Variation In Cellulose Research Articles

Environment aging of lignocellulosic fibers and their composites: Visual, mechanical, and microstructural aspects

The current experimental investigation reports the performance of intra-hybrid woven jute-sisal lignocellulosic fibers, and their polypropylene composites subjected to different aging conditions (distilled water, vegetable oil, and alkali solution) for a prolonged time of 6 months. The effect of different aging mediums on chemical composition of fibers, such as, variation in cellulose and hemicellulose content was analyzed to understand the degradation mechanisms and their structure property relationship established. Significant degradation in mechanical properties was observed with exposure to alkali followed by water mediums due to degradation of fibers and thereby results in poor interfacial characteristics, while sustained durability in terms of mechanical properties was observed with oil-based aging. Highest reduction was observed in tensile strength (11 % and 34 %), flexural strength (16 % and 20 %), tensile modulus (44 % and 58 %), and flexural modulus (51 % and 52 %) after 3-month and 6 months of alkali-aging, respectively as compared to un-aged specimens. Furthermore, the visual appeal of materials was significantly affected due to aging in an alkali solution followed by distilled water, while vegetable oil has not shown any visual degradation.

Sustainable Production of Hydrogen from Biomass using Pyrolysis

This study uses biomass to produce hydrogen from biomass via pyrolysis to meet renewable energy demand and reduce environmental effect. Pyrolysis revealed substantial variations in cellulose, hemicellulose, and lignin content in biomass samples. Pyrolysis was tested with different biomass compositions, with Catalyst D converting hydrogen at 80%. Biomass 4 produced the most hydrogen at 120 g/L. Catalyst D was the most sustainable, with 1.8 kWh/kg energy usage, 0.05 kg/kg trash, and 0.15 kg/kg CO2 emissions, according to an environmental impact evaluation. The percentage change study highlighted Catalyst D’s significant pyrolysis performance and environmental sustainability gains. These results show that green biomass may increase biomass-to-hydrogen production efficiency and sustainability, advancing clean energy technology and a more sustainable energy future.

Identification and Parametrization of Key Factors Affecting Levoglucosan Emission During Solid Fuel Burning.

Levoglucosan (LG) is a pyrolysis product of cellulose and hemicellulose at low combustion temperatures. However, LG release cannot be determined only by considering the contents of cellulose and hemicellulose exclusively due to the complexity of combustion processes and the physical-chemical properties of the fuel. This study detected the emission factors (EFs) of LG from 22 different solid fuel samples (including coal and biomass) by considering 18 different fuel properties and five combustion parameters. The average LGEFs during solid fuel burning varied in a range of 0.03-136 mg kg-1, with a magnitude difference of 1-4 orders. While the variations in cellulose (59.5-368 mg g-1) and hemicellulose (73.5-165 mg g-1) contents of fuel samples were only one- to 6-fold. A short combustion duration (<150 min) and a medium combustion temperature (200-400 °C) influenced by volatile and ash contents are crucial for the generation and accumulation of LG. A random forest coupled with the Akaike information criterion stepwise regression model successfully explained 96% of the total LG emission variation using three variables (ash content, cellulose content, and modified combustion efficiency). The ash content promoted coke formation and LG chain cracking by increasing the pyrolysis temperature and is considered the most important factor. The alkali metal in ash can reduce the energy barrier of intramolecular ring contraction reactions and inhibit the dehydration reactions, which led to additional heat being utilized by the competitive pathways of LG formation. This study provided a method to address the parametrization and release mechanisms of combustion source emissions.

Enhanced humus synthesis from Chinese medicine residues composting by lignocellulose-degrading bacteria stimulation: Upregulation of key enzyme activity and neglected indirect effects on humus formation

