scholarly journals Alpine Holocene tree-ring dataset: age-related trends in the stable isotopes of cellulose show species-specific patterns

2020 ◽  
Vol 17 (19) ◽  
pp. 4871-4882
Author(s):  
Tito Arosio ◽  
Malin M. Ziehmer ◽  
Kurt Nicolussi ◽  
Christian Schlüchter ◽  
Markus Leuenberger

Abstract. Stable isotopes in tree-ring cellulose are important tools for climatic reconstructions even though their interpretation could be challenging due to nonclimate signals, primarily those related to tree aging. Previous studies on the presence of tree-age-related trends during juvenile as well as adult growth phases in δD, δ18O, and δ13C time series yielded variable results that are not coherent among different plant species. We analyzed possible trends in the extracted cellulose of tree rings of 85 larch trees and 119 cembran pine trees, i.e., in samples of one deciduous and one evergreen conifer species collected at the tree line in the Alps, covering nearly the whole Holocene. The age trend analyses of all tree-ring variables were conducted on the basis of mean curves established by averaging the cambial-age-aligned tree series. For cambial ages over 100 years, our results prove the absence of any age-related effect in the δD, δ18O, and δ13C time series for both the evergreen and the deciduous conifer species, with the only exception being larch δD. However, for lower cambial ages, we found trends that differ for each isotope and species; i.e., mean δ13C values in larch do not vary with aging and can be used without detrending, whereas those in cembran pine show a juvenile effect, and the data should be detrended. Mean δ18O values present two distinct aging phases for both species, complicating detrending. Similarly, mean δD values in larch change in the first 50 years, whereas cembran pine changes between 50 and 100 years. Values for these two periods of cambial age for δD and δ18O should be used with caution for climatic reconstructions, ideally complemented by additional information regarding mechanisms for these trends.

2020 ◽  
Author(s):  
Tito Arosio ◽  
Malin M. Ziehmer ◽  
Kurt Nicolussi ◽  
Christian Schlüchter ◽  
Markus Leuenberger

Abstract. Stable isotopes in tree-ring cellulose are important tools for climatic reconstructions even though their interpretation could be challenging due to non-climate signals, primarily those related to tree ageing. Previous studies on the presence of tree-age related trends during juvenile as well as adult growth phases in δD, δ18O and δ13C time series yielded variable results that are not coherent among different plant species. We analysed possible trends in the extracted cellulose of tree-rings of 85 larch trees and 119 cembran pine trees, i.e. in samples of one deciduous and one evergreen conifer species collected at the treeline in the Alps covering nearly the whole Holocene. The age trend analyses of all tree-ring variables were conducted on the basis of mean curves established by averaging the cambial-age aligned tree series. For cambial ages over 100 years, our results prove the absence of any age-related effect in the δD, δ18O and δ13C time series for both the evergreen as well the deciduous conifer species, with the only exception of larch δD. However, for lower cambial ages, we found trends that differ for each isotope and species. I.e., mean δ13C values in larch do not vary with ageing and can be used without detrending, whereas those in cembran pine show a juvenile effect and the data should be detrended. Mean δ18O values present two distinct ageing phases for both species complicating detrending. Similarly, mean δD values in larch change in the first 50 yr whereas cembran pine between 50–100 yr. Values for these two periods of cambial age for δD and δ18O should be used with caution for climatic reconstructions, ideally complemented by additional information regarding mechanisms for these trends.


2020 ◽  
Author(s):  
Tito Arosio ◽  
Malin M. Ziehmer-Wenz ◽  
Kurt Nicolussi ◽  
Christian Schlüchter ◽  
Markus Leuenberger

Abstract. A recent analysis of stable isotopes of the Alpine Holocene Tree-Ring Dataset, consisting of samples from 192 larch and cembran pine trees, revealed that δD and δ18O exhibit no trends in adult trees, but evidence trends in the juvenile period of the first 100 years of cambial age. In this work we applied the Spearman statistical analysis on different cambial age classes to verify if these changes were correlated with tree-ring width values, that are known to show age trends. The results prove a significant correlation between tree-ring-width (TRW) and both hydrogen and oxygen stable isotopes before 100 year of cambial age, but not afterwards, in both larch and cembran pine. A trend in the correlation values was also found between the two water isotopes, while no trend was found in correlations involving δ13C. We hypothesized the δD and δ18O values reflect the higher xylogenesis activity of the juvenile period, that is associated with reduced atom exchanges of photosynthates with xylem water. The result indicates that the climate response of δD and δ18O may differ in the juvenile and mature period of tree life at treeline.


