Table of Content

    20 June 2016, Volume 31 Issue 6 Previous Issue    Next Issue
    Experts?? Forum
    Study on the Spatiotemporal Patterns and Contribution Factors of China’s Grain Output Increase during 2003-2013
    FENG Zhi-ming, SUN Tong, YANG Yan-zhao
    2016, 31 (6):  895-907.  doi: 10.11849/zrzyxb.20151220
    Abstract ( )   HTML ( )   PDF (3731KB) ( )   Save
    National grain security plays a critical role in national economy and the people’s livehood. In 2003-2013, China had achieved ten-year consecutive grain production increase that had never appeared in history and attracted a great deal of attention in the worldwide. Till 2015, the grain production has been experienced by the twelve-year consecutive increase. The purpose of this paper is to detect the spatiotemporal patterns and the main contributions of the ten-year consecutive grain production increase from 2003 to 2013. Based on factors contribu-tions analysis and GIS, this paper analyzes the situation and spatiotemporal differences of grain output growth at the national level and the provincial level, with the data of planted area and yield per unit area. The spatiotemporal patterns and the main contribution factors of China’s grain output increase were discussed at the multiple-levels including provincial level and national level. The results showed that: 1) the output growth of rice, wheat and maize (which are called “three major grain crops”) were the main reason of the grain output growth at the national level, whose contribution rate in the total grain output growth was 105.73% due to the decrease of other grain crops such as soybean, broomcorn, millet, etc; 2) maize was the biggest contributor in three major grain crops in 2003-2013, whether the rate of increase (88.63%), contribution rate of grain output growth (56.70%), the speed of incresase (1 026.59×104 t/a) or the universality (29 provinces, municipalities and autonomous regions) of grain output growth, rice was the second, and wheat was the last; 3) at the national scale, the grain output growth caused by the promotion of yield per unit area accounted for 64.50%, which was more than that caused by the expansion of planted area (35.50%); 4) as to the crops, the output growth of rice and maize relied on the expansion of planted area, and the contribution rate of planted area was 56.59% and 64.83% respectively, whereas the output growth of wheat relied on the increase of yield per unit area which has the contribution rate of 73.21%; and 5) the grain output growth appeared in most of provinces during the 10 years, and the provinces in Northeast China, North China, the Huang-Huai-Hai Plain, the middle reaches of the Yangtze River had more significant increase. In general, the main regions with ten-year consecutive grain production increase were the Northeast China Plain, the Huang-Huai-Hai Plain and Xinjiang. The expansion of planted area and the increase of yield per unit area were both significant contribution factors to the grain output growth in 2003-2013, whereas the role of yield per unit area was more obvious.
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    Resource Utilization and Management
    Evolution Trend of Regional Centralization of Grain Production in China
    CHAI Ling-huan, ZHU Hui-yi
    2016, 31 (6):  908-919.  doi: 10.11849/zrzyxb.20150536
    Abstract ( )   HTML ( )   PDF (2171KB) ( )   Save
    Regional specialization and regional division are important symbols of agricultural modernization. And they are also unavoidable for China’s agricultural development in the future. Since it is influenced by marketization of agricultural production and some policy factors such as cultivated land protection, agricultural subsidies and price protection, currently the direction of regional specialization and regional division is unclear in China. However, the centralized trend of agricultural production provides important clues to this question. In this paper, three main grain crops, rice, wheat and corn, are taken as the research object. Based on the provincial grain production in China from 1981 to 2013, the centralization index was adopted to reveal the evolution characteristics and evolution trend of regional centralization of the grain production in China. The results indicated that the centralization degree of grain production increased obviously. Besides, wheat production had the highest degree of centralization among the three grain crops, and presented a stable trend of centralization. However, the centralization degrees of rice and corn production both experienced a U-shaped change process, illustrating that rice and corn production had undergone space restructuring during this period. According to the trend, rice production centralized in Heilongjiang, Hunan and Jiangxi; wheat production centralized in Henan, Shandong, Anhui and other traditional wheat production regions; and corn production centralized in Heilongjiang and Inner Mongolia. Those results implied that specialized regions of grain production were likely to be formed in these areas and the surroundings. Strengthening the basic construction of farmland in these areas will help to promote regional specialization and regional division of China’s grain production.
