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At least 19 recordsLinked to original sources

PubMed2003

Ozone sensitivity of Fagus sylvatica and Fraxinus excelsior young trees in relation to leaf structure and foliar ozone uptake.

During the summer of 2001, 2-year-old Fraxinus excelsior and Fagus sylvatica plants were subjected to ozone-rich environmental conditions at the Regional Forest Nursery at Curno (Northern Italy). Atmospheric ozone concentrations and stomatal conductance were measured, in order to calculate the foliar fluxes by means of a one-dimensional model. The foliar structure of both species was examined (thickness of the lamina and of the individual tissues, leaf mass per area, leaf density) and chlorophyll a fluorescence was determined as a response parameter. Stomatal conductance was always greater in Fraxinus excelsior, as was ozone uptake, although the highest absorption peaks did not match the peaks of ozone concentration in the atmosphere. The foliar structure can help explain this phenomenon: Fraxinus excelsior has a thicker mesophyll than Fagus sylvatica (indicating a greater photosynthesis potential) and a reduced foliar density. This last parameter, related to the apoplastic fraction, suggests a greater ability to disseminate the gases within the leaf as well as a greater potential detoxifying capacity. As foliar symptoms spread, the parameters relating to chlorophyll a fluorescence also change. PI (Performance Index, Strasser, A., Srivastava, A., Tsimilli-Michael, M., 2000. The fluorescence transient as a tool to characterize and screen photosynthetic samples. In: Yunus, M., Pathre, U., Mohanty, P., (Eds.) Probing Photosynthesis: Mechanisms, Regulation and Adaptation. Taylor & Francis, London, UK, pp. 445-483.) has proved to be a more suitable index than Fv/Fm (Quantum Yield Efficiency) to record the onset of stress conditions.

Air Pollutants↗

PubMed2002

GA(3)-induced expression of a new functional AAA-ATPase (FsA1) is correlated with the onset of germination in Fagus sylvatica L. seeds (beechnuts).

A full-length cDNA clone, named FsA1, has been isolated from a cDNA library constructed using mRNA from Fagus sylvatica L. dormant seeds (beechnuts). This clone shows high identity with members of the AAA superfamily, for ATPases Associated with a variety of cellular Activities, encoding subunit 8 of the 26S proteasome or Tat binding proteins (TBPs). Direct biochemical evidence supporting Mg(2+)-dependent ATPase activity has been obtained by expressing FsA1 in Escherichia coli as histidine tag fusion protein and using the recombinant protein in the stimulation of ATP hydrolysis. Analysis of the expression of FsA1 transcripts during stratification shows an increase in the presence of gibberellic acid (GA(3)), a treatment that proved to be efficient in breaking dormancy and increasing germination percentages of these seeds, while the addition of paclobutrazol, a well-known GA biosynthesis inhibitor, greatly reduces the expression of the clone. A low level of expression was maintained in the stratification control in H(2)O, where dormancy is slowly released. These results show that this new member of the AAA-ATPase family is up-regulated by GAs and its expression correlated with the germination arise in Fagus sylvatica seeds. The possible function of this protein during the transition from dormancy to germination is discussed.

Adenosine Triphosphatases↗

PubMed2003

Three-dimensional lamina architecture alters light-harvesting efficiency in Fagus: a leaf-scale analysis.

