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The frequency, intensity, and duration of extreme droughts, with devastating impacts on tree growth and survival, have increased with climate change over the past decades. Assessing growth resistance and resilience to drought is a crucial prerequisite for understanding the responses of forest functioning to drought events. However, the responses of growth resistance and resilience to extreme droughts with different durations across different climatic zones remain unclear. Here, we investigated the spatiotemporal patterns in growth resistance and resilience in response to extreme droughts with different durations during 1901-2015, relying on tree-ring chronologies from 2389 forest stands over the mid- and high-latitudinal Northern Hemisphere, species-specific plant functional traits, and diverse climatic factors. The findings revealed that growth resistance and resilience under 1-year droughts were higher in humid regions than in arid regions. Significant higher growth resistance was observed under 2-year droughts than under 1-year droughts in both arid and humid regions, while growth resilience did not show a significant difference. Temporally, tree growth became less resistant and resilient to 1-year droughts in 1980-2015 than in 1901-1979 in both arid and humid regions. As drought duration lengthened, the predominant impacts of climatic factors on growth resistance and resilience weakened and instead foliar economic traits, plant hydraulic traits, and soil properties became much more important in both climatic regions; in addition, such trends were also observed temporally. Finally, we found that most of the Earth system models (ESMs) used in this study overestimated growth resistance and underestimated growth resilience under both 1-year and 2-year droughts. A comprehensive ecophysiological understanding of tree growth responses to longer and intensified drought events is urgently needed, and a specific emphasis should be placed on improving the performance of ESMs.
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Sequías , Resiliencia Psicológica , Bosques , Árboles , Especificidad de la Especie , Cambio ClimáticoRESUMEN
Boreal forests are facing profound changes in their growth environment, including warming-induced water deficits, extended growing seasons, accelerated snowmelt, and permafrost thaw. The influence of warming on trees varies regionally, but in most boreal forests studied to date, tree growth has been found to be negatively affected by increasing temperatures. Here, we used a network of Pinus sylvestris tree-ring collections spanning a wide climate gradient the southern end of the boreal forest in Asia to assess their response to climate change for the period 1958-2014. Contrary to findings in other boreal regions, we found that previously negative effects of temperature on tree growth turned positive in the northern portion of the study network after the onset of rapid warming. Trees in the drier portion did not show this reversal in their climatic response during the period of rapid warming. Abundant water availability during the growing season, particularly in the early to mid-growing season (May-July), is key to the reversal of tree sensitivity to climate. Advancement in the onset of growth appears to allow trees to take advantage of snowmelt water, such that tree growth increases with increasing temperatures during the rapidly warming period. The region's monsoonal climate delivers limited precipitation during the early growing season, and thus snowmelt likely covers the water deficit so trees are less stressed from the onset of earlier growth. Our results indicate that the growth response of P. sylvestris to increasing temperatures strongly related to increased early season water availability. Hence, boreal forests with sufficient water available during crucial parts of the growing season might be more able to withstand or even increase growth during periods of rising temperatures. We suspect that other regions of the boreal forest may be affected by similar dynamics.
