论文部分内容阅读
通常采用的对比木选择法,应看作是一种家系内选择法(指在天然林中应用时——译者注)。如以对比木和中选木组成的树群为单位,群间环境变异(C~2)在总变异中所占的比例较小(当采用5株对比木时为17％或更小),那么对比木选择法的遗传改良效是要比个体选择法小。假如对比木与候选木是有亲缘关系的话,即使C~2较大,个体选择法也比对比木选择法的效果好。已发表的关于天然林中树木亲缘关系和C~2的估计值表明,在很多树种中,对比木选择法实际上比个体选择法所获得的遗传增益小。在任何情况下,对比木选择法都很少比个体选择法更有效。作者建议,在选择优树时,采用新的方法校正立地条件的差异。
The commonly used method of contrasting wood selection should be considered as a family selection method (referring to the use of natural forest - translator note). For example, in the case of a tree group consisting of contrasting wood and middle selection tree, the proportion of environmental variation among groups (C ~ 2) was smaller in the total variation (17% or less when using 5 contrasting wood), then Comparison of wood selection method of genetic improvement is smaller than the individual selection method. If the contrast wood and candidate wood are related, even if C ~ 2 larger, individual selection method is better than the contrast wood selection method. Published estimates of tree genetic relationship and C ~ 2 in natural forests show that in many tree species, the comparative wood selection method is actually smaller in genetic gain than the individual selection method. In any case, comparative wood selection is seldom more effective than individual selection. The authors suggest that new methods be used to correct for differences in site conditions when choosing the optimal tree.