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    Test on Convergence Trait of Water Resource Intensity in Mainland China: An Empirical Research Based on Panel Data at Provincial Level
    ZANG Zheng, ZOU Xin-qing
    2016, 31 (6):  920-935.  doi: 10.11849/zrzyxb.20150599
    Abstract ( )   HTML ( )   PDF (5301KB) ( )   Save
    Aimed at comprehensive evaluation on water resources utilization efficiency of each water sector in mainland China, this paper, referencing the connotation of energy intensity, defined the concept of water resource intensity, water resource relative intensity from the viewpoint of compound system. With the panel data of water sectors, the convergence trait of water resource intensity in mainland China from 2003 to 2013 was tested. The results showed that the inter provincial variations of residential water intensity and agricultural water intensity were smooth and steady, showing no obvious σ-convergence; the industrial water intensity showed the trend of divergences-steady-converges; the σ-convergence of eco-environmental water intensity fluctuated greatly but the convergence rate was big and the inter provincial differences narrowed rapidly. Water resources relative intensity in 80% provinces of mainland China received continuous positive influence. They were not influenced by the short-term impact and did not show stochastic convergence trait. Water resource intensity of each water sector showed β-absolute convergence. Convergence rate was 3.17% (for residential water), 4.21% (for agricultural water), 1.82% (for industrial water) and 12.41% (for eco-environmental water), respectively. Eco-environmental water intensity in eastern China, residential water and eco-environmental water intensity in western China, and water resource intensity of all the water sectors in the middle showed club convergence. The β-conditional convergence occurred in all the water sectors. The major driving forces on the convergence of residential water, industrial water and eco-environmental water were proportion of tertiary industrial, standard reaching-rate of industrial wastewater discharge and annual precipitation, respectively. The major restrict factors on convergence of residential water, industrial water and eco-environmental water were total export-import volume, GNP per capita and standard reaching-rate of industrial wastewater discharge, respectively.
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    Resource Economy
    Study on Rent Dissipation and Land Use Behavior of Suburban Rural Housing Land under the Background of Urbanization
    ZHU Feng-kai, ZHANG Feng-rong
    2016, 31 (6):  936-947.  doi: 10.11849/zrzyxb.20150680
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    With the rapid development of urbanization and rapid evolution of urban and rural relationship, the location and function of the rural housing land have been undergoing profound transition. The sustained brisk demand for construction land raises the potential value of rural housing land. However, due to the urban-rural dual land system, there are restrictions on the transactions and usage of collective construction. The regulation of property rights puts part of the rent value of rural housing land into the “public domain”. In that case, the land resource could not be allocated to the best use. The “non-exclusive income” left in the “public domain” tends to dissipate, not only because of the inefficient resource allocation, but also because of the rent competition among the land users. As a kind of economic waste, rent dissipation will be reduced to the greatest extent by related resource consumers.
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    Research on Spatial Distribution, Types and Conservation Modes of Urban Ecological Land:Case Study of Guangzhou City, China
    CHEN Shi-dong, YUAN Qi-feng
    2016, 31 (6):  948-960.  doi: 10.11849/zrzyxb.20150701
    Abstract ( )   HTML ( )   PDF (6997KB) ( )   Save
    To relieve the ecological conservation pressure resulting from the rapid urbanization, it is necessary to define the concept of “urban ecological land”. Urban ecological land refers to the ecological space composed of agricultural land in the urban system, which is generally confined to the urban area, merging into the urban function group with large scale of space. According to the urban space reconstruction process of Chinese urbanization, we deduce two assumptions of urban ecological land: 1) the distribution of urban ecological land is in circular mode; 2) the ecological value of the urban ecological land depends on the relationship between demand and supply, which can be characterized by the location and abundance ratio of the ecological land. The empirical study was implemented by taking the administrative towns and streets of Guangzhou City as the minimum space unit, and the results showed that: 1) From the perspective of location, the urban ecological land in Guangzhou can be divided into the core circle, the transition circle and the outer circle, which proved the hypothesis of “circular distribution mode”. 2) The urban ecological land can be divided into three categories and twelve levels according to the indicators of location and abundance ratio, which provided the reference for making effective conservation policy. 3) The ecological functions of farmland is a public product, but its ecological rent is in the dissipation situation due to the dual failure of the government and the market. Finally, after summarizing the nationalized mode in the core circle and the regional coordination mode in the outer circle, the paper proposed to protect the transition circle by establishing farmland development right.
