Collection and arrangement of the historical records of climatic changes andenvironment evolution, especially in the aspect of calamities, are made on the history documents ofpast 1500 years about Hai'an region, J...Collection and arrangement of the historical records of climatic changes andenvironment evolution, especially in the aspect of calamities, are made on the history documents ofpast 1500 years about Hai'an region, Jiangsu Province. There existed two obvious flooding-droughtfrequently-occurring periods: one was from 1550 AD to 1850 AD and another was 1000 AD to 1200 AD.The period of 1550 AD to 1850 AD is interrupted by two relatively arid and cold climatic periods:one was from 1630 AD to 1700 AD and another was 1750 AD to 1820 AD. The main characteristic of thecalamity periods is that they occurred by turns, and sometimes, both drought and flooding occurredin the same year. The instability of the climatic changes in the Little Ice Age may be the mainreason of the frequently-occurring flooding and drought in Hai'an region. Research results also showthat the frequently-occurring periods of flooding and drought is in close relationship with thesolar activity, and therefore, occurrence of the flooding and drought may be in relation with theintensity of the solar activity. This hypothesis may need further study in the future.展开更多
Abstract：The carbon isotopic composition （δ13C） of tree rings was used to assess changes in intrinsic water-use efficiency （Wi） to increasing atmospheric CO2 and climate change during the period of 1891–2003. F...Abstract：The carbon isotopic composition （δ13C） of tree rings was used to assess changes in intrinsic water-use efficiency （Wi） to increasing atmospheric CO2 and climate change during the period of 1891–2003. Five Qinghai spruce （Picea crassifolia） stands were selected in the Qilian Mountains, growing along a precipitation gradient. All five δ13C were correlated to each other, but two sites （DDS and CLS）, which are far from the main body of the mountains, show relative weak connections to other sites. Although trees at all sites had improved their Wi in response to increasing atmospheric CO2 concentration, spruce growing in the regions far away from the main body of the mountains were less sensitive to improved Wi than those of other sites. Based on the correlation between carbon isotope discrimination （Δ） and Palmer Drought Severity Index （PDSI）, the drought history covering the period of 1891–2003 was reconstructed in the study region. The two most severe drought epochs of the late 1920s and the last decade were caused by reduced precipitation and climate warming, respectively. Our results will be useful in assessing any further spatial climate-related bioclimatic information.展开更多
文摘Collection and arrangement of the historical records of climatic changes andenvironment evolution, especially in the aspect of calamities, are made on the history documents ofpast 1500 years about Hai'an region, Jiangsu Province. There existed two obvious flooding-droughtfrequently-occurring periods: one was from 1550 AD to 1850 AD and another was 1000 AD to 1200 AD.The period of 1550 AD to 1850 AD is interrupted by two relatively arid and cold climatic periods:one was from 1630 AD to 1700 AD and another was 1750 AD to 1820 AD. The main characteristic of thecalamity periods is that they occurred by turns, and sometimes, both drought and flooding occurredin the same year. The instability of the climatic changes in the Little Ice Age may be the mainreason of the frequently-occurring flooding and drought in Hai'an region. Research results also showthat the frequently-occurring periods of flooding and drought is in close relationship with thesolar activity, and therefore, occurrence of the flooding and drought may be in relation with theintensity of the solar activity. This hypothesis may need further study in the future.
基金supported by the Natural Science foundation in China (Grant No. 40871002,40501076)the Knowledge Innovation Project of the Chinese Academy Sciences (KZCX2-YW-QN308)the Self-determination Project of State Key Laboratory of Cryospheric Sciences (SKLCS09-03)
文摘Abstract：The carbon isotopic composition （δ13C） of tree rings was used to assess changes in intrinsic water-use efficiency （Wi） to increasing atmospheric CO2 and climate change during the period of 1891–2003. Five Qinghai spruce （Picea crassifolia） stands were selected in the Qilian Mountains, growing along a precipitation gradient. All five δ13C were correlated to each other, but two sites （DDS and CLS）, which are far from the main body of the mountains, show relative weak connections to other sites. Although trees at all sites had improved their Wi in response to increasing atmospheric CO2 concentration, spruce growing in the regions far away from the main body of the mountains were less sensitive to improved Wi than those of other sites. Based on the correlation between carbon isotope discrimination （Δ） and Palmer Drought Severity Index （PDSI）, the drought history covering the period of 1891–2003 was reconstructed in the study region. The two most severe drought epochs of the late 1920s and the last decade were caused by reduced precipitation and climate warming, respectively. Our results will be useful in assessing any further spatial climate-related bioclimatic information.
