Temporal and spatial changes in net primary productivity and land surface temperature and their influencing factors in Jiangsu coastal zone in recent 30 years

In the past 30 years, complex climate change and increasingly frequent human activities have caused dramatic ecological evolution and significant spatial heterogeneity in the coastal zone of Jiangsu Province. The Net primary productivity (NPP) and land surface temperature (LST) are two key parameters of ecosystem. By combining the Landsat remote sensing images of the area from 1990 to 2020 with the CASA (Carnegie-Ames-Stanford Approach) computational model and correlation analysis, the spatial and temporal changes of NPP and LST in Jiangsu coastal zone and the influencing factors were analyzed. Results show that, ① due to the utilization of coastal beach resources and the development of aquaculture, the coastlines of Jiangsu have been gradually moving toward the sea, and the extent of moving to the sea in the southern part is greater than that in the northern part. ② The NPP and LST of Jiangsu coastal zone in the past 30 years show significant spatial and temporal heterogeneity. Temporally, the monthly mean values of NPP in 1990s, 2000s, 2010s, and 2020s are 102.88, 88.23, 156.62, and 98.90 g C·m⁻², respectively, showing a decreasing-increasing-decreasing trend, while the mean values of LST are 32.6, 31.7, 28.3, and 37.6 ℃, showing a decreasing and then increasing trend. Spatially, the distributions of NPP and LST in the northern and southern parts of Jiangsu coastal zone showed certain differences. ③ NPP was the highest in forest land and the lowest in farming ponds; and LST values were the highest in artificial buildings and relatively low in wetlands, waters, and farming ponds. In addition, NPP and LST tended to increase gradually with increasing temperature and the increase of vegetation coverage led to the increase of NPP and decrease of LST.