We report a 1556 year-long tree-ring width chronology for the Hexi Corridor, in the arid Northwestern China,established by applying the signal-free regional curve standardization method to 416 juniper ring-width serie...We report a 1556 year-long tree-ring width chronology for the Hexi Corridor, in the arid Northwestern China,established by applying the signal-free regional curve standardization method to 416 juniper ring-width series. We found that drought in early summer(May–June) is the primary controlling factor for tree growth in this area. We then developed an early summer moisture(i.e., scPDSI) reconstruction from 455 CE to present. Our reconstruction captures multi-centennial scale moisture variations, showing two long-term dry periods during 800–950 CE and 1000–1200 CE, and two long-term wet periods during 1200–1450 CE and 1510–1620 CE. We found strong similarities between hydroclimatic changes in the Hexi Corridor and Qaidam Basin from interannual to centennial timescales; however, at multi-centennial(>300 years) timescales, hydroclimatic variations in the two regions showed significant regional differences. The Hexi Corridor witnessed a generally dry Medieval Climate Anomaly(MCA, here 800–1200 CE) and the drying 20 th century, whereas the Qaidam Basin experienced highprecipitation periods during the MCA and 20 th century. The different correlation pattern with Northern Hemisphere temperature suggest that the Qaidam Basin will receive more precipitation under global warming, whereas the Hexi Corridor will become dryer in the future.展开更多
Two tree ring-width chronologies of Sabina tibetica were developed based on cores sampled in Qumalai and Zhiduo, southern Qinghai Plateau. The response function analysis showed that the chronologies were sensitive to ...Two tree ring-width chronologies of Sabina tibetica were developed based on cores sampled in Qumalai and Zhiduo, southern Qinghai Plateau. The response function analysis showed that the chronologies were sensitive to temperature and precipitation from April to June in the plateau. Moisture index (MI) was defined, reconstructed and extended back to AD 1550. The cross-validation method was used to check the stability of the calibration equation, and the result indicated that the equation was stable. Six severe dry periods were found in this region in the past 453-year reconstruction, which were 1592 to 1610, 1649 to 1665, 1687 to 1697, 1740 to 1750, 1818 to 1829 and 1918 to 1933. Five severe wetting periods were 1669 to 1682, 1700 to 1709, 1800 to 1814, 1898 to 1909 and 1935 to 1950. Spectrum analysis indicated that there existed long-term cycles of 60.4 and 53.4 a, solar cycle of 11 a and short-term cycles of 8, 6 and 4 a in the reconstructed series.展开更多
Two robust precipitation reconstructions were conducted by combining tree-ring chronologies, dryness/wetness indices from historical documents, and climate data from the global grid. It was found that the recurrent dr...Two robust precipitation reconstructions were conducted by combining tree-ring chronologies, dryness/wetness indices from historical documents, and climate data from the global grid. It was found that the recurrent drought history of a region can help us understand the variability of precipitation. Several dry/wet periods during the past four centuries and potential cycles of precipitation variation were determined. Furthermore, the reconstructions are not only consistent well with each other in North-central China, but also in good agreement with variations of precipitation in northeastern Mongolia, the Longxi area in Gangsu Province and the Dulan area of Qinghai Province, and the snow accumulation of the Guliya glacier. These synchronous variations indicate that it is valuable to study various climate records, find common information and determine the driving force of climate change.展开更多