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Taiga , Árboles , Asia , Bosques , Estaciones del Año , AguaRESUMEN
Objective: Most patients with osteosarcoma (OS) have an extremely poor prognosis. The primary purpose of this investigation was to explore the biological effect of Lnc-CLSTN2-1:1 on OS and the potential processes involved. Materials and procedures: We selected differentially overexpressed Lnc-CLSTN2-1:1 from our laboratory's existing RNA sequence analysis data (fibroblast osteoblast (hFOB 1.19) and three osteosarcoma cell lines (HOS, MG63, and U2OS) as the research object. Next, we detected Lnc-CLSTN2-1:1 in the osteosarcoma HOS cell line and fibroblast cells using qRT-PCR. We evaluated cell proliferation ability using EdU incorporation test, CCK-8 test, and cell clone formation; cell invasion and migration were assessed using the Transwell test, while flow cytometry examined cell cycle, apoptosis, and reactive oxygen species (ROS); Subsequently, the activity changes of selenase (GPx) glutathione peroxidase and (TrxR) thioredoxin reductase were detected. In addition, changes in related proteins were analyzed through Western blotting. Results: The expression of Lnc-CLSTN2-1:1 in osteosarcoma cells was significantly increased. The proliferation, invasion, and migration of osteosarcoma cells were significantly inhibited by knockdown of the expression of Lnc-CLSTN2-1:1, and the cell cycle-related signaling pathway PI3K/AKT/GSK-3ß/cycinD1 was also inhibited. However, insulin-like growth factor-1 (igf-1) could reverse this process. In addition, we examined the activity of two selenophenases (TrxR and GPx) and the changes of ROS before and after Lnc-CLSTN2-1:1 knockdown. The results showed that both TrxR and GPx activities were reduced after Lnc-CLSTN2-1:1 knockdown, resulting in the inhibition of antioxidant stress levels, while intracellular ROS levels were high, which eventually caused killing effects on tumor cells due to the imbalance between oxidative stress and antioxidant stress. Conclusion: Our results showed that Lnc-CLSTN2-1:1 enhanced anti-oxidative stress TrxR and GPx selenoprotein activities through the PI3K/AKT signaling pathway while counteracting the loss of reactive oxygen species ROS produced by mitochondria to osteosarcoma cells, which protected osteosarcoma cells and thus promoted the proliferation and metastatic ability of OS.
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Convolutional neural networks can automatically identify tree species based on the images of structural features of tree-rings samples. In this study, we used a tree-ring image dataset for different species to achieve tree-ring based species automatic identification with high accuracy by four convolutional neural network models (LeNet, AlexNet, GoogLeNet, and VGGNet), aiming to determine the identification accuracy of the models, clarify the species misidentification during the automatic processes, and explore the identification differences among the models. The results showed that tree species identification derived from the trained convolutional neural network models was reliable, with the GoogLeNet and LeNet showed the highest (96.7%) and lowest (66.4%) identification accuracy. The tree species identifications using different models were highly consistent. Quercus mongolica and Abies nephrolepis showed the highest (100% for AlexNet) and lowest identification accuracy, respectively. Misidentification could occur among tree species with similar tree-ring structure. The identification accuracy of the models was higher at family and genus levels than that at the species level. The identification accuracy of broadleaf tree species was higher than that of coniferous trees due to distinct radial structure among broadleaf species. Overall, our method achieved a high accuracy for tree species identification, and provided a fast, convenient, and automatic tree species identification by detecting specific tree-ring properties with convolutional neural network.
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Redes Neurales de la Computación , ÁrbolesRESUMEN
Plantation ecosystems are more vulnerable than natural ones to global climate change. Using the dendrochronology method, we established tree-ring width chronologies of Pinus tabuliformis distributed in the semi-arid region of Northeast China. We examined its growth dynamics, analyzed the relationship between radical growth and climate factors, and explored the effects of global warming on the growth and distribution of P. tabuliformis. The results showed that tree-ring width chronologies of P. tabuliformis were negatively correlated with mean temperature of growing season (May-July), and positively correlated with precipitation and Palmer drought severity index (PDSI) in the early growing season (April) and in the growing season (May-July). Water availability was the main limiting factor for the radial growth of P. tabuliformis. Along the increasing precipitation gradient from southwest to northeast, tree growth became more sensitive to annual mean temperature, and the correlation with annual precipitation shifted from positive to negative, indicating that tree growth in the relative arid area (southwest of the study area) was more severely restricted by water availability. Drought stress caused by climate warming resulted in growth declines at some sites in the southwest area. With the continuous warming-drying climate, the distribution boundary of P. tabuliformis in the study area would shrink locally, with the suitable growth boundary moving northward.
