Spatiotemporal variation of kNDVI and its response to climatic factors in Beijing-Tianjin-Hebei region
[Objective]The study aimed to explore the response mechanisms of vegetation dynamics in the Beijing-Tianjin-Hebei region to cli-mate factors for a deeper understanding of the causes behind these alterations.It also served as scientific evidence for guiding ecological resto-ration efforts in the region.[Method]Trends analysis,partial correlation analysis,machine learning techniques,and explainable method were employed to examine the spatiotemporal changes in the kernel normalized difference vegetation index(kNDVI)in the Beijing-Tianjin-Hebei region from 2000 to 2020,as well as to investigate the differential responses of kNDVI within the region and across different land use types to precipitation and temperature.[Result]The findings indicated an improving trend for the kNDVI in the Beijing-Tianjin-Hebei region,with a growth rate of 0.025 per decade.The northwest region exhibited more significant improvement,particularly in forests,which accounted for ap-proximately 17％of the total area.The kNDVI of grasslands showed the fastest growth rate,increasing by 0.061 per decade.The surrounding areas of the southeastern cities were obviously degraded,and the cultivated land kNDVI changed frequently,showing more improvement.The correlation between kNDVI and temperature and precipitation displayed a marked positive trend,with a negative correlation found only around the southern cities.The multi-year SHAP value of precipitation was 0.028,and the multi-year SHAP value of temperature was 0.016,both of which had a positive impact on kNDVI in the Beijing-Tianjin-Hebei region.The overall impact of precipitation on kNDVI was stronger than that of temperature.The kNDVI response of Beijing-Hebei-Tianjin to climate was characterized by regional disparities.The kNDVI of the cul-tivated land in the southeast plain region and the forest and grassland in the northwest mountain region were significantly promoted by precipi-tation.In contrast,the kNDVI of the sparse vegetation areas around the cities and Zhangjiakou was negatively affected by precipitation.For the northwest woodland and grassland kNDVI,the promotion of temperature was stronger than precipitation.Temperature had a certain negative impact on the cultivated land kNDVI located in the southern plain,while the urban and rural areas,industrial and mining areas,and residen-tial land kNDVI were most negatively affected by temperature.[Conclusion]Vegetation change in the Beijing-Tianjin-Hebei region showes a stronger positive response to precipitation,with distinct regional spatial differences in the kNDVI response to climate factors for various land use types.
Vegetation changekNDVIClimatic factorSHAP interpretation methodBeijing-Tianjin-Hebei region
NETL
NSTL
万方数据
