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The European Dendroecological Fieldweek (EDF) is a one-week course that takes place every year at varying locations in Europe according to the principle "Bring tree-ring research to the people". The EDF welcomes early-career to advanced researchers, but also forest service and other federal agency employees and private people interested in tree-ring sciences from all over the world. It encompasses a large spectrum of dendrochronological field, laboratory and data analysis methods and scientific fields including climatology, ecology, physiology, geomorphology and archaeology. Multiple scales of observations from the individual cell to the ecosystem level and from seasonal to multi-centennial periods are covered. Work on mini research projects in topic groups alternates with keynote lectures and individual participants' presentations. As one of the first in-person tree-ring meetings since the start of the COVID-19 pandemic the 31st EDF was held in summer 2021 in Val Müstair, Switzerland. Topics included i) Tree age and climate sensitivity of a relict, old-growth Scots pine stand, ii) Blue intensity-based climate sensitivity of Norway spruce growth, iii) Tree rings as indicators of grey larch budmoth outbreaks, iv) Growth of larch trees along an abandoned irrigation channel, v) Wood anatomical characteristics of two alpine creeping shrub species, and vi) Historical dating of a stable and a residential house. Alongside with their educational value these projects allowed novel insight into the age structure and growth dynamics of the sub-alpine forests and beyond in the valley and provided valuable outcome to the local stakeholders such as the Nature Park Biosfera Val Müstair, the local forest service and the public of Val Müstair. Under hindered conditions due to the pandemic, the 31st EDF still demonstrated its strength as an international educational and interdisciplinary scientific field and lab course, combining teaching with the application of cutting-edge technologies. [ABSTRACT FROM AUTHOR]

Old-growth forests, particularly those located at the interface between different bioregions, are unevaluable sources of long-term vegetation dynamics and historical stand response to natural and anthropogenic disturbances. Although old-growth forests are scarce, the information gathered studying them may assist forest ecosystem restoration and management under forthcoming climate and land-use changes. We analysed how complementary dynamics of a mixed old-growth forest composed by temperate ( Fagus sylvatica , Quercus petraea ) and submediterranean ( Quercus pyrenaica ) tree species were driven in response to global changes in the last two centuries. The old-growth forest, named El Hayedo de Montejo, is located at the interface between the Mediterranean and temperate bioregions in the centre of the Iberian Peninsula. The populations of temperate species growing in El Hayedo de Montejo ( F. sylvatica and Q. petraea ) are at the dry and warm edges of their natural distribution area in Europe, whereas the submediterranean species Q. pyrenaica is at the core of the distribution range. In order to analyse the long-term dynamics, we developed basal area increment and disturbance chronologies for each of the tree species under study. Furthermore, we assessed the climate influence on tree growth during the most recent decades. Our results reveal historical shifts in forest dominance (as reflected by growth) induced by changes in climate and forest management between temperate and sub-Mediterranean species. This was particularly noticeable for F. sylvatica and Q. pyrenaica the least and most drought-tolerant species, respectively. A reduction in growth of F. sylvatica unprecedented in the context of the last two hundred years was observed during the last decades concurrent with forest densification and marked changes in climate. Conversely, both oak species seem to be better suited to current environmental conditions as expressed by increasing growth rates. [ABSTRACT FROM AUTHOR]

Abstract: δ 13C and δ 18O of tree rings contain time integrated information about the environmental conditions weighted by seasonal growth dynamics and are well established as sources of palaeoclimatic and ecophysiological data. Annually resolved isotope chronologies are frequently produced by pooling dated growth rings from several trees prior to the isotopic analyses. This procedure has the advantage of saving time and resources, but precludes from defining the isotopic error or statistical uncertainty related to the inter-tree variability. Up to now only a few studies have compared isotope series from pooled tree rings with isotopic measurements from individual trees. We tested whether or not the δ 13C and the δ 18O chronologies derived from pooled and from individual tree rings display significant differences at two locations from the Iberian Peninsula to assess advantages and constraints of both methodologies. The comparisons along the period 1900–2003 reveal a good agreement between pooled chronologies and the two mean master series which were created by averaging raw individual values (Mean) or by generating a mass calibrated mean (MassC). In most of the cases, pooled chronologies show high synchronicity with averaged individual samples at interannual scale but some differences also show up especially when comparing δ 18O decadal to multi-decadal variations. Moreover, differences in the first order autocorrelation among individuals may be obscured by pooling strategies. The lack of replication of pooled chronologies prevents detection of a bias due to a higher mass contribution of one sample but uncertainties associated with the analytical process itself, as sample inhomogeneity, seems to account for the observed differences. [Copyright &y& Elsevier]