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  • 关中平原城市群植被覆盖的时空特征与影响因素

    Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-11-20 Cooperative journals: 《干旱区地理》

    Abstract:植被是全球及区域生态系统环境变化的重要指标,也是对人类社会活动有重要贡献的资源 之一。为了研究关中平原城市群不同区域植被覆盖变化对自然和人文因子的响应,以划分为三个区域的植被作为研究对象,选取2000—2017年MODIS-NDVI遥感数据,运用趋势分析、探索性空间数据分析与地理探测器等方法,从时序演进与空间分布方面研究了18 a内植被覆盖的演化及分布特征,定量分析影响植被覆盖的主导因子。遥感数据要通过投影转换、拼接、最大值合成等方法进行处理,再运用Python程序进行影像批量裁剪,将遥感数据和气象数据进行分区统计,最后对该处理数据进行讨论研究。结论表明:(1)研究期内关中平原城市群植被覆盖呈显著上升趋势,NDVI平均值增速为0.077·(10 a)-1,阶段性变化特征明显,其中2005—2007阶段和2011—2013阶段极显著增加,最大上升速率达到了0.05·a-1。(2)空间上总体呈现“南高北低”的分布特征,研究区总体得到改善;高值区主要分布在南部秦岭北坡,受气候因子的影响更大,植被覆盖增加速度缓慢,达到轻度改善水平;低 值区聚集在黄土高原边缘地区,植被增加趋势明显;中部关中平原极少部分地区植被覆盖出现了轻度退化或严重退化,以西安市及临近城市最为典型。(3)热点区主要分布在秦岭山区及关中平原中部地区,冷点区则集中于黄土高原边缘地区,植被覆盖总体以增长为主。热点区格网数量持续增多,2013年达到最大为45.07%;冷点区域数量不断减少,2017年减少到9.82%;次热点区与次冷点区主要分布在中部平原地带及北部地区,由连片分布转化为零散分布,且总量不断减少。(4)自然因素对植被覆盖的影响最为突出,其中气温和降水为影响植被覆盖的主导因子,决定力q值分别为0.955和0.931,且气温的影响大于降水的影响;人文因子影响力较为显著,GDP因子决定力q 值达到0.387。研究可为当地改善植被覆盖环境提供理论依据。

  • Self-prioritization is modulated by arousal

    Subjects: Psychology >> Experimental Psychology submitted time 2018-01-12

    Abstract: Stimuli related to the self are processed more efficiently in a variety of cognitive tasks. Recent studies have shown that this self-referential bias is modulated by one’s emotional states; however, it remains unclear whether the impact of emotion is primarily attributable to valence or arousal. Experiment 1 measured the self-prioritization effect with a label-shape matching task under four mood states. The results revealed a stronger self-prioritization effect in moods of higher arousal level, and a significant correlation between the arousal ratings and the self-prioritization effect. Experiment 2 further showed that alerting cues, which have been known to elevate the arousal level, boosted the self-prioritization effect measured in a similar label-shape matching task. These results provide clear evidence that arousal modulates self-referential processing