中国植被生长期的时空变化

Spatiotemporal variation of growing season length of vegetation in China

基于822个气象站点1951—2017年的日均温度数据,采用世界气象组织给定的植被生长期(GSL)定义,利用Slope、Mann-Kendall和Hurst指数分析中国各省(区)不同时期的GSL变化趋势及相应时期150、200、250、300和350 d的GSL等值线移动速度。结果表明:研究期间中国北方地区GSL变化显著。GSL增长速度表现为北方快于南方、高海拔快于低海拔。中国大部分地区未来GSL变化趋势与当前的变化趋势相同。北方绝大部分省(区)GSL增长速度在0.1~0.2 d·a-1,西藏的增速最快,为0.44 d·a-1。1981—2000年是中国各省(区)GSL变化最显著的时段。除新疆GSL延长是生长期终日(GSE)主导外,其他各省(区)GSL延长总体是生长期始日(GSS)占主导。在高纬度和高海拔省(区),GSL变化对年均温度的变化更敏感。年均温越高的省(区)GSL也普遍越长。1951年以来,中国150、200、250、300和350 d的GSL等值线出现了明显移动,东北地区200 d等值线的移动速度最快,其平均北移速度为6.11 km·a-1。中国GSL等值线总体移动规律为:等值线数值越大,北移速度越慢。其中,350 d等值线在部分区段甚至出现了南移的情况。中国GSL延长将导致农作物种植边界北移,自然植被生长期延长。该变化对中国农作物的品质、产量和生态系统碳固定的影响还有待深入研究。

We analyzed the variation trend of growing season length(GSL)of different periods in provinces(regions)of China and the corresponding movement velocity of GSL isolines at 150,200,250,300 and 350 days,based on daily mean temperature data of 822 meteorological stations from 1951 to 2017.In this study,the definition of GSL given by the world meteorological organization was adopted,together with Slope,Hurst and Mann-Kendall indices.The results showed that the GSL in northern China changed significantly during 1951-2017.The extension of GSL was faster in the north than the south,and faster in high-altitude areas than low-altitude ones.The trend of future GSL change in most regions of China converged with the current extension trend.The extension of GSL in northern provinces(regions)was generally 0.1-0.2 d·a-1,of which the fastest was Tibet with a speed of 0.44 d·a-1.The period 1981-2000 was the most changeable time of GSL in Chinese provinces(regions).The growing season start(GSS)of all provinces(regions)contributed more to the GSL extension,except for Xinjiang,whose GSL extension was dominated by the growing season end(GSE).In the high-latitude or high-altitude provinces,GSL was more sensitive to the change of mean annual temperature.The higher the mean annual temperature,the longer the GSL.Since 1951,China's GSL isolines of 150,200,250,300 and 350 days showed notable variations.The fastest movement velocity was the 200 days isoline in Northeast China with an average northward movement velocity of 6.11 km·a-1.The general principle of the movement of China's GSL isoline was that the higher the value of the isoline,the slower the northward movement,with even a southward shift in part of the 350 days isoline.The extension of GSL in China would result in the northward shift of crop planting boundary and the extension of natural vegetation growth period.However,the specific impacts of this change on the quality,crop yield,and ecosystem carbon sequestration need further research.