International education and research during the pandemic: 31st European Dendroecological Fieldweek 2021 in Val Mustair, Switzerland

<p>The European Dendroecological Fieldweek (EDF) provides an intensive learning experience in tree-ring research for anyone approaching or working in dendrochronology. Here we present an overview of scientific activities of the 31^st EDF, held in Val M&#252;stair, Switzerland, in summer 2021. Despite the COVID-19 pandemic, the EDF gathered 20 participants and 10 instructors (7 dendrochronologists and 3 local experts) from 10 European countries and provided valuable outcomes for the local stakeholders such as Biosfera, the forest service and the private-public of Val M&#252;stair.</p> <p>During the eight days of the EDF, six groups developed different tree-ring projects, carefully designed with respect to the loal environmental setting. The dendroarchaeology group dated two buildings, an abandonned stable and a house in Val M&#252;stair, providing private owners with accurate construction dates. The dendroclimatology group explored the potential of a relict Scots pine forest growing at ~2000 m asl for climate reconstruction, and created a chronology from 1648 to 2020 CE. The wood anatomy group found that the larger vessel sizes and and higher radial growth rates of two alpine shrub species at moist compared to dry sites, while tree ages were similar at both sites. The Blue Intensity group identified a robust climate signal in the BI chronology of high-elevation Norway spruce trees, which was significantly stronger than in the tree-ring width chronology. One dendroecology group found that growth of local larch trees recorded outbreaks of the grey larch budmoth between 1880 and 1980, a stop of outbreaks after and its return in 2018. A second dendroecology group investigated larch trees along an abandoned irrigation channel and could not detect a significant effect of the irrigation stop on growth.</p> <p>The EDFs continuously provide an essential service to the dendrochronological community, and this even during challenging times. The 31^st EDF was again an educational, scientific and multi-cultural experience in a unique environmental setting. It resulted in highly interesting and valuable scientific outreach and opened up new avenues for future tree-ring research in Val Mustair.&#160;</p>