While homogeneity of forest stands was previously sought to simplify forest management planning, structurally rich stands are increasingly encouraged and implemented in contemporary forest management. One reason for this reversal is that structuring may promote forest stability and resilience as well as the provision of ecosystem services. However, the effect of structure on forest growth is not yet fully understood. In contrast, simple density-growth relationships are commonly used for modelling, forest planning, and as a background for forest management decisions without taking structure into account. Using the example of long-term Norway spruce (Picea abies (L.) H. Karst) stands covering a wide range of structures, densities, and site conditions, we investigated how stand structure modulates tree and forest stand growth and what mechanisms are behind this modulation. First, we show that under otherwise identical conditions, tree size variation increases the crown occupancy of the 3-dimensional space owing to the wider vertical distribution of tree crowns. We furthermore demonstrate that the occupancy of structurally diverse forests increases relative to the occupancy of homogenous forests with increasing stand density. Second, we found that, all other conditions being equal, stand growth increases asymptotically with increasing tree size variation; this applies to both managed and unmanaged forests although the level and rate of increase is higher in dense, un-thinned forests than in thinned forests. Third, we reveal the interdependency between size distribution and size-growth, demonstrating that structural diversity increases the growth efficiency of large trees in dense forests but increases the efficiency of smaller trees in sparsely stocked forests. Ensembles of trees with different sizes and efficiencies can make the best possible use of the growing space and resources and produce maximum stand growth. We discuss how previously contradictory views on the relationships between density and growth, density and symmetry of competition, and size and growth of trees become consistent when structural diversity is taken into account. Based on these findings, we also evaluate how growth responds to structurally oriented high thinning compared with homogenizing low thinning.

In the face of accelerating climate change and increasingly complex disturbance regimes, enhancing forest ecosystem resilience has become a core priority in forest ecology and management. This paper argues that long-term resilience in hemiboreal forests depends fundamentally on the management of ecosystem legacies—structural, compositional, and functional remnants that persist following past disturbances and land use. Organized under the resilience framework, this perspective emphasizes that resilience is not solely a matter of response or effect, but an emergent property shaped by abiotic and biotic legacies, including life history traits, landscape heterogeneity, and both anthropogenic and natural disturbance. In this paper, drawing from disturbance ecology, resilience theory, and regional empirical studies, a conceptual model is presented that integrates legacy attributes, environmental filters, and management objectives to support adaptive restoration strategies. It helps design restoration pathways that are ecologically meaningful, operationally realistic, and robust to novel disturbance regimes. By operationalizing legacy–action linkages, the model offers practitioners concrete entry points for retention, disturbance use, and landscape design to enhance resilience.

Lichens are key components of forest ecosystems, contributing to biodiversity and serving as sensitive indicators of environmental change. Their post-fire dynamics can provide valuable insights into habitat resilience, succession processes, and the ecological impacts of fire. Understanding lichen responses to fire is therefore essential for informing conservation and management in fire-affected forests. This study addresses a key knowledge gap by investigating the recovery dynamics of lichen communities across a post-fire chronosequence in Scots pine-dominated forests in hemiboreal Estonia. Using a space-for-time substitution approach, we examined lichen community composition and richness in stands that experienced stand-replacing fires at different points in time-specifically 16, 27, 42, 73, 84 and 187 years since fire. Lichen communities were surveyed across different substrate types in 18 study plots (each 100 m2), alongside measurements of stand structure and soil characteristics. In total, 96 lichenized taxa (lichens) were recorded in post-fire forest stands, including 10 of high conservation value. The time since the fire was associated with shifts in lichen species composition, however it was not a significant predictor of community-level species richness or Shannon diversity, according to linear mixed models. Richness, diversity, and composition of lichens were significantly influenced by several stand characteristics. In particular, our results highlight the importance of substrate heterogeneity, particularly the availability of deadwood and tree species diversity, in maintaining lichen richness in fire-affected forests. To conserve lichen diversity across landscapes, it is crucial to retain a mosaic of successional stages, as different species thrive at different points along the post-disturbance gradient.

