1371 forest plantation sites in China, we simulated biomass C stock change and quantified management impacts for the time period 2010–2050. Results: Results show that future forest biomass C increment might have been overestimated by 32.5%–107.5% in former studies. We also found that age-related growth will be by far the largest contributor to PF biomass C increment from 2010 to 2050 (1.23 ± 0.002 Pg C, 1 Pg = 1015 g = 1 billion metric tons), followed by the impact of human management (0.57 ± 0.02 Pg C), while the contribution of climate is slight (0.087 ± 0.04 Pg C). Besides, an additional 0.24 ± 0.07 Pg C can be stored if current PFs are all managed by 2050, resulting in a total increase of 2.13 ± 0.05 Pg C. Conclusions: Forest management and age-related growth dominate the biomass C change in PFs, while the effect of climatic factors on the accumulation is minor. To achieve the ambitious goal of forest C stock enhancement by 3.5 Pg from 2020 to 2050, we advocate to improve the management of existing forests and reduce the requests for more lands for forest expansion, which helps mitigate potential conflicts with agricultural sectors. Our results highlight that appropriate planning and management are required for sustaining and enhancing biomass C sequestration in China's PF. [ABSTRACT FROM AUTHOR]

Forests have expanded across Europe over the last centuries as a consequence of farmland (agricultural and pasture) abandonment. Agricultural practices usually increase soil fertility and reduce the diversity and abundance of ectomycorrhizal (ECM) fungi, essential mutualists of many woody species in temperate and Mediterranean forests. The recovery of this biotic interaction after the cessation of human activities is, thus, crucial for the re‐establishment of functional forest ecosystems.Here we addressed the legacies of past land use and the recovery of the mutualism between ECM fungi and Fagus sylvatica trees in recent beech forests (<50 years) in Northeast Spain. Soil and root samples were collected in six long‐established and eight recent beech forests to analyse soil abiotic properties and the ECM fungi associated with beech roots (Illumina DNA metabarcoding of ECM tips).Up to 609 amplicon sequence variants (ASVs) of ECM fungi were identified, with 220 ASVs found in both forest types. Recent forests had a significantly lower soil organic matter and phosphorus content, which had a significant effect on the community structure of ECM fungi in beech roots. Moreover, beech trees in recent forests interacted with less fungal taxa but had a higher relative abundance of Ascomycota. Tarzetta spp. (Ascomycota, Pezizales) and Lactarius blennius (Basidiomycota, Russulales) emerge as the particular taxa associated with recent and long‐established forests respectively.More specialized mutualistic networks with a lower species normalized degree were found in recent forests, which might result in a lower quality and resilience of the ECM mutualism.Synthesis. Land‐use history modulated the mycorrhizal symbiosis in regenerating beech forests through changes in soil organic matter and nitrogen, which were the main drivers of the differences in fungal community composition and functional types associated with beech trees in recent forests. [ABSTRACT FROM AUTHOR]

In Europe, forest area is increasing. These recently established forests can be classified into regenerating after disturbances or expanding into agricultural areas after abandonment. We used European Space Agency land cover maps and MODIS data to investigate which socioenvironmental drivers influenced recent forest expansion and regeneration in Europe from 1992 to 2015 and to compare their productivity by means of the Enhanced Vegetation Index (EVI). Our results showed that forest area increased in Europe by 1.4% from 1992 to 2015. The 66% of this forest area increase corresponded to forest expansion mostly in Mediterranean and temperate regions, while regeneration (34%) dominated in boreal areas. Forest area and land cover diversity in 1992 were the main drivers of local forest area increase from 1992 to 2015. Forest expansion occurred on the warmer zones far from urban areas in the boreal region while it was the opposite in temperate and Mediterranean areas. On the other hand, forest regeneration showed mostly a positive relation with the distance to urban areas and water availability but no relation with temperature. The EVI values in 2015 were higher in expanding than in regenerating forests except in the warmer and drier bioclimates of Europe. These EVI trends suggest a higher productivity of expanding forests, except in areas where they cannot benefit from biological and physicochemical legacies of abandoned agricultural soils for tree growth, owing to water shortage. In sum, our results highlight that recent forest area increase in Europe is mostly caused by forest expansion into former agricultural areas but this is mostly occurring in less productive (warmer and drought-prone) bioclimates where advantages of agricultural legacies may not occur. Ultimately, this casts doubts whether there may be a limit for the role of forest expansion into agricultural areas for carbon sequestration in the long term. [ABSTRACT FROM AUTHOR]

