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The drought resilience of forest ecosystems is generally believed to depend on the dominant tree species' hydraulic traits. These traits define the maximum water transport capacity and the degree of vulnerability to hydraulic failure of a tree species. This work evaluates the effect of the intraspecific variability of hydraulic traits on the simulated tree water use in the Community Land Model (CLM, version 5.0). We selected two contrasting broadleaved tree species and performed a series of numerical experiments by modifying the parameters of the plant vulnerability curve and the maximum xylem hydraulic conductance accounting for the variability within each species. Our prescribed parameter sets represent vulnerable and resistant tree responses to the water deficit. At sites with an ample water supply, the resistant configuration simulates reduced water stress and increased transpiration compared to the vulnerable configuration. Meanwhile, the model results are counter‐intuitive at temporarily dry sites when water availability is the limiting factor. The numerical experiments demonstrate the emergent role of the maximum xylem conductance as a modulator of the plant water use strategy and the simulated transpiration within the model. Using the default value for maximum xylem conductance, the model tends to overestimate the early summer transpiration at drier sites, forcing the vegetation to experience unrealistic water stress later in the year. Our findings suggest that the parameterization of maximum xylem conductance is an important yet unresolved problem in the CLM and similar land surface models. Plain Language Summary: The survival of trees in drought conditions depends on their ability to adapt to water scarcity. Part of this adaptation is characterized by specific plant traits, which are an important component of Land Surface Models and largely determine the relationship between soil moisture and canopy gas exchange. Our study explores how the variability of specific plant traits of individual tree species may affect the selected model's ability to reproduce the water use observed in forest stands in Europe. For climates with a pronounced summer dry period, we found that the default model settings overestimated the vegetation water use in the early growing season, when water is abundant, resulting in severe water stress and underestimated transpiration as the dry season progressed. We specifically demonstrate that a rarely considered plant trait, representing the maximum water transport capacity, plays an essential role in controlling the magnitude of simulated water use and that adjustments to this parameter greatly help to reproduce the vegetation water use observed in seasonally dry climates. Key Points: We explore the impact of the intraspecific variability of plant hydraulic traits on the simulated transpiration by Community Land Model 5.0We find that a choice of plant hydraulic traits that reproduces observed plant transpiration also reduces simulated water stressWe demonstrate the critical role of the maximum xylem conductance in the model and its dependency on factors other than vegetation type [ABSTRACT FROM AUTHOR]

We compare Holocene tree cover changes in Europe derived from a transient Earth system model simulation (Max Planck Institute Earth System Model – MPI-ESM1.2, including the land surface and dynamic vegetation model JSBACH) with high-spatial-resolution time slice simulations performed in the dynamic vegetation model LPJ-GUESS (Lund–Potsdam–Jena General Ecosystem Simulator) and pollen-based quantitative reconstructions of tree cover based on the REVEALS (Regional Estimates of Vegetation Abundance from Large Sites) model. The dynamic vegetation models and REVEALS agree with respect to the general temporal trends in tree cover for most parts of Europe, with a large tree cover during the mid-Holocene and a substantially smaller tree cover closer to the present time. However, the decrease in tree cover in REVEALS starts much earlier than in the models, indicating much earlier anthropogenic deforestation than the prescribed land use in the models. While LPJ-GUESS generally overestimates tree cover compared to the reconstructions, MPI-ESM indicates lower percentages of tree cover than REVEALS, particularly in central Europe and the British Isles. A comparison of the simulated climate with chironomid-based climate reconstructions reveals that model–data mismatches in tree cover are in most cases not driven by biases in the climate. Instead, sensitivity experiments indicate that the model results strongly depend on the tuning of the models regarding natural disturbance regimes (e.g. fire and wind throw). The frequency and strength of disturbances are – like most of the parameters in the vegetation models – static and calibrated to modern conditions. However, these parameter values may not be valid for past climate and vegetation states totally different from today's. In particular, the mid-Holocene natural forests were probably more stable and less sensitive to disturbances than present-day forests that are heavily altered by human interventions. Our analysis highlights the fact that such model settings are inappropriate for paleo-simulations and complicate model–data comparisons with additional challenges. Moreover, our study suggests that land use is the main driver of forest decline in Europe during the mid-Holocene and late Holocene. [ABSTRACT FROM AUTHOR]

Forest dieback in Europe has recently intensified and has become more extensive. This dieback is strongly influenced by meteorological variations of temperature, T2m , and precipitation, P , and can be monitored with forest greenness. This study quantitatively investigates the 3-year meteorological history preceding events of reduced forest greenness in Europe's temperate and Mediterranean biome with a systematic approach. A specific focus lies in the timing of unusually persistent and unusually strong anomalies of T2m and P , as well as their relation to synoptic weather systems. A pragmatic approach based on remote sensing observations of the normalized difference vegetation index (NDVI) serves to identify low-forest-NDVI events at the 50 km scale in Europe in June to August 2002–2022. We quantify the impact of the hottest summer on record in Europe in 2022, which, according to our criteria, negatively affected 37 % of temperate and Mediterranean forest regions, and thereby reduced forest greenness more extensively than any other summer in 2002–2022. The low-NDVI events occurred in particularly dry and hot summers, but their meteorological histories also featured significant anomalies further in the past, with clear differences between the temperate and Mediterranean biome. A key feature is the anomalous accumulation of dry periods (i.e., periods with a P deficit) over the preceding 26 and 34 months in the temperate and Mediterranean biome, respectively. In the temperate biome only, T2m was anomalously persistent during almost the same 26-month period and featured distinctive peaks late in the past three growing seasons. While anomalously strong hot–dry conditions were characteristic of temperate low-NDVI events already in the previous summer, we find hardly any other systematic meteorological precursor in the Mediterranean prior to the event year. The identified dry periods went along with reduced cyclone activity in the Mediterranean and positive anticyclone frequency in the temperate biome. The occurrence of these two weather systems is locally more nuanced, showing, e.g., consistently increased and decreased cyclone frequency over western and northern Europe, respectively, in all event summers. Finally, the systematic meteorological histories are useful to test whether locally observed meteorological impacts, e.g., structural overshoot, systematically influenced the investigated events. In summary, systematic investigations of the multi-annual meteorological history provided clear evidence of how surface weather and synoptic-scale weather systems over up to 3 years can negatively impact European forest greenness. The observation of the record-extensive low-NDVI event in the summer of 2022 underlines that understanding the forest–meteorology interaction is of particular relevance for forest dieback in a changing climate. [ABSTRACT FROM AUTHOR]