The European spruce bark beetle (Ips typographus L.) is one of the most important forest pests of Norway spruce (Picea abies (L.) H. Karst) in Europe, and sanitation felling remains the standard method used to control ongoing infestations. In hemiboreal forest management, sanitation felling is often carried out in spring in combination with trap logs. We hypothesized that winter sanitation felling might also reduce bivoltine populations if a substantial proportion of beetles overwinter beneath the bark. However, field-based comparisons of sanitation timing remain scarce in the European hemiboreal region. We compared three treatments in five forest units in Estonia, focusing on small infestation spots in middle-aged managed spruce stands: winter sanitation felling, spring sanitation felling with trap logs, and untreated controls. Results revealed that late-season attacks represented only a small fraction of infestations and that overwintering survival of new-generation I. typographus adults beneath the bark was extremely low. Winter sanitation felling did not reduce subsequent infestation relative to untreated stands, whereas spring sanitation felling with trap logs reduced infestation probability locally, although the effect remained modest. Overall, stand and landscape context, together with regional beetle population dynamics, influenced infestation patterns more strongly than treatment.

Wind disturbance and climate change increase the risk of major European spruce bark beetle (ESBB) outbreaks. In order to understand the drivers behind the spread, we used a combination of the Random Forest algorithm and logistic regression mixed modelling to generate robust results. We analysed tree and stand characteristics, level of infestation, and nearness to eight major blowdown areas from a summer storm in 2016 in two conservation areas in south-eastern Estonia, Karula National Park and Otepaa Nature Park. The two areas differ in forest site quality (tree growth conditions) and topographical features, spatial distribution of protected and managed patches, and management history, and were therefore analysed separately. Data collection, in 2020, was based on a network of transect-based circular plots surrounding the blowdowns. By the time of the inventory, four years after the storm, the wind-induced spread had largely come to a halt, with only a few freshly infested Norway spruce trees recorded. The study revealed that, besides the often-mentioned factors tree diameter and share of Norway spruce, intensity of initial infestation in the first 10 m outside the storm area was positively correlated with ESBB infestation probability in the surrounding forest in Karula, where forest cover is more contiguous and under more severe management restrictions. Conversely, distance to any type of open area and tree species diversity decreased infestation probability in Otepaa. Furthermore, trees in patches with average site quality class had a significantly higher infestation risk, compared to those in a low site quality class. Distance to the storm area was not a driver behind the outbreak, and neither did the number of infested trees in the initial storm area affect surrounding stands, at this stage. Differences in significance of factors for infestation probability between the two conservation areas were considerable, which hints at even higher complexity of Norway spruce vigour-bark beetle-climate relations at an international level. Since storm area infestation levels and vicinity did not directly affect spatial distribution of ESBB, but infestation levels in our study were nonetheless high, this suggests that research should focus on early detection and prevention strategies at the landscape scale. In that respect, further investigation is required into the role of tree species diversity, stand structural heterogeneity and growth conditions in reducing outbreak risk and favouring a fast recovery from disturbances.

The European spruce bark beetle ( Ips typographus ), a primary concern for forest management in Europe, often co‐infests its host tree Norway spruce ( Picea abies ) with the northern bark beetle ( Ips duplicatus ). To achieve effective bark beetle control, it is crucial to differentiate between the two species. However up‐to‐date research on I. duplicatus in the hemiboreal region of Europe is lacking. In Estonia, I. duplicatus has been considered univoltine. To address previous suspicions, the current pilot study was conducted to explore the voltinism of I. duplicatus . The study confirmed the development of two generations during the activity period of 2024, with the majority of newly emerged adults of the second generation leaving the host tree by October. Calculation of accumulated degree days above the lowest temperature threshold of 6.3°C demonstrated a significant increase in the annual temperature sum over an 80‐year observation period, indicating the extension of the activity period of I. duplicatus . The shift to bivoltinism is significant for forest managers because it leads to greater forest damage across a larger area within a single activity season. In some cases, I. duplicatus can become the primary pest, requiring distinct monitoring and control measures compared to I. typographus . However, the details of overwintering habits and the exact temperature sum necessary to complete a full generation require further investigation.

