This study aims to strengthen dendroclimatic research in tropical dry forests by analyzing tree rings from Handroanthus chrysanthus and Bursera graveolens in southern Ecuador. We developed new dendrochronological records to determine the dendroclimatic potential of the species for evaluating the relationship between precipitation and tree growth. Chronologies were correlated with regional climate parameters, as well as with spatial patterns of Sea Surface Temperature (SST) anomalies. Besides dendroclimatic analyses, we propose enhancing Organic Code of the Environment (COA) regulations to promote the use of forest species with dendroclimatic potential, including Faculty number thirteen. Two tree-ring width chronologies were developed based on 39 H. chrysanthus and 53 B. graveolens trees. Tree growth shows strong correlations with precipitation during the rainy season, indicating that these species preserve reliable climatic information. This evidence supports the use of tree-ring data to inform climate adaptation and forest management strategies. Based on these findings, we propose incorporating a regulation within COA (Faculty no. 13) to "implement measures for the protection, sustainable management, and restoration of long-lived forest species with dendroclimatic potential in southern Ecuador." This enhancement can contribute to evidence-based environmental policy and strengthen climate adaptation strategies in the region.
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 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.
In this article, we introduce new methods for taking core samples from wooden beams for dendrochronological analysis and crossdating from uncharred archaeological wood in arid environments. Although many advancements in the analysis of tree-ring samples have occurred over the century since A.E. Douglass first developed dendrochronology, few advancements in the methods of core sample collection have occurred since those he established. With the methods outlined in this article, we hope to provide researchers new, more effective, and efficient ways to sample archaeological wood on-site, methods that are also aimed at reducing the impact of core sampling on archaeological materials and cultural resources, while also reducing the visual impacts to irreplaceable cultural resources. We developed these methods over years of trial and error, and we encourage others to use this how-to-guide and expand on its applications. Although the techniques and tools we describe were developed in the US Southwest, they are readily applicable to arid and semi-arid regions elsewhere in the world.
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.
