Mapping aboveground biomass and carbon in Shanghai's urban forest using Landsat ETM plus and inventory data

Quantifying the spatiotemporal distribution of forest biomass carbon (FBC) is vital for the management of urban forests in accordance with the rapid urbanization. This paper presents a method for quantifying and estimating the urban FBC in Shanghai, China, between 2005 and 2015, using data from 93 sampling forest plots and Landsat ETM + data. Our study included an analysis of the choice of predicted factors to estimate FBC and the method of carbon density estimation employed in the estimation. The results showed that combining regression analysis and spatial analysis to map forest carbon stocks at city level make available FBC estimates for the urban forests of Shanghai, China. Based on the proposal method, there was a decreasing trend of carbon density from downtown areas to outer suburban areas. About 92 % of the overall FBC storage in Shanghai distributed in the suburban areas whereas the urban areas shared a fraction amounting to only 8 % in 2015. From 2011–2015, the total urban forest carbon storage gradually increased by 32.3 %, whereas the average carbon density gradually decreased by 8.21 % in the urban areas. The associated values both increased continuously from 2005–2011, from 2005 to 2011, but the average carbon storage density decreased in the suburban districts. The total carbon stocks in the estimated forest biomass across Shanghai were about 1.5 Tg in 2005 and 2008, and 1.7 Tg in 2011 and 2015, while the associated average FBC density remained at about 17.5 t/ha from 2005 to 2015. This study provides important information required to manage the urban forest stand for optimal carbon sequestration. © 2020 The Authors