Farmland abandonment has been a widespread land-use change in the Iberian Peninsula since the second half of the 20th century, leading to the establishment of secondary forests across the region. In this study, we aimed to address changes in the recent (1985-2014) emergence patterns of these forests and examine how environmental factors affected their growth by considering differences in leaf-habit types. We used a combination of Landsat-derived land-cover maps and aboveground biomass (AGB) maps from the European Space Agency to assess the secondary forest establishment and growth, respectively, in the study region. We also obtained a set of topographic, climatic and landscape variables from diverse GIS layers and used them for determining changes over time in the environmental drivers of forest establishment and AGB using general linear models. The results highlight that secondary forest cover was still increasing in the Iberian Peninsula at a rate above the European average. Yet, they also indicate a directional change in the emergence of secondary forests towards lower and less steep regions with higher water availability (mean rainfall and SPEI) and less forest cover but are subjected to greater drought events. In addition, these environmental factors differentially affect the growth of forests with different leaf-habit types: i.e., needleleaf secondary forests being less favoured by high temperature and precipitation, and broadleaf deciduous forests being most negatively affected by drought. Finally, these spatial patterns of forest emergence and the contrasting responses of forest leaf-habits to environmental factors explained the major development of broadleaf evergreen compared to broadleaf deciduous forests and, especially, needleleaf secondary forests. These results will improve the knowledge of forest dynamics that have occurred in the Iberian Peninsula in recent decades and provide an essential tool for understanding the potential effects of climate warming on secondary forest growth. [ABSTRACT FROM AUTHOR]

European rural landscapes contain high nature value farmlands that, in addition to being the main economic activity in many rural areas, host habitats and species of great conservation value. The maintenance of these farming systems largely depends on traditional ecological knowledge and the rural lifestyles of the local populations. However, they have not been sufficiently appreciated and protected, and as a result, they are currently threatened. In this study, which was performed in the Madrid region (central Spain), we analyse the social-ecological changes of the rural landscape after the establishment of a protected natural area network. The obtained results highlight a significant loss of these high nature value farming systems and a marked increase in the rewilding processes characterised by scrub–forest transition and the development of forest systems. These processes are linked to the disruption of the transmission of traditional ecological knowledge, which may imply negative consequences for both the high biocultural diversity that these systems host and the cultural identity and the socioeconomics of the rural populations that live there. A useful methodological tool is provided for social–ecological land planning and the design of effective management strategies for the conservation of rural cultural landscapes [ABSTRACT FROM AUTHOR]

Forest regrowth following farmland (agriculture and pasture) abandonment has been positively associated with a number of processes including the regulation of hydrological cycling, the enhancement of soil functioning and an increase in forest productivity and carbon (C) sequestration. Although these changes in ecosystem functioning post‐farmland abandonment have been observed in multiple locations and studies, the ecophysiological basis underpinning these patterns remains unclear. Here, we examine whether increased forest expansion following pastureland abandonment is associated with greater water‐use efficiency (WUE) and legacies from previous land use in terms of nitrogen (N) availability.We thus explored differences in leaf traits and N availability between recently established (post‐1950) beech Fagus sylvatica (L.) forests on former pastureland and long‐established beech forests (pre‐1950). The investigated leaf traits were SLA, leaf N concentration (%N) and intrinsic WUE (iWUE, i.e. the ratio between photosynthesis and stomatal conductance); as well, leaf and soil stable N isotope composition (δ15N) and total %N were used to assess changes in N availability. Finally, we compared the correlation strength between the above‐mentioned parameters and those associated with tree productivity (wood density and basal area increment, BAI) and the richness of ectomycorrhizal fungi (ECM) in these two forest types.Recent forests had greater iWUE than long‐established forests, which was associated more with lower SLA than leaf %N. Leaf and soil δ15N were more robust proxies than %N for detecting differences in N availability. Less negative leaf and soil δ15N values in recent versus long‐established forests suggest, on the one hand, greater N availability, probably due to higher historical N input originating from animal excreta on these former pasturelands, and, on the other hand, an increase in N loss pathways.Our results point to greater correlations between leaf δ15N, tree iWUE and productivity in recent forests than in long‐established forests, thereby suggesting a close link between C and N cycles. Our findings also highlight different N dynamics between the two forest types, with recent forests showing 'leaky' N cycling wherever lower N retention by trees and associated ECM fungi occurs as a legacy of previous land use. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

