Assessing the impact of land surface temperature on urban net primary productivity increment based on geographically weighted regression model

Urbanization had a huge impact on the regional ecosystem net primary productivity (NPP). Although the urban heat island (UHI) caused by urbanization has been found to have a certain promoting effect on urban vegetation NPP, the factors on the impact still are not identified. In this study, the impact of urbanization on NPP was divided into direct impact (NPP(dir)) and indirect impact (NPP(ind)), taking Kunming city as a case study area. Then, the spatial heterogeneity impact of land surface temperature (LST) on NPP(ind) was analyzed based on the geographically weighted regression (GWR) model. The results indicated that NPP, LST, NPP(dir) and NPP(ind) in 2001, 2009 and 2018 had significant spatial autocorrelation in Kunming based on spatial analytical model. LST had a positive impact on NPP(ind) in the central area of Kunming. The positively correlation areas of LST on NPP(ind) increased by 4.56%, and the NPP(ind) caused by the UHI effect increased by an average of 4.423 gC m(−2) from 2009 to 2018. GWR model can reveal significant spatial heterogeneity in the impacts of LST on NPP(ind). Overall, our findings indicated that LST has a certain role in promoting urban NPP.