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    Resource Evaluation
    Analyzing the Effects of Land Cover Change on Vegetation Net Primary Productivity in Guangdong Province
    JIANG Chun, WU Zhi-feng, CHENG Jiong, QIAN Le-xiang
    2016, 31 (6):  961-972.  doi: 10.11849/zrzyxb.20150499
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    It’s of significant importance to understand the effect of LUCC on vegetation net primary productivity (NPP) in global carbon cycle and food security. This study aimed to investigate how the land cover change caused by urban expansion affects the regional NPP in Guangdong Province. The vegetation type data, land cover data, moderate-resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) and meteoro-logical data were combined to simulate the spatial distribution of NPP in the year 2000, 2005 and 2010 in Guangdong Province by using the improved Carnegie-Ames-Stanford Approach (CASA) model. Guangdong Province is divided into four ecological regions: Nanling region, Yuezhong region, the Pearl River Delta and Yuenan region. Then, the spatial pattern of NPP and spatio-temporal dynamics of land cover change were analyzed, and the regional differences of NPP gains/losses caused by land cover change were compared. The results show that: 1) The NPP is heterogeneous in space and forms a series of zones with high value and low value; the Yuezhong region has the highest annual mean NPP, and the lowest NPP value is in the Pearl River Delta. 2) The change of land cover in Guangdong Province increased during 2000-2010, with the maximum changes happening in urban land and cropland, and the Pearl River Delta and Yuezhong region had the most change. 3) Under the condition of climate change, the land cover change resulting from urban expansion caused the overall NPP loss in Guangdong Province; the primary loss is caused by the conversion from croplands and forests to land covers with low productivity, especially the urban land. The NPP losses in different ecological regions are greatly different, the Pearl River Delta and Yuezhong region having more serious NPP loss during 2000-2005, and with a decrease of NPP loss in the Pearl River Delta and increases in other ecological regions during 2005-2010, which indicates that the effects of urban expansion on NPP are complex.
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    Primary Study on Alpine Timberline of Helan Mountain Using RS and GIS
    LIU Tan, KANG Mu-yi
    2016, 31 (6):  973-981.  doi: 10.11849/zrzyxb.20150707
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    The alpine timberline (AT) is an important ecotone of mountain vegetation. Extensive researches have been conducting in this ecotone for its dynamic state of vegetation and sensitivity to climate change. Investigating the location and the distribution of AT in a mountain area is significant for the research of dynamic AT. With the RS data and spatial analysis techniques, it is convenient and efficient to achieve this purpose. The Helan Mountain, which is in the adjacent area of the Yinchuan Plain and the Inner Mongolia Prairie, has a representative altitudinal vegetation-belt spectrum in the arid western part of China. It is a good area for AT research. The AT positions on Helan Mountain were obtained from Landsat 8-OLI and DEM by using RS and GIS methods. The NDVI of major vegetation types and vertical distribution pattern of ATs were analyzed in this study. The results are as follows: 1) The ATs on Helan Mountain appear on the altitudes of 2 900-3 200 m.a.s.l, which is revealed by the vertical distribution pattern of the subalpine conifer forest and alpine scrub, meadow. 2) The mean elevation of AT upper borderline and lower borderline is 3 106 m.a.s.l and 3 022 m.a.s.l respectively. The mean elevations of both AT borderlines are higher on the north and east slopes than on the west and south slopes. 3) The NDVI data is an effective supplement for image classification to detect AT.
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    Assessing the Loss Value of Soil and Water Conservation Resulted from the Mining of Rare Earth Ore in Ganzhou, Jiangxi Province
    ZHOU Xia-fei, ZHU Wen-quan, MA Guo-xia, ZHANG Dong-hai, ZHENG Zhou-tao
    2016, 31 (6):  982-993.  doi: 10.11849/zrzyxb.20150612
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    Mining the rare earth ore without orders not only causes the waste of rare earth resources, but also leads to a series of environmental problems, such as the loss of soil and water, environmental pollution, and so on. Based on the universal soil loss equation (USLE), this article first evaluated the amount of soil erosion in the reference regions and the rare earth ore mining regions by using the investigation data of the rare earth ore, remote sensing data, meteorological data and basic geographic data in Ganzhou, Jiangxi Province, and then analyzed the quantity and lost value of soil and water conservation resulted from the mining of rare earth ore by comparing the results in these two kinds of regions. The results showed that: 1) The soil erosion resulted from the mining of rare earth ore in Ganzhou was very serious. Comparing with the reference regions with lower soil erosion modulus (average of 2 345.9 t/(km2·a)), the average soil erosion modulus in the mining areas and their surroundings were quite high which reached 8 487.5 t/(km2·a), even more than 70 000 t/(km2·a) in the most serious areas. As a whole, the amount of soil erosion caused by the mining of rare earth was 646 917 t. 2) Both the quantity loss and the value loss of soil and water conservation resulting from the mining of rare earth ore were huge. The value loss for soil and water conservation resulted from the mining of rare earth ore was 4 619.213 million yuan in 2013, accounting for 12.35% of the total output value of rare earth ore. The methodology for the assessment of the lost value of soil and water conservation can be used to resolve the similar environment damage evaluations in other mining areas, and the research results provide a basis for the ecological assessment, the price making of the rare earth, and the ecological environment management in mining areas.
