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1.
The Daxing’an Mountains is one of the areas with the most serious climate warming in northern China. Dahurian larch (Larix gmelinii) and Mongolian Scots pine (Pinus sylvestris var. mongolica) are two major coniferous species in boreal forests of the region. Their growth-climate relationship is crucial for understanding the effects of climate change on boreal forest ecosystems. To examine and compare the changes of climate-growth relationship between larch and pine, a total of 418 tree-ring cores of the two species were collected at six sites in the Daxing’an Mountains, and the tree-ring chronologies were developed. The results showed that water availability (Palmer Drought Severity Index, PDSI) played a key role in the stable growth of larch and pine. The temperature and precipitation in January, June-August are important factors affecting the radial growth of the two coniferous species along the latitude gradient. The correlation coefficients of growth and the seasonal temperature and precipitation of larch and pine showed a completely opposite trend with the increase of latitude. In summer and autumn, the correlation coefficients between larch growth and seasonal mean temperature decreased first and then increased with the increase of latitude, while that of pine, on the contrary, increased first and then decreased. In winter, spring and autumn, the correlation coefficients between larch growth and seasonal total precipitation decreased first and then increased with the increase of latitude, while that of pine was opposite. However, the correlation coefficients between larch and pine growth and PDSI showed the same trend with the increase of latitude, decreasing at first and then increasing. Before and after rapid warming (around 1980), the correlation coefficients between larch and pine growth and PDSI showed a completely opposite change. Our findings emphasize that the growth-climate relationships of Dahurian larch and Mongolian Scotts pine shows an opposite trend with latitude, which means that the two species may exhibit a completely opposite response with climate change along the latitude gradient. 相似文献
2.
During the last 25 years, the dendrochronology community has benefited from the application of stable carbon isotopes in tree rings to answer a number of research questions, which has resulted in an exponential burst in the number of publications related to this discipline. Here, we perform a literature review of the most influential topics (scope, methodology, targeted species, and climatic signals) that have shaped the research agenda and its impact on the scholarly output over the recent decades. Based on a total of 550 publications, we observed that: (1) conifers are the most investigated tree functional type, being included in over two-thirds of studies; (2) although being a subject of debate, the material of choice for carbon isotope analyses is still cellulose, for which the extraction procedure has been refined with methodological improvements over the years; (3) a shift in the application of carbon isotopes has occurred from proxies of climatic information for paleoclimatic reconstructions to tools for the understanding of short- and long-term tree functioning; and (4) such shift in research scope is apparently linked to an increasing number of publications showing drought-related signals governing isotope time series in the context of current climate change. Besides, we also assessed the number and outcome of publications analyzing 13C-derived intrinsic water-use efficiency (WUEi) trends within the framework formulated by Saurer et al. (2004). We found that leaf intercellular CO2 concentration responding proportionally to the increase in atmospheric CO2 is the most common scenario reported across continents, but with changing importance relative to other scenarios depending on the biome examined. We also detected that climate plays a dominant role over any potential CO2 fertilization linked to increasing WUEi. Looking for new and thrilling research avenues, future studies should further examine δ13C fluctuations at intra-annual resolution, explore its links to wood characteristics, and disentangle δ13C signals of the distinct wood constituents for a better understanding of tree functioning at varying spatiotemporal scales, also benchmarking vegetation models of different complexities. 相似文献
3.
