长江中下游地区农业气候资源时空变化特征

以1981年为时间节点，将1961-2007年分为1961-1980年（时段Ⅰ）和1981-2007年（时段Ⅱ）两个时间段，分析和比较两个时段的农业气候资源变化特征.结果表明：气候变暖背景下，长江中下游地区1961-2007年温度生长期内≥10 ℃积温气候倾向率平均为74 ℃·d·10 a^-1；时段Ⅱ≥10 ℃积温较时段Ⅰ平均增加了124 ℃·d；与时段Ⅰ相比，时段Ⅱ双季稻的安全种植界限向北推移了0.79个纬度.1961-2007年温度生长期内降水量总体表现为增加趋势；与时段Ⅰ相比，时段Ⅱ降水量增加了1.6%，降水量≥767 mm（双季稻正常生长的需水量）的面积增加了1.13×10.4 km².时段Ⅱ温度生长期内日照时数较时段Ⅰ平均减少了8.1%；近47年中91.1%的气象站点日照时数表现为减少趋势.与时段Ⅰ相比，时段Ⅱ温度生长期内参考作物蒸散量呈略微减少趋势，其低值区扩大、高值区缩小.时段Ⅱ稳定通过10 ℃初日平均较时段Ⅰ提前了2 d，而时段Ⅱ≥20 ℃终日平均较时段Ⅰ推迟了2 d，两个时段 ≥22 ℃终日基本相同.

Spatiotemporal change characteristics of agricultural climate resources in middle and lower reaches of Yangtze River

The period 1961-2007 was divided into twoby the time node of year 1981, and the change characteristics of the agricultural climate resources both in periodⅠ(1961-1980) and in period Ⅱ (1981-2007) were analyzed and compared. The results showed that under the background of global warming, the average climatic trend rate of ≥10 ℃ accumulated temperature in the middle and lower reaches of Yangtze River in temperaturedefined growth season during 1961-2007 was 74 ℃·d·10 a^-1, and the ≥10 ℃ accumulated temperature in period Ⅱ was 124 ℃·d higher than that in period I. Comparing with that in period I, the safe planting boundary of double cropping rice in period Ⅱ moved 0.79° northward. In 1961-2007, the precipitation in temperature-defined growth season had an overall increasing trend. Comparing with those in period I, the precipitationand the area of ≥767 mm precipitation (water requirement for normal growth of double cropping rice) in period II were increased by 1.6% and 1.13×10.4 km², respectively. The average sunshine hour in temperature-defined growth seasonin period II was reduced by 8.1%, comparing with that in period I. In recent 47 years, about 91.1% stations in the reaches showed a decreasing trend in sunshine hours. Comparing with that in period I, the reference crop evapotranspirati on in temperature-defined growth season in period Ⅱ showed a slightly decreasing trend, and its low value region expanded while its high value region narrowed. The beginning date of daily temperature over 10 ℃ was averagely 2 days earlier in period Ⅱ than that in period I, while the ending date was in reverse. The ending date of daily temperature over 22 ℃ was almost the same in periods I andⅡ.