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  • Orginal Article
    XU Erqi,ZHANG Hongqi,DONG Guanglong
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    Temporal changes in soil water erosion factors have not satisfactorily been considered by previous studies into water erosion estimation. To quantitatively assess the individual impact of multiple factors and their temporally and spatially combined effects on water soil erosion,we calculated the soil water erosion volume in the Yili Valley using the Revised Universal Soil Loss Equation. Temporal and spatial change in soil water erosion in the last 30 years (1985 to 2000 and 2000 to 2015)was estimated and the impact of three factors (rainfall,vegetation cover and land use)on soil erosion volume was assessed. We found that soil erosion in the study area was relatively slight. The proportion of area suffering from microerosion reached 83.99%. The areas of slight erosion and moderate erosion accounted for 11.10% and 2.60% of total erosion,respectively. In contrast,the proportion of area with severe erosion was only 2.25% and scattered in southern,middle and northern Tianshan. The area of severe soil erosion is predominately grassland with low vegetation cover. When comparing soil erosion volumes for the Yili Valley across the two time frames,soil erosion characteristics showed an overall improved but locally worsening trend. The area above the light erosion degree significantly decreased. From 1985 to 2000 to 2000 to 2015,the rainfall erosivity factor in the study area increased but the cover management factor and conservation support practice factor decreased. This indicates a negatively combined impact of temporal and spatial change on soil erosion in the Yili Valley. Soil water erosion in the Yili Valley has improved from the first period (1985 to 2000)to the second period (2000 to 2015).

  • Orginal Article
    ZHU Chenggang,LI Weihong,LI Dalong,LIU Zhiming,FU Lei
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    The large scale exploitation of water and land resources in the Yili River Valley in recent decades is the background for this work. The exploitation has mainly been concentrated in the piedmont slope of the valley and this may have affected soil properties and erodibility. Research on soil properties and erodibility can help conduct better prospection of land resources,and develop effective soil and water conservation measures. We selected the piedmont slope of the valley as the research focus and conducted an investigation based on field surveys,sampling and experimental analysis. A typical area of piedmont slope with 400km2 and 127 survey points was selected in order to obtain soil properties. Experience estimation formula of the EPIC model was used to get soil erodibility. This work analyzes the soil properties and soil erodibility under different land use patterns,tests the relationship between soil erodibility and each soil characteristic factor,and analyzes the spatial heterogeneity of soil properties and soil erodibility. We found that newly reclaimed fields increased soil water content,improved soil properties and structure,to some extent,and contributed to reducing soil erodibility. Soil N content and soil organic materials show an obvious decline in newly reclaimed fields than circumjacent uncultured areas. From southwest to northeast the soil becomes better with increasing altitude,such as lower soil bulk density,higher soil organic materials and N,and higher soil water content;soil erodibility is gradually declining. There is a close relationship between soil physicochemical properties and soil erodibility. The spatial heterogeneity of most soil properties,including soil erodibility,is low and at a relatively small scale. The degrees of autocorrelation of the spatial distribution of soil properties are middle to high.

  • Orginal Article
    SUN Guojun,LI Weihong,ZHU Chenggang,YAN Yuhai,WANG Fei
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    Bulk density is one of the basic physical properties of soil and a core indictor of soil degradation. It is important to study spatial variation for preventing soil erosion. Here,we used traditional statistics,GIS technology and spatial interpolation of Ordinary Kriging to analyze spatial variation of topsoil (0 to 20 cm) bulk density in the Yili River Valley. The results showed that the distribution of topsoil bulk density is normal and a K-S single sample test showed that kurtosis is 0.14 and skewness is 0.15. The range of topsoil bulk density was 1.01 to 1.50g/cm3,the average value was 1.25g/cm3;the variation coefficient was 7.6% and indicates weak variation. Semi variance function of topsoil soil bulk density indicated that the nugget was 0.0056;the sill was 0.0083;and the nugget effect was 32.5%,that is to say,the spatial structures of topsoil bulk density are isotropic. Trend analysis of topsoil bulk density indicated that the topsoil bulk density was gradually reduced from south to north and also from west to east. Spatial interpolation of Ordinary Kriging indicated that the distribution of the topsoil bulk density was strip shaped from south to north,and patch shaped from east to west. The internal natural factors of topsoil bulk density were climate (such as temperature and precipitation),soil parent material (such as organic matter and mineral elements),changes in land use (such as conversion of grassland to farm land and transformation into garden and wood land)and these accelerated changes in topsoil bulk density.