Using trap logs to capture Ips typographus and control bark beetle infestations is a traditional forest management method in the hemiboreal region. However, the potential difference in effectiveness between trap logs felled by a chainsaw and those felled by a harvester in capturing bark beetles, particularly I. typographus, has not been investigated. Such differences may be caused by the variation in bark damage resulting from chainsaw versus feed rollers of the harvester head. A study was conducted where trap logs felled with a chainsaw and with a harvester were placed in small clearings created by sanitary cutting after infestations in the previous year by I. typographus– mimicking typical bark beetle control methods. Four weeks after the main flight period began, the number of live beetles were counted on bark samples from trap logs. There were no significant differences in capturing I. typographus depending on the felling method, but differences in accompanying bark beetle species were significant. The densities of Pityogenes chalcographus were greater on trap logs felled by chainsaw, but Polygraphus punctifrons and Crypturgus spp. occurred more likely on the harvester-felled trap logs. Species richness of bark beetles was greater on trap logs felled by harvester. Also, the sum of degree-days (cumulative thermal sum of daily maximum air temperatures above 8.3 °C) positively affected the densities of I. typographus beetles. To avoid re-emergence of mature beetles, frequent monitoring of brood development on trap logs is necessary.

Forest recovery following disturbances is essential for maintaining ecosystem services, especially after large-scale events where regeneration is limited by seed availability. Understanding how environmental and biotic factors influence regeneration across spatial scales is fundamental for landscape-scale management, yet the importance and spatial extent of landscape-scale effects on local recovery remains uncertain. We aimed to assess the relative influence of recovery drivers at plot, patch, and landscape scales on post-disturbance forest regeneration. Specifically, we investigated how local topography, disturbance characteristics, and the spatial arrangement of undisturbed forests affect tree regeneration after severe disturbances, namely windthrows, fires, and bark beetle outbreaks. Our study combines a comprehensive ground-based dataset of post-disturbance regeneration from temperate European forests with Landsat-derived maps of forest cover. We applied a distance-weighted regression approach to evaluate the effect of landscape (i.e., undisturbed forest in proximity of disturbance patches) on recovery, improving upon traditional buffer-based approaches. We found that ¾ of the landscape influence on forest regeneration occurred within 112 m from plot centers, with undisturbed forests nearby positively enhancing regeneration, likely due to increased seed availability. In contrast, plot-level factors, namely disturbance severity and elevation, negatively impacted regeneration, suggesting that regeneration success can be hindered by severe disturbances reducing living biological legacies, as well as harsher local climatic conditions, associated with higher elevations. Our findings underline the importance of integrating landscape-scale management with targeted local interventions to promote post-disturbance forest recovery. Management strategies should consider spatially explicit planning to enhance seed source availability and mitigate severe disturbance impacts.

This study evaluated variation in survival, growth, and stem quality of Norway spruce provenances originating from Estonia, Latvia, and Lithuania in provenance trial to assess the long-term adaptive responses of provenances and identify productive seed sources for future afforestation under changing climatic conditions. Survival was slightly higher for the Jaunjelgava, Viljandi, and Kai & scaron;iadorys provenances, although no consistent geographic trend or association was observed with bioclimatic variables of seed origin. Tree diameter and volume tended to be higher in provenances from southern origins, while northern ones had better stem quality (V & otilde;ru, Viljandi, Smiltene). Some southern and mid-latitude provenances (Kai & scaron;iadorys, Daugavpils) also demonstrated good overall stem quality and low incidence of stem cracks, indicating that high quality is not strictly limited to geographic origin. The incidence of stem cracks was not associated with provenance, and cracks occurred independently of geographic origin or local climatic conditions. 18% of the trees on the site exhibited superior quality. Analysis confirmed strong correlations among growth traits, stem defects, and climate of seed origin, with a clear trade-off between growth and stem quality. Climate variables of the provenance were not significantly correlated with growth traits but showed a modest relationship with stem quality.

