西北地区昼夜增温的不对称性对植被动态的影响

全球变暖有很大的差异性,表现在昼夜增温速度和各个季节的温度增加的速率具有不一致性,夜间增温的速度要快于白天增温的速度,夜间气温的增温对植被变化的影响更为明显。文章利用34年逐月最高温、最低温以及降水量数据,用一元线性回归分析法、反距离权重插值以及二阶偏相关分析法,分析了西北地区白天和夜间气温的非对称时空变化和非对称增温趋势对植被动态的影响,结果表明:西北地区昼夜温度都呈现出上升的趋势,且上升趋势比较明显,白天增温的速度和夜间增温的速度呈现出不对称性,夜间温度升高的速率是白天温度升高速率的1.2倍,昼夜的温差呈现出减小的趋势;西北地区昼夜增温趋势存在不一致性,白天气温的增温速率在-0.02-0.11℃?a-1,夜间气温的增温速率在-0.06-0.2℃?a-1。tmax和tmin在绝大部分地区都呈现上升趋势,但在空间变化的区域上具有不对称性;西北地区植被生长对昼夜增温的响应具有明显的空间差异性,大部分地区的植被对昼夜增温表现为积极的响应,夜间增温对植被的影响要比白天增温对植被的影响是比较明显的;白天和夜间增温的不对称性影响着不同类型的植被,白天气温的升高有利于针叶林植被、草地和阔叶林植被的生长,而夜间气温的升高对灌丛和荒漠植被的生长有积极的影响。

Asymmetry of Day and Nighttime Warming and Their Effects on Vegetation Dynamics in the Inland Areas of Northwest China

There are great differences in global warming, which are manifested in the inconsistency between the rate of day-night warming and that of seasonal warming. The rate of night warming is faster than that of day warming, and the effect of night warming on vegetation change is more obvious. Using 34 year monthly maximum temperature, minimum temperature and precipitation data, and using linear regression analysis, inverse distance weight interpolation and second-order partial correlation analysis, the effects of asymmetric temperature increment on vegetation dynamics in Northwest China were analyzed. The diurnal and nighttime temperature in the region showed an upward trend, and the upward trend was more obvious. The speed of diurnal and nighttime temperature increase showed asymmetry. The rate of nighttime temperature increase was 1.2 times that of daytime temperature increase, and the temperature difference between day and night showed a decreasing trend. The trend of diurnal and nighttime temperature increase was different in Northwest China. The heating rate of daytime temperature is-0.02 ℃?a-1 to 0.11 ℃?a-1, and that of night temperature is-0.06 ℃?a-1 to 0.2 ℃?a-1. Tmax and Tmin showed an upward trend in most areas, but their spatial distribution was asymmetrical. The response of vegetation growth to day-night temperature increase in Northwest China was significantly different. Vegetation in most areas showed a positive response to day-night temperature increase, and the effect of night temperature increase on vegetation was greater than that of day-time temperature. The asymmetry of day and night warming has different effects on different kinds of vegetation. The increase of daytime temperature is beneficial to coniferous forest, grassland and broad-leaved forest vegetation and growth, while the rise of night temperature has a positive impact on the growth of shrub and desert vegetation.