Increasing intensity and frequency of droughts are leading to forest dieback, growth decline and tree mortality worldwide. Reducing tree-to-tree competition for water resources is a primary goal for adaptive climate silviculture strategies, particularly in reforested areas with high planting density. Yet, we need better insights into the role of stand type (i.e., natural forests versus plantations) on the resilience of pine forests to droughts across varying time scales. In this study, we combined dendrochronological data and stable C (δ13C) and H (δ2H) isotopes measured in tree-ring wood as well as in specific wood chromatographically isolated compounds to investigate contrasting responses to drought of natural versus planted stands of two representative pine species, i.e., Pinus pinaster and Pinus nigra in southeastern Europe. Natural stands exhibited about two-fold increase in tree-ring growth in average (basal area at 20 years-BAI20) as compared to planted stands. A response function analysis showed contrasting seasonal growth patterns for both species, which were related to monthly mean temperature and precipitation. Both stand type and species variables influenced growth resilience indices. Both pine species revealed contrasting resilience patterns among forest types; whereas planted stands seemed to be less sensitive to yearly droughts as determined by a higher recovery index (CRc) for P. pinaster, the contrary was found in the case of P. nigra. On the other hand, while resistance CRT and resilience CRS indices were higher for planted than natural forests in the case of P. pinaster, little differences were found for P. nigra. Beyond comparisons, carbon stable isotopes shed lights on the role of forest types in dry sites, being δ13C consistently lower in natural than in planted forests for both pine species (p < 0.05). We concluded that planted forest assimilated more carbon as per unit of water used than natural stands in response to droughts. Both δ13C and δ2H isotopic signals were positively correlated for both species for planted forests. However, a lack of correlation was evidenced for natural stands. Consistent with δ13C observations, δ2H concentrations in woody phenolic compounds (guaiacol and oleic acid) revealed contrasting patterns among forest types. This puts forward that δ2H concentrations in woody phenolic compounds (rather than in woody tree ring) accounts for other confounding factors in tree ring formation that can be associated with forest type. Our results highlight the value of stable isotope approaches versus conventional dendrochronological tools in drought studies and call for the consideration of forest type as an endogenous aspect defining the vulnerability of pine forests to climate. [ABSTRACT FROM AUTHOR]

Air pollution caused by sulphur dioxide (SO 2) and nitrogen oxides (NO x) has negative impacts on forest health and can initiate forest dieback. Long-term monitoring and analysis of these pollution are carried out in Białowieża Forest in NE Poland due to the threats from abiotic, biotic and anthropogenic factors. The main objective of our study was to monitor the levels and trends of air pollutant deposition in Białowieża Forest. During a short-term monitoring period over six years (2014–2021), the concentration of SO 2 in the air decreased significantly (from 2.03 μg m−3 in December 2015 to 0.20 μg m−3 in July 2016), while the concentration of NO 2 in the air showed a non-significant decrease (from 8.24 μg m−3 in December 2015 to 1.61 μg m−3 May 2016). There was no significant linear trend in the wet deposition of S–SO 4 anions. Mean monthly S–SO 4 deposition varies between 4.54 and 94.14 mg m−2month−1. Wet nitrogen deposition, including oxidized nitrogen (N–NO 3) and reduced nitrogen (N–NH 4), showed a non-significant increase. Mean monthly precipitation of N–NO 3 and N–N H 4 ranged from 1.91 to 451.73 mg m−2month−1. Neither did total sulphur deposition nor total nitrogen deposition exceed the mean deposition values for forests in Europe (below 6 ha−1yr−1 and 3–15 ha−1yr−1, respectively). Our results indicate that air pollutants originate from local sources (households), especially from the village of Białowieża, as demonstrated by the level and spatial distribution of air pollutant deposition. This indicates that air pollutants from the village of Białowieża could spread to other parts of Białowieża Forest in the future and may have a negative impact on forest health and can initiate forest dieback. It is therefore important to continue monitoring air pollution to assess the threats to this valuable forest ecosystem. • Deposition of S in Białowieża Forest didn't exceed deposition for forests in Europe. • Deposition of N in Białowieża Forest didn't exceed the limit for managed forests. • The deposition (S and N) was highest in the Białowieża Glade (central part of BF). • The deposition (S and N) was lowest in the southern part of Białowieża Forest. [ABSTRACT FROM AUTHOR]

Recent forest decline in Europe is strongly influenced by meteorological conditions imposed by seasonal variations of temperature, T2m, and precipitation, P, and can be monitored with forest greenness. This study quantitatively investigates anomalous characteristics of the three-year meteorological storyline preceding events of reduced forest greenness in Europe's temperate and Mediterranean biome in the phase space of seasonal-mean anomalies of (T2m, P). A specific focus is on the amplitude, persistence, and co-variability of these anomalies. A pragmatic approach based on remote sensing observations of normalized difference vegetation index NDV I serves to identify low forest NDV I events at the 50 km scale in Europe in June to August 2000-2020. An independent forest disturbance data set is used to qualitatively validate the identified more than 1'500 low NDV I events. These events occur in summers with particularly dry and hot conditions but their meteorological storylines feature significant anomalies during multiple seasons preceding the events, with clear differences between the two biomes. In the Mediterranean biome, the anomalously dry conditions persist over more than 1.5 y prior to the events, whereas T2m is anomalously warm only during the last 0.4 y. In contrast, in the temperate biome, T2m is anomalously large during most of the 2.5 y prior to the events and, most interestingly, the autumn/winter preceding the events is characterized by anomalously wet and warm conditions. These anomalies potentially induce a negative legacy on the following summer drought. The seasonal-mean anomalies of P are strongly determined by synoptic-scale weather systems, such that long dry periods are characterized by a deficit of cyclones and an excess of anticyclones. A final analysis investigates the peculiarities of low NDV I events that occur in two consecutive summers and the potential role of drought legacy effects. In the temperate biome, the second event summer of an event sequence has less hot and less dry anomalies than the first one and than during a single event. In summary, detailed investigations of the multi-annual meteorological storyline of low forest NDV I events provided clear evidence that anomalies of surface weather and synoptic-scale weather systems over time periods of up to 2.5 y can negatively impact European forest activity, with important differences between the temperate and Mediterranean biomes. [ABSTRACT FROM AUTHOR]

European Black Pine (Pinus nigra J.F. Arnold) is a fast-growing conifer, currently distributed in a fragmented pattern from western North Africa through Southern Europe to Asia Minor and is an economically important native conifer in Southern Europe. In Portugal, P. nigra populations are allochthonous, and were planted 50–90 years ago with plant material of unknown origin. This work intended to evaluate and investigate long-term radial growth characteristics of the species on the westernmost part of Europe, outside its natural range, in mainland Portugal. To achieve this objective, six planted stands located in the north and centre of the country were chosen, which were considered representative of the distribution of the species in the country and the most extreme south-western location in Europe. The height and diameter at breast height was measured and the general state of these stands was evaluated. Overall, no mortality was observed except in one site, where trees manifested poor growth. Sampling a set of 15 trees per site, was used to create a database for analysis of the radial development of the species. The 90 trees sampled, with ages ranging from 56–98 years, provided a database of 5308 observations of diameter-age pairs. The Schumacher function was tested for the description of radial growth and provided satisfying results in terms of the model fitness, allowing us to summarize general trends of diameter growth among sites. Complementary analysis of radial growth at a tree age of 50-yr was performed to assess for differences among populations. It was concluded that radial growth differs between sites, and two statistically different groups were identified, although no specific latitudinal or longitudinal gradients were found. The information on the identified growth patterns can be used for decision-making purposes when considering species selection in afforestation or reforestation procedures in the context of adaptive management. [ABSTRACT FROM AUTHOR]