The Cooper's Hawk (Accipiter cooperii) is often classified as a woodland species, but it exhibits marked plasticity by nesting successfully in what was previously thought to be atypical habitat such as urban areas and sparsely wooded grasslands, including the Little Missouri National Grassland in North Dakota. Forest expansion into North Dakota grasslands is likely due to the reduction of natural disturbances such as wildfires and grazing by bison (Bison bison). From the 1970s to 2001, forest cover increased in McKenzie County, North Dakota, by.1000%. From 1950 to 1972 there were two recorded instances of nesting Cooper's Hawks in McKenzie County. In 2001, we recorded 18 active nests, 13 of which were successful, four that failed, and one with unknown fate. Using the 2001 National Landcover Dataset (NLCD), we calculated that the mean proportion of forest cover in circular plots (18.1 km2) surrounding nests was 0.21. We found no relationship between nest fate and proportion of forest land cover. Additionally, we found no significant difference in proportion of forest cover between nest sites and randomly selected sites centered on forest land cover, indicating that Cooper's Hawks were using forest land cover in proportion to its availability. Understanding the relationship between the shifting landscape composition of North Dakota and its avifauna is important for monitoring and managing breeding Cooper's Hawks. [ABSTRACT FROM AUTHOR]

Recent forest expansion in Euro‐Mediterranean countries predominantly results from secondary succession in abandoned farmland, rather than from artificial afforestation. This major forest transition involves the delivery of both ecosystem services and disservices, which must be balanced through new land‐use planning and policy approaches.Ecosystem services arising from this expansion of forests include increased carbon sequestration, water infiltration, provision of forest products, soil retention and forest coalescence. Nevertheless, ecosystem disservices such as reductions in water yield, landscape homogenisation, increased wildfire risk and/or the loss of high nature value managed habitats caution against generalisation of the benefits of such expansion.Most EU funds related to forests are being allocated to conservation, restoration, or fire prevention and extinction efforts, whereas sustainable forest management and the maintenance of multifunctional agro‐silvo‐pastoral mosaics are hampered by the lack of financial incentives and by environmental regulations.Policy implications. We advocate for more‐targeted policies based on landscape planning that favours multifunctionality while reducing environmental and economic uncertainties and maximising the ecosystem service/disservice ratio. The following recommendations follow from this approach: (a) a climate‐smart policy favouring fire‐resistant landscapes and enhancing value chains that stimulate active forest management; (b) the adoption of a territorial perspective, beyond forest and farm‐based measures and payments, that relies on management actions and minimises socio‐ecological tensions; (c) refocusing CAP Pillar II grants from afforestation and forest protection measures to sustainable forest management; (d) transforming the CAP direct payments to support multifunctional farming systems (e.g. agroforestry); (e) a more balanced inclusion of different land uses in the Natura 2000 network and intensification of the support for High Nature Value farming in less‐favoured areas. [ABSTRACT FROM AUTHOR]