Wildfires are natural and ubiquitous disturbances in boreal forests. Assessing their impacts on tree growth and resilience are particularly important to recognize the adaptation strategies of fire-tolerant species and forest succession in fire conditions. To date, the growth resilience of fire-tolerant species in boreal forests remains largely unquantified, and the drivers of resilience are poorly understood. Here, we measured the tree-ring widths of 99 fire-scarred trees from three sites in natural Dahurian larch (Larix gmelinii) forests. Three moderate-severity fire events in years 1987, 1990, and 2000 occurring at three sites were detected from the records of local forestry bureau. Based on tree-ring width data, we calculated resilience components (i.e., resistance, recovery, resilience and relative resilience) to quantify the responses of growth resilience in the larch trees to fires and analyzed their drivers at three sites. Results indicated that fires significantly reduced the tree growth. With the increasing tree age, these reductions were more pronounced. As for resilience components, our study showed a limited resistance but high recovery of tree growth against fires, and resistance tended to increase northwards but recovery showed the opposite, suggesting a growth-survival tradeoff was exhibited in Dahurian larch trees. With an increasing tree age, regional resistance and resilience showed a decreasing trend, whereas recovery and relative resilience showed an increasing trend. Resilience components were mainly affected by the climatic factors in spring. An increase in moisture availability enhanced resistance, a reduction in diurnal temperature range enhanced recovery, and an increase in mean temperature enhanced resilience and relative resilience. This study reveals that Dahurian larch could be even less favorable when faced with moderate or severe fire events, but a high capacity of recovery enables this species to adapt to the fire-prone condition. Moreover, this work highlights that the resilience of tree growth should be considered to understand tree behaviors and survival strategies of boreal forests following fires across fire-prone regions under future climate warming. 相似文献
4.
Tree ring data provide proxy records of historical hydroclimatic conditions that are widely used for reconstructing precipitation time series. Most previous applications are limited to annual time scales, though information about daily precipitation would enable a range of additional analyses of environmental processes to be investigated and modelled. We used statistical downscaling to simulate stochastic daily precipitation ensembles using dendrochronological data from the western Canadian boreal forest. The simulated precipitation series were generally consistent with observed precipitation data, though reconstructions were poorly constrained during short periods of forest pest outbreaks. The proposed multiple temporal scale precipitation reconstruction can generate annual daily maxima and persistent monthly wet and dry episodes, so that the observed and simulated ensembles have similar precipitation characteristics (i.e. magnitude, peak, and duration)—an improvement on previous modelling studies. We discuss how ecological disturbances may limit reconstructions by inducing non-linear responses in tree growth, and conclude with suggestions of possible applications and further development of downscaling methods for dendrochronological data. 相似文献
5.
Different tree species growing in the same area may have different, or even contrasting growth responses to climate change. Korean pine (Pinus koraiensis) and Mongolia oak (Quercus mongolica) are two crucial tree species in temperate forest ecosystems. Six tree-ring chronologies for Korean pine and Mongolia oak were developed by using the zero-signal method to explore their growth response to the recent climate warming in northeast China. Results showed that Mongolia oak radial growth was mainly limited by precipitation in the growing season, while Korean pine growth depended on temperature condition, especially monthly minimum temperature. With the latitude decrease, the relationships between Korean pine growth and monthly precipitation changed from negative to positive correlation, while the positive correlation with monthly temperature gradually weakened. In the contrary, Mongolia oak growth at the three sampling sites was significantly and positively correlated with precipitation in the growing season, while it was negatively correlated with temperature and this relationship decreased with the latitude decrease. The radial growth of Korean pine at different sites showed a clearly discrepant responses to the recent warming since 1980. Korean pine growth in the north site increased with the temperature increase, decreased in the midwest site, and almost unchanged in the southeast site. Conversely, Mongolia oak growth was less affected by the recent climate warming. Our finding suggested that tree species trait and sites are both key factors that affect the response of tree growth to climate change. In addition, the suitable distribution area of Korean pine may be moved northward with the continued global warming in the future, but Mongolia oak may not shift in the same way. 相似文献
6.
