The long-term productivity of a soil is greatly influenced by cation exchange capacity（CEC）.Moreover,interactions between dominant base cations and other nutrients are important for the health and stability of grass...The long-term productivity of a soil is greatly influenced by cation exchange capacity（CEC）.Moreover,interactions between dominant base cations and other nutrients are important for the health and stability of grassland ecosystems.Soil exchangeable base cations and cation ratios were examined in a 11-year experiment with sheep manure application rates 0–1,500 g/（m2？a） in a semi-arid steppe in Inner Mongolia of China,aiming to clarify the relationships of base cations with soil p H,buffer capacity and fertility.Results showed that CEC and contents of exchangeable calcium（Ca2＋）,magnesium（Mg2＋）,potassium（K＋） and sodium（Na＋） were significantly increased,and Ca2＋ saturation tended to decrease,while K＋ saturation tended to increase with the increases of sheep manure application rates.The Ca2＋/Mg2＋ and Ca2＋/K＋ ratios decreased,while Mg2＋,K＋ and Na＋ saturations increased with increasing manure application rates.Both base cations and CEC were significantly and positively correlated with soil organic carbon（SOC） and soil p H.The increases of SOC and soil p H would be the dominant factors that contribute to the increase of cations in soil.On a comparison with the initial soil p H before the experiment,we deduced that sheep manure application could partly buffer soil p H decrease potentially induced by atmospheric deposition of nitrogen and sulfur.Our results indicate that sheep manure application is beneficial to the maintenance of base cations and the buffering of soil acidification,and therefore can improve soil fertility in the semi-arid steppes of northeastern China.展开更多
Ultraviolet（UV） radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. O...Ultraviolet（UV） radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization＇s measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.展开更多
Summary What is already known about this topic?Visceral leishmaniasis(VL)is the most serious form of leishmaniasis.In recent years,reported cases of VL have been gradually increasing in Shanxi Province,China.What is a...Summary What is already known about this topic?Visceral leishmaniasis(VL)is the most serious form of leishmaniasis.In recent years,reported cases of VL have been gradually increasing in Shanxi Province,China.What is added by this report?The report describes the epidemiology of VL from 1950 to 2019 in Shanxi Province and the recent trend of VL reemergence.What are the implications for public health practice?Measures to prevent and control VL,such as health education,improving clinical diagnostics,strengthening epidemiological investigation capacity for VL cases,monitoring surveillance,and use of other evidence-based preventive measures,should be undertaken in Shanxi Province.展开更多
Aims Remote sensing technology has been proved useful in mapping grass-land vegetation properties.Spectral features of vegetation cover can be recorded by optical sensors on board of different platforms.With increas-i...Aims Remote sensing technology has been proved useful in mapping grass-land vegetation properties.Spectral features of vegetation cover can be recorded by optical sensors on board of different platforms.With increas-ing popularity of applying unmanned aerial vehicle(UAV)to mapping plant cover,the study aims to investigate the possible applications and potential issues related to mapping leaf area index(LAI)through integra-tion of remote sensing imagery collected by multiple sensors.Methods This paper applied the collected spectral data through field-based(FLD)and UAV-borne spectroradiometer to map LAI in a Sino-German experiment pasture located in the Xilingol grassland,Inner Mongolia,China.Spectroradiometers on FLD and UAV platforms were taken to measure spectral reflectance related to the targeted vegetation proper-ties.Based on eight vegetation indices(VIs)computed from the col-lected hyperspectral data,regression models were used to inverse LAI.The spectral responses between FLD and UAV platforms were com-pared,and the regression models relating LAI with VIs from FLD and UAV were established.The modeled LAIs by UAV and FLD platforms were analyzed in order to evaluate the feasibility of potential integra-tion of spectra data for mapping vegetation from the two platforms.Important Findings Results indicated that the spectral reflectance between FLD and UAV showed critical gaps in the green and near-infrared regions of the spec-trum over densely vegetated areas,while the gaps were small over sparsely vegetated areas.The VI values from FLD spectra were greater than their UAV-based counterparts.Out of all the VIs,broadband gen-eralized soil-adjusted vegetation index(GESAVI)and narrow-band nNDVI2 were found to achieve the best results in terms of the accuracy of the inversed LAIs for both FLD and UAV platforms.We conclude that GESAVI and nNDVI2 are the two promising VIs for both platforms and thus preferred for LAI inversion to carry spectra integration of the two platforms.We suggest that accuracy on the LAI inversion could be improved by applying more advanced functions(e.g.non-linear)con-sidering the observed bias for the difference between the UAV-and FLD-inversed LAIs,especially when LAI was low.展开更多
