Table of Content

    20 March 2018, Volume 33 Issue 3 Previous Issue    Next Issue
    Resource Utilization and Management
    Main Limiting Factor of the Regional Specialization of Agricultural Land Use in China
    WANG Wei-heng, ZHU Hui-yi
    2018, 33 (3):  361-371.  doi: 10.11849/zrzyxb.20170130
    Abstract ( )   HTML ( )   PDF (1983KB) ( )   Save
    The regional specialization of agricultural land-use in China lags behind those in developed countries and develops slowly, which makes agricultural products of China lack of international competitiveness. However, there is no convincing conclusion that can explain the reason. In this paper, we examined the controllability and limitation of main grain production in the specialization of agricultural land-use based on the specialization index of Hirschman-Herfindahl (SHHI), the planting area data at national and provincial level during 1991-2013 and at county-level in Hangjiahu area during 2001-2013, combined with the analysis of related policies. The reason why the regional specialization of agricultural land-use in China developed slowly was explored. At present, the regional specialization was controlled by the proportion of main grain acreage (PMGA). The SHHI and PMGA had positively correlation at 5% significant level in both temporal and spatial dimensions at both national level and provincial level. At county-level, in spatial dimensions, SHHI had a significant positive correlation with PMGA; in temporal dimensions, there were 76% of counties whose SHHI had significant positive correlation with PMGA. Furthermore, we found that grain protection policy constrained the withdrawal of grain crops, which compressed the growth of other crops and limited the specialization of agricultural land-use. The results indicated that the protection policy of grain (especially main grain) production is the main limiting factor of agricultural land-use specialization in China at the present stage. Therefore, we suggested changing the concept of “grain security” and optimizing the layout of agriculture.
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    Does the Improvement of Agricultural Labor Productivity Shrink Rural Residents’ Income Gap?
    WANG Ya-hui, LI Xiu-bin, XIN Liang-jie
    2018, 33 (3):  372-385.  doi: 10.11849/zrzyxb.20170048
    Abstract ( )   HTML ( )   PDF (8029KB) ( )   Save
    Using the panel threshold model proposed by Hansen, this paper empirically studies the nonlinear relationship between agricultural labor productivity and rural residents’ income gap based on panel data of 29 provincial units from 2000 to 2014. The results show that there are distinctive relations between agricultural labor productivity and rural residents’ income gap divided by thresholds rather than a single linear relationship. In different ranges of thresholds, the influence of agricultural labor productivity on rural residents’ income gap is different. When the agricultural labor productivity is less than per capita 4 372.19 Yuan, the improvement of agricultural labor productivity can effectively narrow the income gap of rural residents; when the agricultural labor productivity cuts across the first threshold of per capita 4 372.19 Yuan, its improvement has little effect on the income gap of rural residents; when it leaps over the second threshold of per capita 6 023.46 Yuan (i.e. the inflection point), its improvement will widen the income gap of rural residents. Currently, the agricultural labor productivity in China has crossed the second threshold, so the expansion of rural residents’ income gap should be concerned by all parties.