The growth of past, present, and future forests was, is and will be affected by climate variability. This multifaceted relationship has been assessed in several regional studies, but spatially resolved, large-scale analyses are largely missing so far. Here we estimate recent changes in growth of 5800 beech trees (Fagus sylvatica L.) from 324 sites, representing the full geographic and climatic range of species. Future growth trends were predicted considering state-of-the-art climate scenarios. The validated models indicate growth declines across large region of the distribution in recent decades, and project severe future growth declines ranging from −20% to more than −50% by 2090, depending on the region and climate change scenario (i.e. CMIP6 SSP1-2.6 and SSP5-8.5). Forecasted forest productivity losses are most striking towards the southern distribution limit of Fagus sylvatica, in regions where persisting atmospheric high-pressure systems are expected to increase drought severity. The projected 21st century growth changes across Europe indicate serious ecological and economic consequences that require immediate forest adaptation. Tree ring data from a network of beech tree stands across Europe show evidence for a recent growth decline from 1986-2016 and project up to 50% growth reductions in some areas of Europe with future climate change. [ABSTRACT FROM AUTHOR]

The Black Death was the largest demographic shock in European history. We review the evidence for the origins, spread, and mortality of the disease. We document that it was a plausibly exogenous shock to the European economy and trace out its aggregate and local impacts in both the short run and the long run. The initial effect of the plague was highly disruptive. Wages and per capita income rose. But, in the long run, this rise was only sustained in some parts of Europe. The other indirect long-run effects of the Black Death are associated with the growth of Europe relative to the rest of the world, especially Asia and the Middle East (the Great Divergence), a shift in the economic geography of Europe toward the northwest (the Little Divergence), the demise of serfdom in western Europe, a decline in the authority of religious institutions, and the emergence of stronger states. Finally, avenues for future research are laid out. (JEL N13, N30, N43, J10, I12, I14, I30) [ABSTRACT FROM AUTHOR]

Species richness, abundance and biomass of insects have recently undergone marked declines in Europe. We metabarcoded 211 Malaise-trap samples to investigate whether drought-induced forest dieback and subsequent salvage logging had an impact on ca. 3000 species of flying insects in silver fir Pyrenean forests. While forest dieback had no measurable impact on species richness, there were significant changes in community composition that were consistent with those observed during natural forest succession. Importantly, most observed changes were driven by rare species. Variation was explained primarily by canopy openness at the local scale, and the tree-related microhabitat diversity and deadwood amount at landscape scales. The levels of salvage logging in our study did not explain compositional changes. We conclude that forest dieback drives changes in species assemblages that mimic natural forest succession, and markedly increases the risk of catastrophic loss of rare species through homogenization of environmental conditions. Sire et al. examine the effects of climate-induced forest dieback and salvage logging on insect diversity in silver fir Pyrenean forests using metabarcoding. Although no consistent variation in species richness was found, forest dieback cause massive changes in community composition particularly affecting rare species. [ABSTRACT FROM AUTHOR]

Forest decline, in course of climate change, has become a frequently observed phenomenon. Much of the observed decline has been associated with an increasing frequency of climate change induced hotter droughts while decline induced by flooding, late-frost, and storms also play an important role. As a consequence, tree mortality rates have increased across the globe. Despite numerous studies that have assessed forest decline and predisposing factors for tree mortality, we still lack an in-depth understanding of (I) underlying eco-physiological mechanisms, (II) the influence of varying environmental conditions related to soil, competition, and micro-climate, and (III) species-specific strategies to cope with prolonged environmental stress. To deepen our knowledge within this context, studying tree performance within larger networks seems a promising research avenue. Ideally such networks are already established during the actual period of environmental stress. One approach for identifying stressed forests suitable for such monitoring networks is to assess measures related to tree vitality in near real-time across large regions by means of satellite-borne remote sensing. Within this context, we introduce the European Forest Condition monitor (EFCM)—a remote-sensing based, freely available, interactive web information tool. The EFCM depicts forest greenness (as approximated using NDVI from MODIS at a spatial resolution of roughly 5.3 hectares) for the pixel-specific growing season across Europe and consequently allows for guiding research within the context of concurrent forest performance. To allow for inter-temporal comparability and account for pixel-specific features, all observations are set in relation to normalized difference vegetation index (NDVI) records over the monitoring period beginning in 2001. The EFCM provides both a quantile-based and a proportion-based product, thereby allowing for both relative and absolute comparison of forest greenness over the observational record. Based on six specific examples related to spring phenology, drought, late-frost, tree die-back on water-logged soils, an ice storm, and windthrow we exemplify how the EFCM may help identifying hotspots of extraordinary forest greenness. We discuss advantages and limitations when monitoring forest condition at large scales on the basis of moderate resolution remote sensing products to guide users toward an appropriate interpretation. [ABSTRACT FROM AUTHOR]

Global warming is accompanied by increasing water stress across much of our planet. We studied soil biological processes and changes in soil organic carbon (SOC) storage in 30 Hungarian oak forest sites in the Carpathian Basin along a climatic gradient (mean annual temperature (MAT) 9.6–12.1 °C, mean annual precipitation (MAP) 545–725 mm) but on similar gently sloped hillsides where the parent materials are loess and weathered dust inputs dating from the end of the ice age. The purpose of this research was to understand how a drying climate, predicted for this region, might regulate long-term SOC sequestration. To examine the effects of decreasing water availability, we compared soil parameters and processes in three categories of forest that represented the moisture extremes along our gradient and that were defined using a broken-stick regression model. Soil biological activity was significantly lower in the driest ("dry") forests, which had more than double the SOC concentration in the upper 30 cm layer (3.28 g C/100 g soil ± 0.11 SE) compared to soils of the wettest ("humid") forests (1.32 g C/100 g soil ± 0.09 SE), despite the fact that annual surface litter production in humid forests was ~ 37% higher than in dry forests. A two-pool SOM model constrained to fit radiocarbon data indicates that turnover times for fast and slow pools are about half as long in the humid soil compared to the dry soil, and humid soils transfer C twice as efficiently from fast to slow pools. Enzyme activity and fungal biomass data also imply shorter turnover times associated with faster degradation processes in the soils of humid forests. Thermogravimetry studies suggest that more chemically recalcitrant compounds are accumulating in the soils of dry forests. Taken together, our results suggest that the predicted climate drying in this region might increase SOC storage in Central European mesic deciduous forests even as litter production decreases. [ABSTRACT FROM AUTHOR]

In summer 2018, Europe experienced a record drought, but it remains unknown how the drought affected ecosystem carbon dynamics. Using observations from 34 eddy covariance sites in different biomes across Europe, we studied the sensitivity of gross primary productivity (GPP) to environmental drivers during the summer drought of 2018 versus the reference summer of 2016. We found a greater drought-induced decline of summer GPP in grasslands (−38%) than in forests (−10%), which coincided with reduced evapotranspiration and soil water content (SWC). As compared to the 'normal year' of 2016, GPP in different ecosystems exhibited more negative sensitivity to summer air temperature (Ta) but stronger positive sensitivity to SWC during summer drought in 2018, that is, a stronger reduction of GPP with soil moisture deficit. We found larger negative effects of Ta and vapour pressure deficit (VPD) but a lower positive effect of photosynthetic photon flux density on GPP in 2018 compared to 2016, which contributed to reduced summer GPP in 2018. Our results demonstrate that high temperature-induced increases in VPD and decreases in SWC aggravated drought impacts on GPP. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'. [ABSTRACT FROM AUTHOR]

