Warmer climate and more frequent extreme droughts will pose major threats to forest ecosystems. Past demography processes due to post-glacial recolonization and adaptation to local environmental ...conditions are among the main contributors to genetic differentiation processes among provenances. Assessing the intra-specific variability of tree growth responses to such changes is crucial to explore a species' potential to cope with climate warming. We combined growth-related traits derived from tree-ring width series with neutral genetic information of 18 European provenances of silver fir (Abies alba Mill.) growing in two common garden experiments in Switzerland.
Analyses based on neutral single nucleotide polymorphisms revealed that the studied provenances grouped into three longitudinal clusters. These three genetic clusters showed differences in growth traits (height and DBH), with the provenances from the eastern cluster exhibiting the highest growth. The Pyrenees cluster showed significantly lower recovery and resilience to the extreme drought of 2003 as well as lower values of growth autocorrelation. QST-FST and correlation analyses with climate of provenance origin suggest that the differences among provenances found in some traits result from natural selection.
Our study suggests that the last post-glacial re-colonization and natural selection are the major drivers explaining the intra-specific variability in growth of silver fir across Europe. These findings highlight the importance of combining dendroecology and genetic analyses on fitness-related traits to assess the potential of a species to cope with global environmental change and provide insights to support assisted gene flow to ensure the persistence of the species in European forests.
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•Long-term growth and its climate responses have a clear genetic basis.•Natural selection and past demography explain intra-specific differences in growth.•Southern provenances are not always the best performers growth-wise.•Combining dendrochronology and genetics can inform assisted migration strategies.
•Drought and frost induce abrupt growth decreases prior to tree death.•Trees respond with growth reduction during and after drought.•Trees experience instantaneous growth reduction after frost.
Tree ...mortality as a crucial element of natural forest dynamics is still a poorly understood process. Abrupt growth decreases are known to occur several years or decades before complete cessation of growth. Hence, identifying and linking these growth decreases to potential inciting factors such as drought and frost will improve our understanding of mortality processes. We analyzed nine Central European tree species including six coniferous species (Abies alba, Picea abies, Larix decidua, Pinus sylvestris, Pinus cembra, Pinus montana) and three broadleaved species (Fagus sylvatica, Quercus spp., Acer pseudoplatanus). Tree-ring data from 848 standing dead trees from 14 forest reserves all over Switzerland were sampled. We applied distributed lag non-linear models to relate abrupt growth decreases to drought and frost. The results indicate for many species that both drought and frost have a moderate to major impact on abrupt growth decreases prior to tree death. While late frost in spring may instantaneously result in sustained abrupt growth decreases in most species except Scots pine and mountain pine, severe drought over several months in spring may either show an immediate negative impact on growth, such as in beech, or feature negative reactions that are lagged by several years, such as in oak and Scots pine. Thus, extreme climatic conditions have an essential influence on abrupt growth decreases that finally result in tree death, although variability of the reactions within and among species is high.
Досліджено сучасний санітарний стан бука лісового (Fagus sylvatica L.), ялиці білої (Abies alba Mill.) та ялини європейської (Picea abies (L.) Karsten) у Національному природному парку "Гуцульщина" ...та визначено першопричини їх ослаблення, втрати біотичної стійкості і продуктивності. З'ясовано, що сучасні екологічні виклики, зокрема такі як глобальні зміни клімату, антропогенний тиск, атаки шкідників та епіфітотійне поширення збудників інфекційних хвороб, є предикторами вразливості лісів, що призводить до порушення стратегій їхнього збереження і відновлення. Розраховано та проаналізовано середні значення показника санітарного стану за 2022-2023 рр. на підставі детального лісопатологічного обстеження 15 пробних площ, а також ідентифіковано видовий склад патологій інфекційного характеру у деревостанах дослідного регіону. Встановлено, що загальний санітарний стан лісів за участю бука лісового, ялиці білої та ялини європейської, що ростуть в умовах Національного природного парку "Гуцульщина", наразі потрібно вважати ослабленим. Середньозважений показник санітарного стану становить 2,50 з варіюванням від 1,39-3,55 (у 2022 р.) і 1,53-3,52 (у 2023 р.). Спостерігається повільне, проте стійке, збільшення площ розладнаних і загиблих деревостанів. Зафіксовано наявність дерев V і VІ категорій стану, осередки бактеріозу, мікозних хвороб і стовбурових шкідників. Під час обстежень відзначено типову симптоматику бактеріальної водянки ялиці (збудник – фітопатогенна бактерія Lelliottia nimipressuralis (Carter 1945)), раку ялиці (збудник – іржастий гриб Melampsorella cerastii (Pers.) J. Schröt. 1887), нектріозу бука (збудник – гриб-ксилотроф Neonectria ditissima (Tul., & C. Tul.) Samuels & Rossman 2006). Серед комплексу афілофороїдних макроміцетів найбільшу кількість видів зареєстровано на деревах бука європейського, найменшу – на ялиці білій. Найпоширенішою виявилася група ксилотрофних базидіоміцетів, серед яких зареєстровано збудники кореневих і стовбурових гнилей (гриби родів Heterobasidion Bref. 1888 та Armillaria (Fr.) Staude 1857, а також видів Phellinus hartigii (Allesch., & Schnabl) Pat., 1903, Fomitopsis pinicola (Sw.) P. Karst. 1881, Fomes fomentarius (L.) Fr. 1849 та ін). Відзначено, що врахування санітарного стану стає ключовим чинником під час розроблення наукових і практичних рішень для забезпечення стійкості та збереження корінних природних лісів Національного природного парку "Гуцульщина".
