|
|
|
Land use and cover change detection and modelling for North Ningxia, China1
Discussion and conclusions
Based on the above change detection and panel analysis, a discussion on land use change mechanism and its future situation and its conclusions are demonstrated as follows:
- The farmland extension is the prevailing rural environment modification in North Ningxia in the period 1987-1999, however, the agricultural output increase plays a relatively weak part in the GDP growth (11.61%). Regression modelling shows that this extension is strongly associated with the agricultural output increase (R2 = 0.731), that is to say, the activities of the rural population are the decisive factors in this kind of land use change:
[Farmland extension] = - 0.3627 + 0.024 [Agricultural output increase]
.(2)
Developing at a rate of 39.3km2/yr or 1.53%, the farmland will be extended by about 432km2 in 2010. In fact, to compensate the loss in urbanisation and village extension (142km2), the farmland should have an increase of 574km2 in 2010 to meet the needs of the population growth. However, soil resources investigation (Wu et al, 2002) suggests that there is little arable land left for future reclamation. The Yinchuan Plain has been fully exploited in its long development history in agriculture, even the infertile sand land in Yongning, Yinchuan and Pingluo counties has been converted into cultivated land since 1987. Then where to find such a large uncultivated land for reclamation in the future?
- The urban extension (34km2 in area), especially in Yinchuan (17.43km2) and Shizuishan (9.39km2), constituting 3.58% of the total change, but its related production increase takes up 88.39% of the total GDP growth. Panel analysis discovers that the urban population growth is the key factors dominating this extension (R2 = 0.971), that is:
[Urban extension] = -0.1519 + 0.1340 [Urban population growth]
...
.(3)
This equation indicates that the socio-economic activities of the increased urban population in industry, commerce and service enterprises play a preponderant role in the urban extension. At the same time, the urban population growth is positively correlated with the industrial output increase (R2 = 0.958) and GDP growth (R2 = 0.992). This means that the urban extension or recent urbanisation is attributed to the activities of the newly incremented urban population in the industry development and other GDP formation domains such as commerce and service enterprises.
At an extension rate of 2.99km2/yr or 2.16%, the urban area will be increased by 41km2 under the contribution of the urban population till 2010.
- Rural built-up area has augmented by 70km2 at a change rate of 5.69km2/yr or 4.23% in the past 12 years. This augmentation is linked with the rural labour force growth, food product increase and agricultural output increase (R2 = 0.9960). Their relationship can be expressed as:
[Rural built-up increase] = -1.0098 + 0.0281 [Agricultural output increase] + 0.2885 [Food product increase] - 1.0305 [Rural labour force increase]
..
.(4)
Rural construction, principally housing in village, is accomplished by the rural labour force to improve the living conditions of the rural people and stock the agricultural production. Driven by these factors, the village will be enlarged by 101km2 in 2010. This means that another 101km2 of the green land will be lost till that time.
- From our detection, land desertification stated by Zhu (1995) was not found in this study area, however, land degradation in a total area of 55.62km2, including coal residue increase (36.20%), vegetation degradation and salinisation (52.25%) and stone pit increase (11.53%), was apparently observed in Yinchuan, Shizuishan and Pinglguo counties. The degradation rate was measured as 4.62km2/yr.
Panel analysis reveals that such degradation is linked with the industrial output increase (R2 = 0.708):
[Land degradation] = 5.0306 + 0.0020 [Industrial output increase]
.
..
.(5)
This is because industry output contains coal mining and coal industry product. Furthermore, industry development needs more and more stones and sands for factory construction. Therefore, industry development promotes the GDP growth and urban extension but at the same time brings about a degradation of land.
In line with the degradation tendency in the last decade, another 50.82km2 of land will be degraded till 2010, which will be spatially related with the coal mining and urbanisation.
|
|
|