Severe drought events are known to cause important reductions of gross primary productivity (GPP) in forest ecosystems. However, it is still unclear whether this reduction originates from stomatal closure (Stomatal Origin Limitation) and/or non-stomatal limitations (Non-SOL). In this study, we investigated the impact of edaphic drought in 2018 on GPP and its origin (SOL, NSOL) using a dataset of 10 European forest ecosystem flux towers. In all stations where GPP reductions were observed during the drought, these were largely explained by declines in the maximum apparent canopy scale carboxylation rate VCMAX,APP (NSOL) when the soil relative extractable water content dropped below around 0.4. Concurrently, we found that the stomatal slope parameter (G1, related to SOL) of the Medlyn et al. unified optimization model linking vegetation conductance and GPP remained relatively constant. These results strengthen the increasing evidence that NSOL should be included in stomatal conductance/photosynthesis models to faithfully simulate both GPP and water fluxes in forest ecosystems during severe drought. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'. [ABSTRACT FROM AUTHOR]

Establishing mixed-species stands is frequently proposed as a strategy to adapt forests to the increasing risk of water scarcity, yet contrasted results have been reported regarding mixing effects on tree drought exposure. To investigate the drivers behind the spatial and temporal variation in water-related mixing effects, we analysed the δ13C variation in 22-year tree ring chronologies for beech and pine trees sampled from 17 pure and mixed pine–beech stands across a large gradient of environmental conditions throughout Europe. In the pure stands, average δ13C values were lower for beech (−27.9‰ to −22.2‰) than for pine (−26.0‰ to −21.1‰), irrespective of site conditions. Decreasing SPEI values (calculated over June to September) were associated with an increase in δ13C for both species, but their effect was influenced by stand basal area for pine and site water availability for beech. Mixing did not change the temporal constancy of δ13C nor the tree reaction to a drought event, for any of the species. While the mixing effect (Δ δ13C = δ13C pure stands − δ13C mixed stands) was on average positive for beech and non-significant for pine across the whole gradient, this effect strongly differed between sites. For both species, mixing was not significant at extremely dry sites and positive at dry sites; on moderately wet sites, mixing was positive for beech and negative for pine; at sites with permanent water supply, no general patterns emerge for any of the species. The pattern of mixing effect along the gradient of water availability was not linear but showed threshold points, highlighting the need to investigate such relation for other combinations of tree species. [ABSTRACT FROM AUTHOR]

• We present new sustainable land system scenarios for Europe for 2050. • Unique values informed each scenario via the Nature Futures Framework (NFF). • Natural grasslands and forests will decline without sustainability targets. • Equal targets under varied NFF scenarios yield diverse outcomes for 20 % of Europe's land. • Identifying convergences/disagreements in sustainability valuations aids dialogue. Ambitious international targets are being developed to protect and restore biodiversity under the Convention on Biological Diversity's post-2020 Global Biodiversity Framework and the European Union's Green Deal. Yet, the land system consequences of meeting such targets are unclear, as multiple pathways may be able to deliver on the set targets. This paper introduces a novel scenario approach assessing the plural implementations of these targets. The Nature Futures Framework (NFF) developed by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services aims to illustrate the different, positive ways in which society can value nature. It therefore offers a lens through which the spatial implementation of sustainability targets may be envisioned. We used CLUMondo, a spatially explicit model, to simulate plural land system scenarios for Europe for 2050. The model builds on current land system representations of Europe and explores how and where sustainability targets can be implemented under projected population trends and commodity demands. We created three different scenarios in which the sustainability targets are met, each representing an alternative, normative view on nature as represented by the NFF, favoring land systems providing strong climate regulation (Nature for Society), species conservation (Nature for Nature), or agricultural heritage features (Nature as Culture). Our results show that, irrespective of the NFF view, meeting sustainability targets will require European land systems to drastically change, as natural grasslands and forests are forecast to expand while productive areas are projected to undergo a dual intensification and diversification trajectory. Despite each NFF perspective showcasing a similar direction of change, 20% of Europe's land area will differ based on the adopted NFF perspective, with hotspots of disagreement identified in eastern and western Europe. These simulations go beyond existing scenario approaches by not only depicting broad societal developments for Europe, but also by quantifying the land system synergies and trade-offs associated with alternative, archetypal, interpretations and values of how nature may be managed for sustainability. This quantification exemplifies a means towards constructive dialogue, on the one hand by acknowledging areas of contention, and bringing such issues to the fore, and on the other by highlighting points of convergence in a vision for a sustainable Europe. [ABSTRACT FROM AUTHOR]

Aim: The aim was to decipher Europe‐wide spatio‐temporal patterns of forest growth dynamics and their associations with carbon isotope fractionation processes inferred from tree rings as modulated by climate warming. Location: Europe and North Africa (30‒70° N, 10° W‒35° E). Time period: 1901‒2003. Major taxa studied: Temperate and Euro‐Siberian trees. Methods: We characterize changes in the relationship between tree growth and carbon isotope fractionation over the 20th century using a European network consisting of 20 site chronologies. Using indexed tree‐ring widths (TRWi), we assess shifts in the temporal coherence of radial growth across sites (synchrony) for five forest ecosystems (Atlantic, boreal, cold continental, Mediterranean and temperate). We also examine whether TRWi shows variable coupling with leaf‐level gas exchange, inferred from indexed carbon isotope discrimination of tree‐ring cellulose (Δ13Ci). Results: We find spatial autocorrelation for TRWi and Δ13Ci extending over a maximum of 1,000 km among forest stands. However, growth synchrony is not uniform across Europe, but increases along a latitudinal gradient concurrent with decreasing temperature and evapotranspiration. Latitudinal relationships between TRWi and Δ13Ci (changing from negative to positive southwards) point to drought impairing carbon uptake via stomatal regulation for water saving occurring at forests below 60° N in continental Europe. An increase in forest growth synchrony over the 20th century together with increasingly positive relationships between TRWi and Δ13Ci indicate intensifying impacts of drought on tree performance. These effects are noticeable in drought‐prone biomes (Mediterranean, temperate and cold continental). Main conclusions: At the turn of this century, convergence in growth synchrony across European forest ecosystems is coupled with coordinated warming‐induced effects of drought on leaf physiology and tree growth spreading northwards. Such a tendency towards exacerbated moisture‐sensitive growth and physiology could override positive effects of enhanced leaf intercellular CO2 concentrations, possibly resulting in Europe‐wide declines of forest carbon gain in the coming decades. [ABSTRACT FROM AUTHOR]

Current knowledge of climate change effects on forest ecology and species conservation should be linked to understanding of the past-time. Abies pinsapo forests constitute a model of an endangered ecosystem, highly vulnerable to ongoing warming, whose populations have been declining for centuries, while the drivers of this local depletion trend remain poorly understood. We hypothesized that long-term disturbances, both human- and natural-induced, have shaped A. pinsapo forests, contributing to these decline processes. Until today, studies using fossil pollen record to identify past climate impacts and land-use changes on A. pinsapo populations have not been done. Here, we investigate forests' dynamics since the late Holocene (1180 cal. AD to present) in Southern Iberian Peninsula from a fossil pollen record by comparing the results obtained with climate fluctuations and land-uses changes. The pollen sequence shows a phase of stability during the Islamic Period (~1180–1400 cal. AD; 'Medieval Climate Anomaly'), followed by increasing degradation at Christian Period concurrent with 'Little Ice Age' (LIA) (ca. 1487–1530 cal. AD). The Modern Period (1530–1800 cal. AD; LIA) is linked to intensive forest management, related to the naval industry. Afterwards, a progressive reduction is recorded during the Contemporary Age period ('Industrial Period') until 'Recent Warming'. In short, historical severe forest management coupled with increasing aridity since LIA appear to influence A. pinsapo forest current species composition and poor structural diversity. These disturbances might be limiting the resilience of A. pinsapo forests under a climate change scenario. A selected forest management could promote a more complex forest structure. [ABSTRACT FROM AUTHOR]