Since the mid‐20th Century, Europe has experienced an unprecedented forest expansion associated with the abandonment of rural landscapes. Secondary forests may provide relevant ecosystem services such as landscape defragmentation, biodiversity conservation, control of hydrological cycling and carbon sequestration.Secondary forests may benefit from the legacies of the former agricultural land use, and exhibit enhanced growth. Moreover, they may differ from long‐established forests in terms of tree species composition and diversity, as community composition has been less modified by succession or management. However, we lack evidence whether the effects of land use legacies on tree species diversity may also result in differences in the response of secondary forests to biotic and abiotic disturbances.We aimed to evaluate the effects of land use legacies on taxonomic and functional diversity and their effects on the response of temperate broadleaf forests to drought and herbivory damage. For this aim, we compared secondary beech Fagus sylvatica forests established after 1950 in abandoned pastures with long‐established (pre‐1950) forests. We calculated indices of taxonomic and functional diversity and determined mean growth and growth response of beech to two drought events (1991, 2006), and insect herbivory damage.Secondary and long‐established beech forests marginally differed in species richness but the former exhibited a significantly higher Shannon diversity index and evenness. Yet, differences in taxonomic diversity did not result in differences in functional diversity between forest types.Mean tree growth was higher in secondary than in long‐established forests and it increased with functional diversity in both forest types. However, diversity was unrelated with the growth response to drought. Insect herbivory damage decreased with increasing functional diversity but only in secondary forests.Synthesis and applications. Promoting functional diversity in temperate broadleaf forests is a promising strategy for enhancing productivity (tree growth) while increasing the ability to cope with biotic disturbances (insect herbivory). This principle should be applied both in the management of long‐established as well as expanding secondary forests. Yet, functional diversity does not seem to ameliorate tree response to drought, highlighting the need for other silvicultural practices to address this environmental challenge. [ABSTRACT FROM AUTHOR]

Context: Land use legacies of human activities and recent post-abandonment forest expansion have extensively modified numerous forest landscapes throughout the European mountain ranges. Drivers of forest expansion and the effects of changes on ecosystem services are currently debated. Objectives: (i) To compare landscape transition patterns of the Alps and the Apennines (Italy), (ii) to quantify the dominant landscape transitions, and (iii) to measure the influence of climatic, topographic and anthropogenic driving factors. Methods: Land cover changes and landscape pattern modifications were investigated at the regional (over 28 years, Alps and Apennines, Corine Land Cover dataset) and landscape scale (over 58 years, 8 Alpine and 8 Apennine sites, aerial images). The main driving factors of post-abandonment forest landscape dynamics were assessed with a statistical modeling approach. Results: Forest expansion was the dominant landscape transition at both Italian mountain ranges, with an annual overall rate of 0.6%. Forest expansion was more extensive at lower elevations in the Apennines where climate is less limiting and extensive abandoned croplands and pastures were available throughout the study period. Distance from pre-existing forest edges in the Alps and elevation in the Apennines emerged as the most important predictors. Conclusions: Forest expansion is most rapid where areas of recent agricultural abandonment coincide with favorable climatic conditions. Thus the prediction of forest landscape dynamics, in these mountain forests with a long history of cultural use, requires knowledge of how the magnitude and timing of land use changes intersect spatially and temporally with suitable conditions for tree establishment and growth. [ABSTRACT FROM AUTHOR]