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    Analysis on Changes of Agricultural Structure and Its Driving Factors in the Middle Reaches of Heihe River at Plot Scale—A Case Study of Zhangye City
    XIAO Xing-yuan, HU Min-yue, LI Xiu-bin, TAN Ming-hong, ZHAO Xiang-wei, ZHENG Lu-qian
    2018, 33 (3):  386-397.  doi: 10.11849/zrzyxb.20170502
    Abstract ( )   HTML ( )   PDF (1974KB) ( )   Save
    Since the middle reaches of the Heihe River is an important grain base in the arid area of Northwest China, studying the agricultural structure change and its driving factors in this area has certain reference significance for farmers’ decision-making on planting and promoting the development of local agriculture. However, there are few studies on the change of agricultural structure and its driving factors at the plot scale. Based on the statistical yearbook and the survey on farmers, this paper analyzes the changes of agricultural structure in the study area during 2001-2014. The paper analyzes quantitatively the driving factors of agricultural structure change by using binary Logistic model and input-output method at two levels, household level and plot level. The results showed that: 1) The crop types in the study area tend to diversify. In 2001, the main planting crops in the study area were wheat, maize, barley and wheat-corn relay intercropping, whose number of plots accounted for 81% of the total number of plots. In 2014, the types of planting crops increased and the number of cash crops (vegetables, potatoes, rape) also increased compared with those in 2001. 2) The mainly planting crop in the study area changed from wheat (31% of the total plots) to corn (38.7% of the total plots), and intercropping changed to monoculture. In 2001, there were 58 intercropping plots (accounting for 22% of the total plots), most of which were wheat-corn relay intercropping plots (47 plots). In 2014, there were only two intercropping plots, and wheat-corn relay intercropping plots all converted to monoculture plots, of which 51% plots changed to corn plots. All rice plots turned to maize plots. 3) At the plot level, the elevation of the planting area, the irrigation quota and the water supply from headwaters have significant effects on the change of agricultural structure (significance level is 1%). The impact of groundwater on agricultural structure change is also significant (significance level is 5%). 4) As rational economic men, the most important factor affecting the planting behaviors of farmers is income. Policy factors (at 5% of significance level), agricultural labors and the area of cultivated land per capita also have effects.
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    Resource Ecology
    The Ecological Effects of Ecological Security Barrier Protection and Construction Project in Tibet Plateau
    HUANG Lin, CAO Wei, XU Xin-liang, FAN Jiang-wen, WANG Jun-bang
    2018, 33 (3):  398-411.  doi: 10.11849/zrzyxb.20170116
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    Tibet Plateau is an important ecological barrier of China. It is also the source region of many rivers and the gene bank of biological species. In order to protect the ecological function of Tibet Plateau, Ecological Security Barrier Protection and Construction Project was carried out in Tibet Plateau since 2008. Based on the objective of the project, this paper assessed the ecological effects of the Ecological Security Barrier Protection and Construction Project scientifically by comparing and monitoring the temporal and spatial changes of ecosystem and its key services between 2000-2008 and 2008-2015 in Tibet Plateau. Comparing the ecosystem in eight years before and eight years after the project, it was concluded that: 1) The ecosystem structure of the Tibet Plateau was stable and less dynamic, and the macro patterns of the ecosystem tended better. The area of forest continued to increase, the desert was significantly reduced, and the area of water and wetland decreased firstly and then increased. 2) The trend of grassland degradation was weakened, and the grassland was obviously restored. The proportion of degrading grassland decreased by 19.9% and the proportion of restored grassland increased by 33%. The vegetation coverage increased 1.9% in Tibet Plateau, especially the alpine meadow. The significantly reduced loading pressure of grassland and the enhanced forage supply capacity both alleviated the contradiction between grassland and livestock. 3) The capacity of ecosystem water conservation increased, the total amount of carbon sinks increased slightly, and the capacity of ecosystem sand fixation increased steadily. However, the increasing rainfall enhanced the erosion, so soil layer could not recover in a short period in spite of the increase of vegetation coverage. Thus, the capacity of soil conservation service declined. 4) The warm and humid climate in the Tibet Plateau is conducive to slow down the process of desertification and promote the ecosystem restoration, and the implementation of the Ecological Security Barrier Protection and Construction Project has positive effects on the improvement of the ecosystem service capacity, especially in the local regions of the project.