Aims A lack of explicit information on differential controls on net primary productivity(NPP)across regions and ecosystem types is largely responsible for uncertainties in global trajectories of terrestrial carbon bal...Aims A lack of explicit information on differential controls on net primary productivity(NPP)across regions and ecosystem types is largely responsible for uncertainties in global trajectories of terrestrial carbon balance with changing environment.The objectives of this study were to determine how NPP of different forest types would respond to inter-annual variability of climate and to examine the responses of NPP to future climate change scenarios across contrasting forest types in northern China.Methods We investigated inter-annual variations of NPP in relation to climate variability across three forest types in northern China,including a boreal forest dominated by Larix gmelinii Rupr.,and two temperate forests dominated by Pinus tabulaeformis Carr.and Quercus wutaishanica Mayr.,respectively,and studied the responses of NPP in these forests to predicted changes in climate for the periods 2011–40,2041–70 and 2070–100 under carbon emission scenarios A2 and B2 of Intergovernmental Panel on Climate Change.We simulated the responses of NPP to predicted changes in future climate as well as inter-annual variability of the present climate with the Biome-BGC version 4.2 based on site-and species-specific parameters.The modeled forest NPP data were validated against values in literature for similar types of forests and compared with inter-annual growth variations reflected by tree-ring width index(RWI)at the study sites.Important Findings Inter-annual variations in modeled NPP during the period 1960–06 were mostly consistent with the temporal patterns in RWI.There were contrasting responses of modeled NPP among the three forest types to inter-annual variability of the present climate as well as to predicted changes in future climate.The modeled NPP was positively related to annual mean air temperature in the L.gmelinii forest(P<0.001),but negatively in the P.tabulaeformis forest(P=0.05)and the Q.wutaishanica forest(P=0.03),while the relationships of modeled NPP with annual precipitation for the three forest types展开更多
Precise quantifi cation of climate-growth relationships can make a major contribution to scientifi c forest management.However,whether diff erences in the response of growth to climate at diff erent altitudes remains ...Precise quantifi cation of climate-growth relationships can make a major contribution to scientifi c forest management.However,whether diff erences in the response of growth to climate at diff erent altitudes remains unclear.To answer this,264 trees of Larix kaempferi from 88 plots,representing diff erent altitudinal ranges(1000-2100 m)and tree classes were sampled and used to develop tree-ring chronologies.Tree-ring growth(TRG)was either positively(dominant)or negatively(intermediate and suppressed)correlated with climate in diff erent tree classes at diff erent altitudes.TRG was strongly correlated with growing season at low altitudes,but was less sensitive to climate at middle altitudes.It was mainly limited by precipitation and was highly sensitive to climate at low altitudes.Climate-growth relationships at high altitudes were opposite compared to those at low altitudes.TRG of dominant trees was more sensitive to climate change compared to intermediate and suppressed trees.Climate factors(annual temperatures;moisture,the number of frost-free days)had diff erent eff ects on tree-ring growth of diff erent tree classes along altitudinal gradients.It was concluded that the increase in summer temperatures decreased water availability,resulting in a signifi cant decline in growth rates after 2005 at lower altitudes.L.kaempferi is suitable for planting in middle altitudes and dominant trees were the best sampling choice for accurately assessing climate-growth relationships.展开更多
Droughts are the most frequent natural disaster in regions at the margins of the East Asian summer monsoon(EASM),which pose threats to agriculture,the economy,and human lives.However,the limitations of only approximat...Droughts are the most frequent natural disaster in regions at the margins of the East Asian summer monsoon(EASM),which pose threats to agriculture,the economy,and human lives.However,the limitations of only approximately 60 years of meteorological observations hamper our understanding of the characteristics and mechanisms of local hydroclimate.Trees growing in the marginal region of the EASM are usually sensitive to moisture variations and have played important roles in past hydroclimatic reconstructions.Here,a 303-year tree-ring-width chronology of Pinus tabulaeformis from Mt.Lama,which is located in the junction of the Liaoning Province and Inner Mongolia,China,was used to reconstruct the May-August Palmer drought severity index(PDSI)in the marginal region of the EASM.The transfer function explains 48.0%(or 47.2%after adjusting for the loss of the degrees of freedom)of the variance over the calibration period from 1946 to 2012.A spatial correlation analysis demonstrates that our PDSI reconstruction can represent the drought variability on the northernmost margin of the EASM.The winter Asian polar vortex area index showed a delayed impact on the summer EASM precipitation in the following year.展开更多
