Phenology is an important indicator of climate change.Studying spatiotemporal variations in remote sensing phenology of vegetation can provide a basis for further analysis of global climate change.Based on time series...Phenology is an important indicator of climate change.Studying spatiotemporal variations in remote sensing phenology of vegetation can provide a basis for further analysis of global climate change.Based on time series data of MODIS-NDVI from 2000 to 2017,we extracted and analyzed four remote sensing phenological parameters of vegetation,including the Start of Season(SOS),the End of Season(EOS),the Middle of Season(MOS)and the Length of Season(LOS),in tundra-taiga transitional zone in the East Siberia,using asymmetric Gaussian function and dynamic threshold methods.Meanwhile,we analyzed the responses of the four phenological parameters to the temperature change based on the temperature change data from Climate Research Unit(CRU).The results show that:in regions south of 64°N,with the rise of temperature in April and May,the SOS in the corresponding area was 5-15 days ahead of schedule;in the area between 64°N and 72°N,with the rise of temperature in May and June,the SOS in the corresponding area was 10-25 days ahead of schedule;in the northernmost of the study area on the coast of the Arctic Ocean,with the drop of temperature in May and June,the SOS in the corresponding area was 15-25 days behind schedule;in the northwest of the study area in August and the southwest in September,with the drop of temperature,the EOS in the corresponding areas was 15-30 days ahead of schedule;in regions south of 67°N,with the rise of temperature in September and October,the EOS in the corresponding area was 5-30 days behind schedule;the change of the EOS in autumn was more sensitive to the change of the SOS in spring,because the smaller temperature fluctuation can cause the larger change of the EOS;the growth season of vegetation in the study area was generally moving forward,and the LOS in the northwest was shortened,while the LOS in the middle and south of the study area was prolonged.展开更多
Four wetland maps for all China have been produced,based on Landsat and CBERS-02B remote sensing data between 1978 and 2008 (1978,1990,2000 and 2008).These maps were mainly developed by manual interpretation and valid...Four wetland maps for all China have been produced,based on Landsat and CBERS-02B remote sensing data between 1978 and 2008 (1978,1990,2000 and 2008).These maps were mainly developed by manual interpretation and validated by substantial field investigation in 2009.Based on these maps,we analyzed the 2008 wetland distribution in China and discussed wetland changes and their drivers over the past 30 years.(i) There were about 324097 km 2 of wetlands in 2008,for which inland marshes or swamps were the most common wetland type (35%),with lakes (26%) second.Most of the wetlands were in Heilongjiang,Inner Mongolia,Qinghai and Tibet,occupying about 55% of the national wetland area.(ii) From 1978 to 2008,China's wetland area continually and significantly decreased,by about 33% based on changes in the wetland map.This was in sharp contrast to the increase in artificial wetlands,which increased by about 122%.Inland marshes accounted for the main loss of total wetlands from 1978 to 2000.From 2000 through 2008,riverine and lacustrine wetlands constituted the main wetland loss.Fortunately however,the rate of wetland loss decreased from 5523 to 831 km 2 /a.(iii) The change ratio of lost natural wetlands (including inland and coastal wetlands) to non-wetlands has decreased slightly over the past 30 years.From 1978 to 1990,nearly all natural wetlands (98%) lost were transformed into non-wetlands.However,the ratio declined to 86% from 1990 to 2000,and to 77% from 2000 to 2008.(iv) All Chinese provinces were divided into three groups according to patterns of wetland changes,which could relate to the driving forces of such changes.Tibet was completely different from other provinces,as it was one representative example in which there was a net wetland increase,because of global warming and decreased human activity since 1990.Increased economic development caused considerable wetland loss in most eastern provinces,and artificial wetlands increased.展开更多
