中文摘要：

全球气候变暖背景下,自然生态环境敏感区农业热量资源的时空特征研究具有重要的现实意义。依据1960~2014年秦岭南北47个气象站数据,利用线性趋势、M-K检验和kriging插值法对无霜期时空变化进行分析。结果显示：从时间上看,秦岭南北无霜期随纬度增加而减少,初霜日和无霜期在年际波动中略有下降后快速上升,终霜日在波动中略有上升后快速下降。55年来无霜期呈显著的延长趋势且发生增多突变,秦岭以北、秦岭南坡、汉水流域和巴巫谷地的延长速率分别为0.400 6、0.280 4、0.396 1和0.407 5 d/a,突变年份分别为1999、2002、2001和1990年。从空间上看,无霜期平均值和标准差由南向北增加,80%站点初霜日推后、终霜日提前和无霜期延长。多数无霜期延长是初霜日推后与终霜日提前的共同影响。无霜期在28个站点呈波动变化,19个站点发生突变,突变时间多在1990s~2000s,2000s的突变区域面积最大且集中分布在东北部。分析结果可为气候变化对生态环境和农业生产布局的影响提供参考。

英文摘要：

It is of great significance to study the spatio-temporal variations of agricultural heat resources in ecological sensitive region under the background of global warming. Based on the meteorological data of 47 weather stations in the northern and southern regions of the Qinling Mountains（QLM） from 1960 to 2014, the spatial distribution, spatio-temporal variation and jump features were analyzed by using the methods of linear trend, Mann-Kendall test and Kriging interpolation. The results showed that, the frost-free period decreased with the increase of latitude in the northern and southern regions of QLM. The time trends were consistent in the four regions, namely the first frost date and the frost- free period declined slightly but increased dramatically thereafter, while the last frost date increased slightly but declined rapidly thereafter. Over the past 55 years, the frost- free period has significantly prolonged, with the increase of mutation. Among the northern areas to the QLM, southern slope of QLM, Hanshui River Basin and valleys in Daba and Wushan mountains, the prolonging rates of frost-free period were 0.4006d/a,0.2804d/a,0.3961d/a, and 0.4075d/a, respectively; the years of mutation were 1999, 2002, 2001 and 1990 respectively. The mean and standard deviation of the frost-free period in each station increased from south to north. It was also found that the first frost date lengthened, the last frost date advanced earlier and the frost-free period were extended over 80% stations. The frost-free period was prolonged by the delayed first frost date, together with an earlier last frost date. There were 28 stations with fluctuation characteristics and 19 stations with mutations in the northern and southern regions of QLM. The mutation timing of the frost-free period occurred primarily from 1990s to 2000s, and varied considerably in the 2000s, which had the largest regions of mutation and mainly concentrated in the north-east regions. The results are expected to provide referece for optimizing ecological e