Norway spruce, which is sensitive to drought, and Scots pine, which is drought-resistant, are two of the most significant conifer species in Europe. In mixed stands, they can utilize resources more efficiently than in pure stands, leading to higher yields and reduced risk. Tree ring research is often used to study their growth in response to complex environmental factors. Machine learning, though rarely applied to tree ring analysis, might be well suited for modelling these complex relations. Data from 22 triplets (1 mixed and two pure plots of Norway spruce and Scots pine) covering a temperature and precipitation gradient of 3.2-9.2°C and 613 to 1075 mm respectively, were used in this study. On each plot, trees were mapped and measured for dbh, height and height to the crown base. 4490 increment cores were collected and synchronized in the lab. A random forest model with relative DBH, age, competition, mixture and climate variables explained 76.4% of the variation and proved effective in describing ecological relationships.

Shelterwood cutting (SC) has been highlighted as an alternative method to clear-cut (CC) -based even -aged forest management. However, compared to CC, the effect of SC on stand carbon (C) balance is still poorly understood at the ecosystem level. We examined the prompt effect of SC versus CC on ecosystem net primary production (NEP) on a short-term scale, using the C budgeting method combined with eddy covariance (EC) measurements in hemiboreal mature Scots pine stands. The early effect of SC on annual C budget after removing 30 - 40 % of the growing stock revealed diverse patterns in the studied stands; NEP varied from 0.62 to -1.3 t C ha -1 yr - 1 for the C sink and the C source, respectively. However, C loss decreased already in the second post -thinning year and levelled out attaining -0.41 t C ha -1 yr - 1 , which is close to balance. Furthermore, C loss declined in the second post -harvesting year at the CC sites as a result of the increased production of the ground vegetation and the decreased soil heterotrophic respiration (Rh) flux. However, C loss from dry mesotrophic clear -cuts was almost -1.8 t C ha -1 yr - 1 for both study sites. Since estimation of the individual C fluxes for C budgeting is associated with variability -induced errors, the estimated values of NEP contain uncertainties of various levels. The estimated annual cumulative Rh flux was significantly higher in the SC versus CC areas and the mean annual Rh values across the study sites were 3.57 +/- 0.25 and 2.59 +/- 0.09 t C ha -1 yr - 1 , respectively. Annual estimated NEE after SC was 1.8 +/- 0.52 t C ha -1 yr - 1 , gross primary ecosystem production was 9.28 +/- 0.97 and total ecosystem respiration was 7.47 +/- 0.28 t C ha -1 yr - 1 . The discrepancy between the estimated values of NEE and NEP was 1.2 t C ha -1 yr - 1 . In the short term SC demonstrated some advantage over CC from the perspective of the C cycle, but the difference in NEP values between the SC and CC treatments was not convincingly overwhelming. Hence, SC allows to maintain the forest cover for a longer period and to avoid drastic changes in the landscape; still, after SC, C budget varied between the C sink and the C source.