Recent climate warming is usually hypothesized to cause tree growth decline in the semi-arid regions where forests are particularly vulnerable to warming induced increases of water deficit. But there is still a large knowledge gap of climate warming effects on tree growth of cold temperate forest in the sub-humid region. Here we assess how climate warming has affected tree growth in the Wolong National Natural Reserve, Southwestern China, where recent warming might not cause tree growth decline because of the cold-humid climatic conditions. Tree-ring data from four co-dominant coniferous species (Larix potaninii var. macrocarpa, Tsuga chinensis, Abies faxoniana and Juniperus saltuaria) along an elevation gradient (from 2700 m to 3700 m) all imprinted temperature signals, and were both positively and significantly correlated with instrumental record of temperature data during the analyzed period of 1954–2010. Furthermore, the rising temperature since 1980 induced pervasive tree growth increases and stronger temperature signals for the coniferous species along the elevation gradient. The tree-ring chronology recorded a strong coherence with instrumental temperature since 1980 and was successful to keep up with the pace of climate warming rate. If climate warming continues, further increases in forest growth could be expected, and the terrestrial carbon sink will be strengthened for the local forest ecosystem in the future. 相似文献
7.
8.
Climate transition zone is a sensitive area of climate change and ecological transition where forests are vulnerable to climate extremes. Extreme droughts are increasing in frequency and magnitude under climate change, resulting in structure and function changes of forest ecosystems. Here, to analyze climate-growth relationships and quantify tree resilience to extreme droughts, we developed six tree-ring-width chronologies from P. tabulaeformis and P. massoniana sampling sites in Mt. Jigong region, Central China. The results indicated that all chronologies from the two species had good consistency, precipitation in current April and mean temperature in current August or mean minimum temperature from current August to October were the main limiting factors of the two tree species growth, but the responses of P. massoniana ring-width to climatic factors was more complex than that of P. tabulaeformis. The results also showed that tree growth of 1999–2005 was the lowest growing period during 1979–2018, and P. massoniana grew better than P. tabulaeformis before 2005 and vice versa after 2005. Comparing low growth years of trees, we identified to study tree growth resilience. The calculations from 1988, 1999–2005 and 2011 drought years indicated that P. tabulaeformis had more increased resilience to extreme droughts than that of P. massoniana, and the two species had stronger ecological recovery and resilience under global warming and non-extreme drought conditions in the recent 40 years. These results have implications for predicting tree resilience and identifying tree species in heterogeneous forest landscapes vulnerable to future climate change in climatic transition zone. 相似文献
9.
Himalayan Mountains provide unique opportunities for the extension of shrub-ring based dendroclimatology beyond the upper tree limit. However, little is known about limiting climate factors of shrub growth under harsh environmental conditions. We established a new ring-width chronology of a Himalayan shrub rhododendron (Rhododendron campanulatum D. Don) at the upper Krummholz treeline in the Mt. Gaurishankar massif, central Himalaya, Nepal. Bootstrapped correlation analysis showed positive relationships between radial growth and temperatures of all months from previous November to current October. Correlations were the highest with winter (December-February) minimum temperature (r = 0.781, p < 0.001), indicating that radial growth of R. campanulatum is strongly sensitive to winter minimum temperature. The linear regression model explained 61 % of the actual winter minimum temperature variance during the calibration period 1960–2013. Periods of low and high minimum winter temperatures in the central Himalaya were consistent with cool and warm episodes found by other regional winter temperature reconstructions from the Himalayas and the Tibetan Plateau. Spatial correlation analysis with land surface temperatures revealed the spatial representativeness of our reconstruction for a larger geographical territory over the Himalayas and the Tibetan Plateau. Furthermore, winter temperature in the central Himalaya is teleconnected with the December-February India-Burma trough. The persistent increasing winter temperature in recent decades in the central Himalaya coincides with continental-scale warming. Alpine vegetation in humid regions of the Himalayas may benefit from winter warming via an earlier start and extension of the growing season, as long as moisture availability is sufficient. 相似文献
10.
