Climate models project increasing temperatures, evapotranspiration, and droughts for the Mediterranean Basin, which will trigger more frequent and dangerous fire events. Here, we evaluate the combined effects of drought and wildfire on seasonal tree growth on Aleppo pine stands at the intra- and inter-annual level. Indexed earlywood width (EWI), latewood width (LWI), and latewood proportion (LWPI) series were obtained from unburned and burned stands located at four sites along a precipitation gradient in southeastern Spain. The combined effect of drought in 1994 and 1995 and wildfire in August 1994, negatively impacted seasonal growth in the short term (1994–1999 period) at the site with higher water availability. At the driest site, however, no significant effects were found. We found fewer negative pointer years at the wettest burned stand than at the wettest unburned stand during the post-fire 1994–2012 period, and the opposite pattern was found at the driest site, i.e. more negative pointer years at the driest burned stand than at the driest unburned stand. This result indicates that the drier sites were more sensitive to cumulative impact of drought and wildfire disturbances in the long term, whereas the wetter sites were more sensitive in the short term. Our results demonstrate the seasonal growth plasticity of Aleppo pine to combined disturbances depends on site water availability. This study will help forest managers to implement climate change strategies, such as prescribed fires (controlled low-medium severity fires) to prevent wildfire hazards more efficiently in Aleppo pine stands with high water availability.

In temperate regions, the analysis of climate signals encoded in the wood rings allows assessing tree sensitivity to climate and its potential effects on growth and yield. In Mediterranean regions, the cork oak (Quercus suber L.) has received limited attention for dendrochronological studies because tree rings are faint and cork rings with a clear annual banding have been rather neglected. We analyzed the climatic signal of cork-ring chronologies for AD 1996–2010 from distinct regions in western Algeria [a mountain oak forest called Hafir-Zarieffet] and in southern Portugal [a peneplain wood-pasture called Benavente]. The goal was to evaluate the strength and consistency of climate signal and to assess cork growth sensitivity to climate variables (precipitation and temperature). Our results suggest that cork growth encodes a climatic signal. Trends of cork growth, via correlation analysis, including climate variables (on a monthly and seasonal basis) and Lang's index (on an annual basis) were successfully assessed. Drought-driven cork growth reduction is a threshold function of a P-T ratio, and with expected increase in the drought occurrence under changing climate, cork growth is likely to be similarly affected in both regions.

Since its establishment, tree-ring analysis has benefitted several scientific fields. Because of its many advantages, dendrochronology is a first choice to reconstruct past environmental variability. Two major concerns about the current tree-ring reconstruction paradigm are the subjective choices of detrending functions and the lack of fidelity to data of chronology generation methods. It is difficult to recover the original tree-ring data once they have been detrended and standardized. In this study, ensemble empirical mode decomposition (EEMD) is introduced as an objective high-fidelity stand-alone approach for developing tree-ring chronologies. Basic concepts of EEMD, recommended steps in developing chronologies, and available public domain programs are discussed. To demonstrate the potentials of EEMD for chronology development, two examples are provided, one for climate and the other for streamflow reconstructions. In both examples, EEMD chronologies show higher correlations with the instrumental data and have more power in their spectra than the ones developed based on the current tree-ring reconstruction approach. General usage concerns and cautions are also addressed.

We quantified the growth dynamics and climatic responses of three tree species that have dominated Changbai Mountain: Korean pine (Pinus koraiensis), Yeddo spruce (Picea jezoensis), and Erman's birch (Betula ermanii). Standardization curves and moving correlations were used to assess growth rate trends and analyze changes in growth-climate relationships of trees at their upper forest boundaries and individual species elevation limits, respectively. Contrasting growth patterns were observed between trees at each upper forest boundary and species-specific upper elevation limits. Korean pines and Yeddo spruces grew faster at their upper forest boundaries than at their individual species limits. A higher growth rate of Erman's birches at their forest upper boundary only occurred before 1960. Relative to the strong effect of temperature on tree growth at individual upper elevation limits, the stable effect of precipitation and changing effect of temperature on tree growth were observed at the upper forest boundaries. Temperature increases have had a significantly negative effect on Korean pine and Erman's birch since 1980, whereas temperature increases were associated with Yeddo spruce growth. This study elucidated the differential growth patterns and temporal changes in climate–growth relationships of these species between their upper forest boundaries and elevation limits.

We are reporting the first dendrochronological dating of timber from Tajikistan. Thirty samples were collected from two old buildings from a village located in the western Pamir-Alay; eight cores were taken from temple. Most of the construction wood was juniper species. The object chronologies crossdated well with the previously published chronology based on living juniper trees from western Pamir-Alay. The results of dating revealed that investigated structures are composed of wood coming from several periods. The oldest pieces of wood dated back to the 11^th and 12^th Centuries. Most timber samples come from the turn of the 17^th and 18^th Centuries, which were probably the period of intense development of the Artuch village. Besides dating of the wood samples from these historic structures, our investigation provides the opportunity to extend the currently existing regional tree-ring chronology for future climate reconstruction of the Pamir-Alay and High Asia. Dated sequences were assembled into a 1012-year chronology spanning the period 945–2014 C.E. and strengthened the replication of its earliest part (with critical 0.85 EPS value since the beginning of the 13^th Century).