•Tree species’ responses to bark beetle induced canopy disturbance were studied in mixed stands.•Saplings and pole-sized trees responded to forest-gap gradient but not small and tall ...seedlings.•Inter-specific differences in species abundance relative to gap properties were found.•Beech was affected by gap size across all life stages.•Deer browsing has changed regeneration patterns in these forests.
The combined effects of various disturbance types have lasting consequences on forest ecosystems and the services they provide. We examined inter-specific differences in the responses of European beech, silver fir and Norway spruce to canopy disturbance across four life stages (small seedlings, tall seedlings, saplings and pole-sized trees) in two Carpathian old-growth mixed beech forests located in the Gorce National Park (GNP) and Babia Gora National Park (BGNP), Poland. Both study sites were recently affected by spruce bark beetle outbreak. We compared the composition of tree regeneration between forest plots, canopy gaps and expanded areas (i.e. areas located under tree crowns). Moreover, we studied how various gap properties (size, expanded gap to canopy gap size ratio, shape) and other factors (browsing, plant and advanced regeneration cover) shaped regeneration patterns. Inter-specific differences in species abundance relative to gap properties and intra-specific differences in species response across various life stages to gap properties were found. Gap properties had more pronounced effects on saplings and pole-sized trees than on small and tall seedlings. Gap size had the most noticeable effect on beech across all regeneration classes. However, its effect varied from negative to positive depending on life stage. Pole-sized trees of all species responded positively to gap size. Thus, it seems that large gaps provided an opportunity for all species to recruit to canopy. Fir and spruce responded contrastingly to expanded gap to canopy gap size ratio, which reflects differences in their ability to adapt to high-intensity solar radiation. With the exception of beech, the ‘forest-gap’ gradient only affected trees in the advanced life stages (saplings and pole-sized trees). Beech and fir sapling densities and fir pole-sized tree densities were higher when under forest canopy, but spruce pole-sized trees were slightly more abundant in expanded areas. Browsing rates differed between the two study sites; they were more severe in BGNP, where deer densities in the last twenty years have been significantly higher. This intense deer browsing kept silver fir regeneration below the height of 0.5 m and prevented any recruitment to sapling stage. We conclude that even though the recent spruce mortality caused by bark beetle outbreak improved light conditions in both study areas, thus providing good regeneration opportunities to both beech and fir, deer browsing may have long-lasting effects on successional patterns by hindering fir recruitment in BGNP.
•We assessed forest biomass dynamics in mountain forests over 25 years.•Spatiotemporal climate variability had a minor effect on tree biomass increment at the scale of individual plots.•We showed ...that climate, geomorphology, and stand characteristics modify stand dynamics.•Tree species proportion was a significant driver of stand dynamics.•The topographic wetness index indicated sites with higher recruitment and increment and lower mortality.
