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关于实行“两田”经营责任制的探讨
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作者 李勇 胡大银 《农村经济》 北大核心 1990年第3期26-28,共3页
一、现状和问题以家庭经营为主的联产承包责任制,是适应目前我国大多数地区农业生产力发展水平的,具有旺盛的生命力。但是也暴露了一些弊端:1.在土地承包上,实行的是一种“均田制”,不分劳弱劳强和专业优势,按人头平均承包,带来了四个不... 一、现状和问题以家庭经营为主的联产承包责任制,是适应目前我国大多数地区农业生产力发展水平的,具有旺盛的生命力。但是也暴露了一些弊端:1.在土地承包上,实行的是一种“均田制”,不分劳弱劳强和专业优势,按人头平均承包,带来了四个不利:一是不利于充分发挥劳力和地势实现人尽其才,地尽其力;二是不利于生产管理;三是不利于壮大集体经济;四是不利于加强农田基本建设,集体公共福利事业兴建艰难。 展开更多
关键词 经营责任制 土地承包 农业生产力 家庭经营 两田制 发展水平 地力级 农村土地经营 吃饭问题 中低产田土
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The Measurement and Grading of Pressure on Cultivated Land in City-level in Yunnan Province 被引量:3
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作者 杨青 杨子生 《Agricultural Science & Technology》 CAS 2015年第7期1562-1564,共3页
For a long time pressure on cultivated land receives much concern be- cause of close relationship with food security. In Yunnan provice,natural conditions of mountain area are poor and the overall quality of cultivate... For a long time pressure on cultivated land receives much concern be- cause of close relationship with food security. In Yunnan provice,natural conditions of mountain area are poor and the overall quality of cultivated land is :not high. This paper selected state (city) level as research scale,calculated the pressure index on cultivated land of 16 states (cities) in Yunnan provice,revealed the level of tension states (cities) of cultivated land,provided basic basis for determining amount of culti- vated land of provice and states and developing the policy about cultivated land protection.The study indicated that pressure on cultivated land in Dehong belongs to "no pressure" grade,in Qujing and Baoshan belong to "critical pressure "grade,in Yuxi and Zhaotong belong to "moderate-pressure"grade,in Kunming and Nujiang be- longs to "high-pressure" and in the rest 9 states belongs to "low-pressure"grade. 展开更多
关键词 Pressure on cultivated land GRADING Yunnan Province
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Contributions of climate change, land use change and CO2 to changes in the gross primary productivity of the Tibetan Plateau 被引量:6
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作者 LUO Xin JIA Binghao LAI Xin 《Atmospheric and Oceanic Science Letters》 CSCD 2020年第1期8-15,共8页
The ecosystems on the Tibetan Plateau(TP) are highly vulnerable to climate change, rising CO2 concentration, and land-use and land-cover change(LULCC), but their contributions to changes in the gross primary productiv... The ecosystems on the Tibetan Plateau(TP) are highly vulnerable to climate change, rising CO2 concentration, and land-use and land-cover change(LULCC), but their contributions to changes in the gross primary productivity(GPP) of the TP are not clearly understood. In this study, the role of these three factors on the interannual variations(IAVs) and trends of the TP’s GPP were investigated using 12 terrestrial biosphere models. The ensemble simulations showed that climate change can explain most of the changes in the GPP, while the direct effect of LULCC and rising CO2(mainly fertilization effect) contributed 10% and-14% to the mean GPP values, 37% and -20% to the IAV, and 52% and -24% to the GPP’s trend, respectively. The LULCC showed higher contributions to the significant positive trend in the annual GPP of the TP. However, the results from different model simulations showed that considerable uncertainties were associated with the effects of LULCC on the GPP of the TP. 展开更多
关键词 Multi-model ensemble gross primary productivity CO2 land-use and land-cover change Tibetan Plateau
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Impacts of Climate Change on Net Primary Productivity in Arid and Semiarid Regions of China 被引量:15
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作者 WANG Hao LIU Guohua +3 位作者 LI Zongshan YE Xin WANG Meng GONG Li 《Chinese Geographical Science》 SCIE CSCD 2016年第1期35-47,共13页
In recent years, with the constant change in the global climate, the effect of climate factors on net primary productivity(NPP) has become a hot research topic. However, two opposing views have been presented in this ... In recent years, with the constant change in the global climate, the effect of climate factors on net primary productivity(NPP) has become a hot research topic. However, two opposing views have been presented in this research area: global NPP increases with global warming, and global NPP decreases with global warming. The main reasons for these two opposite results are the tremendous differences among seasonal and annual climate variables, and the growth of plants in accordance with these climate variables. Therefore, it will fail to fully clarify the relation between vegetation growth and climate changes by research that relies solely on annual data. With seasonal climate variables, we may clarify the relation between vegetation growth and climate changes more accurately. Our research examined the arid and semiarid areas in