Study on Spatiotemporal Dynamics and Correlation of NPP and NDVI in Dabie Mountain Area Based on MODIS

Based on MODIS satellite remote sensing data of MOD13Q1 NDVI and MOD17A3 NPP from 2000 to 2019, and supported by GIS spatial analysis technology, the temporal and spatial variations of the Normalized Difference Vegetation Index (NDVI) and Net Primary Productivity (NPP) in the Dabie Mountain area during the same period are analyzed comprehensively, and the correlation analysis and regression analysis are employed to investigate vegetation dynamics in the Dabie Mountain area during the period of interest. The findings indicate that: ① In the past two decades, NDVI has exhibited a variation range of 0.73~0.81 and an annual average of 0.78. The spatial distribution of NDVI displays a decreasing trend from the center to the periphery, while also exhibiting fluctuating upward trends between 2000 and 2019. During this period, approximately 78.88% of NDVI values exhibited improvement. ② NPP ranges on 402~576 g/(m²·a) with an average value of 497 g/(m²·a), displaying a spatial distribution characteristic of "high values in central regions and lower values at edges". NPP has exhibited an increase in most regions since 2000. ③ There is a significant positive correlation observed between NPP and NDVI. This relationship is found to be positive across most regions, although the strength of correlation varied among different vegetation types. Coniferous forests exhibit the highest correlation coefficient, followed by the broadleaf forests, shrublands and grasslands, while the cultivated vegetation shows the lowest correlation.