基金supported by the National Key R & D Program of China (Grant No. 2017YFA0603302)the National Natural Science Foundation of China (Grant Nos. 41520104005, 41602192, 41325008 & 41402157)+2 种基金the Belmont Forum and JPI-Climate Collaborative Research Action ‘INTEGRATE’ (Grant No. 41661144008)the support of the Innovation Promotion Association Foundation of CASthe CAS "West Light" Program
文摘We report a 1556 year-long tree-ring width chronology for the Hexi Corridor, in the arid Northwestern China,established by applying the signal-free regional curve standardization method to 416 juniper ring-width series. We found that drought in early summer(May–June) is the primary controlling factor for tree growth in this area. We then developed an early summer moisture(i.e., scPDSI) reconstruction from 455 CE to present. Our reconstruction captures multi-centennial scale moisture variations, showing two long-term dry periods during 800–950 CE and 1000–1200 CE, and two long-term wet periods during 1200–1450 CE and 1510–1620 CE. We found strong similarities between hydroclimatic changes in the Hexi Corridor and Qaidam Basin from interannual to centennial timescales; however, at multi-centennial(>300 years) timescales, hydroclimatic variations in the two regions showed significant regional differences. The Hexi Corridor witnessed a generally dry Medieval Climate Anomaly(MCA, here 800–1200 CE) and the drying 20 th century, whereas the Qaidam Basin experienced highprecipitation periods during the MCA and 20 th century. The different correlation pattern with Northern Hemisphere temperature suggest that the Qaidam Basin will receive more precipitation under global warming, whereas the Hexi Corridor will become dryer in the future.
基金supported by the social benefits program of the Ministry of Science and Technology(Grant No.2001DIB10085)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant Nos.KZCX3-SW-321 and KZCX1-SW-04.)
文摘Two tree ring-width chronologies of Sabina tibetica were developed based on cores sampled in Qumalai and Zhiduo, southern Qinghai Plateau. The response function analysis showed that the chronologies were sensitive to temperature and precipitation from April to June in the plateau. Moisture index (MI) was defined, reconstructed and extended back to AD 1550. The cross-validation method was used to check the stability of the calibration equation, and the result indicated that the equation was stable. Six severe dry periods were found in this region in the past 453-year reconstruction, which were 1592 to 1610, 1649 to 1665, 1687 to 1697, 1740 to 1750, 1818 to 1829 and 1918 to 1933. Five severe wetting periods were 1669 to 1682, 1700 to 1709, 1800 to 1814, 1898 to 1909 and 1935 to 1950. Spectrum analysis indicated that there existed long-term cycles of 60.4 and 53.4 a, solar cycle of 11 a and short-term cycles of 8, 6 and 4 a in the reconstructed series.
基金supported by the National Natural Science Foundation of China (No. 40576035), IGCP464Chinese Offshore Investigation and Assessment (No. 908-01-ZH2)
文摘Two robust precipitation reconstructions were conducted by combining tree-ring chronologies, dryness/wetness indices from historical documents, and climate data from the global grid. It was found that the recurrent drought history of a region can help us understand the variability of precipitation. Several dry/wet periods during the past four centuries and potential cycles of precipitation variation were determined. Furthermore, the reconstructions are not only consistent well with each other in North-central China, but also in good agreement with variations of precipitation in northeastern Mongolia, the Longxi area in Gangsu Province and the Dulan area of Qinghai Province, and the snow accumulation of the Guliya glacier. These synchronous variations indicate that it is valuable to study various climate records, find common information and determine the driving force of climate change.
基金Public Welfare Forestry of the State Forestry Administration of China(201104008)Beijing Municipal Commission of Education for development of Key Laboratory for Silviculture and Conservation.