China(ASAC), which account for one quarter of the total area of China. The ecological environment of these areas is fragile and easily affected by human activities. We analyzed the influence of climate changes, especially the changes in seasonal climate variables, on NPP, with Climatic Research Unit(CRU) climatic data and Moderate Resolution Imaging Spectroradiometer(MODIS) satellite remote data, for the years 2000–2010. The results indicate that: for annual climatic data, the percentage of the ASAC in which NPP is positively correlated with temperature is 66.11%, and 91.47% of the ASAC demonstrates a positive correlation between NPP and precipitation. Precipitation is more positively correlated with NPP than temperature in the ASAC. For seasonal climatic data, the correlation between NPP and spring temperature shows significant regional differences. Positive correlation areas are concentrated in the eastern portion of the ASAC, while the western section of the ASAC generally shows a negative correlation. However, in summer, most areas in the ASAC show a negative correlation between NPP and temperature. In autumn, precipitation is less important in the west, as opposed to the east, in which it is critically important. Temperatures in winter are a limiting factor for NPP throughout the region. The findings of this research not only underline the importance of seasonal climate variables for vegetation growth, but also suggest that the effects of seasonal climate variables on NPP should be explored further in related research in the future. 展开更多
关键词 climate change net primary productivity (NPP) annual/seasonal variability trend analysis arid/semiarid regions of China(ASAC)
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Examining Forest Net Primary Productivity Dynamics and Driving Forces in Northeastern China During 1982–2010 被引量:16
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作者 MAO Dehua WANG Zongming +2 位作者 WU Changshan SONG Kaishan REN Chunying 《Chinese Geographical Science》 SCIE CSCD 2014年第6期631-646,共16页
Forest net primary productivity (NPP) is a key parameter for forest monitoring and management. In this study, monthly and annual forest NPP in the northeastern China from 1982 to 2010 were simulated by using Carnegi... Forest net primary productivity (NPP) is a key parameter for forest monitoring and management. In this study, monthly and annual forest NPP in the northeastern China from 1982 to 2010 were simulated by using Carnegie-Ames-Stanford Approach (CASA) model with normalized difference vegetation index (NDVI) sequences derived from Advanced Very High Resolution Radiometer (AVHRR) Global Invento y Modeling and Mapping Studies (GIMMS) and Terra Moderate Resolution Imaging Spectroradiometer (MODIS) products. To address the problem of data inconsistency between AVHRR and MODIS data, a per-pixel unary linear regres- sion model based on least ~;quares method was developed to derive the monthly NDVI sequences. Results suggest that estimated forest NPP has mean relative error of 18.97% compared to observed NPP from forest inventory. Forest NPP in the northeastern China in- creased significantly during the twenty-nine years. The results of seasonal dynamic show that more clear increasing trend of forest NPP occurred in spring and awmnn. This study also examined the relationship between forest NPP and its driving forces including the climatic and anthropogenic factors. In spring and winter, temperature played the most pivotal role in forest NPR In autumn, precipitation acted as the most importanl factor affecting forest NPP, while solar radiation played the most important role in the summer. Evaportran- spiration had a close correlation with NPP for coniferous forest, mixed coniferous broadleaved forest, and broadleaved deciduous forest. Spatially, forest NPP in the Da Hinggan Mountains was more sensitive to climatic changes than in the other ecological functional re- gions. In addition to climalie change, the degradation and improvement of forests had important effects on forest NPP. Results in this study are helpful for understanding the regional carbon sequestration and can enrich the cases for the monitoring of vegetation during long time series. 展开更多
关键词 FOREST net primary productivity (NPP) Carnegie-Ames-Stanford Approach (CASA) model normalized difference vegeta-tion index (NDVI) northeastern China
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Log evaluation of fractured igneous reservoirs in Songliao Basin 被引量:1
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作者 Baozhi PAN Lihua ZHANG Ying ZHANG Chen HUANG 《Global Geology》 2007年第1期65-68,共4页
