Tree-ring data processing often remains operationally fragmented, with file conversion, crossdating evaluation, and chronology aggregation distributed across independent software tools. To address this work-intensive and error-prone analytical separation, we present an integrated Python-based desktop workflow for dendrochronological data processing comprising four applications: RWLUpdaterApp (Ring Width Length Updater), pos2rwlApp, converterApp, and RWLStatsApp. These tools support: i) conversion of POS (CooRecorder coordinate) files to the Tucson ring-width list (RWL) format; ii) multi-format chronology conversion and diagnostics; iii) COFECHA (a widely used crossdating quality-control program)-assisted crossdating checks; iv) interactive correction of problematic series; and v) automated updating and screening of a combined master chronology. The central component, RWLUpdaterApp, provides folder monitoring, duplicate prevention, live editing tools, and an audit trail of chronology changes. Available as ready-to-run executables for both Windows and macOS, the workflow fills an operational gap in traceable, end-to-end chronology management. Rather than replacing established tools, the workflow connects them into a coherent sequence, reducing repetitive manual effort, lowering file-handling errors, and improving transparency and reproducibility of iterative chronology revision.

ABSTRACT – 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.

As the sub-Arctic and Arctic regions undergoes rapid changes, understanding its hydroclimate history is more critical than ever. A limited availability of moisture-sensitive proxy data severely constrains our insights, underscoring the urgent need for more hydroclimate reconstructions in the region. Here we present a May–June precipitation reconstruction based on ring width from living and dead trees of Scots pine (Pinus sylvestris L.) growing under drought-stressed conditions at 63° N, near Skuleskogen National Park, on the northern part of the east coast of Sweden. The oldest deadwood sample dates back to the mid-11th century, and the Expressed Population Signal (EPS) exceeds 0.85 from 1320 CE until the present (2021 CE), making this the longest tree-ring-based hydroclimate reconstruction from high-latitude Fennoscandia. Unlike typical high-latitude forests in Fennoscandia, the trees at this site thrive under low-pressure conditions and show strong correlations up to approximately |r| = 0.6 over the period 1920–2021 with drought-related variables such as precipitation, cloud cover, solar radiation, potential evapotranspiration and diurnal temperature range. The climate signal is concentrated to a short window between mid-May and early July but reflects climatic conditions over a broad region. Significant spatial correlations extend over most of Sweden as well as large parts of Norway and Finland, indicating sensitivity to large-scale climate systems. The tree-ring chronology also shows clear cyclic patterns, with a particularly strong ∼ 64-year cycle. The modern era stands out for its variability, with 2018 CE emerging as one of the of the driest year in the entire record. There is potential to extend the chronology further back in time, possibly to 1000 CE or earlier, and to extract additional climate information using other tree-ring parameters such as blue intensity.

Annually resolved multi-millennial records of temperature are rare in the Southern Hemisphere (SH), and even rarer are SH records of cool-season temperature. Here we present a new tree-ring chronology extending back to 42 BCE based on Athrotaxis selaginoides from southern Tasmania. The development of this chronology was complicated by multiple tree-age cohorts and growth classes. Additionally, there was a collapse in sample depth between the mid-14th and mid-16th Centuries. Therefore, we used a multiple Regional Curve Standardization (mRCS) approach to standardization but have subsequently employed piecewise adaptive detrending (PAD). PAD utilizes the Friedman Supersmoother to remove the remaining multimillennial trend likely to be the result of changing site conditions rather than climate. The chronology is significantly associated with temperature from winter through to the end of the warm season, but its association with Austral July-October temperatures is both unusual and stable. The collapse in sample depth, and four clear cohorts of trees are most likely associated with landscape scale fire events.

Key message: Climate sensitivity of Pinus sylvestris has changed in minimum density while maximum density remains mostly stable, suggesting the use of additional density parameters could help detect response changes. Abstract: As one of Eurasia's most widely distributed conifer species, Pinus sylvestris L. is frequently used in dendroclimatological reconstructions based on tree-ring width (TRW) and maximum latewood density (MXD). However, the climatic signals of additional parameters such as earlywood/latewood density (EWD/LWD) or minimum density (MND) are often overlooked, leaving their skill unexplored. Here, we investigate the growth responses of multiple P. sylvestris tree-ring parameters to ongoing climate change at two sites with contrasting climatic conditions using well-replicated density data from Scotland and Sweden. Correlations with mean, minimum, and maximum temperatures are strongest for LWD and MXD at both sites, with coefficients ranging from 0.5 to 0.7 for July, August, and the June–August season (p < 0.05). A significant (p < 0.05) negative correlation between MND and July temperatures was identified in the Swedish Torneträsk (TOR) data (p < 0.05), which diminished since the late twentieth century. A comparable inverse MND temperature signal and change into the twenty-first century is not reflected in northern Scotland’s overall wetter and warmer site, suggesting a fundamental physiological change in tree-ring formation under global warming. A shift in the sensitivity of tree growth at northern European sites could reduce the effectiveness of proxies from such locations, posing implications for high-resolution climate reconstructions.

