黄土高原中部主要乡土树种生长过程分析

本文对黄土高原中部油松、侧柏、刺槐、沙棘、胡颓子和火炬树等乡土树种树高、胸径及材积生长量进行了测定，结果表明：研究区树高生长曲线分两种类型，以油松、侧柏等人工实生林为一种类型，即满足“慢一快一缓慢一稳降”生长规律，沙棘、火炬树等萌蘖林开始生长较快，之后逐渐降低并趋于稳定。6树种树高平均生长量为0．4518±0．2763...

Comparative Study on Growth Processing of Main Native Tree Species in the Middle Loess Plateau

In the middle part of the Loess Plateau the curve of tree＇ s height growth can be grouped into two categories, i.e. those following the common pattern of （Slow-rapid-slow-stable drop down）such as Chinese pine and oriental arborvitae plantation, seabuckthorn and Rhus typhina sprouted stands grow up rapidly in the beginning, and then gradually decrease the growth and approach to sta- bilization. Chinese pine, oriental arborvitae, black locust, thorny elaeagnus, seabuckthorn and Rhus typhina average annual growth in height is 0. 4518±0. 2763 meters, the black locust is the highest, the oriental arborvitae is the lowest. The average current annual growth in height of the above-mentioned six trees is 0. 3190±0. 1358 meters, the black locust is the highest, the thorny elaeagnus is the lowest. The average annual growth in diameter at breast height of the 6 species is relatively stable, it is 0. 4170±0. 1714cm, the black locust is the highest, about 3 times of the oriental arborvitae, the broad-leaved trees in higher than the needle-leaved trees, and seedling forest is rather high. The mean current annual growth in diameter at breast height of the 6 species is 0. 3723±0. 1205 cm, the Chinese pine is the maximum, and the oriental arborvitae is the minimum among them. Along with the prelon- gation in ages of the six species, their cumulative timber volume both average annual growth and current annual growth have a trend of increase. The average annual volume growth of the six species is 3. 125× 10^-4 ±4. 8827 × 10^-4m^3, the black locust is the maximum and the oriental arborvitae is the minimum among them, there is about 20 times between the maximum and the minimum. The average current annual volume growth of the six species is 6. 8956× 10^-4±10. 1233 × 10^-4 m^3, the black locust is respectively 2. 38 times and 15.34 times the Chinese pine and the oriental arborvitae. The process of different tree species is different, which is mainly influenced by the amount of precipitation.