Modification of foliage exposition and morphology by seasonal average integrated quantum flux density (Qint) was investigated in the canopies of the shade-tolerant late-successional deciduous tree species Fagus orientalis Lipsky and Fagus sylvatica L. Because the leaves were not entirely flat anywhere in the canopy, the leaf lamina was considered to be three-dimensional and characterized by the cross-sectional angle between the leaf halves (theta). Both branch and lamina inclination angles with respect to the horizontal scaled positively with irradiance in the canopy, allowing light to penetrate to deeper canopy horizons. Lamina cross-sectional angle varied from 170 degrees in the most shaded leaves to 90-100 degrees in leaves in the top of the canopy. Thus, the degree of leaf rolling increased with increasing Qint, further reducing the light-interception efficiency of the upper-canopy leaves. Simulations of the dependence of foliage light-interception efficiency on theta demonstrated that decreases in theta primarily reduce the interception efficiency of direct irradiance, but that diffuse irradiance was equally efficiently intercepted over the entire range of theta values in our study. Despite strong alteration in foliage light-harvesting capacity within the canopy and greater transmittance of the upper crown compared with the lower canopy, mean incident irradiances varied more than 20-fold within the canopy, indicating inherent limitations in light partitioning within the canopy. This extensive canopy light gradient was paralleled by plastic changes in foliar structure and chemistry. Leaf dry mass per unit area varied 3-4-fold between the canopy top and bottom, providing an important means of scaling foliage nitrogen contents and photosynthetic capacity per unit area with Qint. Although leaf structure versus light relationships were qualitatively similar in all cases, there were important tree-to-tree and species-to-species variations, as well as evidence of differences in investments in structural compounds within the leaf lamina, possibly in response to contrasting leaf water availability in different trees.

Fagus↗

PubMed2002

Phylogeographical structure revealed by chloroplast DNA variation in Japanese beech (Fagus crenata Blume).

Intraspecific genetic variation in three non-coding chloroplast DNA (cpDNA) regions (trnT-L and trnL-F spacers, and trnL intron) of Japanese beech (Fagus crenata Blume) was investigated. This species is a major constituent of the typical cool-temperate deciduous forests in Japan. Twenty-one F. crenata populations from throughout Japan, and four F. japonica populations, a close relative of F. crenata, were examined. Seven haplotypes were distinguishable in F. crenata based on nucleotide substitutions and indels. Pairwise nucleotide diversities among haplotypes ranged from 0.0000 to 0.0042 for F. crenata, including F. japonica. The geographical distribution of cpDNA haplotypes was found to be highly structured in F. crenata. Four haplotypes predominated: haplotypes FC1 and FC4 are prevalent on the Pacific Ocean coast, haplotype FC6 is prevalent on the Japan sea coast from the San-in district to Hokkaido, whilst haplotype FC3 is restricted to northern Kyushu and the western-most part of Honshu. Two haplotypes (FC5 and FC7) are restricted to single populations and one haplotype (FC2) is a derivative of FC1. Each of these haplotypes, except FC2, are thought to be derived from different glacial refugia. Phylogenetic analysis showed that neither F. crenata nor F. japonica was monophyletic for the haplotypes, suggesting either ancestral polymorphism or ancient introgression between the lineages of these two Fagus species.

DNA, Chloroplast↗

PubMed1999

Photosynthetic induction responses to variable light under field conditions in three species grown in the gap and understory of a Fagus crenata forest.

Photosynthetic induction responses to abrupt increases in photon flux density (PFD) to 800 and 1500 &mgr;mol m(-2) s(-1) from either darkness or 100 &mgr;mol m(-2) s(-1) were examined in situ in leaves of Fagus crenata Blume, Daphniphyllum humile Maxim., and Acer rufinerve Siebold & Zucc. growing in a gap and the understory of an F. crenata forest. Among the species studied, F. crenata exhibited the highest assimilation rate (A(100)), stomatal conductance (g(s100)) at the background PFD of 100 &mgr;mol m(-2) s(-1), and A(100)/A(max) (A(max) = maximum assimilation rate), in both the gap and the understory. Time required for full induction depended on both background PFD and maximum PFD. The induction period was 2-4-fold shorter at a background PFD of 100 &mgr;mol m(-2) s(-1) than in darkness. For the three understory species, time required to full induction was 2-3-fold longer when irradiance was increased from darkness to 800 &mgr;mol m(-2) s(-1) than when irradiance was increased from darkness to 1500 &mgr;mol m(-2) s(-1). Acer rufinerve showed higher initial stomatal conductance (g(s0)) and a shorter induction period in the understory than in the gap. Fagus crenata exhibited a similar g(s0) and induction period in both habitats. Daphniphyllum humile demonstrated lower g(s0) and a longer induction period in the understory than in the gap. These findings indicate that initial stomatal conductance is closely correlated with the photosynthetic induction response. We conclude that the photosynthetic induction response is affected by the light conditions experienced by plants before the sudden increase in irradiance and by the extent of the increase in irradiance.

