Drivers of LEDD in cropland: China and Zhang Jiachong

Editor's note 30 Apr 2012: Text source D111 section 3.2

Rapid development

Soil loss is the product of natural and anthropogenic factors. However, the anthropogenic factors are the main reason for the current intensity and speed of soil loss in China. Reclamation of steep slopes is the fundamental factor for soil loss. In the upper reaches of the Yangtze River, more than 90% is mountainous terrain and plateau, which is the most critical condition for soil loss. The reduction of vegetation is also a direct reason for soil loss. Forest cover has reduced from more than 30% in the early 1950s to its present level of 15.3% in the upper reaches of the Yangtze River. Destroying forest for land reclamation has caused the loss of 186.67×10⁴ ha of forest cover in Sichuan province between the 1950s and 1980s.

Demand for land for cultivation

In the past 10 years, 6.0×10⁴ ha of cropland have been created from original forest land on steep slopes in Guizhou province. In Bijie region, where soil loss is the most serious, cultivated land increased from 42.9×10⁴ ha in the 1950s to 124 ×10⁴ ha in the 1980s. The increase in cultivated lands is driven by reclamation of the land from forest and grassland clearance on steep slopes. For a long time, sloping land in Sichuan, Guizhou and Yunnan provinces has represented more than two thirds of cultivated land. Thirty percent of the cultivated land is on slopes of more than 25° (Wang 2009). This is due to the fact that too many people and a high birth rate have resulted in a continually increasing population. Local farmers have therefore had to reclaim the forest land for securing food supply.

Combined socio-economic drivers

The drivers of soil loss in China were studied using soil loss case studies. A vulnerable ecological environment is the premise of soil loss (Guo et al. 2004). The economy, population and technology drive the overuse of biological resources, causing serious damage to vegetation through unlimited expansion of agricultural activities. These activities cause destruction of local micro-relief; decrease the existing vegetation and reduce the water retention capacity of the soil. These processes result in severe soil loss. Among all soil loss cases, 97% of cases were driven by multiple socio-economic factors and only three% were driven by a single factor. Of the cases of soil loss caused by multiple factors, 27% were driven by the economy, population and technology; 14% were driven by the economy and culture; 11% were driven by technology, culture and the system. Less than 10% of cases were driven by other factors.

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