In order to reveal effect of urbanization on soil organic carbon fractions and carbon pool management index

soil samples collected from six remnant evergreen broad-leaved forests in the Pearl River Delta were analyzed. The six sampling areas included three urban forests (botanical garden

Baiyunshan and Maofengshan) and three suburb ones (Heshan

Conghuashimen and Dinghushan). Soil samples were collected from 0—10 cm and 10—20 cm soil layers

respectively

and total organic carbon (TOC)

readily oxidizable organic carbon (ROC) and non-readily oxidizable organic carbon (NROC) of the samples were determined. Results were as follows: (1) TOC content of urban forests soil was significantly lower than that of the suburban forests soil (P＜0.05). (2) In the surface soil (0—10 cm layer)

soil carbon pool activity and carbon pool activity index of the urban forests were both significantly higher than those of the suburban forests (P＜0.05)

and in the sub-surface soil (10—20 cm layer)

the above pattern was also observed but there was no significant difference in both indices between these two kinds of forests (P＞0.05). (3) In both two soil layers

soil carbon pool index and carbon pool management index of suburban forests were both significantly higher than those of urban forests (P＜0.05). This study suggests that urbanization increased soil organic carbon activity of the remnant evergreen broad-leaved forests

but urbanization was detrimental to the accumulation of total organic carbon in soil.