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    Dynamic Monitoring of Ecological Vulnerability in Arid Desert Ecological Region of Northwest China and the Quantitative Analysis of Its Driving Forces
    GUO Bing, KONG Wei-hua, JIANG Lin
    2018, 33 (3):  412-424.  doi: 10.11849/zrzyxb.20170068
    Abstract ( )   HTML ( )   PDF (13471KB) ( )   Save
    Under the double stress of global climate change and human activities, the fragile ecosystem in arid desert region of Northwest China has undergone profound changes. Thus, how to evaluate the ecological vulnerability of the arid land has become a hot topic in the field of ecology. Fully considering the characteristics of the eco-environment (desertification, salinization, wind erosion, drought and other disasters) in the study area, we introduced extreme climate event factors (indicating the climate changes) and large-scale landscape pattern indexes (indicating the disturbance of human activities on the ecological landscape) to establish the evaluation system of ecological vulnerability in arid desert region of Northwest China. Then, the spatial-temporal change of ecological vulnerability and its driving mechanism during the past 13 years were analyzed and discussed. The results showed that: the ecological vulnerability of arid desert region in Northwest China generally belonged to the level of moderate or severe vulnerability, and the spatial distribution pattern of ecological vulnerability showed a decreasing trend from east to west and a “E” pattern appeared in the western part, which was significantly affected by the atmospheric circulation and special landform of “Two basins sandwiched with three mountains”. During the period of 2000-2013, the ecological vulnerability in the arid desert region of Northwest China showed a decreasing trend, and the changes were greatly affected by temperature, precipitation and human activities. There were significant relationships between the change intensity of ecological vulnerability and climatic tendencies of precipitation and temperature. The research results can provide decision supports for ecological protection and management in arid desert region of Northwest China.
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    Spatial-temporal Variation of the Vegetation Coverage in Qinling Mountains and Its Dual Response to Climate Change and Human Activities
    DENG Chen-hui, BAI Hong-ying, GAO Shan, LIU Rong-juan, MA Xin-ping, HUANG Xiao-yue, MENG Qing
    2018, 33 (3):  425-438.  doi: 10.11849/zrzyxb.20170139
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    The Qinling Mountains, a key ecological zone of terrestrial ecosystem, has experienced a significant change of vegetation coverage in recent years. Based on MODIS-NDVI data, DEM data and meteorological data such as temperature, precipitation, sunshine, humidity and wind speed, this paper calculated the Fractional Vegetation Coverage (FVC) in Qinling Mountains, analyzed the background characteristics of the “pattern-process-trend” change, and explored the dual response mechanism of the vegetation coverage to climate change and human activities with trend analysis method, multiple regression method-residual method and PLS regression method. The results of the study showed that: First, the FVC in Qinling Mountains showed a significant increase trend at a growth rate of 2.77%/10 a during 2000-2015, with a very significant upward trend in the southern slope at a growth rate of 3.8%/10 a and a non-significant downward trend in the northern slope. In the space, FVC showed the pattern that is “high in the middle, low in the surroundings; high in the west, low in the east; high in the south-slope, low in the north-slope”. Second, the level of FVC in Qinling Mountains varied greatly, and the order of each FVC grade in area was Ⅴ, Ⅳ, Ⅲ, Ⅱ and Ⅰ, the area of Ⅰ and Ⅴ showing significant upward trend while the area of others showing decline trend. Third, the change of FVC at different altitudes was significantly different. There was a significant upward trend under 1 500 m and obvious downward trend at 2 600 m, while there was no obvious change at 1 500-2 600 m. With the increase of altitude, the FVC reached a maximum at 2 200 m. The FVC at 700-3 200 m was more than 0.7 and at 1 300-2 700 m was more than 0.9, and values below 0.5 mainly appeared in high altitude area above 3 400 m. Forth, there were significant spatial differences in the response of vegetation coverage to climatic factors. The response of vegetation coverage to precipitation had time lag, with a lag of one month, while the response to temperature did not have time lag. Fifth, the role of human activities was increasing rapidly, with the growth rate of 2.10%/10 a. The positive effect of human activities on FVC mainly distributed in the eastern region, and the negative effect of human activities mainly distributed in the central and western regions. Finally, the FVC changes were the results of both climate change and human activities, and the impact factors from strong to weak are human activity, precipitation, temperature and potential evapotranspiration.