Land use changes in Europe have resulted in forest loss and fragmentation that have been proved to be key factors driving the decline of various forest bird populations. Quantifying the environmental factors which allow the persistence of forest birds in highly modified landscapes is therefore essential to enhance conservation efforts. In the present study, we defined the environmental factors determining the distribution of seven forest birds (Picus viridis, Dendrocopos major, Dryobates minor, Garrulus glandarius, Poecile palustris, Sitta europea, Aegithalos caudatus) in a central portion of the Po Plain, northern Italy. In the study area, less than 12% of the whole territory is covered by broad-leaved forests (concentrated along the main rivers) and tree plantations. To obtain a full picture of the habitat requirements of these seven forest bird species, we first conducted a survey of their populations using the point count method during the 2015 breeding season, following which, using resource selection functions, we investigated the effect of environmental variables on each species, mainly focusing on the role of natural forests and tree plantations. The effect of variables was assessed both at a home-range scale and at four different scales in the surrounding context. Tree plantations, in addition to natural forests, proved to be important for most of the seven species studied, including forest specialists such as Dryobates minor and Poecile palustris. The distribution of forest species was better explained by habitat amount than by habitat configuration, both at the home-range scale and in the surrounding context. As expected, Sitta europaea was the most sensitive species to land use changes, and broad-leaved natural forests were essential for its persistence in the landscape. [ABSTRACT FROM AUTHOR]

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Forest ecosystems provide a wide range of environmental services with an important role in the Earth’s lifesupport system. Climate change in Southeastern Europe (SEE) and forecasts for the period until 2070 have a huge impact on the present and future planning in forestry and watershed management, due to the observed trends: the increment of mean annual air temperature from 2,5–5,0 °C until the end of the XXI century; redistribution of annual precipitation, with much more precipitation in the spring-summer period, during short, intensive rain events; a decrease of annual precipitation and soil moisture of 10–20 %, with extreme consequences: dieback and disappearance of forests in huge areas of hilly-mountainous regions. Degradation and loss of forests leads to spread and intensification of soil erosion, with frequent torrential floods, mudflows, landslides, and avalanches. Stable forest ecosystems are pillars of sustainable development, repopulation and could provide means and resources to battle and overcome poverty in mountainous regions of southeast Europe. [ABSTRACT FROM AUTHOR]

• By 2100, forest services in Europe are projected to decrease substantially (23%). • Inaction might lead to dramatic services loss in the Mediterranean, up to 54%. • Science-driven management strategies can reduce services loss by up to 15% in Europe. European forests are facing multiple natural and anthropogenic pressures that are expected to become more severe in the next decades. Tree diversity is projected to decline in many areas across the continent. How this will affect the provision of forest services remains an open question, whose answer depends, among others, on the practical and theoretical challenges of incorporating assisted migration into climate adaptation strategies. Here, we tackle the issue by combining a large dataset of tree species occurrences, future climatic projections, and data on tree functional traits and tree-specific forest services into a novel modelling framework. We estimate that, by the end of the century and under a natural dispersal scenario, the provision of forest services would decrease on average by 15% in Europe (for RCP 4.5; 23% for RCP 8.5), and up to 52% (70% for RCP 8.5) in the Mediterranean. To explore if and how management could reduce the projected losses, we simulated a suite of alternative assisted migration strategies aimed at identifying, for each locality, the tree species communities offering the best compromise in terms of resilience to climate change and delivery of specific combinations of ecosystem services. Such strategies could reduce losses of services by 10% (15%) on average in Europe, and even increase service availability in the Alpine and Boreal regions but not in the Mediterranean, where losses will remain as high as 33% (54% for RCP 8.5). Our findings highlight how science-driven management strategies could be vital to reduce an otherwise dramatic, European-wide decline of forest services. Our results are qualitatively robust to different assumptions on future carbon emissions and related climate trajectories. That is, our simulated assisted migration strategies identify similar tree species communities under different pathways (RCP 4.5 vs RCP 8.5). This makes our approach a powerful tool for forest management, as it generates advice that is valid regardless of whether, and to what extent, human society will steer away from business-as-usual emission trajectories. [ABSTRACT FROM AUTHOR]

• Sap flow and stem radial variations were evaluated in mixed floodplain forests. • Stem radial variations and sap flow was reflected in species' sensitivity to drought. • Tree water deficit was coupled to drying soil and sap flow to evaporation demand. • Narrow-leaved ash showed the most conservative water use but the highest stem growth. • Groundwater decline and frequent droughts may alter tree species composition. Recent changes in the floodplain forests of Central Europe, caused mainly by changes in hydrological management and the increased frequency of droughts due to climate change, have led to severe degradation of floodplain ecosystems. Our main objective was to determine the sensitivity of trees to drought by observing the response of the tree phenology, stem radial growth, and physiology (sap flow) of three predominant tree species, namely English oak, narrow-leaved ash, and common hornbeam, to the environmental variables (climate). Stem radial growth began before bud break in ring-porous oak and ash, whereas in diffuse-porous hornbeam, growth onset occurred after leaf formation. The early onset with intense growth during favorable months (April–May) observed in ring-porous species was a major prerequisite for the successful growth of oak and ash at this site. Tree water deficit (TWD), an indicator of stem hydration, was triggered by decreasing soil moisture in all species, and was most prominent in ash, followed by oak. Intriguingly, sap flow was decoupled from TWD in all species and was driven primarily by evaporative demand from the atmosphere. Oak was the least conservative in regulating sap flow under atmospheric drought followed by hornbeam, whereas ash was most restricted and reduced its transpiration during dry periods. In contrast, ash was characterized by the highest radial growth and growth-based water-use efficiency. The lower water storage capacity of oak and ash is likely compensated by deep rooting and drought avoidance strategies, respectively. Tree species that tend to use surface soil water could be severely limited by more extractive species such as hornbeam. Despite the contrasting leaf and wood phenology, stomatal control, and rooting depth among the studied floodplain tree species, they exhibited analogous sap flow and water storage dynamics responses to drier conditions that enabled them to co-exist in the South Moravian Region. Nevertheless, our results suggest that the severe droughts and human-induced alterations in groundwater pose serious threats to floodplain forests in Central Europe, with certain tree species being unable to adapt to these altered conditions. [ABSTRACT FROM AUTHOR]