Heatwaves and summer droughts across Europe are likely to intensify under anthropogenic global warming thereby affecting ecological and societal systems. To place modern trends and extremes in the context of past natural variability, annually resolved and absolutely dated climate reconstructions are needed. Here, we present a network of 153 yew (Taxus baccata L.) tree-ring width (TRW) series from 22 sites in southern England that cover the past 310 years. Significant positive correlations were found between TRW chronologies and both April–July precipitation totals (r > 0.7) and July drought indices (r > 0.59) back to 1901 CE (p < 0.05). We used a suite of residual and standard TRW chronologies to reconstruct interannual to multi-decadal spring–summer precipitation and mid-summer drought variability over western Europe, respectively. Our yew hydroclimate reconstructions capture the majority of reported summer droughts and pluvials back to 1710 CE. Clusters of severe drought spells occurred in the second half of the 18th and mid-twentieth century. Our study suggests that the frequency and intensity of recent hydroclimate extremes over western Europe are likely still within the range of past natural variability.

Study region: Zemu River, Upper Teesta River Basin, Eastern Himalaya

Study focus: In this study, a tree-ring chronology of Abies densa was used as a proxy to reconstruct a century-long May-June streamflow of the Zemu River. The reconstruction was carried out based on a scaling approach which explained 35 % of variance in observed streamflow and was varified by comparing with other regional reconstructions. Moving windowed Pearson correlation was performed to reveal the temporal influence of major climate forcings (e.g., ENSO) with the streamflow of Zemu River.

New hydrological insights for the region: Our study identified a strong negative relationship between tree-growth and observed May-June streamflow in the glacier-fed Zemu River. This counterintuitive, inverse relationship is likely due to the contribution of additional meltwater when conditions are dry and insulation over the glacier is high. The reconstructed streamflow record reveals several high- and low-flow periods above and below the mean value (+/- 1σ) and identifies 30 high-flow years and 33 low-flow years, including some historically recorded floods in 1927, 1968, 1980, 1982 and 1998, and of severe droughts in 1951, 1976 and 2017. Most recently, a positive association between reconstructed streamflow and the ENSO has become apparent, which we attribute to reduced penetration of the Indian Summer Monsoon during ENSO years, which reduces precipitation but maintains for longer warmer and drier conditions that allow glacier melt.

As blue intensity (BI) methods are increasingly employed to generate temperature-sensitive tree-ring records around the globe, the influence of intra-site variation in elevation on climate-growth relationships for BI parameters remains largely unresolved. Here, we develop six latewood blue intensity (LWBI) chronologies along an elevational gradient for two montane conifer species, Abies concolor var. concolor (Gordon & Glend.) Lindl. Ex Hilderb and Picea engelmannii Parry ex Engelm., growing in the arid southwestern United States. In this first documented study to examine the climate response of LWBI from A. concolor, we find positive, significant (p < 0.05) correlations between the LWBI chronology from the highest elevation plot and spring–summer temperatures (April–August, r > 0.46). Moreover, the positive temperature response of A. concolor is generally stronger and more temporally stable than for P. engelmannii across varying seasonal windows. In comparing the differences in climate response across species and elevation, we document distinct clinal relationships between the temperature response of LWBI for A. concolor, where both the strength and temporal stability of the positive temperature signal increases with elevation. Meanwhile, the mid-elevation P. engelmannii demonstrate the highest climate sensitivity. As such, our findings contribute to a more comprehensive understanding of how elevation influences the type and strength of the climatic information embedded within the LWBI parameter from arid, montane conifers growing near their historical range margins.

Background Chir pine (Pinus roxburghii Sarg.) forests are distributed in the dry valleys of Bhutan Himalaya. In the past, these forests have been heavily influenced by human activities such as grazing, burning, resin tapping, and collection of non-timber forest products. Bhutan’s Forest Act of 1969, which shifted forest management from local community control to centralized governmental control, greatly restricted these activities. To understand the implications of the Forest Act on the chir pine forests, we used tree-rings and fire scars to reconstruct the fire history of a chir pine forest in eastern Bhutan. This provided an opportunity to characterize the fire regime before and after the Forest Act of 1969 was implemented and assess the scale and magnitude of changes that have occurred.

