中国温带昼夜增温的季节性变化及其对植被动态的影响

结合1982-2015年归一化植被指数（NDVI）、植被类型和气象数据,分别利用一元线性回归和二阶偏相关分析方法,揭示了中国温带地区的生长季不同季节昼夜增温的时空格局以及昼夜增温的不对称性对各类型植被活动的影响。结果表明：① 近34年来中国温带大部分地区季节性昼夜气温都存在显著的上升趋势;生长季昼夜增温速率呈现出不对称性,春季、夏季白天气温上升速度略快于夜间,秋季夜间增温快于白天;② 不同季节的昼夜增温对植被活动的影响呈现出明显的分异特征,相对于夜间增温,白天增温对植被活动影响程度更大,影响区域更为广泛;相比夏季和秋季,春季昼夜增温对植被活动的影响范围更广;③ 不同类型植被对昼夜增温速率的不对称性产生了不同的响应,并且在不同季节上的响应程度存在差异。

Seasonal variations of day- and nighttime warming and their effects on vegetation dynamics in China's temperate zone

Based on normalized difference vegetation index (NDVI), vegetation type, and meteorological data, this study revealed the seasonal variations of the day- and nighttime warming in growing seasons using unitary linear regression analysis. It examined different effects of asymmetric seasonal warming on vegetation activities in China's temperate zone using the two-order partial correlation analysis method. The results are as follows. (1) The day- and nighttime warming trends from 1982 to 2015 in growing seasons were extremely significant. The day- and nighttime warming rates were featured by asymmetry; daytime warming was slightly faster than nighttime warming in spring and summer. Contrarily, in autumn, nighttime warming was faster than daytime warming. (2) The effects of the day- and nighttime warming on vegetation activity were obviously different; daytime warming had significantly greater and more extensive effects on vegetation than nighttime warming did, and the areas impacted by diurnal warming were broader in spring than in summer and autumn. (3) Different vegetation types responded differently to the seasonal asymmetry in day- and nighttime warming, and the degree of responses showed distinct variations by season.