1982—2015年“一带一路”地区NDVI时空演变规律及其影响因素

Analysis of the Spatiotemporal Evolution of NDVI and Its Influencing Factors in the“Belt and Road”Region from 1982 to 2015

植被的生长状态、变化过程及其驱动因素具有显著的区域差异性,开展相关研究对于改善生态环境具有重要意义。然而,目前对于“一带一路”的归一化植被指数(Normalized Difference Vegetation Index,NDVI)的认识仍不清晰,可能会影响到生态环境改善和绿色“一带一路”建设。为此,本研究采用Theil-Sen中值趋势分析和Mann-Kendall显著性检验、偏相关分析和残差分析等方法探讨了1982—2015年该区域NDVI在像元上的时空演变规律及其影响因素。结果表明:(1)东南亚为植被覆盖度最高的区域,有76%的地区NDVI值在0.68以上;NDVI值低于0.27的低植被覆盖区则主要为西亚、中亚的大部分和中国西北等干旱半干旱地区及俄罗斯北部等高纬度地带;(2)研究区NDVI总体以5.39×10-4/a的速率增加(R2=0.611,p<0.0001)。NDVI显著增加,即植被显著改善的区域占37.67%,包括欧洲西部、勒拿河下游、印度大部分和中国南方地区;NDVI显著降低,即植被显著退化的区域包括中西伯利亚高原、东北平原、中亚的里海和咸海周边地区,面积仅占8.02%,显著改善区域面积是显著退化区域面积的4.70倍;此外植被呈现轻微变化和基本不变的区域共占54.31%;(3)植被同时受降雨、温度和人为活动这三个因素共同影响的区域较少,降雨主控区域主要分布在亚洲中部干旱半干旱区以及热带地区,温度主控区域在欧洲、西亚、青藏高原和俄罗斯北部的分布较广,典型的人为主控区域则分布在俄罗斯中部、印度北部和中国南方沿海地区。本研究结果可以为“一带一路”地区植被保护与生态建设提供科学决策的理论依据。

Significant regional differences exist in the growth state,change process and driving factors of vegetation.However,the NDVI(Normalized Difference Vegetation Index)of the“Belt and Road”remains under studied.As a result,the scientific decision-making in the countries along the route and the construction of“community with shared future for mankind”has been affected.Therefore,this study utilized the NDVI data to describe the spatiotemporal evolution characteristics of vegetation and its driving mechanism in the study area through Theil-Sen median trend analysis and Mann-Kendall significance test,partial correlation analysis,and residual analysis.Results showed that,firstly,the region with the highest vegetation coverage,with superior rainfall and heat conditions,is Southeast Asia.NDVI was higher than 0.68 in 76%of the regions in Southeast Asia.Low vegetation coverage areas are mainly located in arid regions,such as West Asia,Central Asia and high latitudes in Northern Russia.Secondly,the average NDVI value in the study area grew at a rate of 5.39×10-4/a(R2=0.611,p<0.0001).Significant improvement areas are located in Europe,Asia minor peninsula,Lower Lena,India and southern China,and account for 37.67%.Significant decreased areas only account for 8.02%.In addition,slightly changed area and stable area accounts for 54.31%,and the significant improvement areas are 4.70 times that of the significant degraded areas.Thirdly,few areas are affected by these three factors simultaneously.Rainfall-controlled areas are mainly concentrated in arid,semi-arid and tropical regions.Temperature-controlled areas are widely distributed in high latitude and altitude.Human-controlled regions are located in central Russia,northern India and the coastal areas of southern China.The current work clarifies and discusses the spatiotemporal evolution rules and influencing factors of NDVI from 1982 to 2015 in the“Belt and Road”region.Thus,it provides a scientific basis for vegetation protection and ecological construction in this region.