Oak decline, a complex process leading to increased mortality of this species, has been observed in Europe for many years. Previous studies suggest that climate conditions, especially drought, may be one of the most important factors that trigger this phenomenon. The paper investigates the radial growth and wood anatomy features of pedunculate oak (Quercus robur) trees of various health status as well as their response to climate conditions. Wood samples including all annual increments were taken at two sites (western and central Poland, 15 trees each). Based on the crown defoliation level, three health groups (healthy, weakened and dead oaks) were distinguished. Cross-sections were prepared with sliding microtome and Cell P image analysis software was used for the measurements. Tree-ring width (TRW), earlywood vessels density (VDen) and non-weighted vessels diameter (VD) were determined and correlated with mean monthly values of temperature, precipitation, vapour pressure, and Palmer Drought Severity Index (PDSI). Radial increment and anatomical parameters were significantly higher for the healthy oaks than for the weakened and the dead trees. TRW showed smaller dependence on climate than analysed anatomical attributes. No obvious pattern of relationship was found between oak radial growth and climate regarding tree health status. Our results revealed that the drought has a weak impact on the process of oak decline on investigated sites in Poland. 相似文献
11.
The increase in length and severity of drought events predicted for South-Eastern Europe are expected to engender important changes to remaining native forests. To make informed management decisions promoting their conservation, it is important to better understand their responses to climate and environmental disturbances.In this study, we analyze growth responses over a network of 15 sites of Serbian spruce (Picea omorika), an endemic relict conifer species of the Balkan region — with a natural range restricted to the canyon of the Drina river at the border between Serbia and Bosnia Herzegovina — that has already shown signs of decline and dieback likely induced by increasing temperature and drought.Tree-ring analyses spanning the common period from 1974 to 2016 have shown a strong growth reduction and highlighted an increasing negative growth response to summer drought over the last 30–40 years. The strength of the response differed among individuals and sites, where younger trees and those growing at lower altitude suffered more from drought.Management practices oriented at reducing drought impact, such as thinning to reduce competition for water resources and enhance survival of seedlings, together with assisted natural regeneration and migration to more suitable habitats, are recommended for the conservation of this relict species. The measures are even more necessary considering that this species is more vulnerable than others due to its weak capacity to naturally regenerate and compete. 相似文献
12.
The Black Death (1349–1350 in Norway) is often cited as the cause of a severe population decline and building hiatus in the middle of the 14th century. This paper analyses this hypothesis by matching the Black Death with human and environmental impacts on tree-ring growth. The number of buildings dated by dendrochronology in Norway shows a dramatic decline several decades before the plague. In Norway, the building hiatus, which has parallels in several other places in Europe, dates from the late-13th century almost to the 16th century. The first dated houses built after the plague date from the 15th century and many of the logs have exceptionally wide tree rings compared to timber from other periods. Assuming the rapid growth was because of an open landscape, the trees are likely to have grown on infields of farms abandoned due to the 14th century population decline. Since many of these fast-growing trees germinated in the early-14th century and the number of dated buildings drops dramatically several decades before the plague, the Black Death can hardly be the only reason for the population decline in Norway and one plausible explanation is that some environmental impact occurred decades earlier. The dendroclimatological evidence of cold and wet summers in the years before the plague is suggestive, but historical sources also pinpoint famine due to crop failure. They also tell of farms being abandoned several decades before the plague and mention periods of heavy rainfall and famine in the early-14th century. 相似文献
13.
Central Asia is the world’s largest non-zonal arid area, with rare and uneven precipitation. As a sensitive area of global change and with a vulnerable ecological environment, Central Asia is largely affected by global change. Various long-lived conifer species widely distributed in the mountains of Central Asia have become an important proxy for studying historical climatic, hydrological, and vegetation changes in this region. This paper reviews research progress on tree rings in Central Asia; specifically, the current state of research is addressed, highlights and bottleneck problems associated with the research are analyzed and discussed, and suggestions and prospects for further study of dendrochronology in this area are proposed. 相似文献
14.