Recent observations of tree regeneration failures following large and severe disturbances, particularly under warm and dry conditions, have raised concerns about the resilience of forest ecosystems and their recovery dynamics in the face of climate change. We investigated the recovery of temperate forests in Europe after large and severe disturbance events (i.e., resulting in more than 70% canopy loss in patches larger than 1 ha), with a range of one to five decades since the disturbance occurred. The study included 143 sites of different forest types and management practices that had experienced 28 disturbance events, including windthrow (132 sites), fire (six sites), and bark beetle outbreaks (five sites). We focused on assessing post-disturbance tree density, structure, and composition as key indicators of forest resilience. We compared post-disturbance height-weighted densities with site-specific pre-disturbance densities to qualitatively assess the potential for structural and compositional recovery, overall and for dominant tree species, respectively. Additionally, we analyzed the ecological drivers of post-windthrow tree density, such as forest management, topography, and post-disturbance aridity, using a series of generalized additive models. The descriptive results show that European temperate forests have been resilient to past large and severe disturbances and concurrent climate conditions, albeit with lower resilience to high-severity fire compared with other disturbance agents. Across sites and disturbance agents, the potential for structural recovery was greater than that of compositional recovery, with a large proportion of plots becoming dominated by early-successional species after disturbance. The models showed that increasing elevation and salvage logging negatively affect post-windthrow regeneration, particularly for late-successional species, while pioneer species are negatively affected by increasing summer aridity. These findings provide a key baseline for assessing future recovery and resilience following the recent occurrence of widespread disturbance in the region and in anticipation of future conditions characterized by increasing heat and drought stress. As a result of global change, forest disturbances are becoming larger and more severe, which may put forest recovery at risk, especially under a warm and dry climate. Our study shows that European temperate forests have been able to recover after large and severe disturbances and concurrent climate conditions, although with more difficulty after fires compared with other disturbance agents. The main factors negatively influencing tree regeneration after wind disturbances were increasing elevation and the removal of damaged trees from the disturbed forests.image

Trees that survive disturbances are important biological legacies that facilitate forests’ recovery and enhance their structural and species diversity, substantially contributing to the resilience of these ecosystems. The dynamic pattern of legacy syndromes sets the understudied aspects of survivors of wind disturbance into focus. Several factors at tree, stand, and landscape scales alter the susceptibility of the remnant trees, and affect their potential to recover and survive subsequent disturbances. The characteristics of the survivors interact with direct stress and mortality drivers such as changed environmental conditions and pressure by pests and pathogens. Climate change further enhances the post-storm vulnerability of the remaining stand. This literature review analyzes the impact of disturbance parameters (e.g., severity, seasonal timing) and characteristics of the affected forest (e.g., tree species composition, successional stage of a forest stand) on the conditions of survivors through post-windthrow stand development. We attempted to reveal the main agents and processes driving the fate of remnant trees and linked delayed mortality patterns to the main stand-scale wind disturbance regimes in Eurasian and North American boreal and temperate forests: (1) stand-replacing, (2) partially stand-replacing, and (3) fine-scale gap disturbance. We found that after stand-replacing wind disturbance, the spatial location of the remaining trees largely determines their onward fate, whereas these survivors are generally more susceptible to subsequent mortality compared to trees that survived less severe events. After partially stand-replacing wind disturbance, the structure of the remnant stand as well as characteristics of the individual remnant trees (e.g., species, age, size) largely determine their survival probability. Following a fine-scale gap disturbance, the trees at the gap edge are more likely to die, compared to the trees situated in the stand interior, but the mortality-causing processes usually operate on a longer time scale. Our findings contribute to the current knowledge on post-windthrow stand development and offer insights into temporal stability of these increasingly important biological legacies.