文摘Aims A lack of explicit information on differential controls on net primary productivity(NPP)across regions and ecosystem types is largely responsible for uncertainties in global trajectories of terrestrial carbon balance with changing environment.The objectives of this study were to determine how NPP of different forest types would respond to inter-annual variability of climate and to examine the responses of NPP to future climate change scenarios across contrasting forest types in northern China.Methods We investigated inter-annual variations of NPP in relation to climate variability across three forest types in northern China,including a boreal forest dominated by Larix gmelinii Rupr.,and two temperate forests dominated by Pinus tabulaeformis Carr.and Quercus wutaishanica Mayr.,respectively,and studied the responses of NPP in these forests to predicted changes in climate for the periods 2011–40,2041–70 and 2070–100 under carbon emission scenarios A2 and B2 of Intergovernmental Panel on Climate Change.We simulated the responses of NPP to predicted changes in future climate as well as inter-annual variability of the present climate with the Biome-BGC version 4.2 based on site-and species-specific parameters.The modeled forest NPP data were validated against values in literature for similar types of forests and compared with inter-annual growth variations reflected by tree-ring width index(RWI)at the study sites.Important Findings Inter-annual variations in modeled NPP during the period 1960–06 were mostly consistent with the temporal patterns in RWI.There were contrasting responses of modeled NPP among the three forest types to inter-annual variability of the present climate as well as to predicted changes in future climate.The modeled NPP was positively related to annual mean air temperature in the L.gmelinii forest(P<0.001),but negatively in the P.tabulaeformis forest(P=0.05)and the Q.wutaishanica forest(P=0.03),while the relationships of modeled NPP with annual precipitation for the three forest types
基金funded by Fundamental Research Funds of CAF (CAFYBB2022ZA00103)National Natural Science Foundation of China (General Program)(31971652)+1 种基金National Natural Science Foundation of China (32001308)Fundamental Research Funds of CAF (CAFYBB2022ZC001)
文摘Precise quantifi cation of climate-growth relationships can make a major contribution to scientifi c forest management.However,whether diff erences in the response of growth to climate at diff erent altitudes remains unclear.To answer this,264 trees of Larix kaempferi from 88 plots,representing diff erent altitudinal ranges(1000-2100 m)and tree classes were sampled and used to develop tree-ring chronologies.Tree-ring growth(TRG)was either positively(dominant)or negatively(intermediate and suppressed)correlated with climate in diff erent tree classes at diff erent altitudes.TRG was strongly correlated with growing season at low altitudes,but was less sensitive to climate at middle altitudes.It was mainly limited by precipitation and was highly sensitive to climate at low altitudes.Climate-growth relationships at high altitudes were opposite compared to those at low altitudes.TRG of dominant trees was more sensitive to climate change compared to intermediate and suppressed trees.Climate factors(annual temperatures;moisture,the number of frost-free days)had diff erent eff ects on tree-ring growth of diff erent tree classes along altitudinal gradients.It was concluded that the increase in summer temperatures decreased water availability,resulting in a signifi cant decline in growth rates after 2005 at lower altitudes.L.kaempferi is suitable for planting in middle altitudes and dominant trees were the best sampling choice for accurately assessing climate-growth relationships.
基金The Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDB40000000National Natural Science Foundation of China,No.41630531State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,CAS,No.SKLLQG2041。
文摘Droughts are the most frequent natural disaster in regions at the margins of the East Asian summer monsoon(EASM),which pose threats to agriculture,the economy,and human lives.However,the limitations of only approximately 60 years of meteorological observations hamper our understanding of the characteristics and mechanisms of local hydroclimate.Trees growing in the marginal region of the EASM are usually sensitive to moisture variations and have played important roles in past hydroclimatic reconstructions.Here,a 303-year tree-ring-width chronology of Pinus tabulaeformis from Mt.Lama,which is located in the junction of the Liaoning Province and Inner Mongolia,China,was used to reconstruct the May-August Palmer drought severity index(PDSI)in the marginal region of the EASM.The transfer function explains 48.0%(or 47.2%after adjusting for the loss of the degrees of freedom)of the variance over the calibration period from 1946 to 2012.A spatial correlation analysis demonstrates that our PDSI reconstruction can represent the drought variability on the northernmost margin of the EASM.The winter Asian polar vortex area index showed a delayed impact on the summer EASM precipitation in the following year.