Chinese medicine residues (CMHRs) resource is attracting widespread attention, as it is expected to be produced into Humus-rich fertilizer for soil application. This study aimed to promote effective humus (HS) production through lignocellulose-degrading bacteria (LDB) addition and explore the biological regulation mechanism of LDB affecting lignocellulose-to-humus conversion. The results showed higher HS production was achieved, with 109.73 and 111.44 g·kg−1, and HA/FA was raised by 12.70–16.02 % in compost products by LDB addition stimulation. Significant upregulation of β-glucanase and xylanase activities catalyzed higher decomposition of lignocellulose toward more HS potential precursors supply. Furthermore, exogenous LDB intervention induced microbial community restructure and microbial network establishment via enriching synergism functional bacteria, i.e., Thermobifida, Paenibacillus, Nonomuraea, etc. Mantel test results showed that it was variation of cellulose, hemicellulose and HS that affected microbial community succession (p < 0.01, r > 0.6), which represented the positive action of LDB addition stimulation on HS synthesis upregulation. Further exploration suggested LDB had an indirect effect on HS formation by enhanced lignin and hemicellulose conversion based on the Random Forest model and Partial least-squares path modeling results. This research provides new insights into the trigger effects of LDB introduction on upregulating HS synthesis and is expected to propose new perspectives for HS efficient production in CMHRs composting.

Species variation in the hydrogen isotope composition of leaf cellulose is mostly driven by isotopic variation in leaf sucrose.

Experimental approaches to isolate drivers of variation in the carbon-bound hydrogen isotope composition (δ2 H) of plant cellulose are rare and current models are limited in their application. This is in part due to a lack in understanding of how 2 H-fractionations in carbohydrates differ between species. We analysed, for the first time, the δ2 H of leaf sucrose along with the δ2 H and δ18 O of leaf cellulose and leaf and xylem water across seven herbaceous species and a starchless mutant of tobacco. The δ2 H of sucrose explained 66% of the δ2 H variation in cellulose (R2 = 0.66), which was associated with species differences in the 2 H enrichment of sucrose above leaf water ( : -126% to -192‰) rather than by variation in leaf water δ2 H itself. was positively related to dark respiration (R2 = 0.27), and isotopic exchange of hydrogen in sugars was positively related to the turnover time of carbohydrates (R2 = 0.38), but only when was fixed to the literature accepted value of ‰. No relation was found between isotopic exchange of hydrogen and oxygen, suggesting large differences in the processes shaping post-photosynthetic fractionation between elements. Our results strongly advocate that for robust applications of the leaf cellulose hydrogen isotope model, parameterization utilizing δ2 H of sugars is needed.

Cellulose and lignin profiling in seven, economically important bamboo species of India by anatomical, biochemical, FTIR spectroscopy and thermogravimetric analysis

Bamboos, a group of non-timber grasses, offers a great promise for the ligno-cellulosic biomass industry due to their very fast growth resulting rapid accumulation of lignocellulose biomasses, high fibre contents, low maintenance cost and existence of a diverse genetic pool. Despite, not voluminous and significant studies aimed to investigate the anatomy and biochemistry related to the cellulose and lignin synthesis in bamboos. Particularly, there remains a big knowledge gap on the variations of cellulose and lignin contents that exists at the germplasm level. Therefore, this study aimed to analyse chemical composition of ligno-cellulosic biomasses obtained from internode tissues of seven, abundantly available bamboo species of India (Bambusa balcooa, B. tulda, B. bambos, B. nutans, B. striata, Dendrocalamus giganteus, and D. strictus) by performing Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) Spectroscopy and Thermogravimetric analysis (TGA). Four anatomical parameters were used to predict ‘superior’ bamboo species/genotypes with respect to high cellulose vs. low lignin content. Particularly integrated density (ID) of Fast green and Phloroglucinol stains were correlated to the biochemical estimates of cellulose and lignin conducted on 63 samples. Hence the study concludes that stain ID can be used for quick screening of bamboo germplasms having desired ligno-cellulose contents. On the basis of multiple parameters analysed, B. bambos emerged as a reference bamboo for future ligno-cellulose research.

Modified Crosslinked Cellulose/PVA with Glutaraldehyde and Reinforced

Increasing the use of non-degradable plastic packaging causes environmental and health issue. Bioplastic made from cellulose is an alternative solution to this issue due to biodegradable and environmentally friendly.However, the use of cellulose as a bioplastic requires an improved physical and mechanical properties. In this study, we will modify the cellulose by adding polyvinyl alcohol (PVA) film with added glutaraldehyde as a crosslinker and ZnO as a filler to improve the physical and mechanical properties of the bioplastic which produce cellulose/PVA film. Optimization of cellulose/PVA films synthesis was done with variation of cellulose which is 0%, 2%, 6% and 10% and glutaraldehyde 0%, 1%, 3% and 5% will be carried out.Cellulose/PVA film were characterized by SEM, XRD, FTIR and and analyzed for their mechanical properties, transparency, thickness, swelling, solubility, biodegradability, anti-microbial activity and resistance to aging processes. The result showed that adding glutaraldehyde as crosslinker and reinforced with ZnO as a filler had significantly improved the physical and mechanical properties of cellulose/PVA.