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    Study on the Green GDP of Chinese Resource Based Cities:A Case Study of Yulin City in Shaanxi Province
    DOU Rui-yin, LIU Xue-min, ZHANG Yu
    2016, 31 (6):  994-1003.  doi: 10.11849/zrzyxb.20150714
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    Green GDP is a part of traditional GDP that has been removed off the consumption of nature resources and environment loss. It is an important index to measure the sustainability of development. The development of resource based cities relies on the development and utilization of resources. These cities have greater influence on the consumption of nature resources and environment loss compared with other cities; therefore, it is more meaningful to research on the green GDP of these cities. In this paper, based on Odum��s emergy ecological economic theory and methods, and in the case of Yulin, we calculated the unrenewable resources and the environmental losses consumed in the national economic production process of Yulin City from 2005 to 2012, and calculated energy and environment energy loss-currency value of the unrenewable resources and the environmental losses. Finally, the change of the green GDP inYulin from 2005 to 2012 was analyzed. The conclusions are as follows: 1) The proportion of Green GDP in the GDP of Yulin City decreased from 81.2% to 44.1%, and the trend of decline is continuing. 2) The usage of unrenewable energy increased at the rate of 10% each year, and the share of the unrenewable energy in GDP rose from 13.35% in 2005 to 44.8% in 2012, and this is the most important reason that the green GDP of Yulin is low. 3) The unrenewable energy consumption in Yulin City is mainly coal, which takes more than 90% of the usage of fossil energy, accompanied with oil and gas. 4) The environmental loss in Yulin City is mainly waste gas, waste water and solid waste, in which waste gas accounts for more than 80%.
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    Evaluation of the High-Resolution Daily Merged Precipitation Product over China Based on in situ Observations
    CHEN Yuan-yuan, SONG Xiao-dong, HUANG Jing-feng, XIONG An-yuan
    2016, 31 (6):  1004-1014.  doi: 10.11849/zrzyxb.20150173
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    We compared the daily merged precipitation product (DMPP) produced by the National Meteorological Information Center (NMIC) with the observed precipitation data (OPD) from 633 base stations over China during 1998-2010. We analyzed: 1) the temporal and spatial distributions of the error of DMPP, and the inter annual variation of DMPP; 2) the influence of terrain factor on the accuracy of DMPP; and 3) the error of the DMPP with different precipitation intensities. The results showed that the spatial distribution of the average annual precipitation of DMPP agreed well with the observed pattern, and the correlation coefficients of annual precipitation between DMPP and OPD in most areas were greater than 0.8. Specifically, the correlation coefficients in eastern China were generally greater than 0.9. The error characteristics and spatial distributions of DMPP were reasonable, with little interannual variation. The error and variability of DMPP correlated with the terrain features, i.e., the altitude. The altitude has more effect on annual average relative deviation of DMPP than the relief amplitude, and the impact of altitude in the high-altitude regions is greater than in the the low-altitude regions.
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    Characteristics of Extreme Precipitation in China Based on Homogenized Precipitation Data
    WU Wen-bo, YOU Qing-long, WANG Dai
    2016, 31 (6):  1015-1026.  doi: 10.11849/zrzyxb.20150209
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    By using the homogenized daily precipitation data of the 602 stations from 1961 to 2012 in China, the basic temporal and spatial characteristics of extreme precipitation events in China during the last 52 years are discussed based on 11 extreme precipitation indices published by World Meteorological Organization (WMO). The results are as follows. The linear trends of the indices of precipitation extremes suggest that all indices of extreme precipitation are increasing in Northwest China and mid-lower reaches of the Yangtze River except CDD. The linear trends of the indices of precipitation extremes are all decreasing in North China, but are ascending in southeastern coast and South China. The indices exhibit significant interannual and interdecadal variability, and the increasing trends are found in almost all 11 indices since 2000, suggesting that there are more extreme precipitation events in China since then.