Climate change and human activities are driving forces of sandy desertification and the relative role of them in sandy desertification is the hot point in related researches. A study was carried to assess the relative...Climate change and human activities are driving forces of sandy desertification and the relative role of them in sandy desertification is the hot point in related researches. A study was carried to assess the relative role of climate change and human activities in sandy desertification of Ordos region in China. Potential NPP and the difference between potential and actual NPP were selected as indicators to assess the relative role of climate change and human activities in sandy desertification, respectively. Assessing methods were built based on some scenarios for the reversion and expansion of sandy desertification and the relative role of climate change and human activities in sandy desertification of Ordos region were assessed from 1981 to 2000. The results showed that although some local places experienced an expansion of sandy desertification, the change of sandy desertification of Ordos region from 1981 to 2000 showed a stably reversing trend. The relative role of climate change and human activities in sandy desertification of Ordos region varied at different temporal and spatial scales in the reversion and expansion processes. In the reversion of sandy desertification, climate change was the dominant factor in the period of 1981 to 1990 and the reversed areas mainly induced by climate change including Mu Us sandy land and the transition zone between temperate steppe and temperate deciduous scrubs in north east of Ordos region; however, human activities controlled the reversed process during the period from 1991 to 2000 and the areas mainly induced by human activities distributed in all banners of Ordos region. In the expansion of sandy desertification, human activities were the dominant factor in the period of 1981 to 1990 and the expanded areas mainly included the regions around common boundary of Hanggin, Dalad Banners and Dongsheng City; however, climate change dominated the expansion of sandy desertification from 1991 to 2000, the expanded areas equably distributed in the whole of Ordos region except the south east of Otog Qian, Uxin and Jungar Banners.展开更多
Climate change and human activities are the two kinds of driving forces in desertification,and assessing their relative role in desertification is of great significance to deeply understanding the driving mechanisms a...Climate change and human activities are the two kinds of driving forces in desertification,and assessing their relative role in desertification is of great significance to deeply understanding the driving mechanisms and preventing desertification expansion.This paper has systematically reviewed the progress of the researches on assessing the relative role of climate change and human activities in desertification from qualitative,semi-quantitative and quantitative aspects respectively.The authors found that there were still some problems in the previous researches.For example,the subjectivity in assessment was obvious,the assessment cannot be easily repeated,and the assessment and its results were always based on administrative regions and less taken and expressed in a continuous space.According to the progress of previous researches and the works conducted by the authors recently,we put forward a quantitative approach by selecting NPP as a common indicator to measure the relative role of climate change and human activities in desertification and dividing the ecological process of "driving force effect-dynamic response of desertified land" into several scenarios.Meanwhile,validation and scale of assessment should be taken into account when quantitative assessment of the relative role of climate change and human activities in desertification are carried out.展开更多
Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we es- tablished the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven s...Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we es- tablished the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven sampling sites along the transect. We then estimated the soil wind erosion rates by using the ^(137)Cs tracing technique and examined their spatial dynamics. Our results showed that the ^(137)Cs inventories of sampling sites ranged from 265.63±44.91 to 1279.54±166.53 Bq·m^(-2), and the wind erosion rates varied from 64.58 to 419.63 t·km^(-2)·a^(-1) accordingly. In the Mongolia section of the transect (from Tariat to Sainshand), the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc., and the impact of human activities was negligible. While in the China section of the transect (Inner Mongolia), the wind erosion rates of Xilin Hot and Zhengxiangbai Banner were thrice as much as those of Bayannur of Mongolia, although these three sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these two regions of Inner Mongolia.展开更多
Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using 137Cs tracing technique, we estimated the wind erosion rates of different pastures and aband...Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using 137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km?2·a?1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm·a?1, and wind erosion rates up to 6723.06 t·km?2·a?1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not in- duce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.展开更多
