Dendrochronology offers valuable insights into global environmental change, yet the field remains geographically biased toward northern latitudes, leaving tropical Africa relatively underrepresented. The African Dendrochronological Fieldschool (ADF) addresses this gap through training and research to expand knowledge of ring formation and environmental variation, and to build research capacity. We present case studies from the first three ADFs (2021–2023), spanning wood anatomy, dendroecology, dendroclimatology, and dendrochemistry studies from Miombo woodlands near Kitwe, Zambia. Wood anatomical characterization for 13 species, many of which have not been assessed before, indicated two are semi-ring-porous, but most (11 of 13) are diffuse-porous, and five show indicators of annual ring formation. Dendroecological studies characterized stand diversity and establishment history and produced a mixed-species chronology (series intercorrelation = 0.42). Dendroclimatological research yielded chronologies of Brachystegia longifolia and B. boehmii (series intercorrelations of 0.38 and 0.44, respectively) and found significant relationships (p < 0.05) between wet-season precipitation and growth for B. boehmii (r = 0.19–0.37) and the mixed-species chronology (r = 0.23–0.26). Dendrochemical analysis of B. longifolia revealed bioaccumulation of pollutants linked to local soil contamination, including As, Pb, and Sc. These findings demonstrate the applicability of several African tree species for dendrochronological research and underscore the importance of continued capacity building.

The field of dendrochronology is currently undergoing a transition, with an increasing reliance on digital analysis. Recent advances in hardware and software have enabled the rapid acquisition of information from wood in ways that were previously unattainable. However, the variety of digitization tools and the high resolutions achievable present a challenge in maintaining replicability and comparability of results. In addition, the high speed at which data are collected can lead to overlooking important aspects of dendrochronological techniques. For example, awareness of resolution of images for tree-ring measurements or even crossdating may play a minor role when setting tree-ring boundaries or may be biased towards the first samples measured. This commentary addresses potential sources of error in the novel advances of digital techniques and highlights the suitability of combining digital advances with traditional data-control procedures that maintain the robustness and replicability of dendrochronological methods.

Large tropical tree samples are driving new research in dendrochronology. The development of imaging tools for these substantial samples represents a significant challenge. Specifically, tree-ring measurements are strongly associated with images acquired through scanning, with an A3 large-format scanner being the preferred choice for these sizable samples. However, the literature lacks information about image distortions resulting from this approach. To address this gap, we developed a system comprising a table, a mobile scanner lift, and a fixed sample-support unit. This system ensures the production of aligned composite images of wooden disc samples and safeguards the scanning equipment from damage. To test its efficiency, we evaluated distortions in the measurements of treering widths across various digitized images at nine different heights, ranging from 2 to 10 mm. Remarkably, we observed no distortions in the growth ring measurements at any assessed height. Furthermore, the images of samples positioned 2 mm and 3 mm away from the scanner glass were clear, allowing precise measurements of small growth rings between 0.1 and 0.5 mm in size. Our equipment offers flexibility of use with other models and sizes, including A4 scanners. It can digitize wooden discs with diameters ranging from 60 to 200 cm.

Improving our understanding of the growth dynamics of trees along elevation gradients could help us predict their potential to store carbon and their vulnerability to changes in local and global environmental conditions, such as deforestation and climate change. This study is a review and analysis of the results obtained in recent dendrochronological studies of the effect of elevation and climate (temperature and precipitation) on the radial growth of trees in temperate zones, mainly in the Northern Hemisphere. Only 18 (32.1%) of the 56 studies analyzed found a correlation between radial growth of the trees (total chronologies) and elevation. The analysis of 56 chronologies of 46 tree species included in the 110 works reviewed, showed that only in 28.2% of them the correlation between radial growth versus temperature and precipitation was significant: positive in 3.6%, negative in 2.7%, and positive and negative in 21.8%, depending on the season of the year. The wide variation found in the radial growth response of the trees to elevation gradients may be related to multiple environmental factors at a local or regional scale, but also to the different sampling methods used in the studies. However, a moderate proportion of the studies analyzed (close to 30%) show that temperature and rainfall are related to trends in radial growth in different elevation ranges and regions of the world.

Edmund Schulman is rightly honored for quantifying the age of bristlecone pines and discovering individuals significantly older than giant sequoias (Sequoiadendron gigantea), previously thought to be the oldest living things. However, George Engelmann inferred the potential for great age in his description of bristlecone pine (Pinus aristata) almost a century before, in 1863. Staff from Inyo National Forest re-made Engelmann's inference, and publically asserted that White Mountain bristlecones might outlive giant sequoias before Schulman had published any results of his bristlecone research.Schulman sampled White Mountains pines after seeing a photograph and caption associated with an article by founders of the University of California White Mountain Research Station. Although Schulman's correspondence and publications make this clear, incorrect theories regarding his decision to come to the White Mountains have been published and are promulgated at the Schulman Grove Visitor Center in the White Mountains. This paper places Schulman's work in its historic context by recovering forgotten information about attempts by Inyo National Forest staff and White Mountain Research Station to call attention to the trees. It also recovers details of Schulman's and C. Wesley Ferguson's activities in the White Mountains range as documented in field notes and Thomas Harlan's Bristlecone Pine Project database.

Tree-ring research (TRR) in South America (SA) continues to make important contributions in multiple sub-disciplines, including dendrochemistry and dendrohydrology. This report describes some of the advances in TRR in SA presented in a two-day International Meeting Research entitled “An International Network to Promote Advances in Dendrochronology in South America”, organized by the Laboratory of Dendrochronology and Environmental Studies of the Pontifical Catholic University of Valparaiso in Valparaiso, Chile, on January 21–22, 2019. The objective of the meeting was to communicate recent advances in TRR within a network of laboratories in Argentina, Brazil, Chile, Peru, and Uruguay. Novel methodologies and results in dendrochemistry and wood anatomy were also presented by collaborating researchers from German institutions. This report describes some of the research within the subdisciplines of tree-ring science, including dendrochemistry, anatomy and dendrohydrology, and their application to understanding spatio-temporal variability in heavy metal contamination, climate, hydrology, fire regimes and other critical components of South American forest and woodland ecosystems. The meeting demonstrated expansion and diversification of inquiry and applications of TRR in SA, whereby collaboration across research centers has been critical for the advances made in broad-scale comparative studies as well as multi-proxy approaches and the study of global and hemisphere-scale climate phenomena.

Injury from sampling increment cores may induce defense responses in trees, which may vary between species and reflect differing defense allocation strategies against attack by insects and pathogens. We recorded presence of systemic induction of traumatic resin ducts from early-season increment coring in mature white spruce (Picea glauca) and lodgepole pine (Pinus contorta var. latifolia) trees. In the year of coring, traumatic resin ducts formed three months later, 20 cm below the initial coring site in the xylem of white spruce and showed little variation in response among the spruce families. In contrast, lodgepole pine did not form traumatic resin ducts in trees cored earlier in the growing season. Although traumatic resin ducts are induced by biotic and abiotic disturbances, we found a species-specific defense response to increment coring in two common boreal forest tree species.