  • Orginal Article
    SHANG Erping,ZHANG Hongqi
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    Yili Valley is one of the most active area of grassland ecosystem in China. The assessment of Carbon (C) stock and dynamics is crucial for the sustainable utilization of grassland ecosystems. Based on measured data,the Carbon module of the InVEST model was used to evaluate C stocks including above C,below C,dead C and soil organic C and their changes in different grasslands for Yili Valley in the 1980s,2000s and 2010s. We found that the C stock of grasslands in Yili Valley increased from the 1980s to 2000s but decreased from the 2000s to 2010s. C stock in the 1980s,2000s and 2010s was 32.61TgC,39.67TgC,and 25.92TgC,respectively. The C density (C stock per area)was 9.76tC/hm2,12.26tC/hm2,and 8.45tC/hm2,respectively. The carbon density of grassland was mainly in the below carbon density and soil carbon density,and both of them were (7.49~10.35)tC/ hm2,accounting for 84%~89% of grassland carbon density. The carbon storage of different types of grassland was significantly different. The carbon storage is high in typical meadow and typical steppe,which accounted for 53%~60% of grassland C stock;the lowest was desert steppe which accounted for 4%~5% of grassland C stock. The C stock of different grassland has been affected by vegetation type,climate,land use change and grazing activities.

  • Orginal Article
    CUI Dong,LI Weihong,ZHU Chenggang,YANG Yuhai,SUN Guojun
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    Soil organic carbon content from 0 to 60 cm and available nitrogen,available phosphorus,rapidly-available potassium,sucrase,urease and catalase was determined under different land use types in the Yili river Valley. Profile distribution characteristics of soil organic carbon,physical and chemical properties and intrinsic link were analyzed. The results show that organic carbon content,available nitrogen,available phosphorus and available potassium,sucrase,urease and catalase content decreased with increasing soil depth. The carbon content of grassland was higher than cultivated land,garden and forest land. The content of available N in cultivated land was higher than garden,woodland and grassland. The content of available potassium was higher than forest,farmland and grassland. The content of available phosphorus in garden was higher than cultivated land,woodland and grassland. Soil invertase,urease and catalase activity in forest were higher than in cultivated land,grassland and garden. The correlation between organic carbon and available N,available P,available K,and the activity of invertase was significant. The correlation between organic carbon and available N,available P,urease activity and catalase activity was significant. The content of organic carbon in grassland was significantly correlated with available nitrogen,available potassium,available phosphorus and two enzymes (invertase activity and urease activity). The correlation between organic carbon in forest land and available potassium,urease activity and catalase activity was significant.

  • Orginal Article
    XU Yongmei,LIU Hua,WANG Xihe
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    With a cropping area of 1.76 million hectares, grey desert soil(hapliccalcisol)is crucial for agricultural development in Xinjiang in northwest China. The objective of our experiment was to study the effect of different fertilization on carbon sequestration based on a long-term experiment station of grey desert soil. There were six treatments:no fertilization,chemical fertilization,chemical fertilization plus manure and chemical fertilization plus straw returned to the soil(CK,NP,NPK,NPKM,hNPKM,NPKS). The characteristics of soil organic carbon (SOC)sequestration in surface(0~20cm)and subsurface(20~40cm)layers of desert soil were studied from 1989-2011. We found that the SOC stock was improved under all treatments including no fertilizer,chemical fertilizer,and manure fertilizer plots. The SOC stock was elevated by(4.0~43.7)tC/hm2 in the surface layer and(9.0~49.5)tC/hm2 in the subsurface layer. The SOC stock differed across time periods among plots. The SOC stock decreased during the first 5 years and increased slightly during the latter 18 years in the no fertilizer plot. This indicates that the SOC can be sequestrated in relative low fertility soil even with no fertilizer application in arable land. This result also implies that the effect of management on SOC stock can be illustrated based on long term experimentation. SOC stock under the manure plot was increased by 32.1%~152.7% compared with the no fertilizer and chemical only plots. Take into consideration of the layered soil bulk density and quality of soil carbon reserves calculation method can evaluate the carbon sequestration of straw returned objectively.