European forests are expanding and becoming denser following the widespread abandonment of farmland and rural areas. Spontaneous forest regrowth provides a cost‐effective opportunity to restore ecosystems, enhance multifunctionality and sustainability and mitigate climate change. Yet, little is known about the goods and services that such forests provide to people. We assessed the changes in nature's contributions to people (NCP) from spontaneous forest regrowth, i.e. forest expansion and densification, in South‐West Europe.We investigated 65 forest plots in four different landscapes with contrasting ecological and societal contexts. Two landscapes are located in rural areas undergoing human exodus and forest expansion and densification; the other two, in peri‐urban areas with intense land use and forest densification but negligible expansion. For each forest plot, we estimated variables related to ten out of the 18 main NCP defined by the Intergovernmental Science‐Policy Platform on Biodiversity and Ecosystem Services (IPBES). Regulating and material NCP were addressed using variables measured in the field as proxies. Non‐material NCP were studied through stakeholder interviews.Our results show across the cases that forest expansion and densification are generally associated with greater climate regulation and energy provision. Changes in other NCP, especially in non‐material ones, were strongly context‐dependent. The social perception of spontaneous forest regrowth was primarily negative in rural areas and more positive in peri‐urban landscapes.Passive restoration through spontaneous forest expansion and densification can enhance regulating and material NCP, especially when adaptive management is applied. To optimise NCP and to increase the societal awareness of and interest in spontaneous forest regrowth, the effects of this process should be analysed in close coordination with local stakeholders to unveil and quantify the many and complex trade‐offs involved in rural or peri‐urban social perceptions. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Forest restoration has become one of the most important challenges for restoration ecology in the recent years. In this regard, soil fungi are fundamental drivers of forest ecosystem processes, with significant implications for plant growth and survival. However, the post-disturbance recovery of belowground communities has been rarely assessed, especially in highly degraded systems such as mines. Our aim was to compare forests and mined systems for biomass and structure of fungal communities in soil during early stages of tree establishment after disturbance. We performed ergosterol analysis and PacBio and Illumina sequencing of internal transcribed spacer 2 amplicons across soil layers in P. sylvestris, Q. robur and Q. ilex (holm oak) forests and naturally revegetated mined sites. In pine forests, total fungal biomass was significantly higher in litter and humus compared to mineral layers, with dominance of the mycorrhizal genera Tomentella, Inocybe and Tricholoma. Conversely, in oak forests the most abundant mycorrhizal genera were Tomentella, Cortinarius and Sebacina, but the biomass of saprotrophic fungi was greater in the litter layer compared to mycorrhizal fungi, with the genus Preussia being the most abundant. In the revegetated mined sites, ectomycorrhizal fungi dominated in the humus and mineral layers, with the mycorrhizal genus Oidiodendron being dominant. In contrast, in holm oak forests saprotrophic fungi dominated both soil humus and mineral layers, with the genera of Alternaria, Bovista and Mycena dominating the soil humus forest layer, while the genus Cadophora dominated the mineral layer. The habitat-specific differences in soil fungal community composition and putative functions suggest that an understanding of soil–plant–microbial interactions for different tree species and use of specific soil/litter inoculum upon planting/seeding might help to increase the effectiveness of tree restoration strategies in Mediterranean degraded sites.

The Himalayan glaciers, as unique reservoirs of freshwater for densely populated Asian countries, have been receiving considerable attention in public and scientific research. However, little is known about their long‐term fluctuations as related to climate variability. Herein, we reconstructed glacier fluctuation events by tree ring‐based moraine dating and repeated photographs. We assessed these fluctuations over the past 200 years in the Gangapurna and Annapurna III glaciers, located in the central Himalayas. We detected five major glacier fluctuation events in the 1790s, 1920s, 1930s, 1960s, and 1970s. A higher rate of glacier recession was observed from the 1980s onward, coinciding with climate warming. As shown by repeated photographs, the retreating rate of the Gangapurna glacier from 1979 to 2016 (up to 24.4 m yr−1) is much higher than the Annapurna III glacier (7.54 m yr−1) from 1950 to 2016. Their different frontal retreat rates were likely related to microtopography and glacier sizes. Older moraines developed during and after the Little Ice Age (LIA) were already covered by dense forest, presenting the evidence for retreating glaciers and advancing forests in the central Himalayas. Ongoing warming tends to speed up such ecological processes by resetting biophysical environment of the deglaciated forefields. In general, glaciers have shown retreating trends over the last 200 years, presenting a risk for preserving water resources in the Himalayas and nearby regions. Alternatively, advancing forest tends to amplify warming rate by reducing albedo, which is a new issue for investigating ecohydrological feedbacks between mountain forests, climate, and water resources. Plain Language Summary: The Himalayan glaciers, as unique reservoirs of freshwater, have been receiving considerable attention in public and scientific research. However, there is a huge knowledge gap on long‐term glacier fluctuations. For example, Intergovernmental Panel on Climate Change (IPCC) in its Fourth Assessment Report asserted that glaciers in the Himalayas will likely disappear by the year 2035 under the present rate of glacier recession. This statement raised scientific criticisms and presented the necessity to have a better understanding on past glacier fluctuations. However, little is known about long‐term glacier fluctuations and ecological processes on the deglaciated forefields. Herein, we reconstructed glacier fluctuation events by tree ring‐based moraine dating and repeated photographs for the Gangapurna and Annapurna III glaciers over the past 200 years in the central Himalayas. This study presents the first detailed evidence for the fluctuation history of Himalayan glaciers over the past 200 years. According to the minimum age of the moraines, the glacier retreat occurred during the 1790s with successive recessions during the 1920s, 1930s, 1960s, and 1980s. The central Himalayas are characterized by retreating glaciers and advancing forest during the past 200 years, presenting a challenge for ecological assessment and resource management. Key Points: History of Himalayan glacier fluctuations over the past 200 years were evidenced by tree ringFive major glacier fluctuation events were dated in the 1790s, 1920s, 1930s, 1960s, and 1970s and a higher rate of recession was observed during the recent decadesThe central Himalayas is characterized by retreating glaciers and advancing forests over the past 200 years [ABSTRACT FROM AUTHOR]