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Air pollution affects forest health through atmospheric deposition of acidic and nitrogen compounds and elevated levels of tropospheric ozone (O3). In 1985, a monitoring network was established across Europe and various research efforts have since been undertaken to define critical values. We measured atmospheric deposition of acidity and nitrogen as well as ambient levels of O3 on 12, 13, and 14 plots, respectively, in the framework of the Swiss Long-Term Forest Ecosystem Research (LWF) in the period from 1995 to 2002. We estimated the critical loads of acidity and of nitrogen, using the steady state mass balance approach, and calculated the critical O3 levels using the AOT40 approach. The deposition of acidity exceeded the critical loads on 2 plots and almost reached them on 4 plots. The median of the measured molar ratio of base nutrient cations to total dissolved aluminium (Bc/Al) in the soil solution was higher than the critical value of 1 for all depths, and also at the plots with an exceedance of the critical load of acidity. For nitrogen, critical loads were exceeded on 8 plots and deposition likely represents a long-term ecological risk on 3 to 10 plots. For O3, exceedance of critical levels was recorded on 12 plots, and led to the development of typical O3-induced visible injury on trees and shrubs, but not for all plots due to (1) the site specific composition of O3 sensitive and tolerant plant species, and (2) the influence of microclimatic site conditions on the stomatal behaviour, i.e., O3 uptake. [ABSTRACT FROM AUTHOR]

• Phosphite spray enhanced the crown condition of unhealthy Quercus robur trees. • Treatments increased the N, P and Mg leaf contents and fine roots of trees. • Abundance and composition of edaphic and endophytic bacteria were not altered. • Phosphite treatments should be implemented with phosphate fertilization. Forest decline induced by Phytophthora is a global phenomenon that affects many tree species. In central Europe, the health of Quercus robur has been declining due to various biotic and abiotic factors, since the 2000s. In drought-prone areas in the Mediterranean region, forests of Q. ilex show maintained tree mortality since the 1980s. The efficacy of potassium phosphite, applied as a foliar or trunk spray at a range of concentrations between 0 and 35%, was investigated over several years in four field trials with mature oaks. Specifically, Experiments 1 and 2, conducted on Q. robur in Poland indicated that aerial and trunk spray of 35% phosphite improved the crown condition of unhealthy trees. The efficacy of treatments was not dependant on the initial tree health condition, although its effects started earlier in trees that had lower crown transparency. Treatments did not alter the abundance and composition of edaphic and endophytic bacteria of trees. Moreover, aerial spray enhanced the N, P and Mg leaf content and induced the formation of fine roots without compromising the secondary growth of trees. In Experiment 3, conducted in Spain on Q. ilex , foliar spray did not improve the crown condition of trees. However, foliar spray of 0.56% phosphite induced twig growth in treated trees located on a southern exposure. Reduction of Phytophthora inoculum by the use phosphite was not observed. Our study provides the foundation for the development of a cost-effective management tool for Phytophthora in Europe and motivates future research into the optimization of treatments in Q. ilex and Q. robur. [ABSTRACT FROM AUTHOR]

Presents the first article in a series exploring the possible relationship between forest damage and acid rain in Europe. Measurement of forest decline; Methods of data synthesis; Findings on forest decline; The extent of decline.

SUMMARY: Three‐year‐old clonal saplings of Picea abies (L.) Karst. were exposed in chambers to 240μg O3 m‐3 for 70 d, 6hd‐1 and then hardened for 14 d at 4°C day/night. The winter hardiness of trees was tested by subjecting excised shoots, bearing previous and current year's needles, to night temperatures of –6, –9, –12, –15 and – 18°C in a computer‐controlled freezer. No visible injury was observed during the fumigation, hardening period or on the current year's needles of any of the clones. However, during post‐freezing recovery in a mist spray unit four of the clones exposed to ozone developed extensive visible injury on the previous year's needles, in the form of severe, uniform necrosis. The affected needles began to fall prematurely. Induced chlorophyll fluorescence was significantly reduced by O3 in two of the clones that showed post‐freezing injury. This suggested that O3‐induced membrane injury increased the sensitivity of needles to freezing. One clone (no. 4076), which exhibited no effect of ozone on fluorescence kinetics, showed severe ozone‐induced injury of the previous year's needles, developing about 40 d after fumigation independent of temperature. Previous year's needles of O3‐treated plants of this clone showed significantly greater rates of euticular transpiration, so the O3 may have induced gradual desiccation of the needles. The restriction of damage to the older needles of certain clones of Norway spruce is consistent with symptoms of forest decline affecting high‐altitude forests on acid soils. Results indicate that O3 predisposes trees to freezing injury, winter desiccation and drought, and it is proposed that such interactions are important factors contributing to the decline of high‐altitude forests of Norway spruce in Europe. [ABSTRACT FROM AUTHOR]

Discusses the widespread forest decline and dieback of forests in large areas of Europe and North America. Consideration of problems such as airborne pollutants and natural stresses such as climactic factors and pathogens; Analyzation of the impact of power plants, industries, and vehicles on forest death; Ambient ozone levels in Central Europe and West Germany; How agricultural fertilizers are the main anthropogenic source of airborne nitrogen; Generation of acid deposition from sulfur dioxide, nitrogen oxides, and hydrogen chloride.

As with other mountain areas in Europe, the subalpine belt of the Central Spanish Pyrenees (approximately 1600–2200 m a.s.l.) has undergone constant deforestation since the Neolithic era and particularly during the Late Middle Ages, in favour of livestock management and grazing in summer. This furthered the rise of transhumance between the lowlands and the highlands. The abrupt change in land cover triggered a variety of geomorphic processes and landforms that partially contributed to land degradation and an increase in erosion and sediment yield: shallow landslides, solifluction lobes, soil creeping, terracettes, parallel deep incisions (henceforth: gullies) and stone-banked lobes. The main factors explaining the location of the various landforms are elevation, gradient, aspect, plant cover, soil characteristics, and the topographic index. The statistical analysis clearly separates two types of landforms: (i) shallow landslides, solifluction lobes, and areas of soil creeping, located at relatively low elevations, deep soils and fairly gentle gradients; and (ii) terracettes, gullies and stone-banked lobes, which are generally found at high elevations, on thin soils, north-facing slopes and steep gradients. The declining livestock pressure from the beginning of the 19th century, and particularly from the mid-20th century, explains the progressive re-colonization of the subalpine belt by forest and the reduction in shallow landslides over the last few decades. Most likely, this forest recovery will continue in the near future, with the hydrological, geomorphological and biogeographical consequences still being far from understood. • Deforestation in the subalpine belt occurred mainly in the Middle Ages to favour the transhumance systems. • Deforestation has induced the triggering of a variety of land degradation processes. • The spatial distribution of landforms is related to topographic factors and soil depth. • Current reduced grazing results in forest expansion and a declining number of shallow landslides. [ABSTRACT FROM AUTHOR]

