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Povzetek: Cambium phenology is a crucial process in wood production and carbon sequestration of forest ecosystems. Although cambium phenology has been widely studied, research specifically focusing on the cessation of wood formation remains limited. To better understand the influence of environmental and intrinsic factors on the cessation of wood formation, we built and compared three ecophysiological models (temperature sum model, photoperiod-influenced temperature sum model and soil moisture- and photoperiod-influenced temperature sum model) in their ability to predict the date of cessation of xylem cell enlargement (cE) in three major Northern Hemisphere conifer species (Black spruce, Norway spruce and Scots pine). We developed these models based on xylogenesis data collected for 130 site‐years across Europe and Canada. Our results demonstrate that the photoperiod-influenced temperature sum model is well-supported by data across all conifer species, with a RMSE of 9.2 days, suggesting that both temperature and photoperiod are critical drivers of wood growth cessation. However, incorporating soil moisture effects does not improve model performance. Our model effectively captures the inter-site variability in cE across a wide environmental gradient, with a fair model efficiency (ME = 0.51 ± 0.22), but performed less well for annual anomalies (ME = 0.10 ± 0.09). Additionally, we found that the total ring cell number also affected prediction accuracy. Using this model, we reconstructed historical trends in cE over the past six decades and found a trend to delayed cessation dates. This delay varied geographically, with slower shifts at higher latitudes and elevations, likely due to constrained cambial responses and conservative growth strategies in colder regions. Our model framework offers a simple yet accurate approach for predicting wood growth cessation at large spatial scales, providing a basis for integrating cambium phenology into land surface models and forest productivity assessments.
Ključne besede: cambium phenology, ecophysiological models, xylem formation, climate change, global warming, northern hemisphere forests
Objavljeno v DiRROS: 12.02.2026; Ogledov: 467; Prenosov: 165
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Povzetek: 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.
Ključne besede: European beech, daily climatic variables, precipitation, maximum temperature, tree-ring width, range limit
Objavljeno v DiRROS: 06.06.2025; Ogledov: 757; Prenosov: 408
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Povzetek: 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.
Ključne besede: climate change, climate sensitivity, drought, Fagus sylvatica, growth projection, leading edge, trailing edge, tree rings
Objavljeno v DiRROS: 10.02.2025; Ogledov: 884; Prenosov: 600
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Povzetek: Using a unique 8-year data set (2010–2017) of phloem data, we studied the effect of temperature and precipitation on the phloem anatomy (conduit area, widths of ring, early and late phloem) and xylem-ring width in two coexisting temperate tree species, Picea abies and Fagus sylvatica, from three contrasting European temperate forest sites. Histometric analyses were performed on microcores taken from tree stems in autumn. We found high interannual variability and sensitivity of phloem anatomy and xylem-ring widths to precipitation and temperature; however, the responses were species- and site-specific. The contrasting response of xylem and phloem-ring widths of the same tree species to weather conditions was found at the two Slovenian sites generally well supplied with precipitation, while at the driest Czech site, the influence of weather factors on xylem and phloem ring widths was synchronised. Since widths of mean annual xylem and phloem increments were narrowest at the Czech site, this site is suggested to be most restrictive for the radial growth of both species. By influencing the seasonal patterns of xylem and phloem development, water availability appears to be the most important determinant of tissue- and species-specific responses to local weather conditions.
Ključne besede: wood anatomy, early phloem, European beech, late phloem, Norway spruce, sieve element area, xylem-ring width
Objavljeno v DiRROS: 19.01.2024; Ogledov: 1452; Prenosov: 974
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Povzetek: Na Ljubljanskem Barju v Sloveniji smo opravili dendrokronološke raziskave lesa iz eneolitskega koliščarske naselbine Parte-Iščica. Iz struge reke Iščice smo odvzeli vzorce 1237 kolov iz lesa jesena (Fraxinus sp.), jelše (Alnus glutinosa Gaertn.), bukve (Fagus sylvatica L.), jelke (Abies alba Mill.), javorja (Acer sp.), breze (Betula sp.), leske (Corylus sp.), belega gabra (Carpinus betulus L.), topola (Populus sp.), hrasta (Quercus sp.), vrbe (Salixsp.) in bresta (Ulmus sp.). Prevladovali so vzorci jesena, jelše in bukve s 70 %, 9 % in 7 %. Dendrokronološke analize smo opravili na jesenovih, bukovih, hrastovih in jelovih kolih, ki so imeli nad 45 branik. Na osnovi 285 relativno datiranih vzorcev smo sestavili dve jesenovi in eno bukovo kronologijo, dolžin 136, 113 in 105 let. Večje količine lesa, posekanega v istem koledarskem letu, nakazujejo potek gradbenih aktivnosti na kolišču. Po prvih rezultatih radiokarbonskega datiranja uvrščamo koliščarsko naselbino v prvo polovico tretjega tisočletja pred našim štetjem.
Ključne besede: arheologija mokrih tal, datiranje, dendrokronologija, arheološki les, kolišča, mlajša kamena doba, bakrena doba, Ljubljansko barje, jesen (drevo), bukev, Slovenija
Objavljeno v DiRROS: 03.11.2021; Ogledov: 3601; Prenosov: 1920
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