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Arguments - Data Quality |
| Arable Land |
| China's land-use data were
very unreliable in the past. In particular, arable land was greatly underreported.
For many years, China's statistical yearbooks included data on cultivated areas showing a
national total of about 95 million ha. Recent estimates of China's cropland area, which
are around 130-135 million ha, seem to be more reaslistic. |
| Short Description of the Problem |
| Two issues are
critical in this context: |
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The problem of underreporting
in Chinese land-use statistics |
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The question of what is the
most likely area of China's cultivated land |
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| Discussion |
| The problem of underreporting |
Tables & Charts |
For many
years, China's statistical yearbooks included data on cultivated areas showing a national
total of about 95 million ha. For instance, the 1993 yearbook reported a total cultivated
area of 95.43 million ha (CSY, 1993, p. 332); the 1998 yearbook reported 94.97 million ha
(CSY, 1998, p.389). Usually these yearbooks also included time series showing a decline in
the total cultivated area of China since 1987.
In the early 1990s these data were frequently used by scholars both inside and outside
China to demonstrate the "serious losses of cultivated land" that China
supposedly experienced as a result of its rapid economic development. The expansion of
infrastructure and urban sprawl of booming coastal cities in China were frequently cited
as major causes of this decline in cultivated land. For instance, as recently as 1997, a
landmark study on Agricultural Policies in China by the Organisation for Economic
Co-operation and Development (OECD) included a paper by Zhang Linxiu, Huang Jikun, and
Scott Rozelle, in which they reported on "the decline of cultivated land" in
China (see Table 1). They argued that the expansion of residential areas due to population
increase and the growth of rural industries were major factors in the decline. Many other
papers also used these "official" data. While he is not specific on that issue,
Lester Brown (1995) obviously also based his arguments concerning China’s cropland
losses on these statistics. Unfortunately, all these papers and books usually fail to
mention a very important footnote included in each statistical yearbook: "The
cultivated area in this table is underestimated and must be further verified" (CSY,
1998, p. 389). |
Table 1
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| What is the most likely area of China's cultivated land? |
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Today we
know that these Chinese land-use data were not just a little "underestimated,"
but were probably wrong by almost 40%. In 1994 the Chinese State Land Administration and
the State Science and Technology Commission (in collaboration with the UNDP and the FAO)
conducted a major study called "Land Resources, Use and Productivity
Assessment." In a draft version of its main report, the State Land Administration
estimated that China’s cultivated land area was 125.23 million ha in the early 1990s
(see UNDP et al, 1994, p. 38). This view was supported by Alexandratos from the FAO in a
paper published in 1996 (Alexandratos, 1996). Binsheng and Crook also support an estimated
cultivated area of 125 million ha for 1989 (Bingsheng, 1996; Crook, 1993).
Some authors have come up with even higher estimates. Crook, for instance, reported a
revised cultivated area of 139.7 million ha for 1985 (Crook, 1993, p. 34). This estimate
was based on provinical level land surveys published by Wang Tong et al. (1992). Wu
Chuangjun and Guo Huangcheng also estimated China’s cultivated land area to be 136.4
million ha (Wu and Guo, 1994, p. 91). Their estimate is based on surveys, calculations,
and reinterpretation of cartographic material done at the Geographical Institute of the
Chinese Academy of Sciences. Sun Han reviewed various estimates for cultivated land area,
ranging between the "official" 95.7 million ha reported in the statistical
yearbook and an estimate of 144.4 ha (including horticulture) from a survey conducted from
1979-1985. His own estimate was 133.3 million ha (Sun, 1994). In 1995, Smil estimated
China’s total area of cultivated land to be 133-140 million ha (Smil, 1995).
The US government initiated a study by a group of leading scientists (the so-called MEDEA
group) in which secret satellite images were examined. The images showed that
"China grows crops on 47 percent more land than China officially admits"
(MacKenzie, 199?). In 1996, IIASA started a project on land-use changes in China in
collaboration with the Chinese Academy of Sciences in which county-level data on
agricultural land use are analyzed in detail. Aggregation of these county-level data
initially also led to an estimate of cultivated land area in the order of about 135
million ha. Table 2 shows some of the estimates of China’s cultivated land. |
Table 2
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| Related Arguments |
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Arable Land: Trends
Impact Data Quality Prediction Error Intervention
Possibilities Intervention
Costs
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Revision 2.0 (First revision published in 1999)
- Copyright © 2011 by Gerhard K. Heilig. All rights reserved. (First revision: Copyright © 1999 by IIASA.) |
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