Key message: During the past decades, a multitude of oak stands have spontaneously established across the pine-dominated landscapes of the French Landes de Gascogne. Yet their future performance under modern climate change is unknown. We show that coppiced, dominant trees are most prepared to cope with drought episodes, displaying higher basal area increment and lower sensitivity to extreme events. Context: Forest stands dominated by pedunculate oak (Quercus robur L.) have spontaneously established across the pine-dominated landscapes of the French Landes de Gascogne. These oak stands are typically unmanaged and unsystematically coppiced, resulting in mixtures of single- and multi-stemmed (coppiced) trees. Aims: To determine the ability of spontaneous oak forest stands to face climate change–related hazards, by analysing differences in growth (tree-ring width and basal area increment—BAI), wood density and climate sensitivity depending on their tree architecture (single- vs multi-stemmed trees) and their social status in the forest. Methods: We exhaustively cored 15 oak stands (n = 657 trees). We compared stand characteristics and climate sensitivity between tree architectures considering two sampling designs, either all sampled trees (the exhaustive sampling) or those with a dominant status (dominant sampling). At the tree level, we used linear mixed effects models to compare wood density and growth between tree architectures and the trees’ social status within the canopy layer (dominant- vs non-dominant trees). Results: Multi-stemmed trees exhibited higher wood density than single-stemmed trees for diameters > 30 cm. Dominant multi-stemmed trees showed lower sensitivity to extreme events (pointer years), higher BAI but lower annual growth rates than dominant single-stemmed trees. Conclusion: Dominant multi-stemmed trees are potentially the most prepared ones to cope with increasing soil water deficit following drought episodes, at least during the first 60 years of the life of the tree. The vulnerability to face harsher climate conditions for Q. robur stands can be misled when using a dominant sampling design. [ABSTRACT FROM AUTHOR]

Key message: Insect herbivory in novelQuercus ilexL. forests is a highly context- and scale-dependent process. We show that forest composition, tree height and fine-scale spatial location, as well as tree genetic relatedness and ontogeny, can all influence herbivore activity at local to landscape scale. Context: Understanding the intrinsic and extrinsic drivers of herbivory in novel expanding forests is essential to envisage their role for biodiversity conservation. Aims: To analyse the effects of landscape attributes, forest composition, genetic relatedness, ontogeny and leaf traits on insect herbivory in novel Q. ilex forest stands. Methods: In 15 forest patches, we examined effects of patch size and connectivity, forest composition, tree height, specific leaf area (SLA) and nitrogen content on herbivory. In 3 forest patches, we assessed effects of tree genetic relatedness, ontogeny and spatial distribution. Results: Herbivory was lower in pine-oak than in mixed-oak forests owing to the shorter tree height in the former with no effects of patch size or connectivity. Herbivory increased with SLA whereas nitrogen content had no effect. Within patches, herbivory differed among genetic clusters and was reduced in saplings growing near mature oaks and individuals near the forest edge. Conclusion: We illustrate the strong context and scale dependence of tree-herbivore interactions that renders predictions for dynamic systems such as novel oak forests extremely challenging. It implies, however, that the structural heterogeneity of such unmanaged forests allows their function as stepping stones for insect herbivore diversity in fragmented landscapes. [ABSTRACT FROM AUTHOR]