Vertical Variation of Wood Chemical Constituents in )Albizia lebbeck L. Benth.( Trees Grown in Egypt

Basic knowledge of the within tree chemical components variation is essential which affects the wood end-use. Therefore, this study aimed to determine the chemical constituents (cellulose, hemicellulose, lignin, total extractive, ash contents, pH, and the solubility in hot water, cold water, and 1% NaOH) at five different levels (base, 25%, 50%,75%, and 100% of total merchantable stem height) of Albizia lebbeck trees grown in Egypt. The results showed that there was a significant effect of tree height levels on all the measured chemical constituents at 0.05 probability level. There was no specific pattern for the variation in cellulose, hemicellulose, and the solubility in 1% NaOH with the tree height levels. The cellulose and hemicellulose contents were markedly decreased at 100% of total tree height. The lignin content showed a significant gradual increase from the base up to the top of the stem. In contrast, the ash content, total extractives, and the hot and cold-water extractives showed a gradual decrease from the base to the top of the stem. Correlation analysis showed a good negative relationship between lignin and both cellulose and hemicellulose contents. Based on the results of this study, the differences in chemical composition with height along the stem must be taken into account when using the wood of these locally grown trees in various wood industries such as furniture, parquet, plywood, and paneling.

Drying of the Natural Fibers as A Solvent-Free Way to Improve the Cellulose-Filled Polymer Composite Performance.

When considering cellulose (UFC100) modification, most of the processes employ various solvents in the role of the reaction environment. The following article addresses a solvent-free method, thermal drying, which causes a moisture content decrease in cellulose fibers. Herein, the moisture content in UFC100 was analyzed with spectroscopic methods, thermogravimetric analysis, and differential scanning calorimetry. During water desorption, a moisture content drop from approximately 6% to 1% was evidenced. Moreover, drying may bring about a specific variation in cellulose’s chemical structure. These changes affected the cellulose-filled polymer composite’s properties, e.g., an increase in tensile strength from 17 MPa for the not-dried UFC100 to approximately 30 MPa (dried cellulose; 24 h, 100 °C) was observed. Furthermore, the obtained tensile test results were in good correspondence with Payne effect values, which changed from 0.82 MPa (not-dried UFC100) to 1.21 MPa (dried fibers). This raise proves the reinforcing nature of dried UFC100, as the Payne effect is dependent on the filler structure’s development within a polymer matrix. This finding paves new opportunities for natural fiber applications in polymer composites by enabling a solvent-free and efficient cellulose modification approach that fulfils the sustainable development rules.

Determination of polymorphic changes in cellulose from Eucalyptus spp. fibres after alkalization

Delignified fibres from E. benthamii, E. nitens and E. smithii were treated with different NaOH concentrations (up to 30%, w/v) at two different temperatures (25 °C and 80 °C) to investigate the polymorphic and morphological variations in cellulose. The results showed that de-crystallization and the polymorphic transformation of cellulose started at 10% (w/v) NaOH. At 10% (w/v) NaOH, the cellulose II content was similar among the samples from the different species, but changes were observed in the cellulose I content and amorphous fraction. Alkalization at 25 °C had a higher de-crystallization effect than that at 80 °C. E. benthamii showed the highest cristallinity index values and E. nitens the lowest. The crystallite size of cellulose I (L(200)) increased as the NaOH concentration increased, while the temperature seemed to not have a significant influence on the L(200) variation. E. benthamii showed the highest L(200) (3.5–5.0 nm) while E. nitens showed the lowest (3.3–4.5 nm). The crystallite size of cellulose II (L(020)) was higher (4.8–5.2 nm) than that of cellulose I L(200) (3.3–5.0 nm). Alkalization at a higher temperature resulted in a higher cellulose II L(020). Morphologically, at a 0.5% NaOH concentration, the fibres were embedded in a gel-like substance, and, with the NaOH concentration above 10%, the fibres were converted into a swollen and roughened state. Thus, different Eucalyptus species at given NaOH concentrations displayed different structural features, which could lead to procedures and products with different requirements towards the manufacturing of cellulose derivatives.