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Pinus , China , Cambio Climático , Ecosistema , ÁrbolesRESUMEN
Based on the micro-core technology, we can accurately examine the tree cambium phenology and the radial growth at the cellular scale, and reveal the relationship between tree growth and climate. Pinus tabuliformis is one of the constructive species in forests of northern China. We investigated the growth pattern of P. tabuliformis in Shenyang and the changes in cambium and xylem cells throughout the growing season (April to November) in 2020. Results showed that the dividing activity in cambium started in early April and ended at the end of September. Xylem began to grow from the appearance of enlargement cells (mid April) to the end of the disappearance of lignified cells (late October), with a growth trajectory of 'S' shape curve. Approximately 53 xylem cells per row in radical direction were produced in 2020. The maximum growth rate (0.55 ind/row/day) occurred at the end of May, while the change of earlywood and latewood cells occurred at the end of July. When the minimum temperature above 0 â in Shenyang, the cambium began to divide. The minimum critical temperature that affected the beginning and ending of xylem growth was 2-3 â. Precipitation promoted the growth in the growing season. The high temperature and insufficient water supply at the end of July were the main factors driving the differentiation of xylem cells to form earlywood and latewood.
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Pinus , China , Clima , Calor , XilemaRESUMEN
The wood used for funeral utensil in ancient tomb is a kind of valuable materials and important for understanding vegetation, climate and society conditions in the history. Here, we identified the tree species and dated the time of wooden utensils for funeral excavated from tombs in Shuijia Village, Shenyang, using wood anatomy methods and dendrochronological techniques. The results showed that 7 out of the 16 wood samples were identified as Pinus tabuliformis from Pinaceae, 8 were Larix sp. from Pinaceae and most likely Larix olgensis, and the rest one was Acer sp. from Aceraceae. Currently, these tree species are still widely distributed in Liaoning Province, indicating that forest structure (tree species composition) is relatively stable and that the climate at that time was quite similar to that at present. The timbers used for wooden utensils of funeral for civilian tombs had regional biogeographic characteristics and reflected regional social productivity development level in Mukden (now Shenyang) in Qing Dynasty: most of them were native tree species with low cost and high availability; the main timber trees were conifer species, and a few of them were broadleaved trees. These timbers were likely from the forest in Shenyang or mountainous areas in Eastern Liaoning, with Hunhe River waterway being an important transport way for timbers to Shenyang. Some P. tabuliformis and Larix sp. timbers could be cross-dated well, and the growth period of the trees was determined to be 1680s-1770s (early to mid-Qing Dynasty). The variations of tree-ring width of these timbers had good consistency and high climate sensitivity, reflecting the consistency of regional climate and environment. These timbers have the potential to indicate the climate condition of the early to mid-Qing Dynasty.
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Pinus , Árboles , China , Indicadores Ambientales , BosquesRESUMEN
Long noncoding RNAs (lncRNAs) play critical roles in tumour progression and metastasis. Emerging evidence indicates that the lncRNA X inactive-specific transcript (XIST) is dysregulated in several tumor types, including non-small cell lung cancer (NSCLC). However, in NSCLC and other cancers the oncogenic mechanism of XIST remains incompletely understood. Here, we confirmed that XIST is upregulated in human NSCLC specimens, and is especially overexpressed in tumors previously treated with cisplatin (cis-diamminedichloroplatinum(II); DDP). In vitro, XIST knockdown inhibited NSCLC cell growth and promoted DDP chemosensitivity by stimulating apoptosis and pyroptosis. Moreover, XIST's oncogenic effects and ability to promote DDP chemoresistance were largely related to its binding to the TGF-ß effector SMAD2, which inhibited its translocation to the nucleus and prevented the transcription of p53 and NLRP3, crucial regulators of apoptosis and pyroptosis, respectively. Using DDP-resistant NSCLC cells, mouse xenograft studies verified the oncogenic function of XIST and its ability to inhibit programmed cell death, thereby mediating DDP chemoresistance. These findings suggest that XIST expression may serve as a novel biomarker to predict DDP treatment efficacy, and may help in the design of new therapies to circumvent DDP chemoresistance in NSCLC and other tumor types.