Journal Article↗

PubMed2000

Acclimation of leaf characteristics of Fagus species to previous-year and current-year solar irradiances.

To examine the effects of different solar irradiances on leaf characteristics at the leaf primordium and expansion stages, we shaded parts of branches in the upper canopies of two adult beech trees, Fagus crenata Blume and Fagus japonica Maxim., for 4 years. The treatments during the leaf primordium and leaf expansion stages, respectively, were: (1) high light and high light (H, control), (2) high light and low light (HL), (3) low light and low light (LL), and (4) low light and high light (LH). Both number of cell layers in palisade tissue and individual leaf area were affected by the previous-year irradiance, whereas cell length of palisade tissue was larger in LH leaves than in LL leaves, suggesting determination by current-year irradiance. Lamina chlorophyll/nitrogen ratio was higher in HL and LL leaves than in LH leaves, suggesting determination by current-year irradiance. Diurnal minimum values of leaf water potential measured under sunlit conditions were lower in H and LH leaves than in HL and LL leaves. Effective osmotic adjustment was found in H and LH leaves, suggesting that leaf water relations were affected by current-year irradiance. Net photosynthetic rate and stomatal conductance measured under sunlight conditions were higher in H and LH leaves than in HL and LL leaves. Thus, effects of current-year irradiance had a greater effect on leaf-area-based daily carbon gain than previous-year irradiance.

Acclimatization↗

PubMed2002

The effect of drought on mycorrhizas of beech (Fagus sylvatica L.): changes in community structure, and the content of carbohydrates and nitrogen storage bodies of the fungi.

In a water-exclusion experiment, five different ecotypes of beech (Fagus sylvatica L.; representing regions of different environmental and climatic conditions in Baden-Württemberg, Germany) were subjected to drought conditions of different severity between July and September of two consecutive years. Drought stress as characterised by the water content and the pre-dawn water potential of the leaves was related to the degree of mycorrhization, the type of ectomycorrhiza, and the physiological properties of individual fungus/plant interactions at the fine roots of different beech ecotypes. Our data show that decreased soil water availability did not significantly change either the degree of fungal colonisation of beech roots (measured by the amount of ergosterol) or the number of ectomycorrhizal types per root system. Drought did, however, have an influence on the composition of the ectomycorrhizal community, and different mycorrhizal types responded to drought differently in terms of their patterns of occurrence/abundance. While the abundance of the dominant mycorrhizal types, formed with Byssocorticium atrovirens and Lactarius subdulcis, was not affected, drought increased the abundance of mycorrhiza formed between beech and Xerocomus chrysenteron. A detailed analysis of plant and fungal carbohydrates in mycorrhizas indicated that different drought intensities led to distinguishable responses. In plants exhibiting a pre-dawn water potential of down to -1.96 MPa, drought caused the accumulation of sucrose, glucose and fructose, and of fungus-specific compounds such as mannitol and arabitol in mycorrhizal roots at the expense of, e.g. trehalose. The accumulation of sugar alcohols, which constitute compatible solutes known to counteract drought stress, was species-specific. Mycorrhizas with X. chrysenteron formed large amounts of arabitol, while those with L. subdulcis accumulated mannitol. Sustained partitioning of carbon towards the mycorrhizal fungi under drought was also reflected by an increase of nitrogen storage in the fungal vacuoles. In treatments where the pre-dawn water potential reached values of as low as -2.4 MPa, such alterations were no longer found. In such plants, the starch and soluble sugars content was generally reduced, which also resulted in a lack of increase in protective, fungus-specific sugar alcohols. In summary, the data show that, within certain limits, an increase in drought causes a shift in plant/fungus communities. The shift in the pattern of fungus-specific compounds could possibly be used as a sensitive measure of physiological stress imposed on this symbiosis.