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    Research on the Seasonal Variations and Optimization of Landscape Pattern in Poyang Lake Region, China
    NING Li-xin, ZHOU Yun-kai, BAI Xiu-ling, XU Shan-shan, ZHANG Qi-bin, LI Pei-jun
    2018, 33 (3):  439-453.  doi: 10.11849/zrzyxb.20170041
    Abstract ( )   HTML ( )   PDF (8821KB) ( )   Save
    Due to the seasonal changes of temperature, precipitation and other environmental factors, the landscape pattern in a region will show seasonal variations during a year, which will impact the ecological process in the region. Landscape pattern optimization should base on a comprehensive understanding of the landscape pattern and ecological process and adjust the quantity of various landscapes and their distribution and configurations in space to produce the greatest landscape function and ecological benefits. Therefore, a reasonable optimization program of landscape pattern cannot ignore the seasonal changes of landscape pattern and ecological process. In this paper, the Poyang Lake region, demarcated by natural attributes, was chosen as an example for landscape pattern optimization. Based on the theory of landscape ecology, the seasonal variation characteristics of landscape pattern in Poyang Lake region were quantitatively analyzed with GIS spatial analysis technology. The results show that the seasonal variations of the overall landscape pattern in Poyang Lake region were obvious. Compared with those in high water period, the patches in low water period were more fragmented and the shapes of the patches were more complex. The landscapes were less aggregated and the landscape heterogeneity was higher in high water period than in low water period. As for types, the change of bottomland was the most obvious in the landscapes. Based on the seasonal variation of landscape pattern, the ecological components, including source, corridor (three types) and nodes, in high and low water periods of Poyang Lake region were identified and constructed with the Minimum Accumulative Resistance model and GIS spatial analysis module, and an ecological function network of “Patch-Corridor-Matrix” was formed. Through the comparison and analysis of ecological components in different hydrographic periods, the major ecological components which play important roles in maintenance of landscape pattern and function were chosen to build a reasonable landscape pattern optimization program. This program aimed to enhance the connectivity of landscape network and operation of ecological flows, strengthen the stability and sustainability of ecological system. This research provides the reference for the ecological planning and management in Poyang Lake region.
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    Resource Evaluation
    Spatial Characteristics of Coal Transportation Network in China during 1990-2014
    ZHU Meng-jue, ZHUANG Da-chang, LI Tao
    2018, 33 (3):  454-466.  doi: 10.11849/zrzyxb.20170060
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    Coal resource plays an important role in energy production and consumption in China. Based on the input and output matrix of coal in 31 provinces, municipalities or autonomous regions during 1990-2014, this paper uses social network analysis method to analyze the overall temporal and spatial evolution characteristics of coal transportation network and the role of each node and in coal transportation network, and the result shows that: 1) The density of coal transportation network in China fluctuated and experienced quick increase during 1990-2000, increase’s slowing down and then speeding up during 2000-2010, and slow increase during 2010-2014. The fluctuation of increase was partially related to changes in coal policy, international economic situation, coal prices and shipping costs, the increase of China’s overseas coal imports in recent years, overcapacity of coal in domestic country, and so on. 2) The outward central potential of coal network was significantly greater than the inward central potential, and the output of coal centralized in a few provinces and autonomous regions while the demand for coal input was universal. 3) Coal transportation network can be divided into five regions based on the cohesive subgroups of the network, which were Northeast and North China, Central South China, Southeast China, Southwest China and Northwest China. The network linkages among subgroups were quite different. Among them, Shanxi Province and Shaanxi Province, two national coal centers, had strong power in external expansion. The Northeast and North China and Southwest China attracted a lot of investment, but they had weaker external influence. Northeast China transported goods to Southwest China and Central South China and then transport to the Southeast China. Central South China had become the important coal supply and transit area for Southeast China. 4) Based on the analysis of degree centrality, closeness centrality and betweenness centrality of the network, the core nodes of the coal transportation network changed greatly. The control force of Shanxi became lower than before, and Inner Mongolia and Shaanxi had exceeded Shanxi in controlling very big area. The influence area of Inner Mongolia extended from Northeast China to Northwest China and Central South China. The influence area of Shaanxi extended from Central South China to Southeast and Southwest China. The controlling force of Hebei and Hunan also rose. Guizhou and Liaoning had the controlling force raised and became core nodes in the network. Xinjiang had become a new place of coal output, but needed more output channels to enhance its role. The controlling power of Henan, Sichuan, Ningxia, Shandong, Jiangsu, Gansu and other provinces declined in different degrees.
