Dendrochronologia最新文献

The adaptability of plantation ecosystems to climate change has become an important issue in many drylands worldwide. The plantation forests of the Loess Plateau, one of the driest areas in China, have greatly increased, and Picea crassifolia and Pinus tabuliformis are the dominant artificial coniferous species in this region. However, quantitative evaluations of the responses of radial growth to climate change for these two dominant artificial coniferous trees are rare. In this study, we collected tree-ring sample data from four sampling sites in Huajialing and Chankou in the arid Loess Plateau and analysed the radial growth of two artificial conifers and their climate response characteristics (precipitation, temperature, and standardised precipitation evaporation index (SPEI)) using Pearson correlation and the Climwin model. The results showed that (1) low precipitation during the growing season (April-August) and the resulting drought stress were major growth-limiting factors for plantation forests in the arid Loess Plateau, and this impact increased with the duration of drought stress. (2) P. tabuliformis was more susceptible to drought stress than P. crassifolia, and its soil water content at the 0–200 cm depth was already close to the wilting point. (3) The site conditions of planted areas, including initial planting density, elevation, and stand structure (canopy cover), significantly influenced the response of the same tree species to drought stress. (e.g., P. tabuliformis in high-density and low-elevation areas was more susceptible to drought stress than trees in low-density and high-elevation areas). We concluded that forest managers should select appropriate initial planting densities and altitudes and implement pruning and thinning measures at specific ages (15 years for P. crassifolia and 20 years for P. tabuliformis) based on basal area growth curves. Our results provide valuable information for the sustainable management of plantations against the background of climate warming.

The world's forests are currently facing the impacts of climate change and associated extreme events, which are adversely affecting natural ecosystems and increasing risks of forest mortality. In the Mediterranean region, where water is already a limiting factor, drought stress is having a severe impact on tree growth. Different species have developed physiological mechanisms to cope with drought, and an increase in water use efficiency has been observed in several drought-tolerant species. This paper analysed the growth trends and the ecophysiological responses of four widespread Mediterranean species (Pinus pinaster Aiton, Pinus pinea L., Pinus halepensis Mill and Quercus ilex L.) to climate variability, in a natural reserve of the Vesuvio National Park (Southern Italy). Dendrochronological analyses were used to measure tree-ring widths and to estimate basal area increments for each species. Stable isotope analyses of δ¹³C were performed to calculate intrinsic water use efficiency on an annual scale for the four species. Climate-growth relationships suggested that temperatures, in particular annual minimum temperature, had a significant impact on the growth of each species. The species that showed the highest resistance to hot periods and water scarcity was Pinus halepensis, presenting the highest intrinsic water use efficiency values. On the other hand, Quercus ilex was found to be the most susceptible to prolonged drought periods and sensitive to changes in precipitation, resulting in the weakest growth rates during extreme heat and cold periods. Our study demonstrated the importance of better understanding the ecophysiological responses of each species to develop sound conservation and forest management plans.

Butt and root-rot diseases caused by Armillaria sp. and Heterobasidion sp. are highly destructive to conifers worldwide. These diseases lead to loss of growth, wood degradation, and tree mortality, often necessitating premature logging. However, little is known about the effect of infection on the growth and mortality of adult pines during forest development. In this study, mature maritime pines were sampled from two forest sites in south-west France. In 2013, the Sanguinet site provided both healthy (asymptomatic) and Heterobasidion annosum-infected pines, while in 2019 the Mano site also provided Armillaria ostoyae-infected pines. Radial growth dynamics were compared between healthy and infected pines using two complementary approaches taking into account the diameter of each tree: 1. Compensation over 10 years and year by year comparisons of mean (dendrochronogram) between groups of pines with same Last Year of Radial Growth (LYRG); 2. Analysis of covariance by modeling the relationship between basal area increment and basal area in healthy or infected pines for each LYRG. Our results indicate that symptomatic trees infected by Heterobasidion annosum are characterised by a rapid reduction in radial growth across the entire tree circumference. The covariance method was more efficient to show that the radial growth of infected trees was significantly lower (between 25% and 72% loss) in the three years preceding the year of growth arrest, on both sites, i.e., for two different periods of years. For Armillaria ostoyae, growth data shows the same trends than for H. annosum, with a sharp decline over the last 2–3 years of growth. Covariance results for LYRG 2018 and 2019 reveal that infection symptoms significantly reduces the radial growth of infected trees compared to asymptomatic trees over the last three years of growth. These results show that infection of maritime pine by butt and root-rot fungi can lead to a rapid decrease in radial growth, and this decrease is independent of the calendar year of cambial death at breast height.