Carbohydrates↗

PubMed2002

Xylan deposition on secondary wall of Fagus crenata fiber.

Delignified and/or xylanase-treated secondary walls of Fagus crenata fibers were examined by field emission scanning electron microscopy. Microfibrils with a smooth surface were visible in the innermost surface of the differentiating fiber secondary wall. There was no ultrastructural difference between control and delignified sections, indicating that lignin deposition had not started in the innermost surface of the cell wall. There was no ultrastructural difference between control and xylanase-treated sections. Microfibrils on the outer part of the differentiating secondary wall surface had globular substances in delignified sections. These globular substances disappeared following xylanase treatment, indicating that these globules are xylan. The globular substances were not visible near the inner part of the differentiating secondary wall but gradually increased toward the outer part of the secondary wall, indicating that xylan penetrated into the cell wall and continuously accumulated on the microfibrils. Mature-fiber secondary walls were also examined by field emission scanning electron microscopy. Microfibrils were not apparent in the secondary wall in control specimens. Microfibrils with many globular substances were observed in the delignified specimens. Following xylanase treatment, the microfibrils had a smooth surface without any globules, indicating that the globular substance is xylan. These results suggest that cellulose microfibrils synthesized on the plasma membrane are released into the innermost surface of the secondary wall and coated with a thin layer of xylan. Successive deposition of xylan onto the cell wall increases the microfibril diameter. The large amounts of xylan that accumulated on microfibrils appear globular but are covered with lignin after they are deposited.

Cell Wall↗

PubMed2001

Effects of bulk precipitation pH and growth period on cation enrichment in precipitation beneath the canopy of a beech (Fagus moesiaca) forest stand.

The effects of bulk precipitation pH and growth period (growing and dormant) on cation enrichment beneath foliage were examined in a beech (Fagus moesiaca) forest stand during a 48-month period. The bulk precipitation pH values ranged from 4.2 to 7.2. The lowest values were observed in winter due to fossil fuel combustion in a nearby big city. The ratio of monthly ion fluxes of throughfall plus stemflow over monthly ion fluxes of bulk precipitation was chosen as an index of cation enrichment and, therefore, as the dependent variable. Bulk precipitation pH and growth period were chosen as independent factors. Precipitation interception (%) by tree canopies was also taken into account. It was found that the pH factor was significant only for H+ ion enrichment suggesting neutralization of H+ ions in the beech canopy, whereas Mg2+ and K+ enrichment were greater in the growing period, probably as a result of leaching. Crown interception was negatively significant for NH4+-N enrichment.

Acid Rain↗

PubMed2003

Water and lipid relations in beech (Fagus sylvatica L.) seeds and its effect on storage behaviour.

Beech (Fagus sylvatica L.) seeds indicate intermediate storage behaviour. Properties of water in seed tissues were studied to understand their requirements during storage conditions. Water sorption isotherms showed that at the same relative humidity (RH) the water content is significantly higher in embryo axes than cotyledons. This tendency maintains also after recalculating the water content for zero amount of lipids in tissues. Differential thermal analysis (DTA) indicated water crystallization exotherms in the embryo axes at moisture content (MC) higher than 29% and 16% in the cotyledons. In order to examine the occurrence of glassy state in the cytoplasm of beech embryos as a function of water content, isolated embryo axes were examined using electron spin resonance (ESR) of nitroxide TEMPO probe located inside axes cells. TEMPO molecules undergo fast reorientations with correlation time varied from 2 x 10(-9) s at 180 K to 2 x 10(-11) s at 315 K. Although the TEMPO molecules label mainly the lipid bilayers of cell membranes, they are sensitive to the dynamics and phase transformation of the cytoplasmic cell interior. The label motion is clearly affected by a transition between liquid and glassy state of the cytoplasm. The glass transition temperature (T(g)) raises from 253 to 293 K when water content decreases from 18% to 8%. Far from T(g) the motion is described by Arrhenius equation with very small activation energy E(a) in the liquid state and is relatively small in the glassy state where E(a)=1.5 kJ/mol for 28% H(2)O and E(a)=4.7 kJ/mol for 8% H(2)O or less. The optimal storage conditions of beech seeds are proposed in the range from 255 K for 15% H(2)O to 280 K for 9% H(2)O.