Establishment of Miscanthus sinensis with decreased lignin biosynthesis by Agrobacterium–mediated transformation using antisense COMT gene

This study was to determine a transformation system for Miscanthus sinensis, and to optimize factors and conditions required for expression of an antisense caffeic acid O-methyltransferase gene in the M. sinensis (MsCOMT-AS). Transformation of callus derived from seeds and immature inflorescences of M. sinensis was established by using Agrobacterium tumefaciens strain LBA4404 harboring a binary vector pMBP1. In order to establish the stable transformation system, several transformation factors such as explant type, strain, co-culture periods, acetosyringone concentration, and selective markers were assessed. In this study, seven putative transgenic plants were obtained from callus transformation and plantlet regeneration. Various tests including PCR analysis and RT-PCR were used to detect the transgenic insert. The transgenic plants were also characterized for their agronomic and morphological characteristics, expression of MsCOMT-AS gene, and variation in lignocellulosic content. Biomass related traits such as plant height, number of leaves, length of leaf, stem diameter, fresh weight, dry weight, and cell size of the control plants were superior to transgenic plants. Total lignin content of transgenic plants was lower than that of the control plant due to reduced caffeic acid O-methyltransferase (COMT) gene expression related to lignin production. Cellulose and hemicellulose content in transgenic plants were not increased. Variation in cellulose and hemicellulose content had no correlation with variation in lignin content of transgenic plants. In conclusion, transgenic M. sinensis was obtained with down-regulated COMT gene. Lignin synthesis was decreased what offers possibility of crop modification for facilitated biofuel production.

Effects of water table on cellulose and lignin degradation of Carex cinerascens in a large seasonal floodplain

ABSTRACTWater table affects litter decomposition in wetlands, but its effects on the degradation of cellulose and lignin are poorly understood. We performed a decomposition experiment in Poyang Lake Wetland, to determine how water table affected the degradation of cellulose and lignin. After 60 days of decomposition at a site with a relatively highly water table, 46.19% of initial cellulose and 41.95% of initial lignin remained. Decay rates of both cellulose and lignin increased as the depth of the water table increased. Principle component analysis showed that the decay rates of cellulose and lignin increased with increasing soil pH, but decreased with increasing contents of clay and fungi: bacteria ratio. The path model accounted for 66% and 79% of the variation in cellulose and lignin decay rates, respectively, and considered the effects of interactions between the water table and related factors. The cellulose decay rate was affected by the water table with a direct coefficient of 0.47, and an indirect coefficient of 0.65, but the lignin decay rate was indirectly affected by water table (coefficient, 1.25) and directly affected by soil property (coefficient, 0.67). Thus, the water table affected the decomposition of cellulose and lignin via different mechanisms.

Intra-seasonal variability of teak tree-ring cellulose δ18O from northwestern Thailand: A potential proxy of Thailand summer monsoon rainfall

Thailand has been regarded as a transition zone between the Indian and western North Pacific monsoons which produce most of the precipitation in this area and sustain large-scale agricultural activities. Their different moisture sources and associated transport trajectories could result in distinguishable seasonal variations in rainfall oxygen isotopes (δ18O). Knowledge about seasonal variability in Thailand monsoon could facilitate agricultural water management and improve our understanding of the Asian monsoon system. In this study, a detailed examination of the intra-seasonal variability of tree-ring cellulose δ18O in teak trees from Northwestern Thailand was performed. The results show clear intra-seasonal variability in cellulose δ18O, with heavier values in the early rainy season and much lighter values in the later rainy season. Climate correlation analysis indicates that there is a significant and positive correlation between sub-seasonal variation in cellulose δ18O and rainfall δ18O. A weak and negative correlation with relative humidity (RH) has also been identified. However, there is no relation between intra-seasonal variation in cellulose and that of the amount of rainfall. These results imply that intra-seasonal variability of cellulose δ18O in teak trees from Northwestern Thailand may inherit such variability in rainfall δ18O and might be slightly shaded by RH. The spatial correlations with large-scale precipitation in the Merged Analysis (CMAP) and Outgoing Longwave Radiation (OLR) data sets indicated seasonal changes in moisture origin and may potentially be used to explore long-term monsoon climate variability on a seasonal scale in subtropical Southeast Asia.