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    Study on Environmental Flow in Yangtze River Estuary Based on Hydro-economic Analysis
    TANG Yu, SONG Xian-fang, BAUER-GOTTWEIN Peter, BU Hong-mei, YANG Li-hu, ZHANG Ying-hua, HAN Dong-mei, MA Ying, DAVIDSEN Claus
    2018, 33 (3):  467-477.  doi: 10.11849/zrzyxb.20170119
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    Suitable environmental flow requirements are important for maintaining stability of ecosystem in estuary area as well as satisfying social and economic demands for water in upstream area. The aim of this research is to discuss suitable environmental flow in Yangtze River Estuary on the basis of regional water resources allocation. Based on the analysis of economic value of water, a hydro-economic optimization model is built for the middle and lower reaches of the Yangtze River Basin with minimum environmental flow constraint in Yangtze River Estuary. By changing the environmental flow constraint in Yangtze River Estuary, variations of regional water shortages and shadow costs with the environmental flow constraints are discussed. The results show that the regional water shortage begins to increase and the shadow cost of the environmental flow constraint becomes positive when the environmental flow constraint exceeds a certain critical value. Upper and lower limits of suitable environmental flow are obtained according to regional water supply target and shadow costs of the environmental flow constraints. Suitable environmental flows in Yangtze River Estuary at water resources guarantee rates of 20%, 50%, 75% and 95% are 27.10 billion-29.65 billion m3/month, 25.50 billion-27.12 billion m3/month, 23.08 billion-24.62 billion m3/month and 17.72 billion-19.65 billion m3/month, respectively. With these environmental flows, the water demands in upstream area can be satisfied and ecological objectives in Yangtze River Estuary can be realized.
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    Downscaling Method of TRMM Satellite Precipitation Data over the Tianshan Mountains
    FAN Xue-wei, LIU Hai-long
    2018, 33 (3):  478-488.  doi: 10.11849/zrzyxb.20161384
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    The precipitation in mountains is an important supply of water resources in arid areas. The error of hydrology forecast is still high in mountain areas because of complex terrain and lack of data. In recent years, TRMM3B43 data have been widely used in precipitation estimation. However, there is limit of TRMM data in resolution (0.25°×0.25°). Based on the TRMM3B43 data during 2001-2010, a principal component-stepwise regression model for downscaling TRMM3B43 precipitation was built with seven topographic factors (longitude, latitude, altitude, slope, aspect, terrain unobstructed factor, relief degree of land surface) in this paper. The downscaling model can transform the pixel resolution from 0.25°×0.25° to 1 km×1 km effectively. The downscaled precipitation estimations were subsequently validated by observed data at 21 raingauge stations in Tianshan Mountains during 10 years. The results showed that: 1) The downscaled precipitation results have smaller errors than the original TRMM precipitation data, and the maximal improved value of annual average precipitation is 63.16 mm, suggesting the good performance of principal component-stepwise regression downscaling model. 2) The spatial distribution characteristics of precipitation in the Tianshan Mountain can be depicted by downscaled results in detail that the high precipitation values mainly appear in the Yili Valley of the western Tianshan Mountains and the low values appear in Turpan and Hami of the eastern Tianshan Mountains. 3) The downscaled results conform well with the observed data in each elevation zone in the Tianshan Mountains, but the downscaled results overestimated the actual precipitation to some extent. So the downscaling method in this article is feasible, which could provide spatial distribution of precipitation in fine resolution in arid region.