The petrophysical parameters are bad in most igneous reservoirs of Songliao Basin because of the very low porosity and permeability.The evaluation of igneous reservoirs has not been fully studied so far.The current te... The petrophysical parameters are bad in most igneous reservoirs of Songliao Basin because of the very low porosity and permeability.The evaluation of igneous reservoirs has not been fully studied so far.The current technique of formation evaluation and interpretation used in sedimentary formations face a series of problems and difficulties.In this study,The PCA was used to identify lithology,a multi-mineral model "QAPM" was proposed."Surface effect" must be considered when evaluating saturation.A software "SIMPLE" was developed and was used to deal with the logging data in over 70 wells with good results were achieved. 展开更多
关键词 igneous reservoirs LITHOLOGY Songliao Basin QAPM Model
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Secondary relative evaluations on regional technology innovation capability in SMEs
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作者 毕克新 孙金花 冯英浚 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2005年第6期620-625,共6页
According to this problem that every regional technology innovation of SMEs and innovation environment are different, the method on secondary relative evaluation to measure the innovation capability of SMEs in 9 provi... According to this problem that every regional technology innovation of SMEs and innovation environment are different, the method on secondary relative evaluation to measure the innovation capability of SMEs in 9 provinces and 3 municipalities is developed in this paper. First the Fuzzy Integral Comprehensive Evaluation is adopted to measure the comprehensive index states of technological innovation of SMEs in different regions, and then the BCC model in Data Envelopment Analysis is used to calculate the secondary relative evaluation of regional technology innovation capability in SMEs, so that this method not only settles the relevance between indexes influencing regional technology innovation capability of SMEs, but also eliminates the influence of objective basic condition, and then provides bases for every region to make out policies and rules on technological innovation of SMEs and for enterprise to establish relevant strategy of technological innovation. 展开更多
关键词 regional SMEs technological innovation capability secondary relative evaluation fuzzy integral data enenvelopment analysis
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Improving Simulation of the Terrestrial Carbon Cycle of China in Version 4.5 of the Community Land Model Using a Revised V_(cmax) Scheme 被引量:4
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作者 WANG Yuan-Yuan XIE Zheng-Hui +1 位作者 JIA Bing-Hao YU Yan 《Atmospheric and Oceanic Science Letters》 CSCD 2015年第2期88-94,共7页
The maximum rate of carboxylation (Vcax) is a key photosynthetic parameter for gross primary produc- tion (GPP) estimation in terrestrial biosphere models. A set of observation-based Vcax values, which take the ni... The maximum rate of carboxylation (Vcax) is a key photosynthetic parameter for gross primary produc- tion (GPP) estimation in terrestrial biosphere models. A set of observation-based Vcax values, which take the ni- trogen limitation on photosynthetic rates into consideration, are used in version 4.5 of the Community Land Model (CLM4.5). However, CLM4.5 with carbon-nitrogen (CN) biogeochemistry (CLM4.5-CN) still uses an inde- pendent decay coefficient for nitrogen after the photosyn- thesis calculation. This means that the nitrogen limitation on the carbon cycle is accounted for twice when CN bio- geochemistry is active. Therefore, to avoid this double nitrogen down-regulation in CLM4.5-CN, the original Vcmax scheme is revised with a new one that only accounts for the transition between Vcmax and its potential value (without nitrogen limitation). Compared to flux tower- based observations, the new Vcmax scheme reduces the root-mean-square error (RMSE) in GPP for China's Mainland by 13.7 g C m-2 yr-1, with a larger decrease over humid areas (39.2 g C m 2 yr-1). Moreover, net primary production and leaf area index are also improved, with reductions in RMSE by 0.8% and 11.5%, respectively. 展开更多
关键词 CLM4.5 Vcmax gross primary production net primary production leaf area index
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Quantifying the impacts of fire aerosols on global terrestrial ecosystem productivity with the fully-coupled Earth system model CESM 被引量:2
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作者 LI Fang 《Atmospheric and Oceanic Science Letters》 CSCD 2020年第4期330-337,共8页
