‚TION
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Soils data for the study area were compiled from
1:500,000 and 1:200,000 scale soil maps of Shanghai
City and Jiangsu Province, respectively. The maps
were constructed using the Chinese classification and
mapping system, which were translated to reflect FAO
soil units and phase mapping units. In addition,
1:50,000 Defense Mapping Agency topographic maps
were used to identify the study area slope
characteristics. The FAO classification was then
recoded to provide their Fertility Capability
Classification (FCC) equivalents, which describe soil
fertility limitations.
Land use changes were determined by GIS overlay of
land cover from sequential years. Only conversions
between agriculture and developed, and forest and
developed were considered. The land use change data
were then overlain with the soils information to relate
the quality of the soil to the converted area. Data
generated by GIS overlay were summarized
statistically to provide total area estimates for type of
land use conversion and quality of soil impacted by
the conversion.
3. RESULTS AND DISCUSSION
The research described above addresses two
fundamental questions about land use conversion
beginning with 1) a description of the extent of land
use conversion, followed by 2) an impact assessment
of the land use changes on soil resources.
Land Use Conversion: Table 2 lists the land use
characteristics of the study area for the years 1984,
1992, and 1994. As can be seen, most of the land in
1984 is dedicated to agricultural production, with only
1.9% of the area utilized by the developed land
category. Most of the forest area resides on upland
areas which exist as high hills, approximately 220
meters in elevation.
By 1992 developed land uses increased by a little more
than 1% throughout the study area, representing an
increase of 41.9 km“. Most of this conversion,
approximately 98.1%, was from agriculture to
developed land. Conversion of forest to developed
uses involved 1.9% of the total area converted between
1984 and 1992, approximately .8 km.
The rate of change in land uses increased dramatically
from 1992 to 1994. The major change was an
increase in developed land which by 1994 occupied
5.8% of the total area, almost-a 98% increase from
1992. The doubling of developed land since 1984
represents the conversion of 110.4 km”. As seen in
1992 most of this conversion, 96. 1%, was the result of
removing agricultural land from production and
International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998
utilizing it for residential, commercial or extractive
purposes. Some 2.7 km’ of forest were lost to
developed land uses during the two year span between
images.
Table 2. Urban land use statistics.
Land Use Percent of Area Area km?
1984
Developed 1.9 74.4
Agriculture 78.7 3,082.4
Forest S.S 213.4
Water 13.9 544.5
1992
Developed 3.0 116.3
Agriculture 77.7 3,041.7
Forest 54 212.6
Water 13.9 544.5
1994
Developed 5.8 226.7
Agriculture 74.9 2,935.6
Forest 5.4 209.8
Water 13.9 544.3
The greater than 200% increase in developed land
during the 10 year period from 1984 to 1994
potentially has a number of impacts. One of these
areas of concern is the preservation of agricultural
land for feeding the estimated 1.2 billion Chinese
living in the Peoples Republic of China. In the next
section we will discuss the changes in land use within
the context of the impact on the soil resources of the
study area. ;
Soil Impacts of Land Use Conversion: The dramatic
development of land seen between 1984 and 1994
potentially has impacts on the agricultural resources of
the area and has implications for crop production
country-wide. ^ Soils, the foundation upon which
agriculture is based, vary in their productive
capability. Overlaying a FCC soil classification with
the land use change information identified and
described soils lost during the study period.
Table 3 describes the soils of the area based on their
FCC classification. The soils are generally good as
assessed at the scale of the maps, with 93.5% of the
area having soils with no limitations. Among soils
with limitations, gleying was found to be the most
prominent, effecting 4.896 of the soils in the study
area. Gleying may or may not be a serious problem as
rice, which prefers moist conditions, is the most
prominent crop grown in the area. The slope
limitation occurs strictly in the forested upland areas.
Of minimal extent are shallow soils, present in only
.03% of the study area. Overlaying the soils and land
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