Clearcutting is a major forest regeneration method in hemiboreal forests that affects forest carbon (C) fluxes. However, there is a lack of knowledge about the immediate effects of clearcutting and subsequent recovery of C-balance of harvested stands. The eddy covariance (EC) method can be used to better understand forest ecosystems carbon dioxide (CO2) exchange by directly measuring net C and water fluxes. In a hemiboreal forest ecosystem C-fluxes were measured in a recently clearcut area with an EC system mounted atop a tower. The stand was clearcut in February 2019, harvesting residues and stumps retained on-site, and the stand left to regenerate naturally. From 15 November 2019 to 14 November 2020, net ecosystem exchange (NEE) results showed the clearcut was a C-source of 1.817 µmol m-2 s-1 (standard deviation 3.249). Average NEE varied with season; winter NEE was 1.136 µmol m-2 s-1, spring NEE was 1.393 µmol m-2 s-1, summer NEE was 1.929 µmol m-2 s-1, and autumn was NEE 2.811 µmol m-2 s-1. Daytime NEE during the summer months approached C-sink status that was offset by high nighttime C-source values, reflecting the balance between photosynthesis and respiration. C-uptake is sensitive to weather conditions, as well as vegetation development. Through long-term measurement, it is also possible to quantify effects of periods with different weather conditions, such as drought, extreme temperatures or precipitation.

To enhance our understanding of forest carbon sequestration, climate change mitigation and drought impact on forest ecosystems, the availability of high-resolution annual forest growth maps based on tree-ring width (TRW) would provide a significant advancement to the field. Site-specific characteristics, which can be approximated by high-resolution Earth observation by satellites (EOS), emerge as crucial drivers of forest growth, influencing how climate translates into tree growth. EOS provides information on surface reflectance related to forest characteristics and thus can potentially improve the accuracy of forest growth models based on TRW. Through the modelling of TRW using EOS, climate and topography data, we showed that species-specific models can explain up to 52 % of model variance (Quercus petraea), while combining different species results in relatively poor model performance (R2 = 13 %). The integration of EOS into models based solely on climate and elevation data improved the explained variance by 6 % on average. Leveraging these insights, we successfully generated a map of annual TRW for the year 2021. We employed the area of applicability (AOA) approach to delineate the range in which our models are deemed valid. The calculated AOA for the established forest-type models was 73 % of the study region, indicating robust spatial applicability. Notably, unreliable predictions predominantly occurred in the climate margins of our dataset. In conclusion, our large-scale assessment underscores the efficacy of combining climate, EOS and topographic data to develop robust models for mapping annual TRW. This research not only fills a critical void in the current understanding of forest growth dynamics but also highlights the potential of integrated data sources for comprehensive ecosystem assessments.

Wind disturbance and climate change increase the risk of major European spruce bark beetle (ESBB) outbreaks. In order to understand the drivers behind the spread, we analysed tree and stand characteristics, level of infestation and position relative to eight major blowdown areas from a summer storm in 2016 in two conservation areas in south-eastern Estonia. The two areas differ in site quality and topographical features, spatial distribution of protected and managed patches, and management history. Data collection was based on a network of transect-based circular plots surrounding the blowdowns. By the time of the inventory, four years after the storm, the wind-induced spread had largely come to a halt, with only a few freshly infested Norway spruce trees recorded. Logistic regression mixed modelling revealed that, besides the often-mentioned factor tree diameter, intensity of initial infestation in the first 10 meters outside the storm area was also positively correlated with ESBB infestation probability in the surrounding forest. Furthermore, trees in patches with average site quality class had significantly highest infestation risk, compared to those in a low site quality class. Tree species diversity was negatively correlated with infestation probability. Distance to the storm area did not show up as a driver behind the outbreak. Differences in significance of factors for infestation probability between the two conservation areas were considerable, which hints at even higher complexity of Norway spruce health – bark beetle – climate relations at an international level. Research should focus on early detection and prevention strategies at the landscape scale. Tree species diversity and stand heterogeneity at different scales may help keep away or control outbreaks, or at least support a faster recovery from disturbances. Furthermore, establishment of pure Norway spruce stands should be avoided in areas susceptible to drought or with a high storm risk.