Cyclic N-Oxides↗

PubMed2002

Influence of tree internal nitrogen reserves on the response of beech (Fagus sylvatica) trees to elevated atmospheric carbon dioxide concentration.

We examined the influence of plant internal nitrogen (N) reserves on the response of 3-year-old beech (Fagus sylvatica L.) trees to elevated atmospheric CO2 concentration ([CO2]) in a dual 15N and 13C long-term labeling experiment. Trees were grown on sand and received either no N nutrition (-N treatment) or 4 mM N (+N treatment) for 1 year. The -N and +N pretreated trees were then placed in growth chambers and grown in 350 (ambient) or 700 ppm (elevated) of a 13CO2 atmosphere for 24 weeks. In all treatments, trees were supplied with 4 mM 15N during the experiment. Irrespective of tree N reserves, elevated [CO2] increased cumulative carbon (C) uptake by about 30% at Week 24 compared with that for trees in the ambient treatment. Elevated [CO2] also caused a shift in C allocation to belowground compartments, which was more pronounced in -N trees than in +N trees. In +N trees, belowground allocation of new C at Week 24 was 67% in ambient [CO2] compared with 70% in elevated [CO2]. The corresponding values for -N trees were 70 and 79%. The increase in C allocation in response to elevated [CO2] was most evident as an increase in belowground respiration; however, specific root respiration was unaffected by the CO2 or N treatments. Although elevated [CO2] increased root growth and belowground respiration, it had no effect on N uptake at Week 24. As a result of increased C uptake, N concentrations were decreased in trees in the elevated [CO2] treatment compared with trees in the ambient treatment in both N treatments. Partitioning of new N uptake was unaffected by elevated [CO2] in +N trees. In -N trees, however, N allocation to the stem decreased in response to elevated [CO2] and N allocation to fine roots increased, suggesting a reduction in the formation of N reserves in response to elevated [CO2]. We conclude that the response of beech trees to elevated [CO2] is affected by internal N status and that elevated [CO2] may influence the ability of the trees to form N reserves.

Carbon Dioxide↗

PubMed2002

Lignification in beech (Fagus sylvatica) grown at elevated CO2 concentrations: interaction with nutrient availability and leaf maturation.

Beech (Fagus sylvatica L.) seedlings were grown in an ambient or elevated CO2 concentration ([CO2]) either in small stands in microcosms for three to four seasons or individually in pots fertilized at different nutrient supply rates. Leaves at different stages of development, as well as stems and roots at the end of the growing season, were used for analysis of structural biomass and lignin. In elevated [CO2], lignification of leaves was slightly retarded compared with structural biomass production and showed a strong correlation with the activities of ionically, cell-wall-bound peroxidases but not with total soluble peroxidases or covalently wall-bound peroxidases. The effect of elevated [CO2] on lignin concentration of mature tissues was dependent on nutrient supply rate. In leaves and roots, elevated [CO2] increased the lignin concentration in dry mass in N-limited plants. In seedlings grown with high nutrient supply, the lignin concentration in dry mass was unaffected or diminished by elevated [CO2]. Because elevated [CO2] enhanced seedling growth in the high nutrient supply treatments, the total amount of lignin produced per seedling was higher in these treatments. We predict that long-term sequestration of carbon will increase as long as biomass production is stimulated by elevated [CO2] and that tissue quality will change depending on developmental stage and nutrient availability.

