The Characteristics Of Occurrence Of Three Major Harmful Forestry Living Beings In Guyuan Ningxia And The Comprehensive Controls

Myospalax cansus Lyon, Pristiphora erichsonii Hartig and Anoplophora nobilis Ganglbauer are the three most important and most harmful forestry living beings in forestry ecosystem in Guyuan, Ningxia. This research is intended to identify the characteristics of their occurrence and the causes of damages from the actual construction of forestry ecosystem in Guyuan. Taken the consideration of the local forestry condition, nature and economy, this research is intended to offer strategies for comprehensive controlling or destroying these three major harmful forestry living beings and to offer suggestions for ecosystematic construction, such as reforestation and forestry sources protection.The surveys show that the hilly and gully regions on the loess plateau are impotant areas in which Myospalax cansus Lyon occur. The degrees of damaged trees in reforestation fields from the more serious to the less serious are that of Pinus tabulaeformis Garr, of Larix principis-rupprechtii Mayr, of Hippophae ehamnoides, of Prunus armeniaca Linn, of Prunus davidiana (Carr.) Franch, of Salix sp, of Picea crassifolia Kom, of Populus sp, of Robinia pseudoacacia L and of Caragana microphylla Lam. The younger the trees are, the more serious damage they receive.The damages made by Myospalax cansus Lyon vary with the slope directions of the reforestation fields. The slopes on which trees planted are damaged from the more serious to the less serious are shady slopes, semi-shady slopes, semi-lighted slopes and sunny slopes of hills. The flatter the slope is, the more serious damage it has, and vice versa. The damaged ratio of trees planted in fish scale pits is obviously lower than that of trees planted in the tiered-strips with'88542'soil preparation. Pristiphora erichsonii Hartig spreads wide but has a short period of harm. Larix principis-rupprechtii Mayr is the main kind of trees to be damaged, most seriously damaged when the canopy density of the stand is at 0.5~0.6. The damage degrees, varying with slope directions, from the more serious to less serious are on sunny slopes, semi-lighted slopes, semi-shady slopes and shady slopes of hills.Anoplophora nobilis Ganglbauer has spread widely and damaged trees seriously for a long time in Guyuan. However, after large-scaled insect-destroying movements,...