Trend analysis and data reconstruction of cultivated land resources in China: Feng Zhiming/Liu Baoqin from 1949 to 23/ Yang yanzhao

originally published in journal of natural resources, No.1, 25

English title a study of the changing trend of Chinese cultivated land amount and data reconstruction: 1949-23 fengzhi-ming1, LIU Bao-qin 1,2,YANG Yan-zhao 1,2 (1.Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 111,China; 2. Graduate School of the Chinese Academy of Sciences, Beijing 139, China)

Title Annotation Fund Project: Important Direction Project of Knowledge Innovation Project of Chinese Academy of Sciences (KZCX3-SW-333).

Author brief introduction Feng Zhiming (1963 ~), male, born in Pingshan, Hebei Province, researcher, doctoral supervisor, mainly engaged in the study of efficient utilization of agricultural resources and regional sustainable development, and the theoretical discussion of resource science. Institute of Geographical Sciences and Resources, Chinese Academy of Sciences, Beijing 111; Liu Baoqin Institute of Geographical Sciences and Resources, Chinese Academy of Sciences, Beijing 111; Graduate School of China Academy of Sciences, Beijing 139 Yang Yanzhao Institute of Geographical Sciences and Resources, Chinese Academy of Sciences, Beijing 111; Graduate School of China Academy of Sciences, Beijing 139

Abstract Due to statistical reasons, there is no objective description of the change of cultivated land resources in China since 1949. In order to solve this problem, this paper analyzes the data series of cultivated land from different sources in different periods from 1949 to 23, and thinks that the period with more problems in statistical data is from 196 to 1985, and uses the grain output to invert the cultivated land area in different periods, and then deduces the cultivated land quantity from 1986 to 1996 according to the results of the national land use survey, thus re-portraying the changing trend and quantity of cultivated land resources in China since the founding of the People's Republic of China. The results show that the amount of cultivated land resources in China has fluctuated since 1949, but it increased on the whole before 1979, and declined slowly since 198s. After 1999, the amount of cultivated land decreased rapidly due to ecological returning farmland and other reasons, which led to food security and cultivated land security problems in China. After a period of rapid large-scale ecological conversion of farmland, the speed of ecological conversion of farmland in China will gradually slow down, and cultivated land security and food security will become the main problems affecting the change of cultivated land quantity in China. Strict cultivated land protection policy will be implemented, and it is expected that the cultivated land resources in China will stabilize after 21.

English abstract studies of cultivated land change in China have long been tortured by the lack of accurate and reliable data since 1949. by analyzing the cultiva. ted land data from different sources in different phases after 1949, the paper considers the statistics with more errors happens during 196-1985.According to the systematic data on land use gathered in the 1996 survey, based on reverse deduction of the cultivated land area from 1986 to 1996, and deduction of the cultivated land area from 196 to 1985 by stages by employing yield of grain, this paper redescribed the actual changing trend and character of Chinese cultivated land and analyzed the driving force of the policy relative to cult ivated land to cultivated land area change.The result indicated that the Chinese cultivated land amount has been fluctuating since the founding of New China in 1949.It increased as a whole before 1979, and decreased slowly since the 198s.The cultivated land amount decreased rapidly after 1999 because of cultivated land conversion into land for ecolog ical purpose,hence the problems of grain security and cultivated land security result from which need to be paid more attention to.In future, the pace of ecological cultivated land conversion will be slowed down gradually after a fast ecological rescue phase, the grain security and cultivated land security will become the main influencing factors which affect changes of Chinese cultivated land amount.With th e strict implementation of cultivated land protecting policy, The Chinese cultivated land amount will keep steady after 21.

Keywords: land use/cultivated land resources in China/trend analysis/data reconstruction landuse/Chinese cultivated land/trend analysis/ Data reconstruction