  • Orginal Article
    JIAO Limin,DONG Ting,GU Yanyan
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    China is experiencing rapid urbanization and land urbanization and population urbanization have led to urban land sprawl and low-efficiency land use. Analysis of urban spatial resilience and regional differences is of significance for urban spatial planning in China. During urban development,changes in urban construction land area and population cause changes in urban population density over time,reflecting change in urban spatial resilience. We selected 263 cities at the prefecture level and above,and used total population at the year-end and urban construction land area to calculate population density,to calculate the rate of change in density using indicators rank scoring methods to determine urban spatial resilience indicators. We found that all cities can be divided into higher spatial resilience,high spatial resilience,medium spatial resilience,less spatial resilience and low spatial resilience using the natural breaks classification method. Urban spatial resilience decreases from east to west and the highest proportion of higher spatial resilience cities are in eastern China. In central China,high and medium spatial resilience cities are found at a higher proportion. In western China,cities of medium and lower spatial resilience are more common. Along with the urban development,China’s urban population density reduced but urban spatial resilience increased,particularly 2000 to 2006. From the five urban agglomerations in China it is clear that economically developed areas have higher spatial resilience,but the cores of urban agglomerations have medium or low spatial resilience. The application of urban spatial resilience analysis can assist in the design and definition of urban growth boundaries in China.

  • Orginal Article
    ZOU Yafeng,LV Changhe,ZHOU Yu,YANG Rui
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    Potential estimation is important to rural residential land consolidation and critical to its planning. Previous work has focused on how to estimate consolidation potential accurately,but research has ignored the control of overall land use planning. Here,we classified rural residential land as rural urbanization and non-urbanization under the regulation of overall land use planning at the town level. For non-urbanization we constructed an evaluation index system for comprehensive influence in terms of three aspects(spatial layout suitability,production and living facilities accessibility,and rural residential land activity) and evaluated the comprehensive influence of rural residential areas. Based on that,and combined with relevant provisions of township land use planning,we divided rural residential land non-urbanization into internal transformation,optimization in place and village relocation and combination. We estimated land consolidation potential using the Type method,that is,according to different consolidation types we respectively constructed the relevant potential estimation model of land consolidation,Volume Ratio Method for rural urbanization,Idle Land Ratio Method for internal transformation,and Per Capita Construction Land Use based on the Household Willingness Method for village relocation and combination. Xiaohe Town in Yicheng City was our case study and we found a release potential of 117.83hm2 through consolidation by 2020. The research will initiate new ideas for estimating land consolidation potential in rural residential areas.

  • Orginal Article
    WU Chunsheng,LIU Gaohuan,HUANG Chong,LIU Qingsheng,GUAN Xudong
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    The Yellow River Delta has abundant land resources,however,because of long-term exposure to harsh natural conditions and improper human activity,the soil has degenerated and affected agricultural development and ecological protection. This study selected multiple physical and chemical indicators and principal component analysis to construct a minimum data set to determine indicators for soil quality assessment in the Yellow River Delta. Fuzzy Logic Model was used to finish the soil quality assessment and we analyzed the spatial distribution of main land use types across different soil quality grades. The results show that the minimum data set include six soil indices:TN,AP,AK,soil organic matter,all salt and pH. The assessment result maps for soil index values all showed spatial distribution regularities,soil salt content reduced gradually from coasts to inland,and TN and AP had the opposite characteristics. AK and pH showed an even distribution around the study area and soil organic matter content was high in the central area and reduced gradually to the edges. The soil quality value was higher in inland than coastal areas,most of the study area was of a level 3 grade according to the classifications of integrated fertility indexes for fluvo-aquic soils in China. Most farmland,forest and garden had high-class soil,but some were still distributed among level 5 or level 6 and lots of unused land had high soil levels,indicating that land resources in the study area have not been planned appropriately.

