Abstract: The volatiles from Gleditsia sinensis Lam. and Acer truncatum Bunge. , two greening tree species, were investigated by dynamic headspace collection and TCT - GC - MS ( gas chromatograph /mass spectrometry equipped with a thermal desorp tion cold trap device) analysis, the effects of which on the growth of
air-borne microbeswere examined by the method of natural sedimentation too. The results showed that the relative content of 3-hexen-1-ol acetate and acetic acid hexyl ester was the highest in the volatiles of G1sinensis
Lam. and A. truncatum Bunge. , respectively. Decanal, benaldehyde, trans-2-hexenal, nonanal, octanol,
pentanol and 3-hexenolwere the common components in the volatiles of two species. According to microbe-experiment, the number of micro-organisms over the treeswas significantly lower than that in open land. 32hex2
en212ol acetate, acetic acid, hep tyl ester, nonanal, hexanal, trans222hexenal, 12octanol, pentanol and 32hex2
enol inhibited the growth of bacteria and fungi significantly, and the ability of inhibiting the growth of micro2
organisms for 32hexenyl acetate was stronger than that for acetic acid, hep tyl ester. So the results partly ex2
p lained the reasons that the number of fungi and bacteria in the woodland of G1sinensis Lam. and A1truncatum
Bunge. is lower than that in the open land.

Key words: Greening tree species, Gleditsia sinensis, Acer truncatum Bunge., Volatiles, Antimicrobe