Spatio-temporal Variation Of Rice Area In Northeast China And Its Driving Factors

Food security is critical to human livelihood,social stability and sustainable development.During the period of 13 th Five-Year Plan,food security in China is not only challenged by the environmental pressure caused by climate change,but is also affected by the social and economic factors,for example from the international food market.How do these natural and socio-economic factors affect China's food security is one of the urgent issues for the country to achieve its goal on sustainable development.China is the largest producer and consumer of rice in the world,therefore it is important to understand the changes of rice distribution in both spatial and temporal dimensions.Northeast China is one of the major rice producing areas,thus focusing on the factors that influence rice distribution in this region,is urgently needed for its agricultural adjustment and optimization,and would subsequently benefit food security at the national level.This research localizes the spatial production allocation model(SPAM)for mapping rice distribution in Northeast China in the year of 1980,1990,2000 and 2010 at a 10 km spatial resolution.It further analyzes the characteristics of rice distribution in respect of latitude,longitude,elevation and distribution centroid.Moreover,it investigates the relationship between rice distribution and climate factors(e.g.accumulated temperature,precipitation,and cold damage).Finally,it uses a spatial panel model to quantitatively explain the impact of various factors on the changes of rice distribution.The main findings are as follows:(1)Rice area in Northeast China increased by nearly five times from 1980 to 2010,with a noticeable expansion to the north(as high as to 46°N)before 2000.After that,the increased areas mainly are observed at the northern parts of Northeast China.Meanwhile,rice area also expanded eastwards to131°E and toward a higher elevation region(above 200 m).The centroid of rice area in Northeast China moved from 42°58'51”N,124°56'41”E to 44°46'8”N,126°34'53”E,the direction is northeastward and the distance is over 238 km from 1980 to 2010.(2)Over the past 30 years,due to a northward movement of accumulated temperature belts,new rice area began to be observed in the regions with an annual accumulated temperature between 2800 and3400 ?·d,the northward expansion of rice area is basically accordant with the northward trend of accumulated temperature.The trend of precipitation during the study period increased before 2000 and decreased afterwards,however,both increased rice area and decreased rice area appeared in the same precipitation belts,change of rice area in Northeast China are not closely related to the changes in precipitation.Meanwhile,the levels of rice cold damage frequency decreased,especially for the severe cold damage.The new rice area observed in the regions with a frequently occurred cold damage have been declined,thus,change of rice area has a close relationship with rice cold damage in Northeast China.(3)Rice area specialization has a strongest positive effect on rice area expansion,therefore,farmers' planting willingness and annual accumulated temperature above 10 ? are also positive to ricearea expansion after the specialization.In contrast,urbanization,plastic mulchingand frequency of cold damage have a negative effect on rice area.Rice area specialization made the largest positive contribution to the increase in rice area,and agricultural output value,urbanization and total sunshine duration during growing season in a country have the reverse contribution to the increased rice area.