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Antineoplásicos/administración & dosificación , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Cisplatino/administración & dosificación , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/fisiología , ARN Largo no Codificante/metabolismo , Apoptosis , Humanos , Proteína Smad2/metabolismo , Células Tumorales CultivadasRESUMEN
Climate change has profound impacts on the structure and function of forest ecosystem. Under the background of climate warming, the growth patterns and climate responses of different species in different environments determine the development and stability of ecosystems. Using the method of tree chronology with ring width data of Betula platyphylla in Oakley Mountain of Daxing'an Mountains, we examined the relationship between the growth climate response of the pioneer B. platyphylla in larch forest and temperature rise and altitudinal changes. The results showed that climate warming resulted in the differentiation on B. platyphylla in different altitude. The radial growth of B. platyphylla increased significantly at the low altitude area (1050 m), while there were little changes at the relatively high altitude area (1250 m). Before the time of rapid warming (1980), the radial growth of B. platyphylla on two altitude areas were significantly stressed by low temperature in winter (October to February). During the period of rapid warming (1981-2010), low temperature stress in winter did not affect tree growth, with the growing season (May to July) temperature becoming the main limiting factors to the radial growth of B. platyphylla at the relatively high altitude areas. The growth of B. platyphylla increased in the low altitude stands with favorable water and heat conditions. The distribution of B. platyphylla may generally spread to high altitude sites in the study area under climate warming.
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Betula , Ecosistema , Altitud , China , Cambio Climático , Bosques , ÁrbolesRESUMEN
To investigate the effect of elevated O3 on the accumulation of main secondary metabolites in leaves of Ginkgo biloba L., four-year-old trees were exposed in open-top chambers with ambient air and the air with twice ambient O3 concentration in Shenyang in 2006. Elevated O3 increased the concentrations of terpenes, but decreased the concentrations of phenolics in G. biloba leaves. The results showed that secondary compounds from G. biloba leaves responded to the elevated O3 exposure in a different way when compared to previous studies which showed elevated O3 increased the concentrations of phenolics but had no effect on the terpenes in leaves of other deciduous trees. Furthermore, reduced synthesis of phenolics may decrease the resistance of G. biloba to O3 and other environmental factors. On the other hand, the induced synthesis of terpenes may enhance the antioxidant abilities in G. biloba leaves at the end of O3 fumigation.
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Fumigación , Ginkgo biloba/efectos de los fármacos , Ginkgo biloba/metabolismo , Ozono/farmacología , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/metabolismo , Fenoles/metabolismo , Estaciones del Año , Terpenos/metabolismo , Factores de TiempoRESUMEN
Forests are sensitive to climate change at high altitude and high latitude. Dahurian larch (Larix gmelinii Rupr.) has experienced an unprecedented forest retreat northward during the last century. Whether the response of growth to climate has dissimilar patterns at different altitudes, and what the "altitudinal trends" of forest development will be in the future, remains unclear. We dendroclimatically investigated the impacts of climate change on the growth of larch forests along an altitudinal gradient. In total, 721 trees from 25 forest stands, representing an altitudinal range from 400 to 950â¯mâ¯a.s.l. in the Great Xing'an Mountains, northeast China, were sampled and used to develop tree-ring width chronologies. The results suggest that warming caused a decline in larch growth at low altitude, while tree growth increased at high altitude. The growth-climate relationships indicate that October-February temperatures were positively correlated with larch growth at low- and high-altitude sites, but negatively correlated at medium-altitude sites (ca. 600-700â¯mâ¯a.s.l.). April-May (early spring) temperatures and October-January precipitation had positive effects on growth in general (ca. 75% of all sites). The effects of summer temperature/precipitation on larch growth at high-altitude sites were opposite to that at low-altitude sites. This change of response from significantly positive/negative correlation to significantly negative/positive correlation occurred gradually along the altitudinal gradient. The relationships varied significantly with altitude both in the case of temperature (R2â¯=â¯0.425, Pâ¯<â¯0.001) and precipitation (R2â¯=â¯0.613, Pâ¯<â¯0.001). The shift in response of larch forest to changes in summer temperature and precipitation occurred in the areas with a mean annual temperature of ca. -4⯰C and ca. -5⯰C, respectively; larch growth at temperatures lower or higher than these thresholds was limited by temperature and precipitation, respectively.
