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杉木是我国南方主要用材树种之一.其生长从苗期——速生——干材——衰老,具有明显的生长周期.全国林木良种选育协作组(1976)认为杉木选优一般要在中龄以上才比较可靠,在丘陵区最早也只能提早到12年.江苏地处杉木自然分布区的北缘,杉木生长周期短,衰退早.即一般树高4—5年开始速生,9—10年出现峰期,11—12年开始下降,20年以后生长停滞,23年是该地杉木的主伐年龄.因此,在这种情况下,杉木生长变异的规律如何?早期测定的可靠性以及选优能否提前?还未见报导.为了探讨对伐期(23年)的生长变异进行早期测定的可靠性,从而把选优的年龄提前到9年,并用9年生的树高和胸径平方来预测23年生(主伐龄)的材积,我们试就现有的资料,对江苏杉木林分和林分内优势木生长差异的规律和个体成、幼龄生长变异之间相关的变化趋势进行了分析研究,现报告如下:
Cunninghamia lanceolata is one of the main timber species in South China, and its growth is from seedling stage to quick-growing stem-aged wood, with obvious growth cycle. The national tree seed selection group (1976) Above the age was more reliable, the earliest in the hilly area can only be early as early as 12. Jiangsu is located in the northern margin of the natural distribution of fir, fir growth cycle is short, the recession early, which generally 4-5 years old fast growing, 9- The peak appears in 10 years, the decline in 11-12 years, the growth stagnation in 20 years, and the 23 years is the main cutting age of the Chinese fir. Therefore, in this case, how is the rule of Chinese fir growth variation? The reliability of early determination and In order to explore the reliability of early determination of growth variation during the cutting period (23 years), the optimal age was advanced to 9 years and the 9-year tree height and DBH To predict the 23-year-old (the main cutting age) of the volume of materials, we try the existing data on the growth of Jiangsu fir stand and dominance in the law of the growth of wood and individuals into individual, young growth variation between the relevant trends Analytical research is reported as follows: