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Abstract: Introduction: Assessing wood growth phenology over multiple years is essential for understanding the environmental drivers of forest growth and improving large-scale predictions of the carbon cycle. Xylogenesis methods facilitate the assessment of the timing and rate of xylem cell wall thickening, the primary sink of carbon in wood. In angiosperm trees, where wood anatomy is complex, significantly less is known about the factors controlling growth cessation in autumn due to indirect, sinteracting, and lag effects, in contrast to growth resumption in spring. Furthermore, both branch and stem growth must be considered to account for the total aboveground phenology. Methods: In this study, we focused on European beech (Fagus sylvatica) and silver birch (Betula pendula) in a mild temperate region (Northern Belgium). We examined the progress of cell wall thickening in autumn and the seasonal timing of xylem growth cessation for these species’ stems over five years and for their branches over one year in mature trees. In addition, we investigated the same variables in the stems and branches of potted saplings for two years and for oak (Quercus robur) and aspen (Populus tremula) saplings over one year. Results: Our results demonstrate a considerable variation in the progression and cessation of wood growth, with differences of up to a month and a half in growth cessation (early September to late October), predominantly driven by climatic variables. Early cessation of xylem growth in stems was strongly associated with high temperatures in April and August, elevated vapour pressure deficit, and severe soil drought in August. The progression of cell wall thickening in late summer was generally synchronized between branches and stems for every species. However, branches sustained a higher percentage of growth (approximately 2 weeks) in early autumn during non-drought years. Discussion: These findings provide valuable insights for refining models of forest growth and carbon storage, enabling a more comprehensive representation that encompasses the entire tree under different climatic scenarios.
Keywords: phenology, cambium, cell wall thickening, hardwood species, atmospheric drought
Published in DiRROS: 08.09.2025; Views: 253; Downloads: 120
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Abstract: Dry and warm climate conditions in southern Europe represent clear limits for European beech (Fagus sylvatica) growth near the species southern distribution limit, but it is unclear how aridification and changes in seasonal precipitation regimes will affect these forests at the individual level. We explored climate-growth relationships and the seasonality of peak climate signals in European beech using daily climate data and a large collection of tree-ring width series from southern and southeastern Europe through Generalised Linear Mixed Models (GLMMs). In most cases we found a positive and significant influence of precipitation on tree growth, and a significant negative effect of maximum temperature. Predictions from the GLMMs revealed a positive impact of precipitation during an 88 day window from spring to early summer (mid-April to mid-July), for an average tree across our network. This critical growing time window ranged from 75 days in warmer and drier conditions, and extended up to 100 days in areas with mild temperatures and moderate summer precipitation. Maximum temperatures negatively affected trees for an average of 27 day window in summer (June-July). This period was reduced to <10 days in locations with wetter and colder summers, rising up to 45 days in sites with drier and warmer summers. The positive effect of precipitation on growth was stronger and commenced earlier in larger trees. Similarly, the negative effects of maximum temperatures were more pronounced for larger trees. The use of daily climate data and a tree-centred approach allowed for capturing critical temporal dynamics in climate-growth relationships that are often overlooked by conventional methods. These insights significantly enhance our understanding of climatic factors influencing individual beech growth at the edge of its distribution range and their seasonal variations.
Keywords: European beech, daily climatic variables, precipitation, maximum temperature, tree-ring width, range limit
Published in DiRROS: 06.06.2025; Views: 510; Downloads: 244
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Abstract: As major terrestrial carbon sinks, forests play an important role in mitigating climate change. The relationship between the seasonal uptake of carbon and its allocation to woody biomass remains poorly understood, leaving a significant gap in our capacity to predict carbon sequestration by forests. Here, we compare the intra-annual dynamics of carbon fluxes and wood formation across the Northern hemisphere, from carbon assimilation and the formation of non-structural carbon compounds to their incorporation in woody tissues. We show temporally coupled seasonal peaks of carbon assimilation (GPP) and wood cell differentiation, while the two processes are substantially decoupled during off-peak periods. Peaks of cambial activity occur substantially earlier compared to GPP, suggesting the buffer role of non-structural carbohydrates between the processes of carbon assimilation and allocation to wood. Our findings suggest that high-resolution seasonal data of ecosystem carbon fluxes, wood formation and the associated physiological processes may reduce uncertainties in carbon source-sink relationships at different spatial scales, from stand to ecosystem levels.
