Abstract: The Juniperus rigida open wood is the initial plant community on bare area of forest-steppe zone in the Loess Plateau of northern Shaanxi Province. There are two succession periods: xeromorphic steppe plants are dominant in the earlier period, such as Stipa sp, Festuca ovina, Thymus mongolicua and Atemisia frigida, etc.; xero-mesophytes are dominant in the later period, such as Atemisia giraidii, A, gmelinii and Lespedeza davurica, etc. Since soil condition is improved by the plant communty of earlier period, the plants of later period are developing, which is accompanied by soil change from drought to mesophytezation, so the fundamental driving force of the succession is a dynamic of edaphic internal cause succession under the action of plant communities.

Key words: The Loess Plateau, Open wood, Internal cause succession