Fire is a global phenomenon and a major source of aerosols from the terrestrial biosphere to the atmosphere.Most previous studies quantified the effect of fire aerosols on climate and atmospheric circulation,or on the... Fire is a global phenomenon and a major source of aerosols from the terrestrial biosphere to the atmosphere.Most previous studies quantified the effect of fire aerosols on climate and atmospheric circulation,or on the regional and site-scale terrestrial ecosystem productivity.So far,only one work has quantified their global impacts on terrestrial ecosystem productivity based on offline simulations,which,however,did not consider the impacts of aerosol–cloud interactions and aerosol–climate feedbacks.This study quantitatively assesses the influence of fire aerosols on the global annual gross primary productivity(GPP)of terrestrial ecosystems using simulations with the fully coupled global Earth system model CESM1.2.Results show that fire aerosols generally decrease GPP in vegetated areas,with a global total of−1.6 Pg C yr^−1,mainly because fire aerosols cool and dry the land surface and weaken the direct photosynthetically active radiation(PAR).The exception to this is the Amazon region,which is mainly due to a fire-aerosol-induced wetter land surface and increased diffuse PAR.This study emphasizes the importance of the influence of fire aerosols on climate in quantifying global-scale fire aerosols’impacts on terrestrial ecosystem productivity. 展开更多
关键词 Fire aerosols terrestrial ecosystem gross primary productivity land–atmosphere interaction Earth system model
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Study of Chinese Economic "Growth Drag" Caused by Land Resource in the Perspective of the Modified Two-Level CES Production Function 被引量:2
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作者 Yang Yang Wu Cifang 《Chinese Journal of Population,Resources and Environment》 2012年第4期39-43,共5页
The purpose of the study is to measure the "growth drag" according to the characteristic of Chinese land resource.Romer model (2001) holds that every country is inevitably affected by the "growth drag&q... The purpose of the study is to measure the "growth drag" according to the characteristic of Chinese land resource.Romer model (2001) holds that every country is inevitably affected by the "growth drag" due to the limitation of land resource.So it's of profound strategic significance to measure the "growth drag" according to the character of Chinese land resource.Modified two-level CES production function was employed,and this paper modified the hypothesis of the model.The result indicates that the limitation of Chinese land resource casts shadow over the economic development of China,and the growth rate is 0.4618% lower than that without the limitation of land resource.Through implementing the land resource protection policy along with the technology improvement and the substitute effect of other factors to the land resource,China will keep a steady and balanced economic growth. 展开更多
关键词 growth drag modified two-level CES production function land resource economic growth China
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On Estimating Magnitude of a Maximum Sequent Earthquake by Viscoelastic Coulomb Stress Change and a Discussion of the Relationship between the M_S7.3 Earthquakes in Yutian 2008 and 2014
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作者 Chen Yanan Jiang Haikun 《Earthquake Research in China》 CSCD 2015年第4期434-451,共18页
On the basis of the previous studies of the layered crustal model in the Yutian area,combined with the field GPS continuous observation data,we roughly estimate the viscous coefficient of each layer. With the viscoela... On the basis of the previous studies of the layered crustal model in the Yutian area,combined with the field GPS continuous observation data,we roughly estimate the viscous coefficient of each layer. With the viscoelastic horizontal layer model,we calculate the viscoelastic co-seismic Coulomb stress change caused by the Yutian M_S7. 3 earthquakes 2008 and 2014 respectively. Based on the Coulomb stress change,using the calculation method of "direct "aftershock frequency,we come up with the theoretical earthquake frequency directly related to the mainshock and the co-seismic Coulomb stress change in the study area. Then we put forward a method,based on the comparison of theoretical and actual earthquake frequency or the comparison between theoretical and practical earthquake frequency-distance decay curve fitting residuals,to estimate the magnitude of a maximum sequent earthquake,directly related to the mainshock co-seismic Coulomb stress change. Results calculated by different methods show that the maximum follow-up earthquake magnitude caused by the coseismic Coulomb stress change lies from M_S7. 2 to M_S7. 5 following Yutian M_S7. 3 earthquake in 2008; but that of the 2014 Yutian M_S7. 3 earthquake is M_S6. 3. The former is very close to the Yutian M_S7. 3 earthquake in 2014.Because of the same magnitude,relatively close spatial distance,short time interval,the same region of the external force,the strong correlation between two seismic tectonic and a clear stress interaction,we thus consider that the two Yutian M_S7. 3 earthquakes in 2008 and 2014 constitute a pair of generalized double shock type earthquake. This is consistent with the sequence type characteristic of past "double shock"earthquakes in the region. In this paper,the influence of the magnitude lower limit and the b-value in the relationship of G-R on the results is discussed. As a result,when the viscoelastic coseismic Coulomb stress variation is determined,the lower limit of magnitude has little effect on the maximum sequent earthquake magnitude estimation,but b-value of G-R has a greater impact on the results. 展开更多
