Over the period 1982–2015, temperatures have exhibited an asymmetric warming pattern diurnally, as well as seasonally across the Loess Plateau. However, very limited research has studied the implications and effects of such seasonally heterogeneous warming across the Loess Plateau. In this study, we also analyzed the time series trends and seasonal spatial patterns of the maximum (Tmax) and minimum (Tmin) temperatures and evaluated how different vegetation responded to daytime and nighttime warming in the Loess Plateau from 1982 to 2015 based on the NDVI and meteorological parameters (precipitation or temperature). We found that Tmax and Tmin significantly increased throughout the years except for Tmax in autumn, and the diurnal asymmetric warming showed some striking seasonal differences. For example, the increasing rates of Tmin in spring, summer, autumn, and winter were 0.75, 1.20, 1.88, and 1.10 times larger than that of Tmax, respectively. NDVI showed significantly positive correlation with Tmax and Tmin in spring and winter, while NDVI presented significantly positive correlation with Tmin in summer and Tmax in autumn across entire Loess Plateau. Furthermore, we also discovered diverse seasonal responses in terms of vegetation types to daytime and nighttime warming. For instance, Spring NDVI showed significantly positive partial correlations with Tmax and Tmin. In summer, grasslands and wetlands merely displayed significantly positive partial correlations with Tmin. Cultivated land presented significantly positive partial correlation between the NDVI and Tmax (Tmin) in autumn. In winter, cultivated land, forest, and grassland exhibited significantly positive partial correlation with Tmax and Tmin, while only wetland showed a significantly positive partial correlation with Tmax. Our results demonstrated responses of vegetation to climate extremes and enhance a better understanding of the seasonally different responses of vegetation under global climate change at different scale.
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机译:在1982年至2015年期间,整个黄土高原地区的温度在白天和季节均呈非对称变暖模式。然而,非常有限的研究已经研究了整个黄土高原这种季节性非均匀变暖的影响和影响。在这项研究中,我们还基于NDVI分析了1982年至2015年黄土高原地区最高和最高温度(Tmax)和最低(Tmin)的时间序列趋势和季节空间格局,并评估了不同植被对白天和夜间升温的反应和气象参数(降水或温度)。我们发现,除秋季的Tmax外,这些年的Tmax和Tmin均显着增加,并且日非对称变暖表现出一些明显的季节差异。例如,春季,夏季,秋季和冬季,Tmin的增长率分别是Tmax的0.75、1.20、1.88和1.10倍。春季和冬季,NDVI与Tmax和 T em> min em>呈显着正相关,而NDVI与 T em> min p>呈显着正相关。在整个黄土高原地区,夏季为em>,秋季为 T em> max em>。此外,我们还发现了针对白天和夜间变暖的植被类型方面的不同季节响应。例如,春季NDVI与 T em> max em>和 T em> min em>呈现显着正相关。在夏季,草地和湿地与 T em> min em>仅表现出显着的正相关关系。秋季耕地的NDVI与 T em> max em>( T em> min em>)之间存在显着的正相关关系。冬季,耕地,森林和草地与 T em> max em> sub>和 T em> min em> sub>,而只有湿地与 T em> max em> sub>呈显着正相关。我们的结果证明了植被对极端气候的响应,并更好地理解了全球气候变化在不同规模下植被的季节性不同响应。
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