Increasing the expansion of deforestation in forested areas and increasing soil erosion and sediment in downstream of watersheds there necessitates forest development in those areas. So, before any forestry project, site selection of prone areas and land capability evaluation should be considered. The aim of this research was to study forest expansion capability using multicriteria evaluation method in Saqezchichay watershed located in Namin, Ardabil province. First, land use maps for years 1989 and 2019 were prepared using the Support Vector Machine algorithm (Kappa coefficient = 0.91 and overall accuracy = 95.5%). Then, the degraded forestlands were identified and introduced as priority sites for reforestation. In the next step, 12 criteria were weighted using Analytical Network Process and were transformed to the same scale using the Fuzzy method. Finally, all layers were overlaid by the WLC method and resulted in a forestry capability map. Results showed that 28.81 percent of this area have a high or very high potential for reforestation. Moreover, precipitation, temperature, and soil depth were recognized as the most important criteria. The integrated map of the current forest area and the potential map revealed 41.94 percent of the current forest area was in an area with high or very high potential class, whereas 41.1 percent was located in an area with a moderate potential class for forest expansion. Based on the results, the study area has the capability for forest expansion. In addition, the ANP Fuzzy approach was able to identify suitable areas that are appropriate for forest expansion. [ABSTRACT FROM AUTHOR]

Farmland abandonment has been a widespread land-use change in the Iberian Peninsula since the second half of the 20th century, leading to the establishment of secondary forests across the region. In this study, we aimed to address changes in the recent (1985–2014) emergence patterns of these forests and examine how environmental factors affected their growth by considering differences in leaf-habit types. We used a combination of Landsat-derived land-cover maps and aboveground biomass (AGB) maps from the European Space Agency to assess the secondary forest establishment and growth, respectively, in the study region. We also obtained a set of topographic, climatic and landscape variables from diverse GIS layers and used them for determining changes over time in the environmental drivers of forest establishment and AGB using general linear models. The results highlight that secondary forest cover was still increasing in the Iberian Peninsula at a rate above the European average. Yet, they also indicate a directional change in the emergence of secondary forests towards lower and less steep regions with higher water availability (mean rainfall and SPEI) and less forest cover but are subjected to greater drought events. In addition, these environmental factors differentially affect the growth of forests with different leaf-habit types: i.e., needleleaf secondary forests being less favoured by high temperature and precipitation, and broadleaf deciduous forests being most negatively affected by drought. Finally, these spatial patterns of forest emergence and the contrasting responses of forest leaf-habits to environmental factors explained the major development of broadleaf evergreen compared to broadleaf deciduous forests and, especially, needleleaf secondary forests. These results will improve the knowledge of forest dynamics that have occurred in the Iberian Peninsula in recent decades and provide an essential tool for understanding the potential effects of climate warming on secondary forest growth.

European rural landscapes contain high nature value farmlands that, in addition to being the main economic activity in many rural areas, host habitats and species of great conservation value. The maintenance of these farming systems largely depends on traditional ecological knowledge and the rural lifestyles of the local populations. However, they have not been sufficiently appreciated and protected, and as a result, they are currently threatened. In this study, which was performed in the Madrid region (central Spain), we analyse the social-ecological changes of the rural landscape after the establishment of a protected natural area network. The obtained results highlight a significant loss of these high nature value farming systems and a marked increase in the rewilding processes characterised by scrub–forest transition and the development of forest systems. These processes are linked to the disruption of the transmission of traditional ecological knowledge, which may imply negative consequences for both the high biocultural diversity that these systems host and the cultural identity and the socioeconomics of the rural populations that live there. A useful methodological tool is provided for social–ecological land planning and the design of effective management strategies for the conservation of rural cultural landscapes.