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Cambio Climático , Monitoreo del Ambiente , Bosques , Larix/fisiología , Altitud , China , Estrés FisiológicoRESUMEN
The Earth has experienced an unequivocal warming, with the warmest period of the past 150â¯years occurring in the last three decades. Korean pine (Pinus koraiensis), a key tree species in northeast Asia, is predicted to be particularly vulnerable to climate change. Here, we use dendrochronological methods to test whether the observed growth decline of Korean pine in northeast China is related to climate warming and whether climate-growth responses varied with age. A total of 628 cores from 401 trees across 16 sites were sampled over the entire distribution area of Korean pine in China. Samples were divided into three age classes: younger (50-130â¯years), middle (131-210â¯years), and older trees (>210â¯years), and measured by the ring-width index and basal area increment (BAI). Results showed a significant decline in BAI in most sites coinciding with an increase of temperature in the growing season and a decrease in precipitation since the 1980s. Meanwhile, we found that temperature-induced growth decline was significantly related to tree age. The BAI of younger trees decreased significantly and sharply (0.44â¯cm2â¯year-1, Pâ¯<â¯0.0001), while old trees either decreased slightly or stabilized (0.04â¯cm2â¯year-1, Pâ¯=â¯0.33). Tree growth in the southernmost locations was more likely to decline, what was most likely a result of forest-stand age. The age-related growth decline induced by climate warming might be explained by tree species traits, differences in growth rates between age classes and their relation to stress, changes in root system, competition/stand structure or physiological mechanisms. Our results might also predict that early stand process-thinning is exacerbated by warming and drying. This research informs that the age effect of growth response to rising temperature should be considered in forest management under climate change, and particularly models of future carbon cycle patterns and forest dynamics.
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Cambio Climático , Calor , Pinus/crecimiento & desarrollo , Lluvia , Factores de Edad , China , GeografíaRESUMEN
A measurement was made on the vertical direction tree ring stable carbon isotope ratio (delta13C) and tree ring width of Pinus sylvestris var. mongolica in northern Daxing' an Mountains of Northeast China, with the relationship between the vertical direction variations of the tree ring delta13C and tree ring width analyzed. In the whole ring of xylem, earlywood (EW) and bark endodermis, the delta13C all exhibited an increasing trend from the top to the base at first, with the maximum at the bottom of tree crown, and then, decreased rapidly to the minimum downward. The EW and late-wood (LW) had an increasing ratio of average tree ring width from the base to the top. The average annual sequence of the delta13C in vertical direction had an obvious reverse correspondence with the average annual sequence of tree ring width, and had a trend comparatively in line with the average annual sequence of the tree ring width ratio of EW to LW above tree crown. The variance analysis showed that there existed significant differences in the sequences of tree ring delta13C and ring width in vertical direction, and the magnitude of vertical delta13C variability was basically the same as that of the inter-annual delta13C variability. The year-to-year variation trend of the vertical delta13C sequence was approximately identical. For each sample, the delta13C sequence at the same heights was negatively correlated with the ring width sequence, but the statistical significance differed with tree height.