Biomass↗

PubMed2003

Negative regulation of abscisic acid signaling by the Fagus sylvatica FsPP2C1 plays a role in seed dormancy regulation and promotion of seed germination.

FsPP2C1 was previously isolated from beech (Fagus sylvatica) seeds as a functional protein phosphatase type-2C (PP2C) with all the conserved features of these enzymes and high homology to ABI1, ABI2, and PP2CA, PP2Cs identified as negative regulators of ABA signaling. The expression of FsPP2C1 was induced upon abscisic acid (ABA) treatment and was also up-regulated during early weeks of stratification. Furthermore, this gene was specifically expressed in ABA-treated seeds and was hardly detectable in vegetative tissues. In this report, to provide genetic evidence on FsPP2C1 function in seed dormancy and germination, we used an overexpression approach in Arabidopsis because transgenic work is not feasible in beech. Constitutive expression of FsPP2C1 under the cauliflower mosaic virus 35S promoter confers ABA insensitivity in Arabidopsis seeds and, consequently, a reduced degree of seed dormancy. Additionally, transgenic 35S:FsPP2C1 plants are able to germinate under unfavorable conditions, as inhibitory concentrations of mannitol, NaCl, or paclobutrazol. In vegetative tissues, Arabidopsis FsPP2C1 transgenic plants show ABA-resistant early root growth and diminished induction of the ABA-response genes RAB18 and KIN2, but no effect on stomatal closure regulation. Seed and vegetative phenotypes of Arabidopsis 35S:FsPP2C1 plants suggest that FsPP2C1 negatively regulates ABA signaling. The ABA inducibility of FsPP2C1 expression, together with the transcript accumulation mainly in seeds, suggest that it could play an important role modulating ABA signaling in beechnuts through a negative feedback loop. Finally, we suggest that negative regulation of ABA signaling by FsPP2C1 is a factor contributing to promote the transition from seed dormancy to germination during early weeks of stratification.

Abscisic Acid↗

PubMed2003

[Seedling establishment of Fagus engleriana, a dominant in mountain deciduous forests].

The survival and growth of Fagus engleriana seedlings in three light levels, and with and without supplying additional fertilizer (F1 and F0, respectively) for each light level were studied. The three light levels were to simulate the light regimes in the understorey, small gaps and clearings (L1, L2 and L3 about 1%, 18% and 100% of full sunlight, respectively). The seedling development in L1 was severely inhibited by low light intensity. Seedling mortality was remarkably higher in L1 than in L2 and L3, and in F1 than in F0. The death of the seedlings seemed to result from attack of fungal pathogens. Although seedling survival and growth were significantly improved as light intensities increased from L1 to L2, seedlings in L3 developed similarly as those in L2. It is suggested that the young seedlings could not tolerate the shade of closed forest canopy, and fertile patches on the forest floor might not improve seedling establishment. Successful regeneration of the species in the forests needs better light conditions such as those in gaps than those under the closed forest canopy, at least during the phase of seedling establishment.

Biomass↗

PubMed1990

Induction kinetics of delayed fluorescence of sun and shade leaves of Fagus sylvatica in the ms-range.

Induction kinetics of luminescence (= delayed chlorophyll fluorescence or delayed light emission) were measured with sun and shade leaves of a tall beech tree (Fagus sylvatica 'pendula', weeping beech). The kinetics detected in the ms-range are contrasted for the upper and the lower leaf side. The influence of the following parameters is demonstrated: time of dark-adaptation prior to the measurement, intensity of the excitation light and photoinhibitory treatment. The effects are discussed with respect to chlorophyll concentration, absorption of the excitation light, reabsorption of the luminescence and photosynthetic activity of the leaf tissue. It is shown that the luminescence signal and its kinetic are determined mainly by the properties of the mesophyll parenchyma facing the detector. Thus the more densely packed palisade parenchyma at the upper leaf side exhibits a lower luminescence and a slower kinetic than the spongy parenchyma at the lower leaf side, which is characterized by many aerial interspaces. Our study shows that luminescence kinetics can be applied to interpret the physiological state of a specific leaf tissue. They may serve as an indicator of disorders in the photosynthetic function.