The relationship between the quality of forest seedlings and their outplanting survival and growth has long been recognized. Various attributes have been proposed to measure the quality of planted seedlings in forest regeneration projects, ranging from simple morphological traits to more complex physiological and performance attributes, or a combination thereof. However, the utility and meaning of seedling quality attributes can differ significantly among regions, nursery practices, site planting conditions, species and the establishment purpose. Here, forest scientists compiled information using a common agreed questionnaire to provide a review of current practices, experiences, legislation and standards for seedling quality across 23 European countries. Large differences exist in measuring seedling quality across countries. The control of the origin of seed and vegetative material (genetic component of plant quality), and control of pests and diseases are common practices in all countries. Morphological attributes are widely used and mandatory in most cases. However, physiological attributes are hardly used at the operative level and mainly concentrated to Fennoscandia. Quality control legislation and seedling quality standards are less strict in northern European countries where seedling production is high, and quality control relies more on the agreements between producers and local plant material users. In contrast, quality standards are stricter in Southern Europe, especially in the Mediterranean countries. The control of seedling quality based on plantation and reforestation success is uncommon and depends on the conditions of the planting site, the traditional practices and the financial support provided by each country. Overall, European countries do not apply the "target seedling concept" for seedling production except for seed origin. Seedling production in many countries is still driven by traditional "know-how" and much less by scientific knowledge progress, which is not adequately disseminated and transferred to the end-users. Our review highlights the need for greater harmonization of seedling quality practices across Europe and the increased dissemination of scientific knowledge to improve seedling quality in forest regeneration activities.

Since fire frequency is expected to increase globally due to climate change, it is important to understand its effects on forest ecosystems. We studied the long-term patterns in species diversity, cover and composition of vascular plants and bryophytes after forest fire and the site-related factors behind them. Research was carried out in northwestern Estonia, using a chronosequence of Scots pine ( L.) stands, located on nutrient poor sandy soils, where fires had occurred 12, 23, 38, 69, 80 and 183 years ago. In every stand three 100 m vegetation plots were established to collect floristic and environmental information. The effects on floristic characteristics of time since fire, light, and soil variables were evaluated with linear mixed models, followed by backward variable selection. Compositional variation was analysed with non-metric multidimensional scaling, Multi-response Permutation Procedures, and Indicator Species Analysis. Altogether, 31 vascular plant and 39 bryophyte species were found in vegetation plots. The cover of the vascular plant and bryophyte layers increased with a longer time since fire. Soil and light variables impacted the richness of several vascular plant and bryophyte groups, whereas only the richness of liverworts and dwarf-shrubs correlated with time since fire. Considerable compositional differences were observed in vascular plant and bryophyte assemblages between recently vs. long-time ago burned stands. To conclude, time since fire significantly impacted compositional patterns of vascular plants and bryophytes in pine forests on nutrient poor soils, although time-related trends in species richness were less evident.Pinus sylvestris2

Coastal dunes near the Baltic Sea are often stabilized by Scots pine forests and are characterized by a mild climate. These ecosystems are affected by water shortages and might be influenced by climate extremes. Considering future climate change, utilizing tree rings could help assess the role of climate extremes on coastal forest growth. We used superposed epoch analysis to study Scots pine responses to droughts and cold winters, with focus on frequency, timing, and duration. We measured ring widths (RW) and latewood blue intensity (LBI) on samples extracted from trees growing at dune ridge and bottom microsites at the south Baltic Sea. At the regional scale, we observed some similarities in tree responses to both extremes between RW and LBI within the same microsite type and region. At the local scale, RW and LBI were more frequently influenced by cold winters than droughts. RW and LBI from dune ridges were more frequently influenced by droughts than RW and LBI from dune bottoms. LBI from both microsites was more often influenced by droughts than RW. RW and LBI from both microsites were similarly often influenced by cold winters. At both scales, the response time of RW and LBI after droughts predominantly lagged by one year, while cold winters were recorded in the same year. The typical duration of growth reductions after both extremes was one year for both RW and LBI. Our study indicates that Scots pine from the Baltic Sea region is sensitive to climate extremes, especially cold winters.