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一、调查与分析1981～1983年,在我省黄土高原境内13个县(市),调查了臭椿标准地29块,作解析木25株,现就其生长情况予以分析:(一)臭椿的生长过程:通过臭椿解析木、树干生长过程表(略)和树高、胸径、材积的平均与连年生长量曲线可以看出:1.树高生长在5年前最快,连年生长量达0.72米;5～20年生长较快,连年生长量为0.32～0.46米;20年后生长明显下降,连年生长量仅0.14～0.18米。2.胸径生长在5年前较慢,年平均生长量仅0.81厘米,此后逐年加快;在10～15年时生长达到高峰,连年生长量达1.17厘米,15年后稍有下降。到25～30年间又出现第二
I. Investigation and Analysis In 1981 ~ 1983, 29 counties of Ailanthus altissima were surveyed in 13 counties (cities) in the Loess Plateau in our province, and 25 were analyzed for their growth. The growth of Ailanthus altissima Growth process: Ailanthus altissima analysis of wood, tree growth process table (omitted) and the tree height, diameter at breast height, the volume of the average and annual growth curve can be seen: 1. Tree height growth fastest five years ago, annual growth rate of 0.72 5 to 20 years of rapid growth, annual growth of 0.32 to 0.46 meters; 20 years after the growth decreased significantly, annual growth of only 0.14 to 0.18 meters. The DBH growth slowed down five years ago, the average annual growth was only 0.81 cm, and then increased year by year; the growth reached its peak in 10-15 years, with annual growth rate of 1.17 cm and a slight decrease after 15 years. To 25-30 years appeared again second