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    Spatial Prediction of Cultivated Land Soil Nutrients in Typical Region of Yellow River Delta
    LI Yan-ling, ZHAO Geng-xing
    2018, 33 (3):  489-503.  doi: 10.11849/zrzyxb.20170067
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    A good understanding of the distribution characteristics of soil nutrients is important to achieve the best management of soil nutrients. Kenli County, a typical delta area in Shandong Province in North China, was chosen as the study area of this paper. There were 1 278 soil samples (0-20 cm) collected, processed and analyzed in laboratory. Geostatistical analysis was conducted to elucidate the spatial variations of soil nutrients and interpolate key soil nutrients in space. The semivariogram models of alkali-hydrolyzable nitrogen (AN), available phosphorus (AP) and available potassium (AK) were estimated. The best fitting models were selected based on the residual sum of squares (RSS) and coefficient of determination (R2). The R2 of AP’s spherical model was 0.951, followed by R2 of AN’s exponential model (0.892) and R2 of AK’s spherical model (0.787). The interpolations were employed with Ordinary Kriging (OK), Inverse Distance Weighted (IDW),Universal Kriging (UK),Radial Basis Function (RBF) and Local Polynomial (LP) in GIS software. The prediction accuracy was validated with test data. In order to explore the self-adaptive ability of OK, IDW, RBF and LP, eight datasets with different spatial distribution patterns were designed with AN data. The default optimized model of each method was used on the eight datasets and the results were compared. It comes to the following conclusions: 1) The spatial variations and autocorrelation of AN, AP and AK in the study area are moderate. The best fitted semi-variogram models are spherical model, exponential model and spherical model, whose coefficients of determination were 0.951, 0.892 and 0.787, respectively. 2) The spatial distribution patterns of AN, AP and AK are closely related to the terrain and land use types in the study area, i.e., the contents of key soil nutrients are high in the southwest part of region where there are irrigated land and dry land and northeast part of the region where the cropland is along the Yellow River and affected by the freshwater of the river, and the nutrient contents are lower in the central region where there is paddy field. 3) Compared with Nugget/sill, Moran’s I, the most widely used index to describe spatial autocorrelation, is more robust and effective for measuring spatial autocorrelation of soil nutrients. 4) The influence factors of spatial interpolation are spatial distribution pattern, sample number, spatial autocorrelation and spatial clustered degree (measured with Nearest Neighbor Rate); in dispersed pattern, all methods perform bad; in random pattern, IDW and RBF perform better than OK and LP; in clustered pattern, the adaptabilities of the methods are related with sample number and spatial autocorrelation, and all methods perform almost the same when there are enough samples. This paper ascertained the best interpolation prediction method for the main soil nutrients in the study area, analyzed the variation and the spatial distribution of soil nutrients, and provided a theoretical basis for soil nutrients management and agricultural sustainable development in typical area of Yellow River Delta.
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    Resource Research Method
    Potentiality Evaluation of Three-dimensional Urban Land Use Based on Improved Polygon Area Method—A Case Study of Shenzhen
    XU Zhi-bo, LUO Ting-wen, WEN Chu-jun, YAO Yao
    2018, 33 (3):  504-514.  doi: 10.11849/zrzyxb.20170055
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    Reasonable evaluation of the potentiality of three-dimensional land use can promote the fine management of land use, thus it is of great significance to scientific land management and sustainable urban development. Based on four factors, i.e., social and economic status, land use status, comprehensive development opportunity and eco-environmental restriction, an evaluation system with 13 elements was established and indices were calculated with improved polygon area method to evaluate the potentiality of three-dimensional land use. Multiple-source data, such as statistical yearbook data, census data, land use survey data and building survey data, were used to support the analysis. The method was conducted in Shenzhen to validate the effectiveness of the evaluation. For a more accurate evaluation, Delphi method was used in each of the 11 city clusters to determine the relative importance of different factors on the three-dimensional land use in each region, since the dominant functions of different regions were different. The result showed that: the improved polygon area method could reflect the incomplete substitution relation and emphasize synergistic effect between different factors very well. It could be more pertinent to evaluate the potentiality in a region by using a weight matrix adjusted by the regional difference instead of using a uniform weight. From the perspective of single dimension, regions with the best social and economic status gathered in the central urban area of Shenzhen; regions with high score of land use status were disperse; Qianhai-Houhai area and Longgang Center area were regions with greater comprehensive development opportunity; the eco-environmental restriction of urban built-up area near the basic ecological control line could be more strict and less suitable for three-dimensional land use. Overall, the potentiality of three-dimensional land use in Shenzhen decreased from south to north and from west to east. High potentiality areas accounted for 26.46% of build-up areas (extremely high potentiality areas accounted for 8.65%) and showed overall pattern of dispersion with local clusters. Low potentiality areas accounted for 32.21% of build-up areas and mainly located at the periphery part of urban build-up areas. The central urban area and Qianhai-Houhai area were detected as the highest potential areas. In addition, Longhua-Bantian-Buji area, Longgang Center area, Sha Tau Kok and Baoan Airport New Town were regions with higher potentiality of three-dimensional land use. In a word, the improved polygon area method can estimate the potentiality of three-dimensional land use in Shenzhen very well. Moreover, it can make the practice of three-dimensional land use more scientific and systematic.
