通过分析1981-2006年温度、降水、辐射各气象因子变化对中国玉米调查产量变化的影响，尝试剥离和评估各气象因子变化对中国玉米产量的影响。结果表明：1981-2006年玉米生育期内，中国绝大部分玉米种植区，日平均气温、日均最高温度、日均最低温度均表现为显著升高（全国尺度，平均每10年依次升高了0.39℃、0.37℃和0.40℃），日较差、降水和辐射则仅在部分地区表现出显著变化，且有增有减，因区域而表现不同。1981-2006年期间，中国玉米平均产量变化与生育期内平均温度变化，最高温度和最低温度变化之间，具有显著的线性负相关关系。部分地区的玉米产量变化还与日较差、辐射、降水变化存在显著线性相关关系。与基准年份1981年相比，米生育期内平均温度每上升1℃、日较差每下降1℃、辐射每下降10%和降雨总量每下降10%，对中国部分地区玉米产量影响显著。其中，生育期平均温度每上升1℃对玉米产量影响最大，相较其他因子而言，产量下降的区域（约25.1%）和变化幅度（平均约为-21.6%）都达到最大。1981-2006年，不同气候因子变化在各区域玉米产量的变化中作用有所差异，其中平均温度作为对产量影响的主导因子所占的区域比例最大（约为40%），其次是日较差（23%），而辐射和降水则比例相当，均接近20%。该研究为进一步开展气候变化对玉米产量的影响机制研究和政府部门进行气候变化条件下玉米产量预测、风险评估和制定相关应对措施提供参考。%Impacts of climate change on agriculture has received wide concerns globally, yet a number of questions such as how past climate change affected the crop yields, which climatic variables were the main contributor for observed yield reduction remained unanswered to date, particularly in developing countries. Information about the climatic risks posed on crop growth, and yield responses to the specific climatic risks is prerequisite for understanding the underlying mechanisms of climate change impacts and devising appropriate adaptation strategies. This study first identified the changes of growing-season climatic variables (temperature, precipitation, and solar radiation) from 1982-2006 for China’s maize production. Using the relationships between changes in survey maize yield and climatic variables and their spatial variations, we investigated and untangled the impacts of different climatic variables on maize yield. Our analysis demonstrated that the growing-season temperatures, including daily maximum, minimum and mean temperatures, exhibited significant increase during 1981-2006, indicating the potential climatic risks for maize growth in China. Growing-season diurnal temperature range, precipitation and solar radiation also exhibited detectable changes, but limited to small parts of the maize area. During 1981-2006, there were significant negative correlations between national maize yield and temperatures (include mean, maximum, and minimum temperatures). Maize yield in some maize areas also exhibited linear correlation relationship to growing-season diurnal temperature range, solar radiation, and precipitation. With a 1℃ warming in growing-season temperature, 1℃ increase in diurnal temperature range, a 10% decrease in radiation and precipitation, much of the maize area showed detectable yield response to these changes. Maize experienced depressed yield to the 1℃ warming in growing-season temperature, denoting by roughly a quarter of China’s maize area exhibiting depressed yield and an estimated reduction of 25.1%across the regions that have detectable negative yield responses. The four climatic variables have diverse impacts on the maize yield in terms of the magnitude of yield change and the spatial variation of yield response. We identified the key climatic factor for observed maize yield change for all maize area. Temperature appeared as the first key climatic driver for maize yield change in over 40%maize area, while diurnal temperature range acted as a main player in 23%maize area. Radiation and precipitation shared a small and similar portion of maize area for playing as the key climatic variables for the yield response. We recognized the uncertainties in our study some of which came from reliability of data resource and the use of statistical method. However, this study provided first hand information on maize yield response to historical climatic risks, which advanced the understanding of underlying mechanism of climate change impacts on China’s maize production and assisted the projection of maize yield for future climate change.
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