Keywords: carbon sinks, forests, conifers, intra-annual resolution
Published in DiRROS: 10.02.2025; Views: 511; Downloads: 396
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Abstract: With ongoing global warming, increasing water deficits promote physiological stress on forest ecosystems with negative impacts on tree growth, vitality, and survival. How individual tree species will react to increased drought stress is therefore a key research question to address for carbon accounting and the development of climate change mitigation strategies. Recent tree-ring studies have shown that trees at higher latitudes will benefit from warmer temperatures, yet this is likely highly species-dependent and less well-known for more temperate tree species. Using a unique pan-European tree-ring network of 26,430 European beech (Fagus sylvatica L.) trees from 2118 sites, we applied a linear mixed-effects modeling framework to (i) explain variation in climate-dependent growth and (ii) project growth for the near future (2021–2050) across the entire distribution of beech. We modeled the spatial pattern of radial growth responses to annually varying climate as a function of mean climate conditions (mean annual temperature, mean annual climatic water balance, and continentality). Over the calibration period (1952–2011), the model yielded high regional explanatory power (R2 = 0.38–0.72). Considering a moderate climate change scenario (CMIP6 SSP2-4.5), beech growth is projected to decrease in the future across most of its distribution range. In particular, projected growth decreases by 12%–18% (interquartile range) in northwestern Central Europe and by 11%–21% in the Mediterranean region. In contrast, climate-driven growth increases are limited to around 13% of the current occurrence, where the historical mean annual temperature was below ~6°C. More specifically, the model predicts a 3%–24% growth increase in the high-elevation clusters of the Alps and Carpathian Arc. Notably, we find little potential for future growth increases (−10 to +2%) at the poleward leading edge in southern Scandinavia. Because in this region beech growth is found to be primarily water-limited, a northward shift in its distributional range will be constrained by water availability.
Keywords: climate change, climate sensitivity, drought, Fagus sylvatica, growth projection, leading edge, trailing edge, tree rings
Published in DiRROS: 10.02.2025; Views: 578; Downloads: 403
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Abstract: The wood-based bioeconomy is one of the main pillars of sustainable transformation and decarbonisation of the economy, as it promotes the use of renewable resources, reduces reliance on fossil fuels, and supports the development of eco-friendly industries. The paper provides quantitative insight into the potential impacts of transformation of the wood-based bioeconomy in Slovenia, a small, export-oriented economy with ample, but sub-optimally used, forest resources. The analysis uses an input–output (I-O) model to estimate I-O multipliers of sectors representing the wood-based bioeconomy and to capture their direct and indirect impacts on the Slovenian economy. The baseline performance of the wood bioeconomy sectors and their potential to induce economic activity (Scenario A) are estimated with an adjusted I-O model (based on the national I-O table for 2015), in which hybrid sectors are divided into conventional and bio-based segments. Alternative transformation pathways are translated into four additional scenarios. While Scenario B foresees progress in efficiency and integration within the existing structure of transactions, Scenario C (increased energy use of wood biomass) and Scenarios D/D+ (technology- and capital-intensive restructuring) represent two extreme restructuring pathways of the sector. The results of scenario analysis with the I-O model show that the changes in the input requirement structure of the Slovenian wood-based bioeconomy could result in up to a 17% increase in total output, up to a 20% increase in the number of employees, and up to a 16% increase in incomes, all of them attributed to the most optimistic scenario (D+). The results of the study provide quantified assessments underpinning strategic planning for the wood-based bioeconomy, both in the industry and public policy spheres.
Keywords: wood-based bioeconomy, input–output model, transformation pathways, impact analysis, strategic planning
Published in DiRROS: 09.01.2025; Views: 619; Downloads: 401
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