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    Variations and Periodic Symmetry of Temperature and Precipitation in Inner Mongolia Section of the Yellow River Basin during 1951-2012
    HUANG Xing, MA Long, LIU Ting-xi, WANG Jing-ru, LIU Dan-hui
    2016, 31 (6):  1027-1040.  doi: 10.11849/zrzyxb.20150045
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    The Inner Mongolia section of the Yellow River Basin is the important economy development zone of Inner Mongolia. The research on the changes of climatic factors has great significance on the water resource reservation, ecological environmental protection and local economic and social development in the basin. Based on the data of temperature and precipitation collected from 52 meteorological stations in the research area and the surrounding areas from 1951 to 2012, this thesis adopted the methods of regression analysis, comparison of annual average, 5-year moving average, climate tendency and Mann-Kendall test to analyze the variations of temperature and precipitation and their interrelationship. The results indicate that in recent 62 years the annual average temperature, the annual maximum average temperature and the annual minimum average temperature all show obvious rising trends (0.283 ℃/10 a, 0.235 ℃/10 a and 0.590 ℃/10 a), especially in the 1990s. The temperature in winter increased most significantly, which contributed most to the warming effect. These three kinds of temperature experienced a mutation respectively in 1988, 1989 and 1982. There is great variation of the annual precipitation and it shows a declining tendency (-1.48 mm/10 a), but the falling range is not big. The relationship of the average annual precipitation has good positive correlations with the average annual temperature, the annual average maximum temperature and the annual average minimum temperature in the 1980s and 1990s, while the relations showed antisymmetric change in other periods. From the seasonal perspective, the correlations between the seasonal precipitation and the seasonal average temperature, the seasonal average maximum temperature and the seasonal average minimum temperature in spring are the highest; the correlation of the precipitation and the temperature in summer is similar to the interannual variation; the trend of the precipitation is antisymmetric to the temperature in autumn; the trend of the precipitation and temperature in winter was antisymmetric from the 1990s and was consistent in other periods.
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    The Analysis of the Characteristics and Water Vapor Source of the δ18O in the Precipitation of Typhoon “Matmo” at Fuzhou
    SUN Xiao-shuang, WANG Xiao-yan, ZHAI Shui-jing, LEI Guo-liang, JIANG Xiu-yang
    2016, 31 (6):  1041-1050.  doi: 10.11849/zrzyxb.20150753
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    Water vapor isotopes are not only controlled by the long-term and short-term conditions of climate, but are also very sensitive to extreme synoptic conditions. Hydrogen and oxygen isotopes in atmospheric precipitation not only have a certain response to climate change at different time scales, but also have strong linkages to extreme weather events. The study of precipitation isotopes was based on long and short term sampling in the past, but the study on the changes of the stable isotopes during the extreme precipitation and the source of water vapor is relatively less. This paper takes a typhoon rainfall as an example to reveal the changes of precipitation isotope and its effect mechanism in the typhoon weather. This study analyzed the precipitation and the stable isotopes during the period of No.10 Typhoon “Matmo” that landed Fuzhou in 2014. The range of δ18O in the “Matmo” precipitation is -7.2‰ - -15.4‰. The whole process of precipitation can be divided into three stages. At stage one (3:00 am July 23th to 12:00 am July 23th), the water vapor δ18O is relative heavy (weighted average value is -7.8‰). At this time, the external circulation of the typhoon influenced the sampling spot. At stage two (12:00 am July 23th to 8:00 am July 24th), the water vapor δ18O of sample spot become dramatically lighter (weighted average value is -13.9‰). The precipitation in this stage was 134.8 mm, which accounted for 78% of the precipitation in the observation period, and the effect of precipitation amount was obvious. At stage three (8:00 am July 24th to 17:00 pm July 24th), the typhoon precipitation δ18O become heavy again (weighted average value is -9.2‰)when the precipitation gradually decreased and the typhoon moved away from Fuzhou. The analysis of water vapor flux at 850 hPa and the HYSPLIT-4 simulations of vapor transport trajectories indicated that the water vapor source were primarily from the water vapor channel in the Northwest Pacific and the water vapor channel in the bay of Bengal and the South China Sea.
