Cultivated land conversion and potential agricultural productivity in China
Introduction
Land is a critical input that is needed to keep the development process moving, allowing for the shift of people from the rural to the urban sector (CCICED, 2004). It is possible, however, that as cultivated land is converted to built-up area, it will conflict with national food security goals. While little was heard about this conflict in the late 1990s through 2003, as grain prices rose through the early part of 2004, policy makers and scholars began to debate the role of cultivated land conversions in the rise of food prices (Ministry of Land and Resources, 2004a; Feng et al. 2004; CCICED, 2004). On the one hand, at China's pace of development local leaders and developers in many parts of coastal China and in suburban areas around inland cities are in the middle of a period in which they have already committed large amounts of capital to development zones, factories and housing projects; they obviously are going to need access to land so that their plans can be fulfilled. Tens of millions of jobs in construction in the short run and hundreds of millions of jobs in the longer run depend on completing these projects and continuing on with more in the future. On the other hand, others have labeled the conversion as an irreversible destruction of cultivated land that will hurt national food security (Feng et al., 2004).
Is the rate of cultivated area conversion in China normal relative to the experiences of other rapidly developing nations or is it occurring at such a rapid pace that it is threatening national food security? That is the question that is at the core of the food security versus growth debate. International experience shows that rapid economic growth is always accompanied with shift of land from agriculture to industry, infrastructure and residential use (Ramankutty et al., 2002). Countries in East Asia, North America and Europe have all lost cultivated land during their periods of economic development (Caradec et al., 1999; Hamamatsu, 2002; Ramamkutty et al., 2002).
Although economic growth started later than in many other nations, China has grown extremely fast in recent years (NSBC, 2004). Since 1978 China's economy doubled itself more than three times. By 2002 the economy was about 8.5 times greater than at the beginning of the economic reforms. Such rapid economic growth has significantly improved the livelihood of China's population. During the 25 year period, agriculture also increased substantially, with agricultural GDP rising by around 5% per year. Since the population growth rate during the period was only 1.2%, food availability also improved (Huang et al., 1999). Hence, according to many indicators, rising income and food production have considerably improved China's food security and substantially reduced the rate and severity of poverty (World Bank, 2000). The rise of food output improved so dramatically that between 1983 and 2003, China was a net food exporter during every year. After the mid-1990s the nation also has been a net exporter of grain during every year except 2004 (Anderson et al., 2004).
Despite the achievements, concern over national food security remains as leaders worry that economic growth both increases the demand for land and can weaken incentives for agricultural production (CCICED, 2004). Since the late 1980s structural change allowing the emergence of cash crops, new export opportunities for labor-intensive fruits and vegetables and rising wages encouraged some of China's farmers to move out of grain production. At the same time urbanization and industrialization began to accelerate and cultivated land began to be converted to non-agricultural uses, such as for industrialization, the building of residences and the construction of infrastructure (Seto et al., 2000; Naughton, forthcoming). Such trends are expected to continue into the future as China maintains a high economic growth that can double the nation's economic output once again during the first decade of the 21st century.
Although food security concerns have always been part of the agricultural policy-making equation, at no time in the past decade have they surfaced as they did in 2004. Triggered by five successive years of falling grain sown area and production, food security once again has moved onto the agenda of national agricultural policy makers (CCICED, 2004). Food security concerns rose as the price of China's major grains began to rise in late 2003. Among other actions, in the early part of 2004 the State Council came out with strongly worded directives about the importance of slowing down the conversion of cultivated land to built-up area (Ministry of Land and Resources, 2004b). When the price rises continued, a directive came from the top leadership banning any further conversion, except for under certain extreme conditions (Central Committee of the Communist Party of China and China State Council, 2004). The issue of land conversion also immediately became a topic of intense debate. Interviews with local leaders and the reading of commentaries in local and national periodicals demonstrate that different sets of actors have had strong reactions favoring and opposing the strong measures against continuing with the conversion of cultivated land into built-up area. Some researchers believe the reversal of the policies is unnecessary and could slow down economic growth (CCICED, 2004). Another group of scholars claim the move is critical to maintaining national food security (Brown, 1995; Yang and Li, 2000; Verburg et al., 2000).
Surprisingly, although the issue is so important and has such far-reaching consequences, there is almost no empirical research studying the economic impact of land conversion in China. Several key questions are in need of being addressed. During the reform era, how much cultivated land has been shifted to non-agricultural use? Of the cultivated area that has been lost, how much has been due to urbanization and industrialization? While land is being converted out of cultivated area, how much land has been converted into cultivated area? What are the implications of cultivated land changes to the nation's food security?
Answers to the above questions are critical for China to be able to formulate appropriate policies that can ensure both food security and high economic growth in the coming decades. The overall goal of this study is to answer these questions by examining the changes in cultivated land base, the effect on productivity and its ultimate impact on food security. To meet the goal, changes in China's cultivated area over time and its conversion to built-up area and other uses due to urbanization, industrialization and rural settlement expansion are compared with the experiences of other countries in the world and are examined based on Landsat thematic mapper (TM)/enhanced thematic mapper (ETM) digital images covering China's entire territorial area during the past 15 years. After identifying areas that have changed from cultivated areas to built-up area, we then calculate the corresponding changes in the potential productivity of the agricultural land (henceforth, bioproductivity), using a methodology called Agro-Ecological Zones (AEZ).
