Climate scenarios for Slovenia suggest an increase in the mean annual temperature by 2 °C over the next six decades, associated with changes in the seasonal distribution of precipitation. European ...beech is an ecologically and economically important forest species in Europe, so it is important to understand the influence of changing conditions on its phenology and productivity for the upcoming years. We hypothesise that the ongoing warming and reduction in precipitation during the growing season will shorten the period of xylem development, thus limiting beech growth in the next decades. Xylem formation was monitored weekly from 2008 to 2016 at two sites in Slovenia. Onset and cessation of cell enlargement and secondary wall formation, as well as xylem growth, are used to evaluate climate-growth relationships by means of partial least squares regression and to predict xylem formation phenology and annual xylem increments under climate change scenarios. A positive correlation of spring phenological phases with March–May temperatures is found. In contrast, autumn phenological phases show a negative correlation with August and September temperatures, while high temperatures at the beginning of the year delay growth cessation. According to the selected climate change scenarios, phenological phases may advance by 2 days decade-1 in spring and delay by 1.5 days decade-1 in autumn. The duration of the growing season may increase by 20 days over the next six decades, resulting in 38 to 83% wider xylem increments. The growth of beech is expected to increase under a warming climate in the sites characterised by abundant water availability.
•Xylem and phloem formation and leaf phenology in beech differed between the sites.•At the onset of growth phenological phases were positively related to temperature.•Between the sites, weather ...conditions before the occurrence of the observed phenological phases differed.•This difference may be the consequence of high intra-specific plasticity.•Phloem formation seems to be driven predominantly endogenously.
Xylem and phloem formation, as well as cambium and leaf phenology, and their relation to weather factors, were studied from 2008 to 2010 in beech (Fagus sylvatica L.) trees from two sites in Slovenia with different elevations and weather conditions: Panška reka (PA) (400m a.s.l.) and Menina planina (ME) (1200m a.s.l.). During the vegetation periods leaf phenology and dynamics of xylem as well as phloem formation were monitored. Leaf unfolding, onset of cambial cell production and increased number of active phloem cells occurred simultaneously for each site: in mid-April at PA and in the first week of May at ME; all three events were positively related to temperature in the first part of the growth season. Maximum rate of xylem cell production occurred at PA from 20 May until 9 June and about two weeks later at ME. Maximum phloem cell production occurred more than 1 month earlier at both sites. Cessation of xylem and phloem cell production was observed at PA around 19 August and around 10 days earlier at ME. Differentiation of the last-formed xylem cells was concluded by mid-September at both plots. The differences in xylem and phloem formation phases were smaller in the second part of the growth season and can be ascribed to similar temperatures at both plots. Year to year variability of the observed phases was not statistically significant but the differences between the sites were. Phloem formation seems to be less subjected to fluctuations in environmental conditions since the growth ring widths were comparable at both sites. Temperature and growing degree days before the occurrence of most of the observed phenological phases significantly differed between the sites. This demonstrates that the observed differences in xylem and phloem formation between the sites can be attributed to high intra-specific plasticity of beech.
The interaction between xylem phenology and climate assesses forest growth and productivity and carbon storage across biomes under changing environmental conditions. We tested the hypothesis that ...patterns of wood formation are maintained unaltered despite the temperature changes across cold ecosystems. Wood microcores were collected weekly or biweekly throughout the growing season for periods varying between 1 and 13 years during 1998–2014 and cut in transverse sections for assessing the onset and ending of the phases of xylem differentiation. The data set represented 1321 trees belonging to 10 conifer species from 39 sites in the Northern Hemisphere and covering an interval of mean annual temperature exceeding 14 K. The phenological events and mean annual temperature of the sites were related linearly, with spring and autumnal events being separated by constant intervals across the range of temperature analysed. At increasing temperature, first enlarging, wall‐thickening and mature tracheids appeared earlier, and last enlarging and wall‐thickening tracheids occurred later. Overall, the period of wood formation lengthened linearly with the mean annual temperature, from 83.7 days at −2 °C to 178.1 days at 12 °C, at a rate of 6.5 days °C−1. April–May temperatures produced the best models predicting the dates of wood formation. Our findings demonstrated the uniformity of the process of wood formation and the importance of the environmental conditions occurring at the time of growth resumption. Under warming scenarios, the period of wood formation might lengthen synchronously in the cold biomes of the Northern Hemisphere.