Tree growth is affected by many exogenous and endogenous factors, especially climate and competition. To address the issue of how these factors influence tree growth under global warming, dendroclimatology combined with competition analysis was used to examine the radial growth response of two major species – Pinus massoniana and Schima superba in subtropical monsoon mixed forests in southern China. For growth-climate relationship analysis, residual and ARSTAN chronologies of these two species were compared for the response function analysis over the past several decades. In terms of competition analysis, annual basal area increment (BAI) over several time intervals was calculated and linear mixed model techniques were employed. Several distance-independent competition indices were measured, including density (N), basal area (BA), and sum of diameter at breast height (SDBH). For competition trees with greater diameter (GR) than the subject tree, NGR, BAGR, SDBHGR were also calculated. Growth-climate relationship analysis suggested that tree growth varied in response to climate and was mostly correlated with minimum, mean and maximum air temperature as indicated by the adjusted R2 value. Summer and winter temperatures had a negative effect on tree growth, while early spring temperature showed positive effects. Competition analysis suggested that subtropical trees had been affected by competition in varying degrees. Trees in the oldest forest had the most competition stress, while trees in younger forests were less affected by competition according to the adjusted R2 value. Given that subtropical forests in China have been found to have more smaller trees with recent warming, it is expected that these forests will experience a decreasing effect of competition in near future. This can have profound effects on forest productivity and carbon sequestration potentials in Chinese subtropical forests. 相似文献
15.
This study aimed to investigate the applicability of dendrochronology for assessing the growth dynamics and response to climate variability and to estimate the aboveground carbon stock and carbon sequestration potential of Vitellaria paradoxa in southern Mali. Twenty stem disks were collected from three land-use types (parklands, fallows and protected areas) in Koutiala and Yanfolila districts. We combined a standard dendrochronological approach with biomass allometric equations to estimate the growth and carbon stocks. The results showed that V. paradoxa forms distinct growth ring boundaries but most of the disks from parklands did not successfully cross-date due to management operations like pruning. The tree-ring width showed a significant standardized coefficient of regression with rainfall (r2 = 0.66, p < 0.001) but insignificant correlation with temperature. One-way analysis of variance showed no significant difference (p > 0.05) for C-sequestration as well as for carbon stocks in aboveground biomass for both land-use types and sites. Mean values of the amount of C-sequestered in Yanfolila were 0.112 ± 0.0.065 Mg C ha−1 yr−1 in parklands, 0.075 ± 0.018 Mg C ha−1 yr−1 in fallows and 0.064 ± 0.028 Mg C ha−1 yr−1 in protected areas. In Koutiala, the values were 0.068±0.020 Mg C ha−1 yr−1 in the parklands and 0.053 ± 0.017 Mg C ha−1 yr−1 in the fallows. These results clearly indicate that dendrochronology can be applied to assess growth and carbon sequestration potential of V. paradoxa. These results also suggest that climate change could affect the growth and carbon sequestration potential of V. paradoxa. Given the limited size of our sample, figures on the amount of carbon are indicative calling for applying the tested approaches to larger samples and also to other tree species in West Africa. 相似文献
16.
Abstract. Despite increasing temperatures since the end of the Little Ice Age (ca. 1850), wildfire frequency has decreased as shown in many field studies from North America and Europe. We believe that global warming since 1850 may have triggered decreases in fire frequency in some regions and future warming may even lead to further decreases in fire frequency. Simulations of present and future fire regimes, using daily outputs from the General Circulation Model (GCM), were in good agreement with recent trends observed in fire history studies. Daily data, rather than monthly data, were used because the weather and, consequently, fire behavior can change dramatically over time periods much shorter than a month. The simulation and fire history results suggest that the impact of global warming on northern forests through forest fires may not be disastrous and that, contrary to the expectation of an overall increase in forest fires, there may be large regions of the Northern Hemisphere with a reduced fire frequency. 相似文献
17.