Wood chemistry and density: An analog for response to the change of carbon sequestration in mangroves

This study aimed to resolve the variations of physical and chemical properties of wood records measured in different mangroves with their annual carbon sequestration. The methods of investigation used were to examine growth rate by monitoring breast height diameter, wood chemistry and density, FTIR spectroscopy and thermogravimetry. Carbon sequestration rate showing an increase with density varied between 0.088 and 0.171μgCkg−1AGBs−1, and Avicennia marina showed the maximum value and Bruguiera gymnorrhiza, the minimum. The changes in FTIR bands at 4000–2500cm−1 and 1700–800cm−1 were correlated to the variations in cellulose in mangrove woods and lignin to cellulose ratio ranged between 0.21 and 1.75. Thermal analyses of mangrove wood suggested that the fuel value index (985–3922) exhibited an increase with the decrease in maximum decomposition temperature and density. The seasonal variation of temperature and CO2 were likely to affect chemical properties through changes in wood density.

Chemical and elemental composition of big bluestem as affected by ecotype and planting location along the precipitation gradient of the Great Plains

Three big bluestem ecotypes from central Kansas (Cedar Bluffs and Webster populations), eastern Kansas (Konza and Top of the World populations), and Illinois (12Mile and Fults populations), as well as the Kaw cultivar, were harvested from four reciprocal garden planting locations (Colby, Hays, and Manhattan, KS; and Carbondale, IL) and evaluated for their chemical (glucan, xylan, arabinan, lignin and ash) and elemental (carbon, oxygen, hydrogen, nitrogen and sulfur) compositions. The objective of this research was to study the effects of ecotype and planting location on the chemical and elemental compositions of big bluestem along the Great Plains precipitation gradient (∼1200 to 400mm mean annual precipitation). All the populations revealed a large variation in cellulose (31.8–36.5%), hemicellulose (24.96–29.74%), lignin (14.4–18.0%), carbon (47.3–51.3%), and nitrogen (4.91–6.44%). Planting location had significant effects on both chemical and elemental compositions of big bluestem. Ecotype had significant effects on glucan, xylan, lignin, and ash contents as well as on carbon, oxygen, and hydrogen elemental fractions. In addition, the interaction between ecotype and planting location had significant effects on glucan, lignin, and hydrogen. Planting location had a greater effect on chemical and elemental compositions than the ecotype and interaction between location and ecotype. The total sugar content of the big bluestem (regardless of ecotype) increased as the Great Plains precipitation gradient increased from west to east. Annual precipitation, growing degree days and potential evapotranspiration in 2010 explained up to 97%, 88% and 80% of the variation in compositions, respectively.

Regulation of biomass growth and carbon partitioning in poplar – molecular characterization of a candidate gene

Improvement of plant feedstock for bioenergy production can be achieved by modifying wood chemical properties and increasing biomass productivity. We previously identified a candidate gene for carbon partitioning and growth on chromosome 13 (cpg13) of poplar. Cpg13 was identified as the regulator of carbon partition and growth within a QTL interval that explains 56% of the variation in cellulose to lignin ratio, as well as 20-25% of the heritable variation in biomass. Putative homologues of cpg13 in Arabidopsis are annotated as proteins of unknown function; therefore, the functional characterization of cpg13 is essential. At present, evidence of the functional role of cpg13 is being obtained by the analysis of poplar transgenic plants transformed with RNAi, overexpression and GFP-fused – cpg13 constructs. Preliminary data indicates that down-regulating cpg13 positively impacts growth, while a negative effect is detected in lines overexpressing cpg13. Transgenic poplar 35S::cpg13:GFP shows localization in cell wall, consistent with in silico predictions. Comparative genomics indicate moderate similarity with methyltransferase. Analysis of the impact of differentially regulating cpg13 on lignin and cellulose is currently under way in the mutants. Furthermore, attempts to purify the cpg13 protein are in progress, to define its role through a series of biochemical function assays.

