Simulating long-term food producing capacities in China using a Web-based land evaluation system

摘要

This dissertation presents a modeling approach to assess the long-term food producing capacities, and consequently food security, in China using a Web-based land evaluation system (WLES, http://weble.ugent.be). WLES implements a 3-step quantitative land evaluation model which evaluates the realistic yield of a field crop by considering the effects of (a) radiation and temperature regimes, (b) water stress, (c) limited soil fertility and (d) insufficient crop management. Homogeneous 5 km by 5 km grid datasets of climatic, soil, crop and management parameters were created. Food productions in 2030 and 2050 were simulated using production scenarios involving population growth, urbanization rate, cropland area, cropping intensity, management level and soil degradation. The model predicted that food crops may experience a 9.7% productivity loss by 2030 if the soil is degraded at the current rate (“business-as-usual” scenario, BAU); productivity loss will increase to an unbearable level of 36.7% by 2050, should the soil be twice more degraded than it is now (“double degradation” scenario, 2xSD). China's food producing capacity tends to decline in the long run if the general trend of soil degradation will not be reverted. China will be able to achieve a production of 430 million tons from food crops in 2030 and 410 million tons in 2050 under the BAU scenario, which are 11.5% and 15.5% lower than the 2005 level, respectively. In per capita terms, China will experience a food shortage of 9.8% in 2030 and 7.5% in 2050 even under the “zero-degradation” scenario (0xSD), compared to a 12.7% food surplus in 2005. Per capita food shortage in 2050 will be as high as 22.6% under the BAU scenario and 38.3% under the 2xSD scenario. The results suggest the present-day producing capacity (2005 level) will not be able to sustain the long-term needs under the current management level even if soil degradation is not becoming more limiting. The detrimental effect of soil degradation on food security is so evident that technical measures and policy levers must be activated today in order to avoid, or at least mitigate, the risks of food insecurity tomorrow.