关键词: 渭北黄土高原, 造林树种, 根系分布特征

Abstract: Field observations indicate that stems are dried out from Tettigoniella viridis Linnaeus'laying eggs under the bark on lower part of the stem and that the damaged part dries out earlier than other parts.Similar symptoms are produced by cutting into the bark of potted plants to simulate the effect of insect damage.Fuchsin acid solution ascent is slowed down apparently in the stem sections damaged by the insect,It suggests that the interruption of water ascent in xylem resulted by insect's laying eggs is the primary cause of early-spring dietack of poplar plantation in Xinmin County of Liaoning Province.

Key words: Weibei Loess Plateau, Planting tree species, Root system, Distribution patterns