  • Orginal Article
    GAO Yan,ZHAO Zhenbin
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    Taking Langmusi in central China as a focal area,we conducted semi-structured interviews guided by photos with 396 people (Tibetan=102,Hui=96,tourists=99,and foreign operators=99. With the help of qualitative analysis software NVivo10.0,we analyzed interview content and divided the place into 11 categories (natural sights,Buddhist temples,burial place,Masjid,accommodation locations,village,street and road,legend site,work place,home and school)and established eight main classes (local characteristics,spirituality,group relation,emotion and experience,history and culture,environment adaption,tourism contact and negative perception)and 39 sub-classes on place meaning. We found that natural sights,Buddhist temples,burial place,Masjid and villages are the most important places. Local characteristics,spirituality, group relation and emotion and experience constitute the body of interviewees’ place meaning. Using the correspondence analysis method,we found different emphases on the representation of place meaning for Langmusi. Local residents(Tibetan and Hui)form their sense of place based on religion and community life while outsiders (tourists and operators)form their sense of place mainly on original culture and livelihood. Local residents focus more on Buddhist temples and spirituality,outsiders focus more on burial place and local characteristics,representing competitive relations for place meaning between outsiders (e.g. tourists) and locals (e.g. Tibetans). The competition over local significance reflects the gambling on local power among people,is the impetus for changing Langmusi’s local identity,and offers a way for us to learn about complex social phenomenon during tourism development. The construction of place meaning provides effective help in understanding local conflict,and provides effective approaches to solve contradictions within the national tourism community.

  • Orginal Article
    TANG Chengcai,ZHAO Zongqian,LIU Han,ZHOU Shaorui
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    Due to the special border location,natural landscape,atmosphere,and a variety of cultural integration,China’s borders are a strong attraction for tourists. Border tourism has become a major component of China’s tourism market. Beijing is one of the three traditional tourist origins with strong residential travel capacity. Based on tourism destination choice theory,experimental economics,human geography,PPT scene simulation,personalized custom and depth interview methods we let visitors make combinations of border tourism elements according to willingness and determined the factors affecting border city tourism. The border areas included Dandong,Kashi,Manzhouli,Chongzuo and Xishuangbanna. We found that 38.71% of respondents selected the China-Myanmar bilateral cooperation tourism circle with Xishuangbanna at its core,and 22.58% chose the China-Vietnam bilateral cooperation tourism circle (e.g. Chongzuo). A rich variety of natural ecological landscapes and cultures are the most attractive resources of border cities,and sample percentages are respectively up 51.61% and 41.94%. Sex,occupational income and age all affected the border tourism choices. Beginning with personalized customization and targeting of gender,occupational income and age,we analyze some useful tourism marketing pathways for border city tourism. These results will enrich the theory of border city tourism and destination selection method systems,and provide scientific guidance when marketing China’s border cities.

  • Orginal Article
    ZHANG Chenjun,ZHANG Hengquan,CHEN Qiyong,ZHANG Wanli
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    The LMDI method was used to decompose the factors influencing water use in China into a population effect,regional population distribution effect,regional economic development effect,regional industrial structure effect and regional technical progress effect. We found that technical progress and industrial structural adjustment are two factors inhibiting the increase in water use,especially technical progress. Industrial structural effect of primary industry is the most significant factor in all provinces,but technical progress effect varies across provinces. Economic growth is the main impulse for rising water use which can be seen as the most manifested phenomenon in medium regions. An extended population promotes water use,however little effect working out;population distribution(folw) develops water use in China. Changes in regional economic share exert great influence on decreasing water use,but there is a significant difference between provinces. The rise of the economic share of the eastern region promotes increasing water consumption and proper measures should be taken to solve this unbalanced situation. Provinces should cement water-saving technical innovation and put high value on agricultural water saving. The country should optimize and upgrade industrial structure,transferring agriculture that consumes large sums of water to secondary and tertiary industries with relatively low water use. The eastern region needs to reinforce the financial and technical support towards the lesser developed central and western regions.

  • Orginal Article
    WU Dan
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    Based on water conservancy development for river basins in China and abroad,this study analyzed the interaction mechanism between socio-economic development and water conservancy development in river basins,and the main factors that influence water conservancy development. The article set clear objectives for socio-economic development and water conservancy development,and designs an evaluation index system for water conservancy development in river basins across four dimensions:water resource utilization,water environment protection,water ecological restoration and water disaster prevention. Combined with the weighted composite index method,TOPSIS model and coordinative degree evaluation method,a dynamic evaluation model of water conservancy development in river basins is developed. An empirical analysis was done of the evaluation of the Huaihe River basin in order to analyze dynamic trends in the evaluation index of water conservancy development and the coordinative development degree among regions in this basin in 2000 to 2010. Results illustrate that the index of water conservancy development among four provinces improved from 2000 to 2010. For the growth rate of the index,Jiangsu province has the fastest growth rate,then Shandong,Henan,and Anhui. For the level of water conservancy development in the Huaihe River basin,the highest is Jiangsu,then Shandong,Henan,and Anhui.