Dendroclimatic reconstructions play a key role in contextualizing recent climate change by improving our understanding of past climate variability. The Blue Intensity (BI) measurement technique is gaining prominence as a more accessible alternative to X-ray densitometry for producing climatically highly-sensitive tree-ring predictors. Nevertheless, accurately representing low-frequency trends and high-frequency extremes using scanner-based BI remains a challenge due to color biases and resolution limitations. Herein we introduce several methodological advances in sample surfacing, imaging, and image processing which yield measurement series analogous to BI from ultra-high-resolution (UHR; ∼74 700 dpi) images. Such series capture changes in tree-ring anatomical density by representing wood anatomical structure using binary (i.e., black-white) segmentation of sample images. We refer to this novel technique as Binary Surface Intensity (BSI). By utilizing a UHR system and entirely eliminating color and light intensity as variables, the most substantial drawbacks of scanner BI (i.e., discoloration and resolution biases) are bypassed, resulting in more accurate representations of low-frequency climatic trends and high-frequency extremes. Comparisons of several chronologies developed with the BSI and BI techniques, including a multiparameter dataset from Björklund et al. (2019), showed that BSI datasets outperform BI in terms of common signal (r-bar), but also contain strong climatic signals that can exceed those obtained from BI and X-ray density, and even match density datasets based on quantitative wood anatomy. However, measurement software advancements are still required to unlock the full potential of tree-ring parameters produced using the BSI technique. Ongoing development of this new technique will not only aid the attainment of long unbiased chronologies by overcoming color biases and resolution limitations, but also holds promise for unlocking UHR analyses of surface anatomical (sQWA) parameter datasets from reflected-light images. These advances will lead to more accurate tree-ring-based paleoclimatic reconstructions and could also serve a wider range of dendrochronological applications.

In this study, we present new medieval oak tree-ring chronologies developed on the base of subfossil wood collected from the Luchosa and Chernitsa riverine sediments, as well as samples from archaeological excavations and buildings in Vitsebsk and Polotsk (Northern Belarus). Two absolutely dated tree-ring chronologies for 586–1351AD and 1410–1647AD were built. Dates have been confirmed via comparison with subfossil, archaeology, and historical oaks chronologies from the neighboring regions. It was shown that medieval Baltic tree-ring chronologies include wood from the Zapadnaya Dvina basin. Newly built chronologies can be used for dating and provenancing of oak wood originating from European archaeological sites, historical buildings, and natural archives.

The hydrology of Amazonia is changing due to climate and land-use changes, especially in the southern region, which has warmed and dried faster than other tropical regions. Yet there are no long-term hydrological records to put these changes in a historical perspective. Here we investigate the use of tree-ring carbon (δ¹³C) and oxygen isotopes (δ¹⁸O) to assess the seasonal variation in climate for the southern Amazonia basin. We analysed the intra-annual variation of δ¹³C and δ¹⁸O in 10 segments of each tree ring from 2013 to 2017 from individuals of Hymenaea courbaril, a long-lived and widespread neotropical tree species. We find strong seasonal patterns of tree-ring δ¹³C supporting previous observations of annual growth rhythms for this species. The intra-annual variation in δ¹⁸O shows that the lowest values generally occur just after the middle point of ring formation, corresponding to the peak rainy season. We find strong correlations between the δ¹⁸O in the middle of the growth ring and vapour pressure deficit (r = 0.92, P = 0.02) and precipitation (r = −0.93, P = 0.02). We further find associations between the oxygen isotopic series and the discharge of the Araguaia basin’s main rivers during the rainy period. Our results show that these δ¹⁸O records are sensitive to fluctuations in rainfall and humidity, and thus to river discharge in the region. Longer reconstructions of based on tree-ring δ¹⁸O of Hymenaea courbaril could provide a novel proxy to assess past hydrological changes.