• Higher resilience and resistance to drought events in mixed stands compared to monospecifics. • Higher benefits of mixture in conifer-broadleaved stands. • The identity of the species mediates tree response to drought. • Increased resilience to drought in drier sites. • Complexity of the relationship between tree growth and drought confirmed. Despite growing evidence that diverse forests play an important role in ecosystem functioning, ensuring the provision of different ecosystem services, whether such diversity improves their response to drought events remains unclear. In this study, we use a large tree-ring database from thirty case studies across nine European countries and eleven species, covering from Mediterranean to hemiboreal forests, to test if the growth response to site specific drought events that occurred between 1975 and 2015 varied between mixed and monospecific stands. In particular, we quantify how stands resist those specific drought events and recover after them, thus analyzing their resilience. For each drought event and forest stand we calculated resistance, recovery, resilience and relative resilience and we related the variation in these indices between monospecific and mixed stands with type of admixture, tree species identity, site aridity gradient, stand basal area and stand age. We found a large variability among case studies, even for those that share similar species composition and have similar climates. On average, mixed stands showed higher resistance, resilience and relative resilience to drought events than monospecific stands. However, the beneficial effect of mixtures could not be generalized, being greatly modulated by the type of admixture and tree species identity, and depending on site water supply and stand characteristics, such as basal area and age. The increase in resilience in mixtures compared with monocultures was greater on the conifer-broadleaved admixtures, and to a lesser extent in the broadleaved-broadleaved combinations. The observed response patterns to drought largely varied among the eleven studied species, thus revealing the importance of functional traits for understanding a species' response to drought across its distribution range. Along the site aridity gradient, resilience and relative resilience to drought increased in drier sites for both monospecific and mixed stands, with an observed trend towards higher resilience in mixed stands in the drier and hotter sites. Our results confirm the complexity of the relationships found of resistance, recovery, resilience and relative resilience with drought when comparing pure vs mixed stands. [ABSTRACT FROM AUTHOR]

Pulses of tree mortality caused by drought have been reported recently in forests around the globe, but large-scale quantitative evidence is lacking for Europe. Analyzing high-resolution annual satellite-based canopy mortality maps from 1987 to 2016 we here show that excess forest mortality (i.e., canopy mortality exceeding the long-term mortality trend) is significantly related to drought across continental Europe. The relationship between water availability and mortality showed threshold behavior, with excess mortality increasing steeply when the integrated climatic water balance from March to July fell below −1.6 standard deviations of its long-term average. For −3.0 standard deviations the probability of excess canopy mortality was 91.6% (83.8–97.5%). Overall, drought caused approximately 500,000 ha of excess forest mortality between 1987 and 2016 in Europe. We here provide evidence that drought is an important driver of tree mortality at the continental scale, and suggest that a future increase in drought could trigger widespread tree mortality in Europe. Droughts pose an increasingly important threat to forests. Here the authors analyse a high-resolution Landsat-based dataset of forest canopy mortality in Europe over 1987–2016 to show that drought is already a major driver of tree mortality. [ABSTRACT FROM AUTHOR]

• Fagus sylvatica, Europe's most important temperate hardwood tree species, is drought sensitive. • This review analyses drought responses from the molecular physiological to the whole-tree level. • The large leaf area and the fine root system, rather than the hydraulic architecture, are most sensitive. • Beech suffers from recent growth reductions in large parts of its distribution range. European beech (Fagus sylvatica) is the dominant tree species of Central Europe's natural forests and one of the continent's most important timber species. This highly competitive species is known to be drought-sensitive and thus may increasingly be threatened by climate change-related heat waves and drought in part of its distribution range. Tree responses and tolerance to drought are complex processes that are best understood by adopting a multi-level analysis spanning from the molecular physiological to the tree and stand levels. Here I review recent progress in our understanding of beech drought responses in all relevant fields of research, notably adjustments in cellular biochemistry, responses of photosynthesis, stomatal regulation and leaf water status, the vulnerability of the hydraulic and phloem systems, adaptive responses of the fine root system, leaf area adjustments, long-term declines in radial growth, and drought-induced tree mortality. A special focus is on population differences in drought tolerance as the basis for the selection of drought-hardier provenances. The evidence from the different research fields is brought together with the aim to develop a multi-disciplinary perception of beech drought response, to identify weak components in the species' drought response strategy, and to suggest future research efforts to close knowledge gaps. [ABSTRACT FROM AUTHOR]

• Bark stripped trees were studied from the point of extent of damage, production characteristics and radial growth in relation to climatic factors. • The stand volume of heavily damaged trees was 50–71% lower compared to healthy trees. • The vertical stem decay reached maximally up to 4.5–6.0 m (mean 1.9–3.1 m) with the mean speed of vertical spreading of 5.7–9.6 cm yr−1. Decayed wood accounted for 30–39% of the stem volume. Bark stripping damage and the resultant stem rot to Norway spruce (Picea abies [L]. Karst), one of the most important tree species, poses a serious problem for forest management in Europe. Our research objective was to determine the effect of bark stripping, the subsequent rot decay and the impact of climatic factors in young (42–49 years) spruce stands. Moreover, we compared the differences between damage caused by red deer (Cervus elaphus L.) and sika deer (Cervus nippon Temminck). In all the cases studied, game damage was lower in forest stands when caused by sika deer (SD − 77.3%) compared to red deer (RD − 88.8%); 27.8% (SD) – 32.0% (RD) of stem circumference was damaged in average. Damaged trees showed higher growth variability and were more sensitive to a lack of precipitation and droughts, while air temperature had a higher effect on the growth of healthy trees. The initial game damage was observed in the 11 (SD) – 14 (RD) year of the mean tree age. The stem volume was lower by 25% (SD) – 28% (RD) in lightly damaged trees, and 50% (SD) – 71% (RD) in heavily damaged trees compared to healthy trees. The vertical stem decay reached a maximum of up to 4.5 m (SD) – 6.0 m (RD) (mean 1.9–3.1 m) with the mean speed of vertical spreading of 5.7 cm yr−1 (SD) – 9.6 (RD) cm yr−1. The mean decayed wood accounted for 30% (SD) – 39% (RD) of the stem volume. The peripheral stem damage by bark stripping and the age of the first occurrence were significant factors in predicting damaged crosscut area and vertical rot spreading in the stem. During this time of climate change, the stability of damaged spruce stands has been significantly disturbed by deer game. [ABSTRACT FROM AUTHOR]

• Air pollution influences the success of lichen translocation for conservation purposes. • The translocation of Lobaria pulmonaria is effective only in unpolluted environments. • Higher contents of heavy metals in translocated thalli reflect their lower survival. • Current air quality in Central Europe limits recolonization by sensitive lichens. Species translocation can be considered as a primary conservation strategy with reference to in situ conservation. In the case of lichens, translocations often risk to fail due stress factors associated with unsuitable receptor sites. Considering the bioecological characteristics of lichens, air pollution is among the most limiting stress factors. In this study, the forest macrolichen Lobaria pulmonaria was used as a model to test the hypothesis that the translocation of sensitive lichens is effective only in unpolluted environments. At purpose, 500 fragments or whole thalli were translocated in selected beech forests of Central Europe (the Western Carpathians, Slovakia) where the species disappeared in the past and in oak forests of Southern Europe (Tuscany, Central Italy) where native populations are present. Prior to the translocation (May 2016) and after one year, morphological and ultrastructural features, trace elements as well as chlorophyll a fluorescence emission were analysed. Four years later, the effectiveness of lichen translocation was further evaluated as presence of the transplants and of newly formed individuals. After one year, the translocation ensured an effective survival of the thalli in remote oak and beech forests characterized by a negligible or low contamination by heavy metals. The transplants were considered successful and developed new lobules and rhizines, attaching by themselves to the bark of the host trees, looking overall healthy, without evident signs of alteration also at ultrastructural level. Moreover, in a few cases newly formed individuals were observed after four years. On the other hand, the results highlighted the link between the unsuccess of the translocation and air pollution in other areas of the Western Carpathians and suggested that current air quality still limits the possibility of recolonization in areas where the model species disappeared. [ABSTRACT FROM AUTHOR]