  • Orginal Article
    GAI Mei,WU Huige,QU Benliang
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    Water footprint from the perspective of consumption has established the water resource utilization and human consumption patterns,it measures water resources system of human occupied directly and it is one of the most effective indicators to measure the impact of human life and production activities on the water resources ecological environment system currently. Based on panel date for water footprints of 14 cities in Liaoning province from 2004 to 2013. We then established the water resources utilization absolute and relative efficiency of every city in using stochastic frontier analysis,date envelopment analysis modeling,the Gini coefficient and variable coefficient. We found that the difference reduced and converged for water resource utilization efficiency. The water resource utilization absolute and relative efficiency of Shenyang,Dalian,Anshan and Panjin are on a higher level,while Fuxin and Chaoyang are the lowest. The characteristic of geographical location is distributed across the central inland to southern coastal region and spreads east and west,gradually diminishing in entirety. The water resources utilization relative efficiency of Liaoning is in state of a gradual increase,the gap in water resource utilization absolute efficiency of every city is shrinking. Using cluster analysis to study the spatial-temporal differentiation of water resource utilization efficiency,based on the spatial weighting matrix,we found spatial autocorrelation of water resources utilization efficiency. High-high correlation pattern areas are mainly distributed at the economic level in relatively developed cities in Liaoning,such as Dalian,Anshan,Panjin and other regions. Low-low correlation pattern areas tended to be less developed cities,such as Fuxin,Chaoyang and Huludao. High-low and low-high correlation pattern areas occur between high-high and low-low correlation pattern areas. Enhancing the water resource utilization efficiency of low-low correlation pattern areas will promote the water resource utilization efficiency of surrounding areas,and this is conducive to increasing the overall water resource utilization efficiency across Liaoning.

  • Orginal Article
    LV Mingyuan,CHEN Weixuan
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    The difference in the contribution of industrial structural upgrading to energy efficiency needs to be studied from the structural evolution direction as different directions have different influences on energy efficiency. We decomposed the structural evolution direction into two dimensions of industrial structure rationalization and industrial structure optimization,rebuilt the industrial structural upgrading evaluation index on the basis of factor productivity of labor and capital,and analyzed the effects of industrial structural upgrading on energy efficiency and its growth rate using regular,growth and elastic models. We found that the industrial structural evolution direction has a significant influence on energy efficiency and its growth rate;the improvement in energy efficiency is mainly because of optimization of industrial structure,while a decrease in rationalization level inhibits improvements in energy efficiency and its growth rate. The expansion of the gap between the two directions of industrial structural rationalization and industrial structural optimization is likely to lead to further negative effects to energy efficiency and its growth rate. The rise in the proportion of clean energy in energy consumption structure has a positive effect on improving energy efficiency and its growth rate. Therefore,we believe that the future trend of industrial policy should be to change the status of irrational industrial structure,reduce its inhibitory effect on energy efficiency,and narrow the gap between industrial structural rationalization and optimization. The tendency of future energy policy should improve the proportion of clean energy consumption and substitute energy inputs from natural and other clean energy sources to promote energy efficiency and its growth.

  • Orginal Article
    DING Zhenmin,HUANG Xiujuan
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    Reasonable capital input is key to optimizing the allocation of forest resources and promote tourism efficiency of forest parks. In order to study capital input effects on the tourism efficiency of forest parks in China,a two-stage analysis model of efficiency calculation and influencing factors of tourism efficiency based on efficiency calculation methods was established for forest parks in 31 provinces using data from 2008 to 2014. The study found a nonlinear and inverted U-shaped relationship between capital structure (proportion of state-owned capital investment) and tourism efficiency of forest parks,which means that the state-owned capital investment proportion in a reasonable range will have positive effects on the tourism efficiency of forest parks,while capital of other forms has a positive effect after the proportion exceeding the threshold. Total capital investment is redundant and the output elasticity of capital is relatively small compared to the elasticity of staff and the whole tourism industry,indicating that it is short of efficiency in use of the funds for construction and operation. The capital performs a time-lag effect whiling transforming the process of developing forest tourism. These factors are the main reasons for the decline in tourism efficiency of forest parks in China. Regional development level,traffic conditions and density of forest parks have a significant positive impact on the tourism efficiency of forest parks. The tourism efficiency of forest parks is best in southwest China. It is necessary to optimize capital structures and determine a reasonable scale of investment capital to gradually improve the tourism efficiency of forest resources in China.

