The land use changes and its relationship with topographic factors in the Jing river catchment on the Loess Plateau of China
© Li et al.; licensee Springer 2013
Published: 11 December 2013
A series of soil conservation measures have been carried out to reduce soil loss on the Loess Plateau of China since 1950s, and the biologic measures were implemented according to topographic factors such as slope and elevation; therefore, the changes in topographic factors of land use can indicate the effects of the biologic measures. The objectives of this study were to (i) analyze the land use changes in the Jing River catchment during 1986-2000 and to (ii) examine the effects of biologic measures through relating land use changes with topographic factors. During 1986-2000, the dominant land use types were farmland and grassland (88% of the whole catchment). Compared with 1986, farmland and forest decreased while grassland and construction land increased with little changes in water and unused land. Three main conversion types occurred, i.e. the mutual conversion between forest and grassland, the mutual conversion between farmland and grassland, and farmland converted to other types. The elevation of farmland, forest, construction land and water increased, while that of grassland and unused land decreased. The mean slope gradient of each land use type changed little except for unused land. The above results suggested farmland has greatly decreased on tableland region due to the increase in construction land, forest has moved to gully region while grassland has increased despite elevation and slope. The land use in the Jing River catchment during 1986-2000 was changing to a more reasonable spatial pattern.
The Loess Plateau (6.4 × 105 km2) is situated in north China. It is covered with highly erodible aeolian deposits. Most areas belong to semiarid to sub-humid climate with most precipitation falling in summer months largely in forms of heavy storms. Canopy cover degree is generally low, and land use is predominantly cultivated cropland and improved grassland. The Yellow River, which has highest sediment concentration in the world , runs through the Loess Plateau. Due to the above situation, the Loess Plateau has become one of the most severely eroded areas in the world [2, 3].
Since 1950s, a series of conservation measures including replanting trees and improving grassland, constructing of terraces and sediment-trapping dams were implemented. Among these measures, returning steep farmland to forest and grassland was carried out in most areas to improve the vegetation over. Steep farmland accounts for about 50% of total farmland area on the Loess Plateau, and this situation is worse in the hilly-gully area, where steep farmland covers 70%-90% of the total farmland area and farmland with slopes over 25° accounts for 15%-20% of the total farmland area . Thus, vegetation construction would not only change the spatial distribution of land use, but also alter the slope of each land use type [5, 6]. For example, 25° was usually taken as the critical slope gradient of returning farmland to forest and grassland, which might decrease the slope of farmland and increase that of forest and grassland.
With the implementation of conservation measures, human choices of land use have also changed greatly due to the impacts of elevation [5, 6]. For example, farmland abandonment often occurred on the highest or lowest and the steepest areas while construction land often moved to the flattest areas with good traffic condition and water supplying. Besides, as climatic variations due to elevation differences between ridges and valley bottoms influence the land use types , vegetation construction would consider more about the suitability of plants, for example, forest in the Loess Plateau often moved to the valley with relative rich water now.
Therefore, analyzing the relationships between land use and topographic factors can reflect the effect of vegetation constructions and guide future vegetation restoration. However, this kind of this study is less common. The objectives of this study were to (i) detect the land use changes during 1986-2000 in the Jing River catchment on the Loess Plateau and to (ii) analyze the relationship between land use and topographic factors.
Materials and methods
Two land use maps of 1986 and 2000 (1:100,000), provided by the Environmental and Ecological Science Data Center for West China, were used to analyze the land use changes. The land use was classified into six categories: farmland, forest, grassland, water, construction land (areas for residence, traffic, industry and mining), and unused land.
Elevation and slope gradient was chosen as the indices of topography to study their relationship with land use. GDEM (Global Digital Elevation Model) of 30 m, a product of Trade and Industry of Japan (METI) and the National Aeronautics and Space Administration (NASA), was used to provide the elevation. The elevation was classified into three categories: <1000 m (mainly gully region), 1000-1500 m (mainly tableland region), and >2000 m (mainly hilly region). A slope map was generated through DEM surface analysis operation of ArcGIS 9.2 and the slope gradient was classified into three categories: gentle (<15°), intermediate (15-25°), and steep (>25°) in accordance with the national policy on converting steep lands to other uses.
where K i is the change speed for the i th type land use; U b and U a is the area of a certain land use type at the beginning and end of the study period; T is the time duration of the research. The change speed is thus defined as the change area per year, positive value refers to upward trend and negative value refers to downward trend.
