通过在3种不同立地条件下白桦天然林内选取标准木进行树干解析,研究不同立地条件下白桦的胸径、树高和材积的生长规律。结果表明:立地条件的好坏与白桦的生长量呈正相关,立地条件好的林木速生期出现早、生长量增速明显,但持续增长的时间较短;立地条件差的林木速生期滞后,生长量增速较缓慢,但持续增长的时间较长。林龄70a的白桦单株树木材积平均生长量仍在持续增长,说明经过多次抚育间伐的林分,其数量成熟年龄远大于行业标准所规定的该树种的林分成熟年龄。

Based on trunk analysis on the growth dynamics of DBH,height and volume of standard trees growing in white natural birch forests at three different site conditions,we concluded that site conditions are in direct proportion to Betula platyphylla's production.Forest growing under fine site conditions are featured with earlier fast growing time,more distinct speed increase in growth increment,yet shorter in continuous growth;in contrast,forest growing under worse site conditions has later fast growing time,slower in growth increment increase,yet continuous growth period lasts longer.The average production of 70 years old birch single tree volume is still on the rise,which illustrates that tree quantitative maturity age of forest after thinning is much longer than that of the industry standard.