Abstract Understanding factors that influence resource pulses is an important aspect of ecosystem ecology. We quantified below‐ to aboveground energy and nutrient fluxes during the 2015 periodical cicada emergence from forest habitats in a tallgrass prairie matrix and compared results to our prior studies of the 1998 emergence in the same watershed. We estimated 35.2 million cicadas emerged across 159 ha in 2015, almost 2× more than the 19.6 million across 98 ha in 1998. The 2015 emergence resulted in below‐ to aboveground fluxes of 9.4 metric tons of ash‐free dry mass and 1.12 metric tons of N, both ~2× greater than 1998. This corresponds to 59 kg C/ha and 7 kg N/ha in and adjacent to forested areas in 2015. Increased emergence in 2015 was a result of spatial expansion of cicadas, not higher densities. Periodical cicadas are expanding with forest habitats in this region. Cicadas expand into and oviposit in ~40% of available forest habitat during each emergence. Accordingly, we predict the 2032 emergence will span ~245 ha. Our study demonstrates how human alterations to a landscape, in this case forest expansion linked to fire suppression and reduced grazing, can alter the magnitude and extent of a resource pulse.

Climate change scenarios predict increasing atmospheric CO2 concentrations ([CO2]), temperatures and droughts in tropical regions. Individually, the effects of these climate factors on plants are well established, whereas experiments on the interactive effects of a combination of factors are rare. Moreover, how these environmental factors will affect tree species along a wet to dry gradient (e.g. along tropical forest–savanna transitions) remains to be investigated. We hypothesized that under the simulated environmental conditions, plant growth, physiological performance and survivorship would vary in a manner consistent with the species' positions of origin along this gradient. In a glasshouse experiment, we raised seedlings of three Eucalyptus species, each occurring naturally in a wet forest, savanna and forest–savanna ecotone, respectively. We evaluated the effect of drought, elevated temperature (4 °C above ambient glasshouse temperature of 22 °C) and elevated temperature in combination with elevated [CO2] (400 ppm [CO2] above ambient of 400 ppm), on seedling growth, survivorship and physiological responses (photosynthesis, stomatal conductance and water-use efficiency). Elevated temperature under ambient [CO2] had little effect on growth, biomass and plant performance of well-watered seedlings, but hastened mortality in drought-affected seedlings, affecting the forest and ecotone more strongly than the savanna species. In contrast, elevated [CO2] in combination with elevated temperatures delayed the appearance of drought stress symptoms and enhanced survivorship in drought-affected seedlings, with the savanna species surviving the longest, followed by the ecotone and forest species. Elevated [CO2] in combination with elevated temperatures also enhanced growth and biomass and photosynthesis in well-watered seedlings of all species, but modified shoot:root biomass partitioning and stomatal conductance differentially across species. Our study highlights the need for a better understand of the interactive effects of elevated [CO2], temperature and drought on plants and the potential to upscale these insights for understanding biome changes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Climate influences species growth differently across altitudinal gradients. • Mixed-effects models can accurately predict tree growth. • Suitability maps are useful to design forest management actions. • Tree species could potentially extend their range. Abstract In the past few decades, temperate forests have been negatively altered by numerous anthropogenic activities and by the impact of ongoing climate change. These changes may require management actions to help preserve some forest tree species. In this sense, highly-detailed knowledge of tree growth and survival across territorial and climatic gradients will be important for forest conservation. We developed a novel approach to determine the optimal zones of forest growth and expansion through climate suitability maps, using a dense tree-ring network of four forest species in Moncayo Natural Park and high-resolution climate data. Our results showed that the mixed-effects models developed using climate data and tree size were able to predict between 65 and 80% of growth variability along the climatic gradient. All studied species were influenced by climate, and the relationship between growth and climate significantly differed along the prevailing climate gradient. Moreover, the suitability maps showed that the current species distribution is limited, and their application may serve as a tool for adaptive management in forests subjected to climate change. [ABSTRACT FROM AUTHOR]