Cultivated land is one of the most common forms of land use on the earth, and it is also the land type most affected by human activities. The global cultivated land accounts for 1.2% of the total land area [1], and the change characteristics and dynamics have become an important content of land use/land cover change research. The cultivated land area in China accounts for about 8.6% of the world's cultivated land resources (the data of China's cultivated land area is taken from the results of the national detailed land survey in 1996, and the world's cultivated land area is calculated according to the data of 1997 in the World Resources Report 2-21), accounting for 13.68% of the country's total land area [2], and the change of cultivated land resources is undoubtedly an essential content to accurately describe the land use/land cover change in China. Affected by human activities, the increase and decrease of cultivated land resources are particularly frequent, and there are great differences in the statistical scope and caliber of cultivated land area in China at different times due to various reasons. Many international scholars believe that there are great problems in the confidence of cultivated land statistics in China, such as Crook F W's belief that the cultivated land area in China is underreported [3], and the International Institute of Applied Systems Analysis (IIASA) even thinks that the cultivated land statistics in China may have an error of about 4% [4]. However, there is no convincing conclusion about how the amount of cultivated land resources in China has changed since 1949, whether it has increased or decreased, or whether its volatility has changed. There are many viewpoints that "the cultivated land area in China has basically shown a downward trend since 1957" [5 ~ 7], and the research is basically based on the cultivated land data in the China Statistical Yearbook. However, with the announcement of the results of the national land use survey in the mid-198s and the detailed land use survey in the mid-199s, the above viewpoints began to be widely questioned. In view of this, based on the different historical stages of China since 1949, This paper systematically analyzes the cultivated land data, and reconstructs the cultivated land resources data in the period when the statistics are different from the real situation, trying to reflect the changing trend and dynamic characteristics of cultivated land resources in China since 1949. 1 Empirical Analysis and Basic Judgment of Cultivated Land Data in China since 1949 There are many sources of cultivated land data, and the time period and accuracy reflected are also different. The longest time series is the data of China Statistical Yearbook (1949-present), followed by the data of the increase and decrease of cultivated land published by the Ministry of Land and Resources (State Bureau of Land Management before 1997) since 1987. Among them, the latter is considered as authoritative data, which can basically reflect the real situation of the change of cultivated land resources in China, while the former is now recognized that its "statistical area" is smaller than the actual situation, and this point is also indicated in the data itself. Other data, including "general survey area", "general survey area" or "detailed survey area" obtained by relevant ministries and commissions through investigation, are only for a short period of time or time, but because of their relatively unified classification standards and advanced investigation methods, they can be used as the base for farmland data analysis and inspection. In addition, the data of cultivated land in China provided by some foreign organizations, such as World Resources Report, can also be used as a reference. Since the mid-198s, with the application of high-tech means such as remote sensing in the study of land use/land cover change, the obtained cultivated land data are more timely and can reflect the change characteristics of cultivated land resources in China in recent 2 years in more detail and accurately. 1.1 1949 ~ 196 in the early days of liberation: The statistical data of cultivated land in China can basically reflect the quantity and changing trend of cultivated land resources in China. In 1957, the cultivated land area increased to (1.677 billion mu), which was the peak of the statistical area of cultivated land in China. When New China was founded, all parts of the country were not completely liberated. Therefore, the statistics of cultivated land in 1949 were obtained by using the statistics of the Kuomintang government and revising the estimates. Although the land was generally measured in the land reform from 1949 to 1952, it was a pity that the data of cultivated land at the grass-roots level were not summarized at that time. However, according to statistics, the cultivated land area in China showed a rapid growth trend in the early days of the founding of the People's Republic of China, with an average annual increase from 1949 to 1952, which was consistent with the actual situation in China during that period. In the early days of the People's Republic of China, on the one hand, farmers (including some veterans) restored and reclaimed the abandoned farmland after the war, and on the other hand, the nationwide land reform movement greatly improved farmers' enthusiasm for production. After a long period of war, the surge in cultivated land area is reasonable. According to World Resources Report 1987, in 195, the area of cultivated land in China was, and that in China Statistical Yearbook was. Although it was slightly smaller than the former, the concept of cultivated land in the world resources statistics covered a wider range (cultivated land in the world resources report refers to temporarily and permanently planted land, temporarily grazing grassland, vegetable garden for market and household use and temporarily leisure farmland), so it is more reasonable. In order to determine the agricultural tax, from 1951 to 1953, the whole country carried out the work of checking fields and fixing production. This work is the first comprehensive and thorough land survey since the founding of the People's Republic of China. According to the "Implementation Outline of Agricultural Tax Checking Field and Determining Production" published by the Ministry of Finance on July 5, 1951, it can be seen that the survey was well organized, with unified standards, and was carried out under the extensive participation and supervision of the masses. Although the indigenous measurement method adopted at that time was not accurate enough, and some errors were caused by the disunity of mu system in various places, its accuracy was already relatively high in terms of technical conditions at that time. The cultivated land area in China, which was summarized according to the results of field survey and fixed production, was truly reflected in the statistical data in 1953, with a total amount of. This data can be used as a reference base point of cultivated land area in the early days of liberation in China, and then the data from 1949 to 1952 are checked, and it is found that there is a good convergence between them (the data in 1952 is ). From 1953 to 1957, the statistical work in China was relatively normal. Through a large number of land reclamation in this period, the statistics of cultivated land in 1957 increased to. This figure is also more realistic. 1958-196 was an extremely abnormal period when the cultivated land area in China was greatly reduced. The "Great Leap Forward" led to the imbalance of the national economy, and a large number of cultivated land was occupied and abandoned. Coupled with the impact of natural disasters for three years, according to the estimation of the Ministry of Agriculture and Forestry in 1978, the cultivated land was converted and destroyed from 1958 to 196, and the newly opened wasteland was near, which made up for the net reduction of cultivated land, which was basically consistent with the net reduction of cultivated land in China from 1958 to 196 [8]. Generally speaking, it can be considered that the statistical data of cultivated land until 196 can basically reflect the quantity and changing trend of cultivated land resources in China. 1.2 196-1978 before the reform and opening-up: there was a big gap between the statistical area and the actual cultivated land, and the reliability of the continuous decrease of the statistical area of cultivated land from 196 to 198.