气候变化对亚洲地区植被NDVI变化的影响

Effects of climate changes on the NDVI of vegetation in Asia

以亚洲为研究区,选用1982—2015年长时间序列GIMMS NDVI3g、CRU Ts降雨量、气温和潜在蒸发量(potential evapotranspiration,PET)数据集,运用最大值合成法、Mann-Kendall检验法和相关性分析法识别了34 a间亚洲地区植被覆盖和气候要素的时空变化规律,分析了植被覆盖对气候变化的响应效应,探讨了气候变化对植被动态变化的影响机制。结果表明:①东南亚、日本、印度以及东亚的中国南部沿海等地区的归一化植被指数(normalized difference vegetation index,NDVI)较高,NDVI>0.5,亚洲中部大部分地区植被稀疏;②1982—2015年间,亚洲NDVI呈上升趋势,增长速率为0.0007/a,同时季节性增长明显,其中春季对年际NDVI增长贡献率最大;③亚洲地区的潜在蒸发量表现为西高东低,如在干旱半干旱的中亚、西亚地区较高,PET>40 mm;④亚洲地区气温南高北低,如中国的南部地区气温较高(>15℃),北部地区气温较低(<15℃);降雨量和气温空间分布相似,南高北低,但两者相比较,降雨量趋势更为显著;⑤气温、降雨量、PET对NDVI的影响呈现出区域性,如亚洲北部NDVI的影响因子主要为降雨量与PET,而在亚洲中南部,影响植被NDVI的主要因子则是气温;⑥春、夏季节尤其是夏季,气候变化对NDVI影响显著,秋、冬季节不显著;⑦气候变化对NDVI的影响有明显的滞后性,滞后期为1个月。

Based on the long-time-series(1982—2015)GIMMS NDVI3g and CRU Ts datasets of precipitation,temperature,and potential evapotranspiration(PET)of Asia,this study identified the spatio-temporal variations in the vegetation coverage and climatic elements in Asia in the past 34 years using the maximum-value composite procedure,Mann-Kendall trend tests,and correlation analysis.Furthermore,this study analyzed the response of vegetation coverage to climate changes and explored the influence mechanisms of climate changes on the dynamic changes of vegetation.The results show that the vegetation in Asia during 1982—2015 is as follows:①the vegetation coverage was high(NDVI>0.5)in Southeast Asia,Japan,India,and the southern coasts of China but low in most parts of central Asia;②the NDVI in Asia showed an upward trend at an increasing rate of 0.0007/a.Moreover,the vegetation coverage exhibited a significant seasonal increase,with spring contributing the most to the interannual NDVI;③The PET in Asia was high in the west but low in the east.For example,the PET was high(>40 mm)in arid and semi-arid Central Asia and Western Asia;④The temperature in Asia was high in the south and low in the north.For example,in China,the temperature was higher than 15℃in the south and lower than 15℃in the north.Rainfall exhibited a similar but more significant spatial distribution compared to the temperature;⑤The temperature,rainfall,and PET showed regional effects on NDVI.For example,rainfall and PET served as the main factors influencing NDVI in northern Asia,while the temperature was the main factor influencing NDVI in central and southern Asia;⑥The effects of climate changes on NDVI were significant in spring and especially summer but were nonsignificant in autumn and winter;⑦The effects of climate changes on NDVI showed a significant time lag of one month.