The Changes in North American atmospheric circulation patterns indicated by wood cellulose

General circulation model simulations suggest that during the Last Glacial Maximum, the northern circumpolar vortex intensifi ed and enlarged, a glacial anticyclone developed over the Laurentide Ice Sheet, and the position of the jet stream was shifted southward. However, observations directly related to shifts in wind patterns across the North American continent have not yet been reported. We examined tree-ring cellulose from the Holocene and the last glacial period for: (1) covariation between precipitation δ 18 O (and δD) and relative humidity, and (2) variation of cellulose δ 18 O and δD with longitude. Holocene isotopic features are consistent with modern moisture trajectories. The isotopic features during the last glaciation are dissimilar to those in the Holocene, and constitute direct evidence for an expansion of the polar easterlies to latitudes as low as 40°N. This is the fi rst time that moisture transport patterns have been inferred from covariation between isotopic composition in precipitation and relative humidity, a technique that holds much promise for future studies of atmospheric circulation.

Changes in cell wall composition during ripening of grape berries

Cell walls were isolated from the mesocarp of grape (Vitis vinifera L.) berries at developmental stages from before veraison through to the final ripe berry. Fluorescence and light microscopy of intact berries revealed no measurable change in cell wall thickness as the mesocarp cells expanded in the ripening fruit. Isolated walls were analyzed for their protein contents and amino acid compositions, and for changes in the composition and solubility of constituent polysaccharides during development. Increases in protein content after veraison were accompanied by an approximate 3-fold increase in hydroxyproline content. The type I arabinogalactan content of the pectic polysaccharides decreased from approximately 20 mol % of total wall polysaccharides to about 4 mol % of wall polysaccharides during berry development. Galacturonan content increased from 26 to 41 mol % of wall polysaccharides, and the galacturonan appeared to become more soluble as ripening progressed. After an initial decrease in the degree of esterification of pectic polysaccharides, no further changes were observed nor were there large variations in cellulose (30-35 mol % of wall polysaccharides) or xyloglucan (approximately 10 mol % of wall polysaccharides) contents. Overall, the results indicate that no major changes in cell wall polysaccharide composition occurred during softening of ripening grape berries, but that significant modification of specific polysaccharide components were observed, together with large changes in protein composition.

Variations dimensionnelles accompagnant le traitement thermique de la cellulose sous atmosphàre inerte

In this paper, we study the dimensional variations accompanying the thermal decomposition of cellulose, under nitrogen atmosphere, from the ambient temperature to different final temperatures of the reaction. Consequently, two series of tests are achieved. In the first set, the residue of cellulose is cooled, once the desired temperature is reached. In the second set, when the desired temperature is reached, the residue of cellulose is maintained at this temperature for a duration of time varying from zero to two hours. The dimensional variations are measured on cylinders of 3 mm in diameter and 9 mm in height, prepared from the cellulose powder. The cellulose residues are then analysed using scanning electron microscopy. The results show that the dimensions of cellulose cylinders change in the longitudinal as well as in the transversal direction. Furthermore, the dimensional variations of the first set of these tests reveal the ranges where the cellulose contracts and then dilates. The results of the second set indicate that, when the residue is maintained two hours at the final temperature of reaction, the evolution observed in the first series of tests is hidden. The difference observed in the results of the two series of tests can be explained by the measurements performed, as a function of time, at 300°C and 380°C. These measurements show the influence of residue residence time on the dimensional variations of cellulose. A physical explanation of the exothermic effect accompanying the last stage of cellulose pyrolysis can be provided on basis of the concept of the fracture mechanics, with the dimensional variations and fractographics taken by scanning electron microscopy.

Stable carbon isotopes in tree rings of beech: climatic versus site-related influences

Stable carbon isotopes in tree rings are a promising tool in palaeoclimate research, provided attempts are made to disentangle climatic from local effects (e.g. soil properties, competition, light). The 13C/12C variations in cellulose of tree rings of beech (Fagus sylvatica) were determined at several sites in the Swiss Central Plateau covering the last 50 years. We chose sites which differ in moisture conditions and sampled cores from four to six trees per site. The mean 13C/12C series from the different dry sites (distant by up to 40 km) are closely interrelated suggesting a common external cause. Correlation analysis with climate data proved the total precipitation in the months May, June and July to have the strongest effect on the carbon isotopes (r = – 0.73). This result is in agreement with the commonly used model which relates the isotope discrimination to the water use efficiency. On the other hand, the isotope series of the wet sites are not as well correlated to the climate. At two of the sites (a dry and a humid) tree ring width suddenly increased. We used this effect as a test-case to study the influence of local growth conditions on the climate-isotope relationship.