To analyze the relationship between land use and topographic factors, the two land use maps were combined with DEM or slope gradient map through the grid extension of Arc/Info 9.2. All maps were grid format and the cell size was 30 m×30 m. Through exporting the attribute table of the combined maps and calculating the elevation and slope gradient of different land use type in different year, the effects of biologic measures can be detected.
Results and discussion
Changes in land use
Land use structure and their changes during 1986-2000 in the Jing River catchment
Change types of land use during 1986-2000 in the Jing River catchment
Changes relative to
the entire area (%)
Changes relative to
each land use type (%)
Forest to grassland
Farmland to construction land
Grassland to farmland
Farmland to forest
Grassland to forest
Farmland to grassland
Land use changes in relation to elevation
Land use changes in relation to elevation during 1986-2000 in the Jing River catchment.
Mean elevation (m)
Land use changes (km2)
In general, two trends existed in elevation changes of land use, i.e. the increase in elevation of farmland, forest, water and construction land, and the decrease in that of grassland and unused land. The changes in elevation for each land use type were significant. Specifically, land use changes mainly occurred during 1000-1500 m. Farmland has substantially decreased by 113 km2 below 1500 m while increased by 27 km2 over 1500 m, indicating that a large number of farmland in gully region was transferring to other land use types. Forest increased by 3 km2 below 1000 m and decreased by 128 km2 over 1000 m, suggesting that forest were transferring to gully regions. Grassland and construction land increased despite the elevation. Grassland tended to increase in regions with high elevation while construction land increased preferably in tableland and rive valley with low elevation. The decrease in water mainly occurred over 1000 m. The above changes in elevation of land use were possibly caused by the substantial conversion from forest to grassland, and conversion from farmland to construction land (Table 2).
Land use changes in relation to slope gradient
Land use changes in relation to slope during 1986-2000 in the Jing River catchment
Mean slope gradient (°)
Land use changes (km2)
During 1986-2000, the mean slope gradient of each land use type changed little except for the increase in unused land. The changes in land use mainly occurred at area with slope gradient less than 15°. Farmland decreased by 81 km2 with slope less than 15° possibly because it was used as construction land (Table 2). Forest decreased while grassland increased despite slope gradient, which was possibly caused by the conversion from forest to grassland (Table 2). Unused land decreased in regions with small slope.
Implication of land use changes and its relation to topographic factors
The transferring direction of land use in the Jing River catchment during 1986-2000 can be detected according to the above results. Farmland has decreased greatly on tableland, which was possibly caused by converting farmland to construction land and increasing farmland by constructing terraces. Forest have moved to gully region with low elevation and small slope gradient, indicating that the vegetation construction of the Loess Plateau was getting more rational and considering more about the suitability of planting trees. Grassland has increased at all elevation and slope, implying that the effects of returning steep farmland to grassland and converting from forest to grassland were significant. Construction land has increased despite elevation and slope due to population increase. Unused land has moved to hilly region with high elevation and big slope gradient, suggesting the development and utilization of land use are more intensive.
Overall, the land use in the Jing River catchment during 1986-2000 was changing to a more reasonable spatial pattern, which considered more about the suitability of plants and human needs. This kind of changes will surely benefit the vegetation construction and sustainable development of this region.
The dominant land use types of the Jing River catchment were farmland and grassland. Overall, the land use changed little during 1986-2000, indicating that the soil conservations measures now implemented mainly focused on engineering measures, therefore, more attention should be paid to vegetation construction in the future. However, the land use distributions on elevation and slope gradients were becoming more reasonable, and the spatial pattern of land use were considering more about the suitability of plants and human needs. This kind of changes would indubitably promote the ecological environment and sustainable development of the region.
This study was supported by the National Natural Science Foundation of China (41101022 and 51179161) and the Science and Technology Research and Development Program of Shaanxi Province, China (2013KJXX-18).
The publication costs for this article were funded by Scientific & Technical Development Inc.
This article has been published as part of SpringerPlus Volume 2 Supplement 1, 2013: Proceedings of the 2010 International Conference on Combating Land Degradation in Agricultural Areas (ICCLD'10). The full contents of the supplement are available online at http://www.springerplus.com/supplements/2/S1.
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