The formulation of 17 sustainable development goals (SDGs) in 2015 was a major leap forward in humankind's quest for a sustainable future, which likely began in the 17th century, when declining forest resources in Europe led to proposals for the re-establishment and conservation of forests, a strategy that embodies the great idea that the current generation bears responsibility for future generations. Global progress toward SDG fulfillment is monitored by 231 unique social-ecological indicators spread across 169 targets, and remote sensing (RS) provides Earth observation data, directly or indirectly, for 30 (18%) of these indicators. Unfortunately, the UN Global Sustainable Development Report 2019—The Future is Now: Science for Achieving Sustainable Development concluded that, despite initial efforts, the world is not yet on track for achieving most of the SDG targets. Through the EO4SDG initiative by the Group on Earth Observations, however, the full potential of RS is now being explored at a global scale. As of April 2020, preliminary statistical data were available for 21 (70%) of the 30 RS-based SDG indicators, according to the Global SDG Indicators Database. Ten (33%) of the RS-based SDG indicators have also been included in the SDG Index and Dashboards found in the Sustainable Development Report 2019—Transformations to Achieve the Sustainable Development Goals. These statistics, however, do not necessarily reflect the actual status and availability of raw and processed geospatial data for the RS-based indicators, which remains an important issue. Nevertheless, various initiatives have been started to address the need for open access data. RS data can also help in the development of other potentially relevant complementary indicators or sub-indicators. By doing so, they can help meet one of the current challenges of SDG monitoring, which is how best to operationalize the SDG indicators. [ABSTRACT FROM AUTHOR]

In Central Europe, the predominant conservation strategy in forests is integrative management, seeking to balance economic interests with conservation goals. This is complemented by unmanaged strict forest reserves, most often small and with a history of forest management. Whether and how such reserves contribute to conservation when the surrounding forest is under progressive integrative management remains unclear. We compared forest structure and biodiversity of several taxa between formerly managed forest reserves and stands under progressive integrative management in beech and beech-oak forests. Alpha diversity was higher in reserves for birds and bats and higher in managed stands for plants and beetles, with no significant differences for fungi. Community composition differed between reserves and managed stands for plants, wood-decomposing fungi, beetles and birds. Reserves had 17 indicator species, including three red-listed species, and managed stands had 34, including one red-listed species. Diversity metrics differed between reserves and managed stands for both beech and beech-oak forests. Our results indicate that progressive integrative management and reserves, even when located in formerly managed stands, are complementary approaches benefitting different taxa and hosting partly different communities. Higher numbers of plants and beetles in managed stands were associated with higher light availability, as reserves in our study were undisturbed mature stands characterized by low light availability and low deadwood volumes. To benefit light and deadwood demanding species, new reserves should include early or late successional stands. If this is not feasible, restoration measures prior to designation or where possible under current protection status should be discussed. • Birds are more abundant and bats are more active in forest reserves compared to forest under integrative management. • Plants and beetles are more abundant and have higher species numbers in managed forests. • Community composition of plants, wood-decomposing fungi, beetles and birds differs between managed forests and reserves. • Biodiversity conservation in forests should combine set-aside and integrative forest management. • Forest reserves should include more stands in early and late successional stages with higher light availability. [ABSTRACT FROM AUTHOR]

The diversity of Phytophthora species in declining Fagaceae forests in Europe is increasing in the last years. The genus Quercus is one of the most extended Fagaceae genera in Europe, and Q. ilex is the dominant tree in Spain. The introduction of soil-borne pathogens, such as Phytophthora in Fagaceae forests modifies the microbial community present in the rhizosphere, and has relevant environmental and economic consequences. A better understanding of the diversity of Phytophthora spp. associated with Q. ilex is proposed in this study by using Next Generation Sequencing (NGS) in six Q. ilex stands located in three regions in Spain. Thirty-seven Phytophthora phylotypes belonging to clades 1 to 12, except for clades 4, 5 and 11, are detected in this study, which represents a high diversity of Phytophthora species in holm oak Spanish forests. Phytophthora chlamydospora, P. citrophthora, P. gonapodyides, P. lacustris, P. meadii, P. plurivora, P. pseudocryptogea, P. psychrophila and P. quercina were present in the three regions. Seven phylotypes could not be associated with known Phytophthora species, so they were putatively named as Phytophthora sp. Most of the detected phylotypes corresponded to terrestrial Phytophthora species but aquatic species from clades 6 and 9 were also present in all regions. [ABSTRACT FROM AUTHOR]

Epiphytic richness is continuously declining due to forest fragmentation, logging, burning, agriculture, and livestock. The rate of species loss caused by habitat degradation and loss is more pronounced in Central and South America. Considering the extreme difficulty and time required to identify the more inconspicuous species, rapid diversity assessment methods need to be extrapolated throughout the world. This study correlated lichen growth forms and total epiphytic abundance across 119 forests located in Europe and Central-South America. A total of 54 papers were selected from specific databases focused on lichens. Additionally, data from several unpublished ecological studies were included. Linear regression models showed that epiphytic lichen abundance was highly and positively correlated with the number of growth forms at all geographical levels considered (i.e., Central-South American and European forests, and the combination of both). Thus, the use of growth forms may provide an alternative and complementary way to evaluate epiphytic diversity because most growth forms have cosmopolitan distribution and are easily recognizable. [ABSTRACT FROM AUTHOR]

Detecting and understanding changes or trends in forest health is essential in a context of increasing frequency of extreme weather events. In addition to the climate-induced tree vulnerability, an increase in biotic attacks due to warming and phenology shifts for insects and trees, could amplify the decline of forest health. The knowledge of the reaction of the trees to the past biotic and abiotic constraints is the key to understand their future resilience. For that purpose, we need long time-span observations to detect immediate and delayed effects of environmental factors on forest trees, and the transnational monitoring network of ICP Forest, initiated in the 80s, gives us this opportunity. Since 30 years onwards, defoliation percentages and abnormal leaves colorations are recorded each year on more than 100,000 trees over Europe in order to quantify their health. Despite a difficult interpretation and an uncertain objectivity of these criteria (because of their "expert" visual assessment) numerous studies have been conducted to interpret the interannual variations and the trends of crown conditions data, in regard to environmental constraints. However, very few studies have examined the physiological impact of these leaf losses or discolourations. Our study was launched in this spirit.Because radial growth is a well-established indicator of tree health and physiological status, we cored to the pith 544 beech trees over 89 plots of the French ICP Forest Level I network. Climate series and soil water deficits were computed for each plot, and a classical dendroecology study was performed. To go further, we tried a joined analysis of crown deficit, radial growth signals, climatic and biotic constraints. Our questions were: i) is radial growth and leaf loss controlled by similar climatic factors; ii) can leaf loss explain part of the inter-annual variations of radial growth. To analyse this complex spatio-temporal dataset, we used the Random Forest Regression. This new machine learning method, was applied to predict annual ring width and defoliation using climatic and water balance variables over 6 French ecological regions. Then annual defoliations with pest and disease damages were added to the potential explaining variables in order to predict annual growth.Environmental constraints were identified to explain year-to-year variations of crown conditions and ring-widths. Nevertheless, in the case of beech, current (or lagged) crown condition was not relevant to explain radial growth. This result opens the discussion about the relevance of defoliation assessment as an indicator of tree health. [ABSTRACT FROM AUTHOR]