关键词 The Yutian MS7.3 earthquake in 2008 The Yutian MS7.3 earthquake in 2014 Viscoelastic medium horizontal layered model Viscosity coefficient Viscoelasticity coseismic Coulomb stress changes Maximum sequent earthquake magnitude
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The Impacts of Permafrost Change on NPP and Implications:A Case of the Source Regions of Yangtze and Yellow Rivers 被引量:9
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作者 FANG Yiping QIN Dahe +2 位作者 DING Yongjian YANG Jianping XU Keyan 《Journal of Mountain Science》 SCIE CSCD 2011年第3期437-447,共11页
This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolatin... This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolating functions,and non-linear regression methods.The source regions of the Yangtze and Yellow Rivers were selected as the research areas.Results illustrate that:(1) There is significant non-linear relationship between NPP and GT in various typical years;(2) The maximum value of NPP is 6.17,5.87,7.73,and 5.41 DM·t·hm-2 ·a-1 respectively,and the corresponding GT is 7.1,10.0,21.2,and 8.9 o C respectively in 1980,1990,2000 and 2007;(3) In 1980,the sensitivity of NPP to GT is higher than in 1990,2000 and 2007.This tendency shows that the NPP presents change from fluctuation to an adaptation process over time;(4) During 1980~2007,the accumulated NPP was reduced to 8.05,and the corresponding carrying capacity of theoretical livestock reduced by 11%;(5) The shape of the demonstration region of ecological compensation system,livelihood support system,and science appraisal system in the source regions of Yangtze and Yellow Rivers are an important research for increasing the adaptation capacity and balancing protection and development. 展开更多
关键词 The source regions of Yangtze and Yellow Rivers PERMAFROST Ground temperature (GT) Net primary productivity (NPP) Policy adaptation
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Regional Disparities in China's Mainland at Provincial Level Between 2000 and 2005
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作者 Zhao Jimin Liu Weidong 《Chinese Journal of Population,Resources and Environment》 2009年第3期42-47,共6页
Based on the methodology provided by Organization for Economic Co-operation and Development,we analyze regional disparities in China's mainland at provincial level between 2000 and 2005.It regards regional GDP gro... Based on the methodology provided by Organization for Economic Co-operation and Development,we analyze regional disparities in China's mainland at provincial level between 2000 and 2005.It regards regional GDP growth as the joint result of contribution of a number of factors,i.e.capital productivity,capital per manpower,specialization,employment rate,active population,and population.The results show that for all provincial units,capital per manpower is a dominant contributing factor to the growth of GDP per capita during the period from 2000 to 2005 while capital productivity has quite significant negative impacts.Specialization contributes differently in different provinces.In most provincial units,employment rate and age activity have a positive impact on growth of GDP per capita,though not very significantly. 展开更多
关键词 regional disparity factor decomposition GDP per capita GDP share
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Patterns and mechanisms of belowground carbon responses to changes in precipitation
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作者 Hongyang Chen Qi Zhang +1 位作者 Lingyan Zhou Xuhui Zhou 《Journal of Plant Ecology》 SCIE CSCD 2024年第2期1-17,共17页
It is well known that aboveground productivity usually increases with precipitation.However,how belowground carbon(C)processes respond to changes in precipitation remains elusive,although belowground net primary produ... It is well known that aboveground productivity usually increases with precipitation.However,how belowground carbon(C)processes respond to changes in precipitation remains elusive,although belowground net primary productivity(BNPP)represents more than one-half of NPP and soil stores the largest terrestrial C in the biosphere.This paper reviews the patterns of belowground C processes(BNPP and soil C)in response to changes in precipitation from transect studies,manipulative experiments,modeling and data integration and synthesis.The results suggest the possible existence of nonlinear patterns of BNPP and soil C in response to changes in precipitation,which is largely different from linear response for aboveground productivity.C allocation,root turnover time and species composition may be three key processes underlying mechanisms of the nonlinear responses to changes in precipitation for belowground C processes.In addition,microbial community structure and long-term ecosystem processes(e.g.mineral assemblage,soil texture,aggregate stability)may also affect patterns of belowground C processes in response to changes in precipitation.At last,we discuss implications and future perspectives for potential nonlinear responses of belowground C processes to changes in precipitation. 展开更多