•RWI is negatively impacted by drought and high temperatures.•EVI data can only capture drought/heat stress when physical canopy damage is caused.•EVI based trend analysis has the potential to assess ...areas suitable for beech.
Climate change is predicted to affect tree growth due to increased frequency and intensity of extreme events such as ice storms, droughts and heatwaves. Yet, there is still a lot of uncertainty on how trees respond to an increase in frequency of extreme events. Use of both ground-based wood increment (i.e. ring width) and remotely sensed data (i.e. vegetation indices) can be used to scale-up ground measurements, where there is a link between the two, but this has only been demonstrated in a few studies. We used tree-ring data together with crown features derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) to assess the effect of extreme climate events on the growth of beech (Fagus sylvatica L.) in Slovenia. We found evidence that years with climate extremes during the growing season (drought, high temperatures) had a lower ring width index (RWI) but we could not find such evidence for the remotely sensed EVI (Enhanced Vegetation Index). However, when assessing specific events where leaf burning or wilting has been reported (e.g. August 2011) we did see large EVI anomalies. This implies that the impact of drought or heatwave events cannot be captured by EVI anomalies until physical damage on the canopy is caused. This also means that upscaling the effect of climate extremes on RWI by using EVI anomalies is not straightforward. An exception is the 2014 ice storm that caused a large decline in both RWI and EVI. Extreme climatic parameters explained just a small part of the variation in both RWI and EVI by, which could indicate an effect of other climate variables (e.g. late frost) or biotic stressors such as insect outbreaks. Furthermore, we found that RWI was lower in the year after a climate extreme occurred in the late summer. Most likely due to the gradual increase in temperature and more frequent drought we found negative trends in RWI and EVI. EVI maps could indicate where beech is sensitive to climate changes and could be used for planning mitigation interventions. Logical next steps should focus on a tree-based understanding of the short -and long-term effects of climate extremes on tree growth and survival, taking into account differential carbon allocation to the crown (EVI) and to wood-based variables. This research highlights the value of an integrated approach for upscaling tree-based knowledge to the forest level.
Environmental conditions affect tree-ring width (TRW), wood structure, and, consequently, wood density, which is one of the main wood quality indicators. Although studies on inter- and intra-annual ...variability in tree-ring features or density exist, studies demonstrating a clear link between wood structure on a cellular level and its effect on wood density on a macroscopic level are rare. Norway spruce with its simple coniferous structure and European beech, a diffuse-porous angiosperm species were selected to analyze these relationships. Increment cores were collected from both species at four sites in Slovenia. In total, 24 European beech and 17 Norway spruce trees were sampled. In addition, resistance drilling measurements were performed just a few centimeters above the increment core sampling. TRW and quantitative wood anatomy measurements were performed on the collected cores. Resistance drilling density values, tree-ring (TRW, earlywood width-EWW, transition-TWW, and latewood width-LWW) and wood-anatomical features (vessel/tracheid area and diameter, cell density, relative conductive area, and cell wall thickness) were then averaged for the first 7 cm of measurements. We observed significant relationships between tree-ring and wood-anatomical features in both spruce and beech. In spruce, the highest correlation values were found between TRW and LWW. In beech, the highest correlations were observed between TRW and cell density. There were no significant relationships between wood-anatomical features and resistance drilling density in beech. However, in spruce, a significant negative correlation was found between resistance drilling density and tangential tracheid diameter, and a positive correlation between resistance drilling density and both TWW + LWW and LWW. Our findings suggest that resistance drilling measurements can be used to evaluate differences in density within and between species, but they should be improved in resolution to be able to detect changes in wood anatomy.