Tree aboveground biomass and its increment are sensitive forest and landscape dynamics indicators. Although various methods can measure forest biomass dynamics, only in situ, direct monitoring can substantially reduce the uncertainty related to unknown or uncontrolled factors. Within the present study, we aimed to isolate drivers of tree biomass increment, mortality, and recruitment in the Gorce National Park (GNP), Outer Western Carpathians, Poland. We used a unique database consisting of information collected between 1992 and 2017 (in 5-year intervals) within 389 permanent monitoring plots regularly distributed in the GNP area. This allowed us to calculate tree biomass and its increments and model them using a set of explanatory variables: proportion of particular tree species, mean temperature of the coldest quarter (bio11), mean precipitation of the warmest quarter (bio18), elevation, topographic wetness index (TWI), stand basal area (BA), diameter heterogeneity expressed by the coefficient of variation (DBH CV), and conservation regime. We applied generalized linear mixed-effects models (GLMMs), assuming the beta distribution of response variables, i.e. biomass proportions of increment, recruitment, and mortality of three main tree species: Norway spruce Picea abies (L.) Karst, European beech Fagus sylvatica L., and silver fir Abies alba Mill.
In a large part of the GNP area, tree biomass increased. In the central and southern parts of the park, tree mortality was higher than in other parts, especially between 2002 and 2007, due to bark beetle outbreaks and intense wind damage. Stand dynamics of all species depended mainly on species proportion in stand biomass. The increment of Abies alba increased with TWI but decreased with BA and DBH CV. Recruitment decreased with BA and slope but increased with TWI and DBH CV, while mortality decreased with DBH CV and TWI. For Fagus sylvatica, increment increased with TWI but decreased with BA, elevation, and bio18, while recruitment decreased with BA and increased with TWI. Mortality decreased with DBH CV, bio11, and TWI but increased with BA. Picea abies increment increased with elevation but decreased with BA, slope, and DBH CV and weakly increased with bio11. Recruitment increased with TWI but decreased with BA and DBH CV, while mortality decreased with DBH CV, BA, and bio18. Water retention at the plot level, approximated by TWI, decreased mortality and increased recruitment of the studied species. Therefore, it can serve as an indicator of suitable microsites for their persistence. In addition, the increment was lower in strictly protected forests, while mortality was higher. Our study provided quantitative evidence of how climate, geomorphology, and forest stand characteristics modify stand dynamics.
It is expected that extreme climate events such as droughts will increase in both severity and intensity as a consequence of forecasted climate change. Complementarity among tree species in resource ...acquisition strategy may reduce interspecific competition and increase the occurrence of facilitative interactions, resulting in an improved tree growth and resilience to extreme climatic events. However, the response of individual trees growing in more functionally diverse stands to extreme events is still under debate. We investigate the growth response of silver fir (Abies alba) to an extreme drought event which occurred in 1985â1986 in the Central Spanish Pyrenees and how the growth and resilience of trees relate to their neighbourhood functional diversity, stand heterogeneity and intraspecific and interspecific competition. Dendroecological methods were used to reconstruct radial growth. We recorded all tree species living around each sampled tree and calculated indices of intraâ and interspecific competition among coexisting trees. Functional diversity around each focal tree was calculated by using the Rao's quadratic entropy. Silver fir growth decreased significantly in response to the drought in the vast majority of trees, but most of them showed a growth recovery 3Â years later. Despite most trees showed negative growth trends following the drought event (70%), those trees growing in more functionally diverse stands were more resilient, recovered more quickly and displayed greater growth and growth trends. Synthesis. The presented findings support the growing body of evidence that shows a positive impact of diversity on forest function. In addition, we provide a direct linkage between tree growth response to climate at the individual tree scale and a direct quantification of neighbourhood functional diversity and competition. An enhanced functional diversity facilitating a more efficient use of resources at the interspecific level and potentially increasing facilitative interactions contributes to lessening the negative impacts of extreme events as droughts on forest growth.
•Stable mean fire rotation (mFRI) of ∼200–300yr occurred throughout the Holocene.•P. abies favoured by low to moderate fire severity/area burned.•Disturbance by fire facilitated the establishment of ...F. sylvatica.•F. sylvatica negatively affected by severe/larger size fires.•Humans lengthen FRI and increased charcoal peak magnitude.
