广西大青山柚木人工林生长过程研究

目的]研究柚木人工林生长过程及其与气象因子的相关性,为柚木抚育经营提供理论依据。方法]以优良、中等和差3种生长类型的30余年生柚木人工林为对象,基于样地调查,选取优势木、平均木、被压木进行树干解析,对比分析其生长过程,应用灰色关联分析法揭示气象因子对柚木生长的影响。结果]表明:3种生长类型林分柚木胸径、树高和材积生长过程基本一致,各分级木的生长过程亦相似,其胸径平均和连年生长量随年龄的增大呈先增加后逐渐降低的趋势,树高生长整体上呈下降趋势,材积生长则呈递增趋势。各优良林分的林木及各类型林分的优势木,其胸径、材积平均和连年生长量较大,速生期持续时间长,生长衰减慢,而其树高生长量的优势相对不明显;30余年生时柚木尚未达数量成熟龄。各类型林分间柚木生长与气象因子关系的差异仅体现在胸径,优良林分胸径连年生长量主要受极端低温影响,而中等和差林分则与年均降水量相关性最大;各分级木间柚木生长与气象因子的关系无明显差异;影响树高和材积连年生长量的最主要气象因子分别为年均降水量和年均气温。结论]柚木各生长类型及分级木的生长过程整体趋势基本一致,其差异主要体现在生长量大小和快速生长期长短。约30年生柚木人工林仍未达到数量成熟,后期抚育经营对于其优质大径材高效培育仍不可忽视。

Growth Process of Tectona grandis Plantations in Daqingshan Mountains, Guangxi

Objective] The growth process of Tectona grandis plantations was investigated and its relationship with meteorological factors was analyzed so as to provide evidences for plantation management of this species. Method] Based on investigation of sampling plots, the dominant, mean and suppressed T. grandis trees aged about 30 years were sampled from high, medium and low growth types of its plantations, stem analysis was conducted for each sampled tree, and the growth process of these trees were compared among growth types. Grey correlation analysis was further applied to explore the effects of meteorological factors on annual tree growth of this species. Result] The growth process of stem diameter at breast height (DBH), tree height and individual volume of T. grandis showed no significant difference among the three growth types and three classes of trees. The mean and current annual increments of DBH increased with tree age initially and then decreased, while decreased for those of height and increased for individual tree volume. The dominant trees or trees in high growth type of plantations had higher mean and current annual growth, longer rapid growth duration and slower growth declination of DBH and volume, while the difference in height growth were not obvious relatively. the 30-year-old trees did not reach the quantitative maturity. The difference of relationships between tree growth and meteorological factors among three growth types was only found on DBH. The main factor influencing current annual increment of DBH was extreme low temperature at high growth type, while mean annual precipitation at medium and low growth types. There was no significant difference of relationships between tree growth and meteorological factors among three classes of trees. The main factors influencing current annual increments of tree height and individual volume were mean annual precipitation and mean annual air temperature, respectively. Conclusion] The growth processes of T. grandis are basically consistent in three growth types of plantations as well as for three grades of trees, their differences mainly demonstrate in growth performance and length of rapid growth. Due to the fact that T. grandis plantation do not reach quantitative maturity at the age of 30, tending and management are still important at the late stage for high-quality large-sized timber production of this species.