European beech (
Fagus sylvatica
L.) adapts to local growing conditions to enhance its performance. In response to variations in climatic conditions, beech trees adjust leaf phenology, cambial ...phenology, and wood formation patterns, which result in different tree-ring widths (TRWs) and wood anatomy. Chronologies of tree ring width and vessel features i.e., mean vessel area (MVA), vessel density (VD), and relative conductive area (RCTA) were produced for the 1960–2016 period for three sites that differ in climatic regimes and spring leaf phenology (two early- and one late-flushing populations). These data were used to investigate long-term relationships between climatic conditions and anatomical features of four quarters of tree-rings at annual and intra-annual scales. In addition, we investigated how TRW and vessel features adjust in response to extreme weather events (i.e., summer drought). We found significant differences in TRW, VD, and RCTA among the selected sites. Precipitation and maximum temperature before and during the growing season were the most important climatic factors affecting TRW and vessel characteristics. We confirmed differences in climate-growth relationships between the selected sites, late flushing beech population at Idrija showing the least pronounced response to climate. MVA was the only vessel trait that showed no relationship with TRW or other vessel features. The relationship between MVA and climatic factors evaluated at intra-annual scale indicated that vessel area in the first quarter of tree-ring were mainly influenced by climatic conditions in the previous growing season, while vessel area in the second to fourth quarters of tree ring width was mainly influenced by maximum temperature and precipitation in the current growing season. When comparing wet and dry years, beech from all sites showed a similar response, with reduced TRW and changes in intra-annual variation in vessel area. Our findings suggest that changes in temperature and precipitation regimes as predicted by most climate change scenarios will affect tree-ring increments and wood structure in beech, yet the response between sites or populations may differ.
The phenology of wood formation is a critical process to consider for predicting how trees from the temperate and boreal zones may react to climate change. Compared to leaf phenology, however, the ...determinism of wood phenology is still poorly known. Here, we compared for the first time three alternative ecophysiological model classes (threshold models, heat‐sum models and chilling‐influenced heat‐sum models) and an empirical model in their ability to predict the starting date of xylem cell enlargement in spring, for four major Northern Hemisphere conifers (Larix decidua, Pinus sylvestris, Picea abies and Picea mariana). We fitted models with Bayesian inference to wood phenological data collected for 220 site‐years over Europe and Canada. The chilling‐influenced heat‐sum model received most support for all the four studied species, predicting validation data with a 7.7‐day error, which is within one day of the observed data resolution. We conclude that both chilling and forcing temperatures determine the onset of wood formation in Northern Hemisphere conifers. Importantly, the chilling‐influenced heat‐sum model showed virtually no spatial bias whichever the species, despite the large environmental gradients considered. This suggests that the spring onset of wood formation is far less affected by local adaptation than by environmentally driven plasticity. In a context of climate change, we therefore expect rising winter–spring temperature to exert ambivalent effects on the spring onset of wood formation, tending to hasten it through the accumulation of forcing temperature, but imposing a higher forcing temperature requirement through the lower accumulation of chilling.
A temperature sum model influenced by chilling accumulation predicts the spring onset of xylem enlargement across temperate and boreal latitudes, in four major Northern Hemisphere conifers. This model outperformed heat‐sums and threshold models. On the figure, plots per species show predicted (coloured lines) and observed (grey dots) xylem onset dates, sorted by temperatures during the January–June period. The central plot shows the species‐specific relation between chilling and forcing accumulation.
V Sloveniji imamo z vidika izkoriščenosti potenciala dodane vrednosti sortimentov lesa listavcev izrazite rezerve. Slednje bi lahko izkoristili zlasti s povečanjem gospodarske rabe okroglega lesa ...znotraj Slovenije ter s krepitvijo tehnološko naprednejših načinov predelave okroglega lesa. Cilj te raziskave je z input-output modeliranjem oceniti neizkoriščene potenciale gozdno-lesne verige v Sloveniji, s poudarkom na rabi lesa listavcev. Za celotno gozdno-lesno verigo smo ovrednotili obstoječe stanje in predvideli pet scenarijev nadgradnje gozdno-lesne verige v slovenskem prostoru. Razvili smo nacionalni input-output model za ovrednotenje možnih scenarijev prihodnjega razvoja gozdno-lesnega biogospodarstva. Iz rezultatov scenarijske analize input-output modela je razvidno, da lahko slovensko gozdno-lesno biogospodarstvo preko prestrukturiranja gospodarskih aktivnosti v prihodnosti doseže do 20 % višjo vrednost proizvodnje sektorja, povečanje števila zaposlenih za 24 % ter povečanje dohodka gospodinjstev za 19 %. V prispevku razpravljamo, kako bi nadgradnjo gozdno-lesnega biogospodarstva (glede na opredeljene scenarije) lahko dosegli s povečanjem kapacitet predelave lesa listavcev in podajamo priporočila nosilcem odločanj.
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