Dagmar A. Friedrichs Valerie Trouet Ulf Büntgen David C. Frank Jan Esper Burkhard Neuwirth Jörg Löffler 《Trees - Structure and Function》2009,23(4):729-739
Growth responses to twentieth century climate variability of the three main European tree species Fagus sylvatica, Quercus petraea, and Pinus sylvestris within two temperate low mountain forest sites were analyzed, with particular emphasis on their dependence upon ecological
factors and temporal stability in the obtained relationships. While site conditions in Central (~51°N, 9°E, KEL) and West
(50.5°N, 6.5°E, EIF) Germany are similar, annual precipitation totals of ≅700 mm and ≅1,000 mm describe a maritime-continental
gradient. Ring-width samples from 228 trees were collected and PCA used to identify common growth patterns. Chronologies were
developed and redundancy analysis and simple correlation coefficients calculated to detect twentieth century temperature,
precipitation, and drought fingerprints in the tree-ring data. Summer drought is the dominant driver of forest productivity,
but regional and species-specific differences indicate more complex influences upon tree growth. F. sylvatica reveals the highest climate sensitivity, whereas Q. petraea is most drought tolerant. Drier growth conditions in KEL result in climate sensitivity of all species, and Q. petraea shifted from non-significant to significant drought sensitivity during recent decades at EIF. Drought sensitivity dynamics
of all species vary over time. An increase of drought sensitivity in tree growth was found in the wetter forest area EIF,
whereas a decrease occurred in the middle of the last century for all species in the drier KEL region. Species-specific and
regional differences in long-term climate sensitivities, as evidenced by temporal variability in drought sensitivity, are
potential indicators for a changing climate that effects Central-West German forest growth, but meanwhile hampers a general
assessment of these effects. 相似文献
18.
Climate change has profound effects on forest ecosystems. Schrenk spruce (P. schrenkiana) is a natural conifer species endemic to the arid inland areas of Asia. In this study, the relationship between tree-ring parameters of P. schrenkiana and major meteorological factors were analyzed, and the main limiting factors for tree radial growth and stable carbon isotope fractionation were explored. Our results indicate that moisture stress before and during the growing season have an important influence on radial growth of P. schrenkiana, especially, the correlation coefficient between tree-ring width and vapor pressure deficit (VPD) from previous August to current July is as high as −0.622 (n = 51, p < 0.01). Collinearity analysis further supports the conclusion that the limiting factor for the radial growth of P. schrenkiana is moisture. Although the correlation analysis results show that the tree-ring δ13Ccorr is significantly positively correlated with sunshine duration (SD), additional analysis based on first order difference variables suggests that the climate factor may not be the only limiting factor for the stable carbon isotope fractionation of tree rings in the Sayram Lake Basin. This lays the foundation for the assessment of forest management practices and carbon sink capacity in light of future climate change. 相似文献
19.
The observed northern limit of the deciduous forest formation in North America is shown to agree closely with the reported –40°C average annual minimum temperature isotherm. This indicates that supercooling as a means of resisting freezing stresses may set a physiological limit on the northern expansion of the deciduous forest formation.Abbreviation LTE=
Low Temperature Exotherm 相似文献
20.
George P. Malanson 《Population Ecology》2018,60(3):287-295
The role of intraspecific variability is being examined to improve predictions of responses to climate change or invasions and in research on diversity. Simultaneously, the probability and implications of increased high-frequency climate variability have been raised. An agent based model simulated two species on an environmental gradient representing an alpine treeline; a trend in its volatility was added. The species have different levels of variability, and each individual has further unique heterogeneity. Environmental volatility and individual heterogeneity were based on tree ring data from Pinus albicaulis. Simulations show that increasing volatility leads to population declines, including extinctions, and to sharper ecotones, and this impact is only slightly lessened by higher heterogeneity. Some simulation runs reveal an unanticipated selection for greater individual variability when volatility creates strong negative anomalies that fall short of extinction events. Increasing volatility can have significant ecological impacts because negative anomalies are not balanced by positive ones. 相似文献