2020 ◽  
Author(s):  
Tito Arosio ◽  
Malin M. Ziehmer-Wenz ◽  
Kurt Nicolussi ◽  
Christian Schlüchter ◽  
Markus Leuenberger

2020 ◽  
Vol 16 (6) ◽  
pp. 2153-2172 ◽  
Author(s):  
Takeshi Nakatsuka ◽  
Masaki Sano ◽  
Zhen Li ◽  
Chenxi Xu ◽  
Akane Tsushima ◽  
...  

Abstract. Oxygen isotope ratios (δ18O) of tree-ring cellulose are a novel proxy for summer hydroclimate in monsoonal Asia. In central Japan, we collected 67 conifer wood samples, mainly Chamaecyparis obtusa, with ages encompassing the past 2600 years. The samples were taken from living trees, archeological wood, architectural wood, and buried logs. We analyzed stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) in tree-ring cellulose in these samples (more than 15 000 rings in total) without using a pooling method and constructed a statistically reliable tree-ring cellulose δ18O time series for the past 2500 years. However, there were distinct age trends and level offsets in the δ18O record, and cellulose δ18O values showed a gradual decrease as an individual tree matures. This suggested it is difficult to establish a cellulose δ18O chronology for low-frequency signals by simple averaging of all the δ18O time series data. In addition, there were opposite age trends in the cellulose δ2H, and δ2H gradually increased with tree age. There were clear positive correlations in the short-periodicity variations between δ18O and δ2H, probably indicating a common climate signal. A comparison of the δ18O and δ2H time series in individual trees with tree-ring width suggested that the opposite age trends of δ18O and δ2H are caused by temporal changes in the degree of post-photosynthetic isotope exchange with xylem water (physiological effect), accompanied by changes in stem growth rate that are influenced by human activity in the forests of central Japan. Based on the assumptions that cellulose δ18O and δ2H vary positively and negatively with constant proportional coefficients due to climatological and physiological effects, respectively, we solved simultaneous equations for the climatological and physiological components of variations in tree-ring cellulose δ18O and δ2H in order to remove the age trend. This enabled us to evaluate the climatic record from cellulose δ18O variations. The extracted climatological component in the cellulose δ18O for the past 2600 years in central Japan was well correlated with numerous instrumental, historical, and paleoclimatological records of past summer climate at various spatial and temporal scales. This indicates that integration of tree-ring cellulose δ18O and δ2H data is a promising method to reconstruct past summer climate variations on annual to millennial timescales, irrespective of the growth environment. However, analytical and statistical methods need to be improved for further development of this climate proxy.


2008 ◽  
Vol 38 (5) ◽  
pp. 1144-1158 ◽  
Author(s):  
Matthew Brookhouse ◽  
Cris Brack

In this study, we examine within-tree variance in proportionate tree-ring width (prw) and correlation between radii (rwt), samples (rbh), and trees (rbt) in four eucalypt species common throughout eastern Victoria, Australia. In all species and sites studied, rwt and rbh differ significantly between cambial-age and sample-height classes. Differences between rwt and rbh are nonsignificant between tree-age or radial-azimuth classes. Significant differences in prw exist between cambial-age, tree-age, and sample-height classes and between radii on different compass bearings. Whilst differences in rwt and rbh between cambial-age classes appears to be the result of variation in mechanical demands with increasing stem size, stem deformation may account for differences between sample-height classes. Variation in prw appears to be due to stem geometry, stem eccentricities associated with root buttressing, and tree-age dependent variation in the rate of radial growth. No significant differences in rbt exist between sample-height classes. Analysis of the expressed population signal statistic indicates that site-level and species differences are far more significant than sample position on variance within tree-ring width series collected from eucalypts. We discuss the implications of the current work for eucalypt dendroclimatology.


