1990-2010年中国耕地变化对粮食生产潜力的影响

1990年以来,在国家生态环境保护工程实施、经济快速增长等因素的影响下,中国耕地数量与空间格局发生了巨大变化,对粮食生产潜力造成了巨大影响。本文采用GAEZ模型,结合中国气象、地形、土壤等因素,定量分析了中国耕地粮食生产潜力空间特征以及1990-2010年中国耕地变化对粮食生产潜力的影响。主要结论如下：① 2010年全国耕地粮食生产潜力总量为10.55亿t,全国耕地平均粮食生产潜力为7614 kg/hm²。中国耕地粮食生产潜力存在显著的空间差异,总体表现为东部高而西北部较低的趋势,并且高值区主要分布在长江中下游地区和华南区。② 1990-2010年的20年间,中国耕地粮食生产潜力变化表现出明显的时空差异,总体呈现南减北增、总量减少的基本特征。新增耕地粮食生产潜力的重心逐步由东北向西北转移。耕地粮食生产潜力总量净减少297万t,占2010年全国实际粮食总产量的0.29%。③ 在1990-2000年与2000-2010年两个时期,耕地变化对耕地粮食生产潜力影响差异明显。前10年,耕地粮食生产潜力总量净增加1011万t,主要集中在东北平原区和北方干旱半干旱区;后10年,耕地粮食生产潜力总量净减少1308万t,主要集中在长江中下游地区和黄淮海平原区。从总体看,近20年来耕地粮食生产潜力总量增加主要是由林、草地和未利用土地开垦所导致,而耕地粮食生产潜力总量减少主要是由城市扩展和退耕还林还草所导致。

Impact of farmland changes on production potential in China during recent two decades

Quantity and spatial pattern of farmland has changed, which leads to significant change of farmland potential productivity under the influence of national ecological environmental protection project and the rapidly increased economic growth during the last two decades. In this study, farmland potential productivity in China was calculated based on meteorological data, terrain elevation data, soil data and land use data in 1990, 2000 and 2010 by using the Globe Agricultural Ecology Zone model (GAEZ). Then, the changes in farmland potential productivity in response to farmland change from 1990 to 2000 were subsequently analyzed. (1) In 2010, total farmland potential productivity is 1.055 billion tons in China, and the average farmland potential productivity is 7614 kg/hm², which shows tremendous heterogeneity in spatial pattern. The productivity in eastern China is high, while that of northwestern China is low. High value region of farmland potential productivity is mainly distributed in South China and the middle and lower reaches of the Yangtze River. (2) The obvious tempo-spatial heterogeneity of farmland change from 1990 to 2010 has a significant influence on the farmland potential productivity in China. The trend shows the farmland potential productivity decreased in southern China and increased in northern China. Furthermore, the gravity of the growth of farmland potential productivity moves gradually from northeastern to northwestern China. The net decrease of farmland potential productivity is 2.97 billion tons, which occupies 0.29% of the national total productivity. (3) There is a huge difference of the farmland potential productivity in response to farmland change between two periods from 1990 to 2000 and from 2000 to 2010. During the first decade, net increase in the cultivated land areas is 10.11 billion tons, which primarily spread across Northeast China Plain and arid and semiarid regions of North China. During the next decade, net decrease in the cultivated land areas is 13.08 billion tons, primarily distributed in the middle and lower Yangtze River region and the Huang-Huai-Hai Plain. In general, during the last two decades, the reason for the increase of the farmland potential productivity may contribute to the reclamation of grassland, woodland and unused land, and the reason for the decrease of the farmland potential productivity may result from the urbanization that occupies the cultivated land and Green for Grain Project that returns farmland to forests and grasslands.