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    The Simulation of Cropland Abandonment Based on Multi-agent System and Land Transformation Model: A Case Study of Mizhi County, Shaanxi Province
    SONG Shi-xiong, LIANG Xiao-ying, CHEN Hai, MAO Nan-zhao
    2018, 33 (3):  515-525.  doi: 10.11849/zrzyxb.20170040
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    The integration of different models has been one of the effective ways to simulate LUCC. In this paper, several steps were designed to reveal the interactive mechanism between macroscopic pattern of cropland abandonment and microcosmic behaviors of agents. Firstly, a multi-agent decision-making model under bounded rationality was constructed which took the interactions among different agents into consideration. Secondly, the effectiveness of Land Transformation Model (LTM) in simulating the macroscopic pattern of cropland abandonment in the study area was tested through the training on SNNS platform and the comparison with historical data. Thirdly, Cropland Abandonment Simulation Model (CASM) was formed by integrating multi-agent system (MAS) and LTM, and the rationality and feasibility of the CASM was explored. The result showed that the percent correct metric (PCM) of CASM was 71%, which was 3% higher than the PCM of LTM. This result indicated that CASM can not only simulate and analyze the distribution of spatial pattern of cropland abandonment in Mizhi County, but also effectively reveal the micro driving mechanism of cropland abandonment. Finally, several advices of future research were given to improve the explanatory ability of CASM, e.g., the effect of policy, market and the decisions of different levels of agents (such as the rural cooperation and government) on the cropland abandonment should be considered.
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    Comprehensive Discussion
    Paradigm Shift in the Study of Land Carrying Capacity: An Overview
    JIN Xiang-mu, LI Chen
    2018, 33 (3):  526-540.  doi: 10.11849/zrzyxb.20170149
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    In accordance with Kuhn’s paradigm theory, four main evaluation paradigms of land carrying capacity were explored and combed, namely, the evaluation paradigms based on limiting factors, comprehensive multi-factors, reference areas, and ecological footprints. The four evaluation paradigms were compared from the perspective of history background and spatial scale. It is found that the paradigm based on limiting factors had the longest history and was fully developed, while the paradigms based on comprehensive multi-factors, reference areas, and ecological footprints were all based on the former but developed along separate paths. The reason for the paradigm shifting is that the realistic questions which need to be explained and solved were always changing with time and space. There is no good or bad paradigms, but each one has its specific adaptability. To evaluate the land carrying capacity on the scales of global and country, the paradigm based on limiting factors or on ecological footprints may be better choice, while the paradigm based on comprehensive multi-factors or on reference areas is more appropriate for land carrying capacity evaluation at city and county levels. However, the research of the latter two paradigms is relatively weak, the outcome of which, namely, the rating of carrying capacity, or the relative value of carrying capacity has limit value in guiding land management. Therefore, it is urgent to strengthen the research of land carrying capacity at the city and county scales and to improve the effectiveness and maneuverability of guiding practice.
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