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Carbono/metabolismo , Pinus sylvestris/crecimiento & desarrollo , Tallos de la Planta/anatomía & histología , Isótopos de Carbono/análisis , China , Ecosistema , Pinus sylvestris/química , Tallos de la Planta/químicaRESUMEN
By using open-top chamber (OTC) and the techniques of dendrochronology, this paper studied the growth of Pinus armandii under elevated ozone, and explored the evolution dynamics and adaptation mechanisms of typical forest ecosystems to ozone enrichment. Elevated ozone inhibited the stem growth of P. armandii significantly, with the annual growth of the stem length and diameter reduced by 35.0% and 12.9%, respectively. The annual growth of tree-ring width and the annual ring cells number decreased by 11.5% and 54.1%, respectively, but no significant change was observed in the diameter of tracheid. At regional scale, the fluctuation of ozone concentration showed significant correlation with the variation of local vegetation growth (NDVI).
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Contaminantes Atmosféricos/farmacología , Atmósfera/análisis , Ozono/análisis , Pinus/crecimiento & desarrollo , Simulación por Computador , Ozono/farmacología , Pinus/metabolismoRESUMEN
Based on BIOME-BGC model and tree-ring data, a modeling study was conducted to estimate the dynamic changes of the net primary productivity (NPP) of Pinus tabulaeformis forest ecosystem in North China in 1952-2008, and explore the responses of the radial growth and NPP to regional climate warming as well as the dynamics of the NPP in the future climate change scenarios. The simulation results indicated the annual NPP of the P. tabulaeformis ecosystem in 1952-2008 fluctuated from 244.12 to 645.31 g C x m(-2) x a(-1), with a mean value of 418.6 g C x m(-2) x a(-1) The mean air temperature in May-June and the precipitation from previous August to current July were the main factors limiting the radial growth of P. tabulaeformis and the NPP of P. tabulaeformis ecosystem. In the study period, both the radial growth and the NPP presented a decreasing trend due to the regional warming and drying climate condition. In the future climate scenarios, the NPP would have positive responses to the increase of air temperature, precipitation, and their combination. The elevated CO2 would benefit the increase of the NPP, and the increment would be about 16.1% due to the CO2 fertilization. At both ecosystem and regional scales, the tree-ring data would be an ideal proxy to predict the ecosystem dynamic change, and could be used to validate and calibrate the process-based ecosystem models including BIOME-BGC.
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Dióxido de Carbono/análisis , Cambio Climático , Ecosistema , Pinus/fisiología , Tallos de la Planta/anatomía & histología , China , Simulación por Computador , Modelos Biológicos , Pinus/crecimiento & desarrolloRESUMEN
Based on the theory and methodology of dendrochronology, the tree ring width chronology of Pinus sylvestris var. mongolica in Mangui of Great Xing' an Mountains was developed, and the relationships between the standardized tree ring width chronology and local climate factors (temperature and precipitation) as well as the effects of climate factors on the P. sylvestris var. mongolica radial growth were analyzed. In this region, the mean monthly temperature in April-August of current year was the main factor limiting the radial growth, and the increasing mean monthly temperature from April to August had negative effects to the radial growth. The simulation of the variations of the radial growth by the mean monthly temperature change in April-August showed that the radial growth of P. sylvestris var. mongolica would present a declining trend accompanied with the warmer and drier regional climate condition.
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Cambio Climático , Ecosistema , Pinus sylvestris/crecimiento & desarrollo , Tallos de la Planta/crecimiento & desarrollo , China , Fenómenos Cronobiológicos , Conservación de los Recursos Naturales , Calentamiento Global , Tallos de la Planta/anatomía & histologíaRESUMEN
Based on the established tree-ring width chronology of Larix gmelinii in Kuduer, Great Xing' an Mountains, this paper analyzed the relationships between L. gmelinii tree-ring width chronology and related climatic variables, including air temperature, precipitation, and PDSI. In the study area, the L. gmelinii tree-ring width chronology was significantly negatively correlated with the air temperature in May and July (P<0.01), had no significant correlation with precipitation, but significantly positively correlated with the PDSI in June-August (P<0.05), suggesting that hydro-thermal variables had significant coupling effects to the radial growth of L. gmelinii in its growth season, particularly in May and July. The L. gmelinii tree-ring width chronology had significant correlations with large scale climatic regimes such as the Pacific Decadal Oscillation (PDO) in both low and high frequency variations, illustrating the significant effects of the remote oceanic climatic regimes to the local tree growth.