Esophageal cancer exhibits one of the highest incidence and mortality rates in China. Malignant tumors caused by esophageal cancer, and the relationship to environmental factors has been the focus of many public healt...Esophageal cancer exhibits one of the highest incidence and mortality rates in China. Malignant tumors caused by esophageal cancer, and the relationship to environmental factors has been the focus of many public health studies. This study applied spatial analysis to ascertain the relationship between water pollution and esophageal cancer mortality rates nationwide. We employed two datasets, including a national investigation of esophageal cancer rates and distribution, and national water quality grades in China's primary rivers and lakes. Esophageal cancer data were grouped based on different water quality grades, which included a scaled buffer distance from rivers and lakes. Non-parametric correlation analyses were performed to examine the presence or absence of the following correlations: (i) eso- phageal cancer mortality and buffer distance from rivers and lakes; and (ii) esophageal can- cer mortality and water quality grade values. The present study revealed a significant positive correlation between widespread water pollution and esophageal cancer mortality nationwide; and a significant negative correlation between esophageal cancer mortality, and buffer dis- tance from rivers and lakes.展开更多
Using ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) infrared remote sensing data we inversed the parameters of urban surface heat fluxes applying the PCACA model and theoretical position alg...Using ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) infrared remote sensing data we inversed the parameters of urban surface heat fluxes applying the PCACA model and theoretical position algorithm, and then we analyzed the influence of different land use types on the surface heat fluxes and energy balance. In this study Kumagaya, a city in Saitama Prefecture, Japan, was selected as the experimental area. The result shows that the PCACA model is feasible for the surface heat fluxes estimation in urban areas because this model requires less parameters in the procedure of heat fluxes estimation in urban areas with complicated surface structure and can decrease the uncertainty. And we found that different land-use types have indicated the height heterogeneity on the surface heat fluxes significantly. The magnitudes of Bowen ratio in descending order are industrial, residential, transportation, institutional, dry farmland, green space, and water body. Under the same meteorological condition, there are distinct characteristics and regional differences in Bowen ratios among different surface covers, indicating higher sensible heat flux and lower latent heat flux in the urban construction land, while lower sensible heat flux and higher latent heat flux in the vegetation-covered area, the outskirt of the urban area. The increase of urban impervious surface area caused by the urban sprawl can enlarge the sensible heat flux and the Bowen ratio, so that it causes the increasing of urban surface temperature and air tem- perature, which is the mechanism of the so-called heat island effect.展开更多
基金Major Special Project-The China High-Resolution Earth Observation System,No.30-Y20A07-9003-17/18。
文摘Phenology is an important indicator of climate change.Studying spatiotemporal variations in remote sensing phenology of vegetation can provide a basis for further analysis of global climate change.Based on time series data of MODIS-NDVI from 2000 to 2017,we extracted and analyzed four remote sensing phenological parameters of vegetation,including the Start of Season(SOS),the End of Season(EOS),the Middle of Season(MOS)and the Length of Season(LOS),in tundra-taiga transitional zone in the East Siberia,using asymmetric Gaussian function and dynamic threshold methods.Meanwhile,we analyzed the responses of the four phenological parameters to the temperature change based on the temperature change data from Climate Research Unit(CRU).The results show that:in regions south of 64°N,with the rise of temperature in April and May,the SOS in the corresponding area was 5-15 days ahead of schedule;in the area between 64°N and 72°N,with the rise of temperature in May and June,the SOS in the corresponding area was 10-25 days ahead of schedule;in the northernmost of the study area on the coast of the Arctic Ocean,with the drop of temperature in May and June,the SOS in the corresponding area was 15-25 days behind schedule;in the northwest of the study area in August and the southwest in September,with the drop of temperature,the EOS in the corresponding areas was 15-30 days ahead of schedule;in regions south of 67°N,with the rise of temperature in September and October,the EOS in the corresponding area was 5-30 days behind schedule;the change of the EOS in autumn was more sensitive to the change of the SOS in spring,because the smaller temperature fluctuation can cause the larger change of the EOS;the growth season of vegetation in the study area was generally moving forward,and the LOS in the northwest was shortened,while the LOS in the middle and south of the study area was prolonged.