Background:C4 plants have increased substantially during the past several decades in the grasslands of the Mongolian Plateau due to regional warming.Here,we explore how the patterns of abundances of C4 annuals and C4 ...Background:C4 plants have increased substantially during the past several decades in the grasslands of the Mongolian Plateau due to regional warming.Here,we explore how the patterns of abundances of C4 annuals and C4 perennials change over space and time.Methods:A total of 280 sites with C4 plants were surveyed in four types of grasslands in 9 years.The relative biomasses of C4 plants(PC4),C4 annuals(PA4),and C4 perennials(PP4)were calculated.Structural equation modeling was used to analyze the drivers of changes in PA4 and PP4.Results:At the regional scale,PA4 on average was 11%(±19%,SD)and PP4 was 13%(±19%,SD).Spatially,C4 annuals dominated the C4 communities within an east–west belt region along 44°N and tended to spread toward northern latitudes(about 0.5°)and higher altitudes in the east mountainous areas.The abundance of C4 annuals decreased,while that of C4 perennials increased.The patterns of C4 annuals and C4 perennials were mainly controlled by temperature,growing season precipitation,and dynamics between the two life forms.Conclusions:C4 annuals exhibited competitive advantages in normal and wet years,while C4 perennials had competitive advantages in dry years.Grazing as a main human disturbance increased C4 annuals,but had no significant effect on C4 perennials.展开更多
基金funded by the National Natural Science Foundation of China (41371251,31370009)the National Basic Research Program of China (2011CB403204)
文摘The long-term productivity of a soil is greatly influenced by cation exchange capacity（CEC）.Moreover,interactions between dominant base cations and other nutrients are important for the health and stability of grassland ecosystems.Soil exchangeable base cations and cation ratios were examined in a 11-year experiment with sheep manure application rates 0–1,500 g/（m2？a） in a semi-arid steppe in Inner Mongolia of China,aiming to clarify the relationships of base cations with soil p H,buffer capacity and fertility.Results showed that CEC and contents of exchangeable calcium（Ca2＋）,magnesium（Mg2＋）,potassium（K＋） and sodium（Na＋） were significantly increased,and Ca2＋ saturation tended to decrease,while K＋ saturation tended to increase with the increases of sheep manure application rates.The Ca2＋/Mg2＋ and Ca2＋/K＋ ratios decreased,while Mg2＋,K＋ and Na＋ saturations increased with increasing manure application rates.Both base cations and CEC were significantly and positively correlated with soil organic carbon（SOC） and soil p H.The increases of SOC and soil p H would be the dominant factors that contribute to the increase of cations in soil.On a comparison with the initial soil p H before the experiment,we deduced that sheep manure application could partly buffer soil p H decrease potentially induced by atmospheric deposition of nitrogen and sulfur.Our results indicate that sheep manure application is beneficial to the maintenance of base cations and the buffering of soil acidification,and therefore can improve soil fertility in the semi-arid steppes of northeastern China.
文摘Ultraviolet（UV） radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization＇s measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.
基金the China Mega-Project on Infectious Disease Prevention(No.2018ZX10713001).
文摘Summary What is already known about this topic?Visceral leishmaniasis(VL)is the most serious form of leishmaniasis.In recent years,reported cases of VL have been gradually increasing in Shanxi Province,China.What is added by this report?The report describes the epidemiology of VL from 1950 to 2019 in Shanxi Province and the recent trend of VL reemergence.What are the implications for public health practice?Measures to prevent and control VL,such as health education,improving clinical diagnostics,strengthening epidemiological investigation capacity for VL cases,monitoring surveillance,and use of other evidence-based preventive measures,should be undertaken in Shanxi Province.