Our study finds that, contrary to popular perception, there was not a large shift of land from agricultural to non-agricultural uses. In fact, although a large area of cultivated land was converted to built-up area, China's farmers and others converted even more land into land that could be used for cultivation. Hence, in a net sense China's cultivated land actually increased between 1986 and 2000. Because of differential qualities between land converted into and out of cultivated area, we do find that there was a fall in the bioproductivity of China's cultivated land. It is important to note, however, that the net decline in bioproductivity over the study period was so small that the rise in total cultivated area was almost large enough offset it. In the end there was only a very slight decrease (−0.3%) in total agricultural potential output, which is a measure that capture changes in both cultivated area and average bioproductivity. Based on this, it can be claimed that there was no adverse effect on food security from land conversion between 1986 and 2000. A final section also examines briefly the situation since 2000 and likewise concludes that land conversion has not had a major negative effect on food security.
Addressing such a broad topic obviously is not possible to do in a single paper. Consequently, we need to limit the paper's scope. In particular, while we address at length the nature of the change of land use and the impact that it has on agricultural productivity potential, we do not address the impact of other dimensions of urbanization. Urbanization frequently is accompanied by a number of other economic forces, such as increasing income, changing consumption patterns and rising wages. Although all of these may affect agricultural production and productivity, a complete analysis of them is not included here. The interested reader is directed to a number of other papers that have examined such issues in greater detail (for example, Huang and David, 1993; Huang and Bouis, 2001). We also abstract away from regional disparities in the paper. Although issues of access of food by people in different parts of China could be an issue, its discussion also is beyond the scope of the paper. Concerns about the difficulty of moving food around the country, however, should be allayed by reading Huang et al. (2004). In this paper, the improvements to China's markets are documented and it is shown that agricultural commodity markets are becoming increasingly competitive, integrated and efficient.
Section snippets
Cultivated land conversion in an international perspective
While many scholars and policy makers in China often discuss the loss of cultivated land as if it were happening due to the weak property rights and other characteristics that are unique to China, a review of the international literature shows that land conversion is not only occurring in China (Ramankutty et al., 2002). In fact, land conversions happen in all countries, especially those that are rapidly developing. For example, in Japan cropland has been declining during the last three decades
Methodology
In trying to assess the trends in the quantity and quality of China's cultivate land, some researchers have relied on secondary data collected by those in the nation's land administration (Crook, 1993; Ash and Edmonds, 1998; Fischer et al., 1998; Smil, 1995, Smil, 1999; Zhang et al., 2000; Seto et al., 2000). Unfortunately, there are many reasons to be concerned about the quality of the statistical system's land conversion data. Local officials, who benefit from land sales, have an incentive to
Data
One of the strengths of our study is the quality of data that we use to estimate cultivated land use change and potential agricultural productivity. Satellite remote sensing digital images for our purposes are the most suitable data for detecting and monitoring LUC at global and regional scales (Kok, 2004). There are a number of choices. Satellite sensors, such as Landsat TM, and the French SPOT system, have been used successfully for measuring deforestation, biomass burning and other land
Results
Using Landsat imagery and associated methods we estimate changes in China's cultivated land between 1986 and 2000. In the first part of the section we examine the changes in the areas of different land uses. In the second part we estimate changes in the average potential agricultural productivity of the land. From these two components we can come up with an estimate of the net impact of land conversions on food security during the late 1980s and 1990s.
Cultivated land changes since 2000
While our paper so far has established, on the basis of Landsat data, that land conversions did not negatively affect food security between 1986 and 2000, we have no Landsat data after 2000. Therefore, it could be that the recent concern by observers is purely being voiced about trends in more recent years. According to published data since 1997 (which are more consistent than a longer time series due to the fact that the Ministry of Land and Resources of China collected all of the post-1997
Conclusions
Our study finds that after the 25 years of rapid economic growth, unlike the perception of many, there has not been a large shift of land, especially in a net sense, out of cultivated area. In fact, in terms of the overall retention of cultivated land, China's agriculture is actually doing well relative to other nations. Indeed, net cultivated land actually increased during the study period, 1986–2000. Our decomposition of cultivated land changes show that nearly half of lost cultivated land
Acknowledgments
The authors would like to thank Jian Liu, Bernie Sonntag and two anonymous reviewers for comments on earlier versions of this manuscript and Jiyuan Liu, Yimou Wang, Wancun Zhou, Rendong Li, Nan Jiang, Shuwen Zhang, and Shixin Wu for their supports on the remotely sensed data. The financial supports from the National Natural Science Foundation of China (70503025 and 70021001), Chinese Academy of Sciences (KZCX3-SW-418) and China Council for International Cooperation on Environment and
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