关键词 belowground processes BNPP nonlinear PRECIPITATION soil C
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Cropland Dynamics and Their Influence on the Productivity in Northern Shaanxi,China,for the Past 20 Years:Based on Remotely Sensed Data 被引量:4
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作者 刘文超 刘纪远 +2 位作者 颜长珍 秦元伟 闫慧敏 《Journal of Resources and Ecology》 CSCD 2014年第3期272-279,共8页
In this paper,we mainly focused our research on northern Shaanxi district,which is a pilot area of the Grain for Green Project.We compared the spatial distribution patterns of croplands and their productivity for the ... In this paper,we mainly focused our research on northern Shaanxi district,which is a pilot area of the Grain for Green Project.We compared the spatial distribution patterns of croplands and their productivity for the past 20 years(from the end of the 1980 s to 2010).Cropland dynamics for the past 20 years were interpreted from medium- and high-resolution remote sensing images(Landsat TM/ETM+).In addition,using the GLO-PEM and AGRO-VPM models with a medium resolution and long time series remote sensing dataset(AVHRR/MODIS),net primary productivity(NPP) and its relationship with cropland were estimated.Finally,the effect of cropland change on productivity was analyzed.The results show that during the first decade of the research period,cropland area and productivity in northern Shaanxi experienced a small boost,while in the latter decade,both cropland area and NPP were significantly reduced.The main cause of the increase in cropland was the reclamation of large area of grassland and unutilized land to meet the food demands of the local population as well as to compensate for the occupation of urban constructions.While the main cause of the decrease in cropland was the implementation of the Grain for Green Project.In addition,urbanization was also a key factor.Overall,during the past 20 years,the total area of cropland in northern Shaanxi decreased by 42.56%,and cropland NPP dropped by 41.90%.This study is of great importance for the assessment of regional cropland security,food security and scientific planning of regional land use. 展开更多
关键词 Northern Shaanxi CROPLAND remote sensing land use change net primary productivity
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Responses of Grassland Net Primary Productivity to Environmental Variables in Northern China
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作者 刘芳 张红旗 +1 位作者 许尔琪 康蕾 《Journal of Resources and Ecology》 CSCD 2016年第2期92-100,共9页
Various environmental factors affect net primary productivity (NPP) of grassland ecosystem. Extensive reports on the effects of environmental variables on NPP can be found in literature. However, the agreement on th... Various environmental factors affect net primary productivity (NPP) of grassland ecosystem. Extensive reports on the effects of environmental variables on NPP can be found in literature. However, the agreement on the relative importance of various factors in shaping the spatial pattern of grassland NPP has not yet been reached. Here a grassland in situ NPP database comprising 602 samples in northern China for 1980-1999 was developed based on a literature review of published biomass and forage yield field measurements. Correlation analyses and dominance analysis were used to quantify the separate and combined effects of environmental variables (climate topography and soil) on spatial variation in NPP separately. Grassland NPP ranged from 4.76 g C m-2a-1 to 975.94gCm-2a-1, showing significant variations in space. NPP increased with annual precipitation and declined with annual mean temperature significantly. Specifically, precipitation had the greatest impact on deserts, followed by steppes and meadows. Grassland NPP decreased with increasing altitude because of water limitation, and positively correlated with slope, but weakly correlated with aspect. Soil quality showed positive effects on NPP. Annual precipitation was the dominant factor affecting the spatial variability of net primary productivity, followed by elevation. 展开更多
关键词 Grassland net primary productivity Field measurements Environmental variables Dominant factor Northern China
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Climatic Changes Dominant Interannual Trend in Net Primary Productivity of Alpine Vulnerable Ecosystems 被引量:10
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作者 YANG Yihan WANG Junbang +2 位作者 LIU Peng LU Guangxin LI Yingnian 《Journal of Resources and Ecology》 CSCD 2019年第4期379-388,共10页