基金supported by the National High-tech R&D Program of China(2009AA122003)
文摘Four wetland maps for all China have been produced,based on Landsat and CBERS-02B remote sensing data between 1978 and 2008 (1978,1990,2000 and 2008).These maps were mainly developed by manual interpretation and validated by substantial field investigation in 2009.Based on these maps,we analyzed the 2008 wetland distribution in China and discussed wetland changes and their drivers over the past 30 years.(i) There were about 324097 km 2 of wetlands in 2008,for which inland marshes or swamps were the most common wetland type (35%),with lakes (26%) second.Most of the wetlands were in Heilongjiang,Inner Mongolia,Qinghai and Tibet,occupying about 55% of the national wetland area.(ii) From 1978 to 2008,China's wetland area continually and significantly decreased,by about 33% based on changes in the wetland map.This was in sharp contrast to the increase in artificial wetlands,which increased by about 122%.Inland marshes accounted for the main loss of total wetlands from 1978 to 2000.From 2000 through 2008,riverine and lacustrine wetlands constituted the main wetland loss.Fortunately however,the rate of wetland loss decreased from 5523 to 831 km 2 /a.(iii) The change ratio of lost natural wetlands (including inland and coastal wetlands) to non-wetlands has decreased slightly over the past 30 years.From 1978 to 1990,nearly all natural wetlands (98%) lost were transformed into non-wetlands.However,the ratio declined to 86% from 1990 to 2000,and to 77% from 2000 to 2008.(iv) All Chinese provinces were divided into three groups according to patterns of wetland changes,which could relate to the driving forces of such changes.Tibet was completely different from other provinces,as it was one representative example in which there was a net wetland increase,because of global warming and decreased human activity since 1990.Increased economic development caused considerable wetland loss in most eastern provinces,and artificial wetlands increased.
基金Chinese National Academic Institutional Commonweal Research Programs (Grant No. 2005DIA3J006)
文摘Climate change and human activities are driving forces of sandy desertification and the relative role of them in sandy desertification is the hot point in related researches. A study was carried to assess the relative role of climate change and human activities in sandy desertification of Ordos region in China. Potential NPP and the difference between potential and actual NPP were selected as indicators to assess the relative role of climate change and human activities in sandy desertification, respectively. Assessing methods were built based on some scenarios for the reversion and expansion of sandy desertification and the relative role of climate change and human activities in sandy desertification of Ordos region were assessed from 1981 to 2000. The results showed that although some local places experienced an expansion of sandy desertification, the change of sandy desertification of Ordos region from 1981 to 2000 showed a stably reversing trend. The relative role of climate change and human activities in sandy desertification of Ordos region varied at different temporal and spatial scales in the reversion and expansion processes. In the reversion of sandy desertification, climate change was the dominant factor in the period of 1981 to 1990 and the reversed areas mainly induced by climate change including Mu Us sandy land and the transition zone between temperate steppe and temperate deciduous scrubs in north east of Ordos region; however, human activities controlled the reversed process during the period from 1991 to 2000 and the areas mainly induced by human activities distributed in all banners of Ordos region. In the expansion of sandy desertification, human activities were the dominant factor in the period of 1981 to 1990 and the expanded areas mainly included the regions around common boundary of Hanggin, Dalad Banners and Dongsheng City; however, climate change dominated the expansion of sandy desertification from 1991 to 2000, the expanded areas equably distributed in the whole of Ordos region except the south east of Otog Qian, Uxin and Jungar Banners.
基金National Natural Science Foundation of China, No.40901054 Acknowledgement The authors would like to thank the anonymous experts for their reviewing our manuscript We are also very grateful to Wenya Li for correcting the English of this manuscript.
文摘Climate change and human activities are the two kinds of driving forces in desertification,and assessing their relative role in desertification is of great significance to deeply understanding the driving mechanisms and preventing desertification expansion.This paper has systematically reviewed the progress of the researches on assessing the relative role of climate change and human activities in desertification from qualitative,semi-quantitative and quantitative aspects respectively.The authors found that there were still some problems in the previous researches.For example,the subjectivity in assessment was obvious,the assessment cannot be easily repeated,and the assessment and its results were always based on administrative regions and less taken and expressed in a continuous space.According to the progress of previous researches and the works conducted by the authors recently,we put forward a quantitative approach by selecting NPP as a common indicator to measure the relative role of climate change and human activities in desertification and dividing the ecological process of "driving force effect-dynamic response of desertified land" into several scenarios.Meanwhile,validation and scale of assessment should be taken into account when quantitative assessment of the relative role of climate change and human activities in desertification are carried out.
