The distribution and variations of permafrost in the Xidatan region, the northern permafrost boundary of the Qinghai-Tibet Plateau, were examined and analyzed using ground penetrating radar(GPR), borehole drilling, an...The distribution and variations of permafrost in the Xidatan region, the northern permafrost boundary of the Qinghai-Tibet Plateau, were examined and analyzed using ground penetrating radar(GPR), borehole drilling, and thermal monitoring data. Results from GPR profiles together with borehole verification indicate that the lowest elevation limit of permafrost occurrence is 4369 m above sea level in 2012. Compared to previous studies, the maximal rise of permafrost limit is 28 m from 1975 to 2012. The total area of permafrost in the study region has been decreased by 13.8%. One of the two previously existed permafrost islands has disappeared and second one has reduced by 76% in area during the past ~40 years. In addition, the ground temperature in the Xidatan region has increased from 2012 to 2016, with a mean warming rate of ~0.004℃ a^(-1) and ~0.003℃ a^(-1) at the depths of 6 and 15 m, respectively. The rising of permafrost limit in the Xidatan region is mainly due to globalwarming. However, some non-climatic factors such as hydrologic processes and anthropic disturbances have also induced permafrost degradation. If the air temperature continues to increase, the northern permafrost boundary in the Qinghai-Tibet Plateau may continue rising in the future.展开更多
This study proposes an equivalent-elevation method to evaluate the integrated effects of latitude and elevation on regional and local-scale permafrost distribution in the Qinghai-Tibet Plateau,and to model the general...This study proposes an equivalent-elevation method to evaluate the integrated effects of latitude and elevation on regional and local-scale permafrost distribution in the Qinghai-Tibet Plateau,and to model the general permafrost-distribution patterns in regional and local-scale area.It is found that the Gaussian curve―an empirical model describing the relation between variations of altitudinal permafrost lower limit (PLL) and latitude in the Northern Hemisphere―could be applied in regional-and local-scale areas in the Qinghai-Tibet Plateau in a latitude-sensitive interval of 30°-50°N.The curve was then used to evaluate the latitudinal effect on permafrost distribution through transforming the latitudinal effect into a kind of altitudinal difference of PLL.This study then calculated the local equivalent-elevation value by overlaying the altitudinal difference of PLL onto real elevation at a certain location.The equivalent-elevation method was verified in an experimental subwatershed of the Qinghai-Tibet Plateau.However,feasibility of the method should be further tested in order to extend for future studies.The use of equivalent-elevation values can build a platform for comparing the regional general permafrost distribution in the plateau,and for basing further evaluations of local factors' effects on regional permafrost distribution.展开更多
In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southe...In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southern margin of the Eastern Asia latitudinal permafrost body. Under a warming climate, permafrost undergoes rapid and extensive degradation. In this study, the frost-number (Fn) model based on air temperatures and ground surface temperatures was used to predict the distribution of the Xing’an permafrost, and, temporal and spatial changes in air and ground-surface temperatures from 1961 to 2019 are analyzed. The results show that Northeast China has experienced a rapid and substantial climate warming over the past 60 years. The rises in mean annual air and mean annual ground-surface temperatures were higher in permafrost zones than those in the seasonal frost zone. The frost numbers of air and ground-surface temperatures were calculated for determining the southern limit of latitudinal permafrost and for permafrost zonation. The southern limits of discontinuous permafrost, sporadic permafrost, and latitudinal permafrost moved northward significantly. According to the air-temperature frost-number criteria for permafrost zoning, compared with that in the 1960s, the extent of Xing’an permafrost in Northeast China had decreased by 40.6% by the 2010s. With an average rate of increase in mean annual air temperatures at 0.03 ℃ a^(−1), the extent of permafrost in Northeast China will decrease to 26.42 × 10^(4) by 2020, 14.69 × 10^(4) by 2040 and to 11.24 × 10^(4) km^(2) by 2050. According to the ground-surface temperature frost-number criteria, the southern limit of latitudinal permafrost was at the 0.463. From the 1960s to the 2010s, the extent of latitudinal permafrost declined significantly. Due to the nature of the ecosystem-protected Xing’an-Baikal permafrost, management and protection (e.g., more prudent and effective forest fire management and proper logging of forests) of the Xing’an permafrost eco-environment should be strengthened.展开更多
基金supported by the National Natural Science Foundation of China (Grant no. 41601069) the State Key Program of National Natural Science of China (Grant No. 41730640)the Independent Project of the State Key Laboratory of Frozen Soils Engineering (SKLFSEZT-32 and SKLFSE-ZQ-37)
文摘The distribution and variations of permafrost in the Xidatan region, the northern permafrost boundary of the Qinghai-Tibet Plateau, were examined and analyzed using ground penetrating radar(GPR), borehole drilling, and thermal monitoring data. Results from GPR profiles together with borehole verification indicate that the lowest elevation limit of permafrost occurrence is 4369 m above sea level in 2012. Compared to previous studies, the maximal rise of permafrost limit is 28 m from 1975 to 2012. The total area of permafrost in the study region has been decreased by 13.8%. One of the two previously existed permafrost islands has disappeared and second one has reduced by 76% in area during the past ~40 years. In addition, the ground temperature in the Xidatan region has increased from 2012 to 2016, with a mean warming rate of ~0.004℃ a^(-1) and ~0.003℃ a^(-1) at the depths of 6 and 15 m, respectively. The rising of permafrost limit in the Xidatan region is mainly due to globalwarming. However, some non-climatic factors such as hydrologic processes and anthropic disturbances have also induced permafrost degradation. If the air temperature continues to increase, the northern permafrost boundary in the Qinghai-Tibet Plateau may continue rising in the future.
