An analysis of region disparities between land productivities and land use comprehensive conditions in China

To analyze the region disparities between land productivities and land use comprehensive conditions helps to disclose the impact of land use conditions on land productivities, and to provide decision foundation about how to improve the land potential productivities. Establishing a 500m×500m grid digital ground model of China's land productivities and land use comprehensive conditions, the article puts forward the main ideas, content, and methods of analyzing the region disparities between land productivities and land use comprehensive conditions. Choosing a region of the worst grade of the land productivities, the article contrasts its relevant natural conditions, socio-economic conditions and comprehensive conditions of land use with its land productivities. The conclusions are as the following: in the region of the worst land productivities, its land use socio-economic conditions are mainly among the second or third grade, and its natural conditions of land use are mainly among the third grade, but not among the worst grade of the two aspects. It indicates that in the region of the worst grade of land productivities, there is a great potential to improve its land productivity, according to its current comprehensive conditions of land use. I. CONSTRUCTION OF LAND USE COMPREHENSIVE DIGITAL GROUND MODEL Digital ground model, a digital description of one or varied ground feature of space distribution, which adding one-dimensional or multi-dimensional ground feature of vector space to two-dimensional geographical space, is a kind of substance of geographical systematic space data bank or the sum of all, and the essential generality of digital ground model is two-dimensional geographical space location and digital description. For what it is, the digital description of reflecting all features of spatial distribution of land use could be named land use comprehensive digital ground model. The spatial distribution of the LUCDGM is described by x, y level coordinate, while the features of it mainly contain land use natural condition (terrain and landforms, water temperature condition, vegetation etc.)、 land resources survey data and other related social economic factors. The basic data of land use natural condition are established according to the environment factors data of national space distinguishing rate 500m*500m provided in China “the Ninth Five-Year Plan” key item. Among them, the temperature and humidity data are established by collecting the meteorological data of 1915 stations in whole country. II. THE TOTAL THOUGHT OF ANALYZING THE DIFFERENCE BETWEEM LAND PRODUCTIVITY AND LAND USE COMPREHENSIVE CONDITIONS The main aim of analyzing the difference between land productivity and land use comprehensive conditions is to disclose the different influences of condition factors on land productivity by comprehensively analyzing their differences, and to provide decision foundation about how to improve the land potential productivity. The Fig.1. is a total thought chart about the analyzing process. The calculation of land productivity, using the main components analyzing comprehensive evaluation method, synthesizes the two indexes of agriculture total output value in unit land area and grain yield in unit planting area into one. 2381 0-7803-9050-4/05/$20.00 ©2005 IEEE. 2381 General land use degree is comprehensively reflected by varied indexes, such as land use rate, reclaiming wasteland rate, cultivated land multiple crop index, woodland index, grassland use index, water surface use rate, town land use volume rate, building density, etc. According to land use classification in “the Ninth Five-Year Plan” item and other available materials, the article chooses the indexes of land use rate, reclaiming wasteland rate, woodland index, grassland index, water area index and town land use index to calculate the land productivity by adopting the main components analyzing comprehensive evaluation method. The social economic condition of land use contains lots of factors. Because of the obtaining data at present, including chemical fertilizer usage, agricultural machinery force, electricity usage, population, village population and village labor force indexes etc of all counties, the preliminary construction of digital ground model of social economic conditions can be set up only on these indexes. Agriculture input condition is a total index reflecting agriculture input intensity. To some extent, the differences of agriculture input conditions comprehensively reflect the difference of agriculture input intensity. The article chooses three indexes, chemical fertilizer usage, agricultural machinery force, electricity usage, in unit land area to comprehensively reflect agriculture input conditions. III. EXAMPLE ANALYSIS According to the total thought of the analyzing, multilevel difference analysis between land productivity and land use comprehensive conditions can be done. Land productivity usually accords with land use degree, land use natural conditions and social economic conditions, but it is not difficult to understand from determining the nature that land use degree, land use natural conditions and social economic condition etc may be different even if in the region of the same land productivity grade. There are many reasons for disappointing land productivity in some regions, maybe such as the poor degree and natural conditions of land use and the social economic conditions etc; or some bad unknown conditions among them, or only one poor condition; even all of these conditions are good, other social economic conditions could influence the land productivity comprehensively. The understanding of these concrete differences can help to state related policy-making body to make scientific decision. On one hand, we should know the difference of comprehensive conditions of the same land productivity grade on the macro-level; on the other hand, we can improve some land use conditions to increase the land productivity on the micro-level. Tab. I. Land use degree classification in the first grade region of land productivity Grade Grid number Area (km) Percentage (%) 2 295962 73990.5 0.07 3 949714 237428.5 0.23 4 1636691 409172.75 0.40 5 386222 96555.5 0.09 6 459741 114935.25 0.11 7 356937 89234.25 0.09 8 40633 10158.25 0.01