European larch (Larix decidua Mill.) holds significant importance as a forest tree species throughout the Alps and in certain regions of central Europe. Its extensive use as construction timber has made it a subject of substantial interest in dendroarchaeological studies aimed at understanding the long-term interactions between human societies and forests. Precise dating of felling phases, accurate estimation of the age of harvested wood, and information on the geographical origin of wood play a crucial role when it comes to characterize these interactions. In this study, we compiled a large dataset of L. decidua samples from across the European Alps to provide a robust statistical model that predicts the cambial age of L. decidua trees based on the number of heartwood rings. By extension, this model can be used to estimate the number of sapwood rings so as to approximate the felling date and to more precise date archaeological larch timber. The model requires almost complete heartwood sequences (<5 missing rings) to achieve accurate estimations. Our results also evidence that the ratio between the number of sapwood and heartwood rings varies across the Alps. At the same time, the indicator developed in this work is not suitable for a determination of wood origin, raising doubts about the effectiveness of attempts aimed at dendroprovenancing L. decidua based on sapwood.

The interactions between fire occurrence-human-climate are highly complex to understand and also difficult to predict due to having many sources of variations in fire regimes. However, we can gather information about the effect of human influence on the regional fire regimes where human influence is high, and the history of locations is well-known by conducting retrospective fire history studies in locations. Here, we present the impact of human settlements on fire occurrence by comparing and discussing the previous drought-driven tree-ring-based fire history reconstruction sites in western Anatolia. For this purpose, we collected cross-sections from Miyarcık highland, Antalya, and developed a 519–y long (1503–2021 CE) composite fire chronology using dendrochronological methods. Our study site location is known for the seasonal inhabitants of “Yörüks”, who led a nomadic life in the Taurus Mountains for centuries, and forests were used for livestock grazing. Since the temperatures increase significantly at the beginning of spring in the lower elevations of Antalya, the yörüks move towards the upper highlands with their animals from May to November. We found lower fire frequency and no fire-climate association compared to other sites that experienced drought-driven wildfires, even though this site is located in a high-fire-risk region. Low-frequency fires might be due to moderate-level livestock grazing by yörüks in this area. Grazing contributes to reducing the amount of accumulated combustible materials, causes discontinuity of fuel in the understory of forests, and affects the dynamics of the spatial distribution of wildfires. This study showed that moderate-level grazing might support effective fire management activities as fuel management because of modifying the fuel properties, changing the fuel-fire interaction (e.g., the fuel continuity and amount of accumulated fuel), and reducing the wildfire probability over space and time.

Generally, organisms living near the periphery of their range experience increased environmental stress compared to individuals of the same species growing at the core of their geographic distribution. The greater environmental stress at the ecological limits of a species distribution normally leads to greater sensitivity to growth-limiting factors. For some tree species, this can lead to the development of unique growth morphologies such as strip-bark or partial cambial dieback. Previous studies have concluded that the growth differences induced by CO₂ fertilization effects in high elevation strip-bark trees makes them unsuitable for climate reconstructions. However, comparisons of strip-bark and whole-bark growth morphologies at high latitude and low elevation sites are limited. This study compares the growth of strip-bark and whole-bark jack pine (Pinus banksiana Lamb.) trees near Yellowknife, Canada. Annual ring widths from trees of each morphological type were measured, and the results indicate the growth of the two populations are statistically different from one another prior to the late 19th century. After the late 19th century, growth of the two populations remains statistically different, but the average mean growth of strip-bark trees increases 44% after 1891 while average mean growth of whole-bark trees decreases nearly 11%. Climate sensitivity of the two populations was tested using monthly and seasonal climate indices from 1943 to 2015 and results indicate the two populations share similar responses to climate. The results of this research suggest these strip-bark and whole-bark trees share similar climate-growth relations at inter-annual timescales, however, their growth trends diverge at decadal to centennial timescales. The timing of cambial dieback was dated to a short time interval in the early 19th century which coincided with a period of cool summer temperatures across the northern hemisphere. Increased growth in strip-bark trees after ∼1891 could be related to CO₂ fertilization effects, although further studies into intrinsic water use efficiency would be helpful in assessing this possibility more accurately.