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Cambio Climático , Larix/anatomía & histología , Larix/crecimiento & desarrollo , Tallos de la Planta/anatomía & histología , China , Fenómenos CronobiológicosRESUMEN
An open-top chamber experiment was conducted to study the effects of high concentration O3 (80 nmol x mol(-1)) on the superoxide anion radical (O2*-) generation rate, hydrogen peroxide (H2O2) content, activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR), and ascorbic acid content in Pinus tabulaeformis leaves. Under high concentration O3 exposure, the superoxide anion radical generation rate and H2O2 and malondialdehyde (MDA) contents increased, while the ascorbic acid content and the activities of SOD, APX, DHAR, MDHAR, and GR increased in early growth season but decreased then to a level lower than the control, which illustrated that the antioxidant system of P. tabulaeformis did respond in an acclimation way in the early growth season, but could not bear the damage of long-term elevated O3 exposure.
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Ácido Ascórbico/metabolismo , Ozono/análisis , Pinus/enzimología , Superóxido Dismutasa/metabolismo , Atmósfera/análisis , China , Peroxidación de LípidoRESUMEN
Dendroclimatic methods were used to investigate the relationships between the growth of Chinese pine (Pinus tabulaeformis Carr.) and the climatic parameters in Mulan-Weichang of Hebei Province. The results showed that Chinese pine presented high sensitivity to climatic changes, and its earlywood width showed the highest sensitivity. There was a significant negative correlation between the tree-ring width chronology of Chinese pine and the air temperature in May-June. The precipitation and relative humidity in June had strong positive effects on the growth of earlywood, the precipitation from September to next September had significant positive effects on Chinese pine growth, and the relative humidity in winter more strongly affected the growth of latewood than of earlywood. There was a definite correlation between the tree-ring width chronology of Chinese pine and the large scale climate fluctuation. From 1951 to 2006, the increase of air temperature in study area was significant, and the sensitivity of Chinese pine to the variations of local temperature and precipitation decreased, presenting an inverse transforming trend with increasing temperature. Greater differences were observed between the reconstructed and observed data of mean temperature in May - June in a century scale, suggesting that the tree-ring growth of Chinese pine in study area had a greater fluctuation of sensitivity to the variation of climatic factors.
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Ecosistema , Pinus/crecimiento & desarrollo , Tallos de la Planta/crecimiento & desarrollo , Tiempo (Meteorología) , China , Humedad , Pinus/fisiología , Tallos de la Planta/anatomía & histología , Lluvia , TemperaturaRESUMEN
Taking Chinese pine in Qianshan Mountains as a sample, the tree ring width chronology including standard, residual, and Arstan chronologies was established. The results showed that the tree ring width of Chinese pine had a higher correlation with the temperature in May - July and in September - November, and significant positive correlations were observed between the tree ring width and the extreme minimum temperature in July and mean minimum temperature in September. The chronology had significant or very significant correlations with the extreme minimum temperature in December and next January, mean minimum temperature in January, annual precipitation, and the precipitation in April, May and last December. Chinese pine had stronger responses to the monthly/yearly water vapor pressure and relative humidity. The yearly and most monthly evaporation had negative effects on the growth, being most significant for the evaporation in April - July. The narrowed tree rings recorded by the chronology demonstrated the 30 times of extreme drought since 1 800. The growth of Chinese pine in Qianshan Mountains was also affected by the climate changes on global and hemisphere scales. There existed 11-, 23- and 50- year- common periodicity between the chronology and solar activity, and 10-, 20- and 45- year- common periodicity between the chronology and geomagnetic activity.