胡杨叶黄期对气候变化的时空响应与区域差异

利用中国绿洲的41个胡杨分布区地面气象站点近57 a的逐日平均气温资料,运用线性趋势、Arc GIS的反距离加权(IDW)插值法、Morlet小波功率谱、Mann-Kendall检验和相关分析法等方法,分析中国绿洲胡杨叶黄期的时空特征、区域增暖响应与差异。结果表明:近57 a来,中国绿洲胡杨叶黄起止日均明显推迟、叶黄期呈延长的变化趋势,变化倾向率分别为0.72 d·(10a)^-1、1.39 d·(10a)^-1(α≥0.05)和0.66 d·(10a)^-1;胡杨叶黄起止日均呈自西南向东北逐渐提前的变化规律,其中,柴达木绿洲推迟趋势最明显,新疆南部绿洲不明显。除新疆北部外,叶黄期呈自南向北逐渐缩短的变化规律,空间差异十分明显;且分别存在2.2 a、3.0 a和5.2~5.6 a的短周期,与大气环流2~4 a和厄尔尼诺2~7 a的周期相吻合;胡杨叶黄起止日及叶黄期分别在2003年、1990年、1961年发生了突变,各绿洲区突变不尽相同;研究区胡杨叶黄起止日与叶黄期分别与前期(6-8月和7-9月)月平均气温、所在月(9-11月)平均气温呈显著相关,相关系数分别为0.703、0.697和0.715(α≥0.001)。反映了中国绿洲胡杨叶黄期对全球气候变暖的响应既敏感又有区域差异。

Spatiotemporal Response of Leaf-Yellow Period of Populus euphratica to Climate Change and Its Regional Difference

In this paper,the average daily temperature data from 41 meteorological stations in Chinese oases where the Populus euphratica trees grow during the period from 1960 to 2016 were used to analyze the spatiotemporal response of the leaf-yellow period of P.euphratica to climate change and its regional difference.In the study the methods of multi-year trend line,inverse distance weighted interpolation(IDW),Morlet wavelet power spectrum,Mann-Kendall mutation test and correlation analysis were applied.The results revealed that the beginning and ending dates of the leaf yellow of P.euphratica were postponed over the last 57 years,and the leaf-yellow period was gradually prolonged.The change trend rates were 0.72,1.39(α≥0.05)and 0.66 days/decade respectively,which revealed that the beginning and ending dates of the leaf yellow of P.euphratica became earlier along a southwestnortheast transect of Chinese oases.Especially the postponement trend was the most obvious in the Qaidam Oasis but not in the oases in south Xinjiang.In addition to north Xinjiang,the leaf-yellow period became shorter along a southnorth transect of Chinese oases,and the spatial disparity was extremely significant.There were the 2.2-,3.0-and 5.2-5.6-year short cycles of the beginning and ending dates of leaf yellow of P.euphratica,and they were consistent with the 2-4-year general atmospheric circulation and the 2-7-year El Ni1o events.Mutations of the starting and ending dates and periods of leaf yellow of P.euphratica occurred in 2003,1990 and 1961 respectively,but they were different from different oases.There were the significant correlations among the starting and ending dates and period of leaf yellow of P.euphratica and the mean monthly temperatures in the periods from June to August,from July to September and from September to November,and their correlation coefficients were 0.703,0.697,and 0.715(α≥0.001),respectively.The results showed that the response of the leaf-yellow period of P.euphratica to global warming was sensitive and regionally different.