Objective To choose the ideal greening species for Beijing by evaluating the sulfur dioxide absorption and accumulation capacity of 9 common urban greening tree Species in Beijing, and to provide scientific basis for structure optimization of urban greening in the future.

Method BaSO₄ turbidimetry was used to determine the sulfur contents in the sample leaves under different pollutant conditions. Then the relative sulfur absorption capacity and average contaminative index were calculated to evaluate the sulfur dioxide absorption and accumulation capacity. By comparing the dissimilarity, the ideal greening species were screened out.

Result (1) There is significant difference in sulfur contents and relative sulfur absorption capacity among species under different pollutant conditions. The capacity is positively correlated with the pollution levels. (2) There are obvious differences in sulfur dioxide absorption and accumulation capacity among the 9 species under same pollutant conditions. It is proved that Salix matsudana is the best (the average relative sulfur absorption capacity is 2.38 mg·g^-1 and the average contaminative index is 2.23), followed by Sophora japonica (the average relative sulfur absorption capacity is 1.18 mg·g^-1 and the average contaminative index is 2.09), Ailanthus altissima, Cotinus coggygria, Populus tomentosa and Acer mono are the medium, and Ulmus pumila, Platycladus orientalis and Pinus tabuliformis are poorer.

Conclusion Salix matsudana and Sophora japonica could be the ideal species for urban greening in Beijing.