The Three-River Headwaters(TRH), which is the source area of Yangtze River, Yellow River and Lancang River, is vulnerable and sensitive, and its alpine ecosystem is considered an important barrier for China’s ecologi... The Three-River Headwaters(TRH), which is the source area of Yangtze River, Yellow River and Lancang River, is vulnerable and sensitive, and its alpine ecosystem is considered an important barrier for China’s ecological security. Understanding the impact of climate changes is essential for determining suitable measures for ecological environmental protection and restoration against the background of global climatic changes. However, different explanations of the interannual trends in complex alpine ecosystems have been proposed due to limited availability of reliable data and the uncertainty of the model itself. In this study, the remote sensing-process coupled model(GLOPEM-CEVSA) was used to estimate the net primary productivity(NPP) of vegetation in the TRH region from 2000 to 2012. The estimated NPP significantly and linearly correlated with the above-ground biomass sampled in the field(the multiple correlative coefficient R2 = 0.45, significant level P < 0.01) and showed better performance than the MODIS productivity product, i.e. MOD17 A3,(R2 = 0.21). The climate of TRH became warmer and wetter during 1990-2012, and the years 2000 to 2012 were warmer and wetter than the years1990–2000. Responding to the warmer and wetter climate, the NPP had an increasing trend of 13.7 g m^–2(10 yr)^–1 with a statistical confidence of 86%(P = 0.14). Among the three basins, the NPP of the Yellow River basin increased at the fastest rate of 17.44 g m^–2(10 yr)^–1(P = 0.158), followed by the Yangtze River basin, and the Lancang River, which was the slowest with a rate of 12.2 g m^–2(10 yr)^–1 and a statistical confidence level of only 67%. A multivariate linear regression with temperature and precipitation as the independent variables and NPP as the dependent variable at the pixel level was used to analyze the impacts of climatic changes on the trend of NPP. Both temperature and precipitation can explain the interannual variability of 83% in grassland NPP in the whole region, and can explain high, medium and low coverage of 78%, 84% and 83%, respectively, for grassland in the whole region. The results indicate that climate changes play a dominant role in the interannual trend of vegetation productivity in the alpine ecosystems on Qinghai-Tibetan Plateau. This has important implications for the formulation of ecological protection and restoration policies for vulnerable ecosystems against the background of global climate changes. 展开更多
关键词 Three-River Headwaters alpine ecosystems net primary productivity climate changes
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Effect of Land Use and Land Cover Change on the Changes in Net Primary Productivity in Karst Areas of Southwest China:A Case Study of Huanjiang Maonan Autonomous County 被引量:5
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作者 ZHANG Mengyu ZHANG Li +4 位作者 REN Xiaoli HE Honglin LV Yan WANG Junbang YAN Huimin 《Journal of Resources and Ecology》 CSCD 2020年第6期606-616,共11页
Karst areas in southwest China have experienced significant land cover and land use change(LUCC)due to utilization for human activity and a comprehensive rocky desertification control project(RDCP)since 2008.It is imp... Karst areas in southwest China have experienced significant land cover and land use change(LUCC)due to utilization for human activity and a comprehensive rocky desertification control project(RDCP)since 2008.It is important to quantify the effect of LUCC on ecosystem productivity in this region for assessing the overall benefit of this ecological restoration project.In this study,we used using MODIS land cover and NPP products to investigate the relative contribution of LUCC to the change in net primary productivity(NPP)during 2008–2013 in Huanjiang County,one of first one hundred pilot counties to implement RDCP.Our results show that NPP increased in 95.53%of the county,and the average growth of NPP in non-rocky desertification area was higher than in rocky desertification or potential rocky desertification areas.LUCC has an important contribution(25.23%)to the NPP increase in the county,especially in the LUCC area(70.97%),which increased the average NPP by 3.9%and 10.5%,respectively.Across the six RDCP regions in the county,the average increase in NPP for the vegetation restoration measure of governed karst area is significantly greater than in the ungoverned karst area,and the positive change in NPP increased with the increasing implementation area of the vegetation restoration measure. 展开更多
关键词 land use change net primary productivity karst area comprehensive control project for rocky desertification
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Regional inequality, spatial spillover effects, and the factors influencing city-level energy-related carbon emissions in China 被引量:9
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作者 苏文松 刘艳艳 +3 位作者 王少剑 赵亚博 苏咏娴 李世杰 《Journal of Geographical Sciences》 SCIE CSCD 2018年第4期495-513,共19页
