关键词: 耕地, 复种指数, 格局与过程, 功能与效应, 优化调控, 可持续

Abstract: To feed the China’s growing population, more food needs to be produced using currently available cropland. Further expansion of cropland seems to be unlikely as it largely conflicts with biodiversity conservation, greenhouse gas emission mitigations, and hydrological changes. Crop yield growth is also confronting with large challenges as it becomes more difficult to sustain further yield increase as farmers’ yields approach the potential threshold. Increasing cropping intensity may thus provide another promising opportunity to increase food production. An increase in cropping intensity by increasing the number of crops per cropping cycle or intercropping with other crops can increase the frequency of harvests each year, resulting in increased food supplies without additional cropland expansion. This paper, from the perspective of agricultural land systems, proposed the overall study framework of multiple cropping systems and provided an overview of current research progresses in the three key research priorities. It was indicated that: (1) Multi-faceted patterns and processes of multiple cropping systems were the basis for subsequent analysis. It should consider not only the quantity, spatial distribution, regional difference of potential or actual multiple cropping systems, but also the cropping intensity gaps so as to expand the harvest areas by closing these gaps. (2) Understanding of the effects of multiple cropping systems on socio-economic and biophysical systems was the core task. Currently, most of studies were focused on the positive contribution of multiple cropping systems to food production, and less attention was paid to its impacts on eco-environment. Interdisciplinary approaches and cross-scale integration are critically necessary for better understanding the complex effects and feedbacks of multiple cropping systems on regional resource allocation, socio-economic development and eco-environment health. (3) How to sustainably increase the multiple cropping indexes was facing great challenges. It was important to link the multiple cropping systems with other parallel systems to understand their synergies and trade-offs, in order to build up a sustainable pathway for increasing future cropping intensity. All these solutions would substantially promote the interdisciplinary integration and would contribute to better understand the coupled human-environment interactions across time, space and scales.

Key words: cropland, multiple cropping index, pattern and process, function and effect, optimization and regulation, trade-off, sustainable