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北京市西山是首都的重点绿化地区。油松是西山地区最主要的造林树种,占全部造林面积的三分之一以上。由于采用了较为细致的造林技术,如水平条整地、大苗带土坨栽植、及时抚育等,油松在这个地区的初期生长是普遍良好的。这种状况曾经造成了一种假象,似乎在西山地区油松生长不受立地条件的限制。大约在15年生以后,林木生长因立地条件不同而产生的不同效应越来越明显。长期的春旱及瘠薄的土壤造成了一些地方的油松林生长停滞,对病虫害的抗性减弱,难于成材。个别旱年甚至还引起了局部地方的油松死亡。所以,研究立地因子对油松生长的影响,确定油松在西山地区的适生立
Beijing Xishan is the key green area of the capital. Pinus tabulaeformis is the most important afforestation species in Xishan area, accounting for more than one third of all afforestation area. As a result of a more detailed reforestation technology, such as the level of land preparation, seedlings with Tu Tuo Tuo, timely nurturing, etc., the initial growth of Pinus tabulaeformis in the region is generally good. This situation has created the illusion that it appears that the growth of Pinus tabulaeformis in the Xishan Mountains is not restricted by site conditions. After about 15 years of age, different effects of tree growth due to different site conditions are more and more obvious. Prolonged drought and infertile soils have caused the growth of Pinus tabulaeformis forest in some areas to be stagnant, and the resistance to pests and diseases is weakened, making it difficult for farmers to become successful. Individual dry years even caused the death of Pinus tabulaeformis in some areas. Therefore, the study site factors on the growth of Pinus tabulaeformis to determine the suitable stand in the Xishan area of Pinus tabulaeformis