关键词: 白桦, 树干解析, 生长规律, 成熟年龄

Abstract: 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.

Key words: Betula platyphylla, the stem analysis, tree quantitative maturity age, growth dynamics