种子采自天然林和人工林，两者都可能是经过去劣留优作为母树林的。

Seed crops are collected from both natural stands and plantations which may have been culled to form seed stands .

种子采自天然林和人工林，两者都可能是经过去劣留优作为母树林的。

Seed crops are collected from both natural stands and plantations which may have been culled to form seed stands.

林分内个体间差异极大,存在着一批优良木,经去劣疏伐可将林分改造成母树林.

Numbers of fine trees existing in stand roughing and transforming stand to be a seed stand.