基金Under the auspices of Major State Basic Research Development Program of China(No.2010CB951402)National Natural Science Foundation of China(No.41101067)+1 种基金Foundation for Excellent Youth Scholars of Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences(No.Y184A91001)Research Program of State Key Laboratory of Frozen Soil Engineering of Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences(No.SKLFSE-ZQ-10)
文摘This study proposes an equivalent-elevation method to evaluate the integrated effects of latitude and elevation on regional and local-scale permafrost distribution in the Qinghai-Tibet Plateau,and to model the general permafrost-distribution patterns in regional and local-scale area.It is found that the Gaussian curve―an empirical model describing the relation between variations of altitudinal permafrost lower limit (PLL) and latitude in the Northern Hemisphere―could be applied in regional-and local-scale areas in the Qinghai-Tibet Plateau in a latitude-sensitive interval of 30°-50°N.The curve was then used to evaluate the latitudinal effect on permafrost distribution through transforming the latitudinal effect into a kind of altitudinal difference of PLL.This study then calculated the local equivalent-elevation value by overlaying the altitudinal difference of PLL onto real elevation at a certain location.The equivalent-elevation method was verified in an experimental subwatershed of the Qinghai-Tibet Plateau.However,feasibility of the method should be further tested in order to extend for future studies.The use of equivalent-elevation values can build a platform for comparing the regional general permafrost distribution in the plateau,and for basing further evaluations of local factors' effects on regional permafrost distribution.
基金The project is fully funded by the Natural Science Foundation of China Program(Grant Nos.42001052 and 41871052)Startup Research Funding of Northeast Forestry University for Chengdong Outstanding Youth Scholarship(YQ2020-10)+1 种基金Chengdong Leadership(LJ2020-01)the State Key Laboratory of Frozen Soils Engineering Open Fund Project(Grant No.SKLFSE202008).
文摘In boreal forest ecosystems, permafrost and forest types are mutually interdependent;permafrost degradation impacts forest ecosystem structure and functions. The Xing’an permafrost in Northeast China is on the southern margin of the Eastern Asia latitudinal permafrost body. Under a warming climate, permafrost undergoes rapid and extensive degradation. In this study, the frost-number (Fn) model based on air temperatures and ground surface temperatures was used to predict the distribution of the Xing’an permafrost, and, temporal and spatial changes in air and ground-surface temperatures from 1961 to 2019 are analyzed. The results show that Northeast China has experienced a rapid and substantial climate warming over the past 60 years. The rises in mean annual air and mean annual ground-surface temperatures were higher in permafrost zones than those in the seasonal frost zone. The frost numbers of air and ground-surface temperatures were calculated for determining the southern limit of latitudinal permafrost and for permafrost zonation. The southern limits of discontinuous permafrost, sporadic permafrost, and latitudinal permafrost moved northward significantly. According to the air-temperature frost-number criteria for permafrost zoning, compared with that in the 1960s, the extent of Xing’an permafrost in Northeast China had decreased by 40.6% by the 2010s. With an average rate of increase in mean annual air temperatures at 0.03 ℃ a^(−1), the extent of permafrost in Northeast China will decrease to 26.42 × 10^(4) by 2020, 14.69 × 10^(4) by 2040 and to 11.24 × 10^(4) km^(2) by 2050. According to the ground-surface temperature frost-number criteria, the southern limit of latitudinal permafrost was at the 0.463. From the 1960s to the 2010s, the extent of latitudinal permafrost declined significantly. Due to the nature of the ecosystem-protected Xing’an-Baikal permafrost, management and protection (e.g., more prudent and effective forest fire management and proper logging of forests) of the Xing’an permafrost eco-environment should be strengthened.
