自然因子对四川植被NDVI变化的地理探测

许多研究已表明基于遥感的植被指数在地表过程和全球变化研究中具有重要作用,对认识植被变化的驱动因素具有重要意义,但自然因子对植被变化影响仍然难以量化。应用地理探测器模型,研究四川地区自然因子变化对植被分布的空间模式和植被变化的交互影响,并确定了促进植被生长的各主要自然因子最适宜特征。结果表明：① 2000-2015年,四川植被覆盖度状况良好,中高、高植被覆盖面积之和均超过94%;归一化植被指数（NDVI）转化表现为NDVI > 0.4以上区域转化明显,中高和高植被覆盖区面积分别呈显著下降和上升趋势;植被覆盖时空变化差异显著,植被覆盖较高区域位于四川盆地东北部、川西北高原地区,植被覆盖较低区域分布于四川盆地中部城市密集区域。② 土壤类型、高程和年均温度变化等因子较好地解释了植被状况的可变性。③ 自然因子对植被NDVI影响存在交互作用,自然因子协同效应呈现相互增强和非线性增强关系,两种因子交互作用增强了单因子的影响。④ 研究揭示的促进植被生长的各主要因子最适宜特征,有助于更好地理解自然因素对植被NDVI变化的影响及其驱动机制。

Influence of natural factors on vegetation NDVI using geographical detection in Sichuan Province

Many studies have shown the importance of using remote sensing to establish a vegetation index for land surface processes and global change research, it is of great significance to understand the driving factors of vegetation change, but the causes for vegetation change and the impact of geographical factors on vegetation change remain elusive. In this study, we examined the geographical factors and spatial patterns of vegetation change and the interactive effects of the geographical factors on vegetation change, and identified the most suitable characteristics of the main geographical factors that promote vegetation growth using the Geographical Detector Model, a new method of spatial counting to detect spatial variability and identify the driving factors. Our results showed that the vegetation cover was in good condition, the coverage area was of medium height, and there was more than 94% of high height vegetation. The spatiotemporal change in vegetation cover was significant from 2000-2015; the transformation of the normalized differential vegetation index (NDVI) was manifested as the transformation of NDVI > 0.4, and the cover area of medium and high height vegetation had a significant decreasing and increasing trend, respectively. The vegetation cover was better in the western and northern Sichuan plateau, while it was poor in the central urban areas of the Sichuan Basin and the Panxi area. Soil type, elevation, and the average annual temperature change could well explain the variability in vegetation condition. The influence of geographical factors on NDVI was interactive; the synergistic effect of the geographical factors on NDVI showed mutual and non-linear enhancement, and the interaction of the two factors enhanced the influence of a single factor on NDVI. This study reveals the most suitable characteristics and the main factors that promote vegetation growth, which is helpful to better understand the influence of natural factors and the driving mechanisms of vegetation NDVI change.