2020 ◽  
Vol 8 ◽  
Author(s):  
Tito Arosio ◽  
Malin Michelle Ziehmer-Wenz ◽  
Kurt Nicolussi ◽  
Christian Schlüchter ◽  
Markus Leuenberger

The analysis of the stable isotope of the tree-ring cellulose is an important tool for paleo climatic investigations. Long tree-ring chronologies consist predominantly of oaks and conifers in Europe, including larch trees (Larix decidua) and cembran pines (Pinus cembra) that form very long tree ring chronologies in the Alps and grow at the treeline, where tree growth is mainly determined by temperature variations. We analyzed δ13C, δ18O and δ2H isotopes in the cellulose extracted from tree-rings of wood samples collected at high altitude in the Swiss and Tyrol Alps, covering the whole Holocene period. We found that larch cellulose was remarkably more depleted in deuterium than that of cembran pine, with mean δ2H values of −113.4 ± 9.7‰ for larch and of −65.4 ± 11.3‰ for cembran pine. To verify if these depleted values were specific to larch or a property of the deciduous conifers, we extended the analysis to samples from various living conifer species collected at the Bern Botanical Garden. The results showed that not only the larch, but also all the samples of the deciduous larch family had a cellulose composition that was highly depleted in δ2H with regard to the other evergreen conifers including cembran pine, a difference that we attribute to a faster metabolism of the deciduous conifers. The δ18O values were not statistically different among the species, in agreement with the hypothesis that they are primary signals of the source water. While the δ13C values were slightly more depleted for larch than for cembran pine, likely due to metabolic differences of the two species. We conclude that the deciduous larch conifers have specific metabolic hydrogen fractionations and that the larch unique signature of δ2H is useful to recognize it from other conifers in subfossil wood samples collected for paleoclimatic studies. For climate information the absolute δ2H values of larch should be considered carefully and separate from other species.


Author(s):  
Paolo Cherubini ◽  
Giovanna Battipaglia ◽  
John L. Innes

Abstract Purpose of Review Society is concerned about the long-term condition of the forests. Although a clear definition of forest health is still missing, to evaluate forest health, monitoring efforts in the past 40 years have concentrated on the assessment of tree vitality, trying to estimate tree photosynthesis rates and productivity. Used in monitoring forest decline in Central Europe since the 1980s, crown foliage transparency has been commonly believed to be the best indicator of tree condition in relation to air pollution, although annual variations appear more closely related to water stress. Although crown transparency is not a good indicator of tree photosynthesis rates, defoliation is still one of the most used indicators of tree vitality. Tree rings have been often used as indicators of past productivity. However, long-term tree growth trends are difficult to interpret because of sampling bias, and ring width patterns do not provide any information about tree physiological processes. Recent Findings In the past two decades, tree-ring stable isotopes have been used not only to reconstruct the impact of past climatic events, such as drought, but also in the study of forest decline induced by air pollution episodes, and other natural disturbances and environmental stress, such as pest outbreaks and wildfires. They have proven to be useful tools for understanding physiological processes and tree response to such stress factors. Summary Tree-ring stable isotopes integrate crown transpiration rates and photosynthesis rates and may enhance our understanding of tree vitality. They are promising indicators of tree vitality. We call for the use of tree-ring stable isotopes in future monitoring programmes.


2003 ◽  
Vol 33 (10) ◽  
pp. 1905-1914 ◽  
Author(s):  
Irina P Panyushkina ◽  
Malcolm K Hughes ◽  
Eugene A Vaganov ◽  
Martin AR Munro

We reconstructed air temperature for two periods in the growth season from cell dimension and cell number variability in cross-dated tree rings of Larix cajanderi Mayr. from northeastern Siberia. Thirteen tree-ring chronologies based on cell size, cell wall thickness, and cell number were developed for AD 1642–1993. No clear evidence was found of an age-related trend in cell dimensions in the sampled materials, but cell numbers were correlated with cambial age. The chronologies contain strong temperature signals associated with the timing of xylem growth. We obtained reliable reconstructions of mean June temperature from the total cell number and July–September temperature from the cell wall thickness of latewood. June temperature and July–September temperature covaried for most of the period from AD 1642 to AD 1978. After that time, June temperature became cooler relative to July–September temperature. This difference caused disproportional changes in earlywood tracheids because of the late start of growth and cool conditions in June followed by warming during the rest of the season. The identification of this unusual recent change has shown that intraseasonal resolution may be achieved by cell dimension and cell number chronologies.


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