关键词: 公园绿地, 公园绿地, 郁闭度, 乔木胸高断面积, 绿量, 热岛效应, 重庆市

Abstract: The North China Plain (NCP) is a main grain production base in China, therefore, it is very important to study the impacts of climate change on the production potential of wheat-maize cropping system in NCP. The yield potential of wheat-maize cropping system in NCP was simulated by EPIC model, and the yield gap was calculated according to the actual yield. The results were as following. (1) The potential and waterlimited yield for wheat-maize cropping system during 1961-2007 were 19.7-22.2 t/hm2 and 13.2-21.7 t/hm2, with the regional average of 21.2 t/hm2 and 16.4 t/hm2, respectively. (2) Both potential and water-limited yield of wheat-maize cropping system showed an increasing trend, with an annual increasing range from 20 kg/hm2 to 40 kg/hm2 and from -95.0 kg/hm2 to 70.2 kg/hm2, as affected by climate change. Meanwhile, the waterlimited potential increased in the south but had a decreasing trend in the north. (3) The yield gap between the potential and actual yield of wheat-maize cropping system from 2001 to 2007 was 20.3%-72.2%, with a regional average of 48.2%. In spatial distribution, the area of high yield gap located in the south, the area of low yield gap located in the middle, and the area of middle yield gap located in the north. As a result, there has been a large potential yield increase in wheat-maize cropping system in NCP since 1960, water and nutrient use efficiency should be improved in order to enhance the yield increasing potential in NCP, specially in the south of the region.