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    Resource Research Method
    Soil Salinity Estimation and Remote Sensing Inversion Based on Near-ground Multispectral and TM Imagery in Winter Wheat Growing Area in the Yellow River Delta—Case Study in Kenli County and Wudi County, Shandong Province
    ZHANG Tong-rui, ZHAO Geng-xing, GAO Ming-xiu, CHANG Chun-yan, WANG Zhuo-ran
    2016, 31 (6):  1051-1060.  doi: 10.11849/zrzyxb.20150669
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    The Yellow River Delta is an important area of reserve land. Because of the great effects of the soil salinization on the agricultural production in this area, momentarily acquiring the soil salt content and its distribution in the region is of great significance. We first collected near ground and multispectral images and surface soil salinity data using ADC portable multispectral camera and EC110 portable salinometer, and extracted the growing areas of winter wheat in the Yellow River Delta with two phases of remote sensing images. We built a soil salinity estimation model based on the vegetation index from near earth multispectral images, and then, the fitted the model to the OLI image of the Yellow River Delta to obtain the spatial distribution of soil salinity in winter wheat growing areas in the target region. The soil salinity in the winter wheat growing areas was analyzed. Results indicated that the best model of estimating salt content of soil was the linear model of SAVI (Y=-0.754x+0.870, n=80), estimated R2 being 0.747 and the accuracy being 81.44%; the winter wheat planed in the study area decreased from the southwest inland to the northeast coast; 76.90% of the total cultivated area has the soil salinity ranging between 1.5-3.0 g/kg, and 14.09% of the total cultivated area has the soil salinity more than 3.0 g/kg. This study has probed into soil salinity estimation methods based on the near earth multispectral data and OLI images, which provides a quick and effective approach for crop management and soil salinity estimation in the Yellow River Delta.
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    Prime Farmland Protection Zoning Based on Bayesian Network
    GUAN Xiao-dong, HE Jian-hua
    2016, 31 (6):  1061-1072.  doi: 10.11849/zrzyxb.20150639
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    Basic farmland protection zoning is the key issue of implementing land protection and ensuring food security. At present, most of the related studies on farmland protection zoning are based on the evaluation of the suitability of cultivated land, with no consideration of the change process of cultivated land in the past. Therefore, they cannot ensure the zoning result to adapt to the trend of cultivated land change, leading to the prime farmland being frequently occupied and adjusted. To guarantee the stability of prime farmland as well as its cultivation quality, we put forward a method of zoning farmland based on Bayesian network (BN) model in this paper, which includes both factors concerning cultivated land suitability condition and its dynamic change. With data of land use status in Daye City at two time points (1997 and 2012), the factors about suitability and changes of cultivated land are obtained. Suitability factors are used to reflect the quality of cultivated land, and the factors about changes are used to study the change disciplinarian of cultivated land. Using the basic farmland potential as the target variable, we defined the structure of the network by expert knowledge. The BN was trained by Maximum Likelihood Method with 57 085 random sample points. The results show that, only 60% farmland in Daye City remains stable from 1997 to 2012. In the three dynamic factors, the influence of building occupancy is the greatest, which accounts for 28.2%, followed by the internal adjustment, 17.4%, the influence of ecological footprint is the least, which accounts for 4.65%. The results of sensitivity analysis also indicate that building occupancy has the greatest influence on the potential value of the prime farmland, with the highest variance reduction of 26.8%. The variance reductions of the distance to the center of city (0.43%) and the center of the town (0.58%) are greater than that of the distance to the road (0.14%) or the railway (0.28%), reflecting that urban expansion has greater impact on the occupation of basic farmland than transportation construction. In natural condition factors, the influence of the distance to the water area is the minimum, which is less than 0.02%, while soil erosion has the greatest variance reduction of 0.34%. It can be deduced that soil erosion, but water, is the most important nature factor to destroy the stability of cultivated land in Daye City. Then, using the values of suitability factors in 2012, we obtained the relative potential value of each cultivated land parcel as the prime farmland through forward reasoning of the trained network, and zoned the farmland with the potential value of the target variable. The results show that, compare to traditional land evaluation method, the zoning model based on BN can improve the stability of agricultural value and ensure the quantity and quality of prime farmland. It is a new and effective model for farmland protection zoning.
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