Carbon storage and sequestration of urban street trees in Beijing, China

Abstract

Anthropogenic carbon dioxide (CO 2 ) emissions from cities have significantly increased over the past several decades along with rapid urbanization. To what extent anthropogenic CO 2 emissions generated from cities can be offset through conserving or increasing carbon (C) stored within urban areas themselves is a significant scientific question. The role of urban street trees in offsetting anthropogenic CO 2 emissions still remains uncertain. Here, using data from field surveys, tree growth measurements, and governmental statistical yearbooks, we estimated the C storage and C sequestration capacity of street trees in Beijing. Results showed that the C density and C sequestration rate in Beijing's urban street trees were about 1/3~1/2 of the corresponding magnitudes of non-urban forests in China. However, the total C sequestration of street trees in Beijing's urban districts was 3.1 ± 1.8 Gg C yr -1 (1 Gg = 109 g) in 2014, equivalent to only about 0.2% of its annual CO 2 -equivalent emissions from total energy consumption, indicating a rather limited role in offsetting overall anthropogenic CO 2 emissions.