Kinetics↗

PubMed1988

Exclusive accumulation of Z-isomers of monolignols and their glucosides in bark of Fagus grandifolia.

In addition to Z-coniferyl and Z-sinapyl alcohols, bark extracts of Fagus grandifolia also contain significant amounts of the glucosides, Z-coniferin, Z-isoconiferin (previously called faguside) and Z-syringin. The corresponding E-isomers of these glucosides do not accumulate to a detectable level. The accumulation of the Z-isomers suggests that either they are not lignin precursors or that they are reservoirs of monolignols for subsequent lignin biosynthesis; it is not possible to distinguish between these alternatives. The co-occurrence of Z-coniferin and Z-isoconiferin demonstrate that glucosylation of monolignols can occur at either the phenolic or the allylic hydroxyl groups.

Acetylation↗

PubMed1988

Ultrastructure in leaves of Fagus silvatica and Carpinus betulus individuals tolerant and susceptible to SO2 and heavy metal pollutants.

The ultrastructure characteristics of leaves during the development of cell organelles, in the "greening process" of spring, have been studied in pollutant-tolerant and susceptible individuals of beech (Fagus silvatica) and hornbeam (Carpinus betulus) in an area polluted with SO2 (the main pollutant may reach 0.06-2.72 mg/m3), heavy metals, and other gases discharged by non-iron metal processing factories. Leaves from tolerant beech and hornbeam individuals did not undergo ultrastructural changes compared to control leaves in an unpolluted area. The susceptible and very susceptible individuals of both species gradually undergo modification in organelle ultrastructure not only during the first steps of greening and momentary exposure to air pollution, but also as a result of long-term exposure to chronic pollution in the forest.

Air Pollutants↗

PubMed2001

Variations of wood delta(13)C for the past 50 years in declining Siebold's beech (Fagus crenata) forests.

Markedly damaged stands have been observed in Siebold's beech (Fagus crenata) forests on the Tanzawa Mountains, Japan, which are located close to densely populated and heavily industrial areas. We measured the delta(13)C records for the past 50 years (1944-1997) in wood cellulose sampled from relatively healthy trees in declining forests on Mt. Hinokiboramaru (1600 m). This may provide information on the history of stresses related to environmental changes, which have caused the decline symptoms. The results showed that, for all of the trees studied, wood delta(13)C has decreased with time. Also, the difference in delta(13)C among trees grew abruptly after the mid-1960s, which almost coincides with the time when the decline symptoms were markedly observed. Some trees with large reduction of wood delta(13)C exhibited the strong decreases in radial growth. This suggests that the reduction of tree growth may have been more greatly influenced by decreasing carboxylation rate than by stomatal limitation. It is unlikely that water stress and SO(2) and O(3) stresses have induced the growth reduction, because those stresses cause increasing wood delta(13)C. This is supported by the facts that wet conditions and relatively low SO(2) and O(3) levels have been observed near Mt. Hinokiboramaru. In addition, analyses of wood Ca showed no evidence that acid fog and soil acidification have affected the wood delta(13)C and growth through effects on the nutrient uptake of trees. However, what type of stresses have induced the large reduction of wood delta(13)C and growth for some of the trees studied remains unknown because of the lack of sufficient data for evaluation. In contrast, lesser reduction of wood delta(13)C from the other trees may be related to an increase in the plant water-use efficiency with increasing atmospheric CO(2) concentration.

Journal Article↗