Data show that carbon emissions are increasing due to human energy consumption associated with economic development. As a result, a great deal of attention has been focused on efforts to reduce this growth in carbon e... Data show that carbon emissions are increasing due to human energy consumption associated with economic development. As a result, a great deal of attention has been focused on efforts to reduce this growth in carbon emissions as well as to formulate policies to address and mitigate climate change. Although the majority of previous studies have explored the driving forces underlying Chinese carbon emissions, few have been carried out at the city-level because of the limited availability of relevant energy consumption statistics. Here, we utilize spatial autocorrelation, Markov-chain transitional matrices, a dynamic panel model, and system generalized distance estimation(Sys-GMM) to empirically evaluate the key determinants of carbon emissions at the city-level based on Chinese remote sensing data collected between 1992 and 2013. We also use these data to discuss observed spatial spillover effects taking into account spatiotemporal lag and a range of different geographical and economic weighting matrices. The results of this study suggest that regional discrepancies in city-level carbon emissions have decreased over time, which are consistent with a marked spatial spillover effect, and a ‘club' agglomeration of high-emissions. The evolution of these patterns also shows obvious path dependence, while the results of panel data analysis reveal the presence of a significant U-shaped relationship between carbon emissions and per capita GDP. Data also show that per capita carbon emissions have increased in concert with economic growth in most cities, and that a high-proportion of secondary industry and extensive investment growth have also exerted significant positive effects on city-level carbon emissions across China. In contrast, rapid population agglomeration, improvements in technology, increasing trade openness, and the accessibility and density of roads have all played a role in inhibiting carbon emissions. Thus, in order to reduce emissions, the Chinese government should legislate to inhibit the effects of factors that promote the release of carbon while at the same time acting to encourage those that mitigate this process. On the basis of the analysis presented in this study, we argue that optimizing industrial structures, streamlining extensive investment, increasing the level of technology, and improving road accessibility are all effective approaches to increase energy savings and reduce carbon emissions across China. 展开更多
关键词 carbon emissions spatial spillover effects dynamic spatial panel data model Chinese carbon emission reduction policies environmental Kuznets curve
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The Effect of Higher Warming on Vegetation Indices and Biomass Production is Dampened by Greater Drying in an Alpine Meadow on the Northern Tibetan Plateau 被引量:5
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作者 WANG Jiangwei FU Gang +1 位作者 ZHANG Guangyu SHEN Zhenxi 《Journal of Resources and Ecology》 CSCD 2017年第1期105-112,共8页
In order to understand whether or not the response of vegetation indices and biomass production to warming varies with warming magnitude,an experiment of field warming at two magnitudes was conducted in an alpine mead... In order to understand whether or not the response of vegetation indices and biomass production to warming varies with warming magnitude,an experiment of field warming at two magnitudes was conducted in an alpine meadow on the northern Tibetan Plateau beginning in late June,2013.The normalized difference vegetation index(NDVI),green normalized difference vegetation index(GNDVI) and soil adjusted vegetation index(SAVI) data were obtained using a Tetracam Agricultural Digital Camera in 2013–2014.The gross primary production(GPP) and aboveground plant biomass(AGB) were modeled using the surface measured NDVI and climatic data during the growing seasons(i.e.June–September) in 2013–2014.Both low and high warming significantly increased air temperature by 1.54 and 4.00°C,respectively,and significantly increased vapor pressure deficit by 0.13 and 0.31 kP a,respectively,in 2013-2014.There were no significant differences of GNDVI,AGB and ANPP among the three warming treatments.The high warming significantly reduced average NDVI by 23.3%(-0.06),while the low warming did not affect average NDVI.The low and high warming significantly decreased average SAVI by 19.0%(-0.04) and 27.4%(-0.05),respectively,and average GPP by 24.2%(i.e.0.21 g C m^(-2) d^(-1)) and 44.0%(i.e.0.39 g C m^(–2) d^(-1)),respectively.However,the differences of the average NDVI,SAVI,and GPP between low and high warming were negligible.Our findings suggest that a greater drying may dampen the effect of a higher warming on vegetation indices and biomass production in alpine meadow on the northern Tibetan Plateau. 展开更多
关键词 ANPP GPP NDVI Tibetan Plateau warming magnitude
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