基金Supported by the National Natural Science Foundation of China (Grant No. 40571130)the Key Project of International Cooperation, CAS (Grant No. GJHZ06)+1 种基金the Director Foundation of Institute of Geographic Sciences and Resources Research, CAS (Grant Nos. 06W60000SZ and 06W60001SZ)the Open Foundation of Key Laboratory of Water Cycle & Related Land Surface Processes, CAS (Grant No. WL2005001)
文摘Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we es- tablished the Tariat-Xilin Gol transect from northwest to southeast across the Mongolian Plateau, and selected seven sampling sites along the transect. We then estimated the soil wind erosion rates by using the ^(137)Cs tracing technique and examined their spatial dynamics. Our results showed that the ^(137)Cs inventories of sampling sites ranged from 265.63±44.91 to 1279.54±166.53 Bq·m^(-2), and the wind erosion rates varied from 64.58 to 419.63 t·km^(-2)·a^(-1) accordingly. In the Mongolia section of the transect (from Tariat to Sainshand), the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc., and the impact of human activities was negligible. While in the China section of the transect (Inner Mongolia), the wind erosion rates of Xilin Hot and Zhengxiangbai Banner were thrice as much as those of Bayannur of Mongolia, although these three sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these two regions of Inner Mongolia.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40571130 and 40701150)the Key Project of International Cooperation, CAS (Grant No. GJHZ06)+3 种基金the Scientific Database of CAS (Grant No. INF105-SDB-A3)the Director Foundation of Institute of Geographic Sciences and Resources Research, CAS (Grant Nos. 06W60000SZ and 06W60001SZ)the Open Foundation of Key Laboratory of Water Cycle & Related Land Surface Processes, CAS (Grant No. WL2005001)the Key Project of Natural Science Foundation of Inner Mongolia of China (Grant Nos. 200608010602)
文摘Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using 137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km?2·a?1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm·a?1, and wind erosion rates up to 6723.06 t·km?2·a?1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not in- duce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.
基金National Key Technology Research & Development Program,No.2012BAC19B10
文摘Esophageal cancer exhibits one of the highest incidence and mortality rates in China. Malignant tumors caused by esophageal cancer, and the relationship to environmental factors has been the focus of many public health studies. This study applied spatial analysis to ascertain the relationship between water pollution and esophageal cancer mortality rates nationwide. We employed two datasets, including a national investigation of esophageal cancer rates and distribution, and national water quality grades in China's primary rivers and lakes. Esophageal cancer data were grouped based on different water quality grades, which included a scaled buffer distance from rivers and lakes. Non-parametric correlation analyses were performed to examine the presence or absence of the following correlations: (i) eso- phageal cancer mortality and buffer distance from rivers and lakes; and (ii) esophageal can- cer mortality and water quality grade values. The present study revealed a significant positive correlation between widespread water pollution and esophageal cancer mortality nationwide; and a significant negative correlation between esophageal cancer mortality, and buffer dis- tance from rivers and lakes.
基金The Young Scientist Fund of National Natural Science Foundation of China, No.40901224 National Basic Research Program of China, No.2010CB950900 Open Fund of State Key Laboratory of Remote Sensing Science, No.2009KFJJ005
文摘Using ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) infrared remote sensing data we inversed the parameters of urban surface heat fluxes applying the PCACA model and theoretical position algorithm, and then we analyzed the influence of different land use types on the surface heat fluxes and energy balance. In this study Kumagaya, a city in Saitama Prefecture, Japan, was selected as the experimental area. The result shows that the PCACA model is feasible for the surface heat fluxes estimation in urban areas because this model requires less parameters in the procedure of heat fluxes estimation in urban areas with complicated surface structure and can decrease the uncertainty. And we found that different land-use types have indicated the height heterogeneity on the surface heat fluxes significantly. The magnitudes of Bowen ratio in descending order are industrial, residential, transportation, institutional, dry farmland, green space, and water body. Under the same meteorological condition, there are distinct characteristics and regional differences in Bowen ratios among different surface covers, indicating higher sensible heat flux and lower latent heat flux in the urban construction land, while lower sensible heat flux and higher latent heat flux in the vegetation-covered area, the outskirt of the urban area. The increase of urban impervious surface area caused by the urban sprawl can enlarge the sensible heat flux and the Bowen ratio, so that it causes the increasing of urban surface temperature and air tem- perature, which is the mechanism of the so-called heat island effect.