基金Funding support for this study included the National Natural Science Foundation of China(nos.41871296,41371371 and 41501441)Open Fund of Key Laboratory of Geographic Information Science,Ministry of Education)+2 种基金East China Normal University(no.KLGIS2017A05)Hubei Provincial Natural Science Foundation of China(no.ZRMS2017000737)Large Scale Environment Remote Sensing Platform Project from Wuhan University(nos.16000009,16000011 and 16000012).
文摘Aims Remote sensing technology has been proved useful in mapping grass-land vegetation properties.Spectral features of vegetation cover can be recorded by optical sensors on board of different platforms.With increas-ing popularity of applying unmanned aerial vehicle(UAV)to mapping plant cover,the study aims to investigate the possible applications and potential issues related to mapping leaf area index(LAI)through integra-tion of remote sensing imagery collected by multiple sensors.Methods This paper applied the collected spectral data through field-based(FLD)and UAV-borne spectroradiometer to map LAI in a Sino-German experiment pasture located in the Xilingol grassland,Inner Mongolia,China.Spectroradiometers on FLD and UAV platforms were taken to measure spectral reflectance related to the targeted vegetation proper-ties.Based on eight vegetation indices(VIs)computed from the col-lected hyperspectral data,regression models were used to inverse LAI.The spectral responses between FLD and UAV platforms were com-pared,and the regression models relating LAI with VIs from FLD and UAV were established.The modeled LAIs by UAV and FLD platforms were analyzed in order to evaluate the feasibility of potential integra-tion of spectra data for mapping vegetation from the two platforms.Important Findings Results indicated that the spectral reflectance between FLD and UAV showed critical gaps in the green and near-infrared regions of the spec-trum over densely vegetated areas,while the gaps were small over sparsely vegetated areas.The VI values from FLD spectra were greater than their UAV-based counterparts.Out of all the VIs,broadband gen-eralized soil-adjusted vegetation index(GESAVI)and narrow-band nNDVI2 were found to achieve the best results in terms of the accuracy of the inversed LAIs for both FLD and UAV platforms.We conclude that GESAVI and nNDVI2 are the two promising VIs for both platforms and thus preferred for LAI inversion to carry spectra integration of the two platforms.We suggest that accuracy on the LAI inversion could be improved by applying more advanced functions(e.g.non-linear)con-sidering the observed bias for the difference between the UAV-and FLD-inversed LAIs,especially when LAI was low.
基金supported by the DFG within the DFG research group 536(MAGIM)the National Natural Science Foundation of China(31630010 and 31320103916).
文摘Background:C4 plants have increased substantially during the past several decades in the grasslands of the Mongolian Plateau due to regional warming.Here,we explore how the patterns of abundances of C4 annuals and C4 perennials change over space and time.Methods:A total of 280 sites with C4 plants were surveyed in four types of grasslands in 9 years.The relative biomasses of C4 plants(PC4),C4 annuals(PA4),and C4 perennials(PP4)were calculated.Structural equation modeling was used to analyze the drivers of changes in PA4 and PP4.Results:At the regional scale,PA4 on average was 11%(±19%,SD)and PP4 was 13%(±19%,SD).Spatially,C4 annuals dominated the C4 communities within an east–west belt region along 44°N and tended to spread toward northern latitudes(about 0.5°)and higher altitudes in the east mountainous areas.The abundance of C4 annuals decreased,while that of C4 perennials increased.The patterns of C4 annuals and C4 perennials were mainly controlled by temperature,growing season precipitation,and dynamics between the two life forms.Conclusions:C4 annuals exhibited competitive advantages in normal and wet years,while C4 perennials had competitive advantages in dry years.Grazing as a main human disturbance increased C4 annuals,but had no significant effect on C4 perennials.