  • Orginal Article
    CHEN Jie,JIAO Jianling,LI Fangyi,LI Lanlan
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    Sectors’ CO2 emissions is one of the largest drivers of accelerated global warming and China needs to urgently face this environmental issue. The mitigating order of sector and development countermeasures are significant for mitigating CO2 emissions. Promoting industrial structural upgrades and environmental technology are two important approaches currently used by China to mitigate greenhouse gas emissions. Here,from the aspects of structural adjustment and technological progress,a general framework for the mitigating order of sector and development countermeasures was innovated to mitigate CO2 emissions and release environmental pressures. This study was based on the Ghosh input-output model and sensitivity analysis. We analyzed all sectors in China and combined them into 40 sectors,adopted an input-output table for 2002 and 2012,and CO2 emission data. In order to better control growth in CO2 emission from sectors we analyzed five typical sector indicators. We found that technological progress should be preferentially carried out in 18 sectors(including nonmetal mineral products) to reduce emissions;13 sectors (including oil and gas extraction),should limit development speed because this would have a large effect on emissions and low economic impact. We arrived at four countermeasures. On the one hand,further applied research has proven the practicality and scientificity of this general method;and on the other hand it provides a solid foundation for government and reference of emission reduction policies to adjust industrial structure,develop environmental technology and reduce carbon emissions. The method here is applicable to many countries and regions that want to achieve a low carbon economy.

  • Orginal Article
    HE Lingyun,YANG Xuejie,YIN Fang,ZHONG Zhangqi
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    Based on the analysis of the influence of energy price and resource tax on carbon emissions,we used regulatory models and ridge regression to estimate and compare the reduction effect of energy price and resource tax on carbon emissions from 2001 to 2013. We compressed energy price and resource tax as a comprehensive variable,considered the transmission process of ‘resource tax to energy price’,and then estimated the comprehensive emission reduction effect of these two levers. The dynamic effect of the two levers and the effectiveness of related policies of regulation were then analyzed. We found that through the economic aggregate (economic structure and energy efficiency path) both of the levers can lead to carbon emission reductions;however,the effect is small and 0.1162 and 0.0869,respectively. In contrast,the effect of energy price is higher than that of resource tax. The comprehensive effect of the two levers through structure and efficiency is 0.0359 and 0.2779 respectively,which is higher than that of a single lever;furthermore,the effect of the price lever through structure and efficiency is 0.0237 and 0.2246,respectively,which is 0.2061 and 0.200 for resource tax. The effect of efficiency is more significant than structure. In comparison,the structural path is more effective for energy price and the efficiency path is more effective for resource tax. The carbon emission reduction effect of the two levers is dynamic and greatly influenced by related polices. Since the implementation of policies is influenced by many factors and there is a time lag effect,emission reduction effects of related levers may be insignificant. Emission reduction is a systematic project and requires coordination among different policy tools.

  • Orginal Article
    ZHANG Dan,ZHANG Weifeng
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    Sustainable agriculture that increases production,improves soil productivity and reduces pollution is a hot topic in China. It is therefore necessary to evaluate carbon footprints with a Life Cycle Assessment method for low carbon agricultural practice innovation,carbon trading and carbon labels. We reviewed 22 published results for emission from rice,wheat and maize production and found that reliable approaches to quantify the carbon footprint remain vague. This has resulted in a large degree of uncertainty about the intensity of carbon footprints,even on the same crop. For example,the amount of carbon footprints of rice production ranged from 1895kgce/hm2 (ce i.e. CO2 equal)to 11 811kgce/hm2. Both positive and negative values for net emissions of wheat and maize production were obtained from previous papers. This suggests that wheat and maize production can result in carbon sequestration and carbon emissions depending on different evaluation approaches. Different system boundaries,greenhouse gas categories,approaches for data collection and units of carbon footprint could explain uncertainty. We develop a concept model to quantify carbon footprints of crop production using Life Cycle Assessment. The carbon footprint consists of three components:(1)production of agriculture inputs,such as chemical fertilizer,pesticides and so on;(2)grain production in fields;and(3)soil carbon sequestration due to grain production. The carbon emission factors include direct emission factors of CO2,CH4 and N2O and indirect emission factors of ammonia volatilization and nitrate leaching. The key emission factors were derived from big data measured at different sites and our model can quantify emissions at different scales in different regions.