Allelopathic effects of the revegetation species Juniperus sabina L. in semiarid areas of China

Juniperus sabina L. is a native evergreen conifer of the Mu Us Sandy Land. It has prostrating stems that can prevent sand shifting and is an important revegetation species. Allelopathy is a phenomenon in which the chemical substances released from one individual have effects, both inhibitory and promotive, on other individuals and it has a considerable impact on revegetation. In this study, to effectively use J. sabina for revegetation, we clarified the allelopathic effects of J. sabina on the germination and initial growth of the native species Artemisia ordosica Krasch. in comparison with a non-native cultivated lettuce (Lactuca sativa L. ‘Great Lakes 366’) in semiarid areas of China, and identified volatile allelochemicals. To evaluate the allelopathic effects of J. sabina, the dish pack method, which measures the effects of volatile compounds on seed germination and initial growth, was applied and gas chromatography–mass spectrometry was used to identify the volatile allelochemicals. The volatile compounds from J. sabina had almost no effects on the germination of lettuce seeds, while the germination ratio of A. ordosica seeds was extremely low. The major volatile compounds were sabinene, α-pinene, and β-myrcene, which are monoterpenes and species selective. J. sabina has several advantages as a revegetation woody species; however, our results suggest that J. sabina could have strong inhibitory effects on some specific native species of the Mu Us Sandy Land. Therefore, to effectively use J. sabina for revegetation, it is important to consider both its negative and positive effects.