Fire frequency and severity are key parameters in evaluating fire-mediated changes in ecosystems, but these metrics are rarely reconstructed at extensive temporal scales. Notably our understanding of the role of fire regime dynamics in the functioning and biodiversity of Central Eastern European temperate forests is limited because investigation of the effect of fire has been neglected. To fill this gap in knowledge, we applied a multi-proxy approach (macrocharcoal, charred remains, pollen, plant macrofossils) to two sedimentary sequences spanning stands of closed canopy Picea abies to the P. abies treeline located in the northern Carpathians, Romania. We found that climate exerts a broad-scale influence, whereas vegetation feedbacks strongly modulate this fire-climate relationship. Fire has been almost continuously present throughout the Holocene with a remarkably stable mean fire rotation (∼250yr) with fires of mostly low to mid severity and/or small to medium size. Humans have shifted the fire regime during the last 2800years to slightly longer fire return intervals (mean 300yr) and more biomass consumption per fire. We found that P. abies was favoured by low to moderate fire severity/area burned. The establishment of late-successional, shade tolerant Fagus sylvatica was facilitated by fire disturbances, but its expansion coincided with major gaps in fire events. This highlights the key role of fire in the expansion of F. sylvatica that seems only possible in a low/small to mixed severity/size fire regime with a sufficiently long fire return interval. High magnitude charcoal peaks negatively affected F. sylvatica. We found more diverse pollen assemblages, especially taxa linked to anthropogenic impact, at times of moderate fire disturbance corroborating the intermediate disturbance hypothesis. In terms of forest management, our results show that, contrary to current understanding, fire is a natural and important driver of vegetation change in this region. The anticipated increase in fire activity with the climate warming and/or augmented fuel accumulation may threaten the dominant forest ecosystems, given that these are adapted to low frequency and severity fires. We advise forestry to consider the effects of fire as part of climate-change conservation strategies. Diversifying the forest tree mixture with more fire-resistant native species is desirable in order to mitigate the effects of increased fire occurrence and severity.
•The radial increment of Abies alba Mill. in older and younger generations is diverse.•GAM allows for precise modelling of tree-ring growth and detects significant growth changes.•The radial ...increment variation indicates a potential significant reduction in tree-ring widths in the future.•Changes in the growth rate increase the probability of a significantly low DBH increment.
Tree-ring patterns are indicators of a tree's responses to various stressors and may be employed to predict forest decline. The primary aim of this study was to analyse and model tree-ring growth in Abies alba Mill. trees from older (OG; A. alba trees aged 136–300 years) and younger (YG; A. alba trees aged 45–135 years) generations in Central Europe in Poland, with particular attention paid to growth trends before, during, and after growth decline. The hypothesis was as follows: the radial increment variation can predict an abrupt growth decrease during growth decline. A novel approach was introduced to analyse growth trends based on a generalised additive model (GAM). The first derivative of the GAM spline and the Bayesian confidence intervals show inflection points and periods of significant growth changes. Three clusters for A. alba trees in OG (OG-A, OG-B, and OG-C) and four clusters for A. alba trees in YG (YG-A, YG-B, YG-C, and YG-D) were distinguished. Tree-ring widths of A. alba showed minimum values between 1980 and 1985. During this period, the mean tree-ring widths of A. alba in OG and YG were less than 1.0 and 1.5 mm, respectively. Generally, in the investigated area, A. alba decline began after 1960 (1965), and A. alba recovery began after 1980 (1985). The results of this study indicate that an abrupt growth reduction is typically a consequence of tree-ring width dynamics prior to decline. The radial increment variation indicates the degree of A. alba growth decline, and when the number and size of changes in tree-ring growth dynamics increases, the probability of a low radial increment occurring during A. alba decline increases. Early detection of A. alba trees at risk of decline may facilitate efforts to enhance the resistance of stands to disturbances and climate changes.
The response of forest ecosystems to increased atmospheric CO₂is constrained by nutrient availability. It is thus crucial to account for nutrient limitation when studying the forest response to ...climate change. The objectives of this study were to describe the nutritional status of the main European tree species, to identify growth‐limiting nutrients and to assess changes in tree nutrition during the past two decades. We analysed the foliar nutrition data collected during 1992–2009 on the intensive forest monitoring plots of the ICP Forests programme. Of the 22 significant temporal trends that were observed in foliar nutrient concentrations, 20 were decreasing and two were increasing. Some of these trends were alarming, among which the foliar P concentration in F. sylvatica, Q. Petraea and P. sylvestris that significantly deteriorated during 1992–2009. In Q. Petraea and P. sylvestris, the decrease in foliar P concentration was more pronounced on plots with low foliar P status, meaning that trees with latent P deficiency could become deficient in the near future. Increased tree productivity, possibly resulting from high N deposition and from the global increase in atmospheric CO₂, has led to higher nutrient demand by trees. As the soil nutrient supply was not always sufficient to meet the demands of faster growing trees, this could partly explain the deterioration of tree mineral nutrition. The results suggest that when evaluating forest carbon storage capacity and when planning to reduce CO₂emissions by increasing use of wood biomass for bioenergy, it is crucial that nutrient limitations for forest growth are considered.
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