Earlywood (EW) and latewood (LW) chronologies can be used to analyze seasonal climatic variation. We constructed and analyzed total ring (RW), EW, and LW ring growth in Abies religiosa and Pinus pseudostrobus trees from the Monarch Butterfly Biosphere Reserve and evaluated their climatic signal (monthly precipitation and mean average, minimum and maximum temperatures) in the growth of tree rings by correlation and response function analyses. Precipitation during October and December of the previous year and during January, February, April, and May of the year of growth had a positive influence in the growth of both P. pseudostrobus and A. religiosa. Mean maximum temperatures had a negative effect on tree growth in both species. Additionally, growth of A. religiosa was more sensitive to variations of mean, minimum, and maximum temperatures in comparison with P. pseudostrobus, and monthly mean minimum temperature was positively correlated with EW and LW series in A. religiosa. We conclude that EW and LW growth of A. religiosa and P. pseudostrobus might be reduced by lower precipitation during the winter-spring season. Consequently, in the eventuality of warmer and drier climate during the latter season as projected by climate change scenarios, growth rates of A. religiosa could become severely affected, negatively impacting the overwintering habitat of the monarch butterfly (Danaus plexippus L.).

We present the microscopic analysis of growth-ring boundary anatomy of 27 tree species from a moist tropical forest in Bangladesh and evaluate their dendrochronological potential. We observed high inter-species variability in the anatomical features that define growth-ring boundaries. Marginal parenchyma, fibre zones, and thick-walled latewood fibres were identified as the dominant anatomical features delineating growth-ring boundaries. The evaluation of growth-ring boundary distinctness in thin-sections and scanned images revealed that 25 out of 27 studied species (93%) showed distinct to fairly distinct growth-ring boundaries. Cluster analysis of wood anatomical features was used to select an additional 5 species for further investigation. Ring-width series of these species crossdated well within the same tree. Between trees crossdating was also successful in all 5 species. The Gleichläufigkeit (GLK; i.e. the proportion of agreement/disagreement of inter-annual growth tendencies among the trees) varied among species between 0.55 and 0.71. A strong synchronization of tree-ring series between trees suggests that growth rings are annual and influenced by common environmental factors. The derived tree-ring series, estimated tree ages, and growth trajectories underline the high potential of our study area for answering a variety of climatological, ecological and archaeological questions by applying dendrochronology. This study will therefore provide a new endeavor in tropical dendrochronology of South Asian moist tropical forests.

Mexican beech (Fagus grandifolia subsp. mexicana) has been classified as an endangered species because of its restricted distribution. The current distribution of Mexican beech, which is considered a Miocene relict, is limited to Tropical Montane Cloud Forests (TMCF) in the mountains of the Sierra Madre Oriental in eastern Mexico. We used dendroclimatic techniques to evaluate the effects of climate variability on the growth of Mexican beech within three forest fragments. The independent chronologies developed for the three sites were 152–178 years long. Cross-sections helped to assess the quality of the crossdating and detect false rings. Over the last 180 years, Mexican beech trees have lower mean radial growth than rates exhibited by other Fagus species. Mexican beech growth appears to be influenced by growing-season temperatures, especially mean maximum temperature. The response appears to be positive at the beginning of the growing season but becomes negative later. These results suggest that the persistence of Fagus-dominated forests in Mexico is dependent on local-scale climatic conditions of the TMCF. Mexican beech forests are associated with micro-climatic conditions that will control the fate of these forests in the face of on-going climate change.

Growth-ring analysis is a valuable source of information for reconstructing environmental history. In this study, ring-width series of a sample of Fagus grandifolia subsp. mexicana were used to identify the main events that have affected populations of this species. Core samples were extracted in three representative beech forests in Mexico. These are forests where F. grandifolia subsp. mexicana dominates the canopy. A total of 3355 years of growth rings were measured and three ring-width chronologies were generated. Average annual ring widths were similar between the three sites and ranged from 0.98 to 1.08 mm. A pattern of multiple suppressions and releases was observed, mainly associated with local events, but with a slight climatic influence. Correlations between the ring-width index and climate variables were not statistically significant, with the exception of a seasonal January–June precipitation pattern (1982–2001). There has not been a large-scale disturbance of natural or human origin in the beech forests of the state of Hidalgo in the past 150 years, except in El Gosco, where anthropogenic disturbances have increased in the past decade.

The South American Dendroecological Fieldweek (SADEF) associated with the Third American Dendrochronology Conference was held in El Bolsón, Argentina, in March 2016. The main objective of the SADEF was to teach the basics of dendrochronology while applying specific knowledge to selected research questions. The course included participants and instructors from six different countries. This report describes activities of the course and briefly summarizes exploratory group projects. The Introductory Group developed an Austrocedrus chilensis chronology from 1629–2015 and documented a persistent decline in growth since 1977 which supports the fact that the current severe drought is the most severe in the 386-year record. Based on regional A. chilensis chronologies from 32° to 39°S Latitude, the Stream Flow Reconstruction Group developed a regional 525 year-long reconstruction from Río Chubut and found the most severe drought episodes from 1490 to the present occurred from 1680–1705, 1813–1828, 1900–1920, 1993–2002, and from 2011 to the present. The Drought Reconstruction Group used A. chilensis annual tree-ring width chronologies to develop preliminary spatial field reconstructions of the Palmer Drought Severity Index spanning the Central Andes region. The reconstructions explain up to 81% of the 1907–1975 PDSI variance, indicating this tree species is powerful for informing on historical drought especially in very arid domains. The Dendroecology Group documented three spreading fires since the 1850s with a 12-year return interval but lack of fire for the last 94 years; they also documented a persistent decline in their chronologies in recent years, dating back to 1965.