Results We developed a 120-year chir pine fire chronology from nine sites within a single forested landscape. Between 1900 and ~ 1970, fires were small and patchy. When fires occurred, they were limited to one to two sites within the larger study area. After 1970, there was a distinct shift in fire activity, with fires in 1985, 1989, 1996, 2000, and 2013 burning > 90% of sample plots. Fire activity was positively associated with La Niña conditions (wetter, cooler) in the preceding year. This is likely the result of increased accumulation and connectivity of fuels on the forest floor in wetter years.

Conclusions Prior to 1970, the fire regime in the studied chir pine landscape in eastern Bhutan was dominated by patchy, low-intensity fires indicating that the fire regime was fuel limited. After 1970, fires became larger and more frequent. This shift was associated with the enactment of the Bhutan Forest Act in 1969, which regulated grazing and implemented a policy of strict fire exclusion in government-reserved forests. This likely led to a large buildup of fuels, particularly after La Niña years. Historical patterns of grazing and low-intensity fires prior to the Forest Act kept fuel loads low and disconnected. The cessation of most human activities in these forests after 1969 resulted in an increase in fuel loads and connectivity within the landscape. This has greatly reshaped fire regimes in the chir pine forests of eastern Bhutan over the past half century.

Antecedentes Los bosques de pino chir, o pino indio de hoja larga (Pinus roxburghii Sarg.) están distribuidos en los valles secos del Himalaya en Bután. En el pasado, estos bosques fueron fuertemente influenciados por actividades humanas como el pastoreo, fuegos, colección de resinas, y recolección de productos no forestales. La ley forestal de Bután de 1969, que cambió el manejo forestal desde el control comunitario local a uno ejercido por las autoridades gubernamentales centrales, restringió fuertemente esas actividades. Para entender las implicancias de esta ley forestal sobre los bosques de pino chir, usamos los anillos de crecimiento y cicatrices de fuego para reconstruir la historia de fuego en un bosque de pino chir en el este de Bután. Esto proveyó de una oportunidad para caracterizar el régimen de fuegos antes y después que la aplicación de esta ley forestal fuera implementada en 1969, y determinar así la escala y magnitud de los cambios ocurridos.

Resultados Desarrollamos una cronología del pino chir de 120 años en nueve sitios dentro de un paisaje de bosque uniforme. Desde 1900 y hasta 1970, los incendios fueron pequeños y ocurrían en parches. Cuando estos ocurrían, estaban limitados a 1–2 sitios dentro de la gran área de estudios. Después de 1970, hubo un cambio distintivo en la actividad de los incendios, con ocurrencia en los años 1985, 1989, 1996, 2000, y 2013, quemando > 90% de las parcelas de muestreo. La actividad de los incendios fue asociada positivamente con condiciones de la Niña (más húmedas y frías) en el año precedente al evento de incendio. Este es probablemente el resultado de una acumulación incremental y mayor conectividad del combustible en el suelo forestal en años húmedos.

Conclusiones Antes del año 1970, el régimen de fuego en el paisaje de pino chir estudiado en el este de Bután, estaba dominado por fuegos de baja intensidad y que ocurrían en parches, indicando que ese régimen estaba limitado por la disponibilidad del combustible. Luego de 1970, los incendios comenzaron a ser más frecuentes y abarcaban mayores superficies. Este cambio estuvo asociado con la puesta en vigencia de la Ley Forestal de 1969, que regulaba el pastoreo e implementaba una política estricta de exclusión del fuego en reservas forestales gubernamentales. Esto llevó a un gran crecimiento y acumulación de combustibles, particularmente luego de años Niña. Los patrones históricos de pastoreo y baja intensidad de los incendios previos a la puesta en vigencia de la Ley forestal, mantenían la carga de combustibles a niveles bajos y desconectados entre sí dentro de ese paisaje. La implementación de esta ley reconfiguró dramáticamente los regímenes de fuego en los bosques de pino chir en el este de Bután en los últimos 50 años.

The jet stream is an important dynamic driver of climate variability in the Northern Hemisphere mid-latitudes1–3. Modern variability in the position of summer jet stream latitude in the North Atlantic–European sector (EU JSL) promotes dipole patterns in air pressure, temperature, precipitation and drought between northwestern and southeastern Europe. EU JSL variability and its impacts on regional climatic extremes and societal events are poorly understood, particularly before anthropogenic warming. Based on three temperature-sensitive European tree-ring records, we develop a reconstruction of interannual summer EU JSL variability over the period 1300–2004 ce (R2 = 38.5%) and compare it to independent historical documented climatic and societal records, such as grape harvest, grain prices, plagues and human mortality. Here we show contrasting summer climate extremes associated with EU JSL variability back to 1300 ce as well as biophysical, economic and human demographic impacts, including wildfires and epidemics. In light of projections for altered jet stream behaviour and intensified climate extremes, our findings underscore the importance of considering EU JSL variability when evaluating amplified future climate risk.