<正>以小黑杨为研究材料，研究不同栽植密度1000、500、250株/hm2对林木幼龄材、成熟材生长量的影响。结果表明：不同栽植密度的林木幼龄期为12～13a，栽植密度对林木幼龄材、成熟材年轮数影响均不显著；栽植密度对林木幼龄材、成熟材宽度及面积的影响极显著，随着栽植密度的减小，幼龄材宽度及面积明显增大，而对于成熟材，500株/hm2的林木生长量较大；不同栽植密度林木幼龄材面积比例达74％～83％，栽植密度最小的林分幼龄材比例最大；幼龄材生长速率要比成熟材大10倍左右，不同栽植密度间幼龄材、成熟材生长速率差异明显。相比而言，栽植密度对小黑杨幼龄材的影响较大。

The bioassay of the methanol extract from different parts of Taxus chinensis var. mairei seed was carried out and the inhibitors were identified using GC-MS methods, in order to investigate the relationship between the inhibitors and the dormancy of T. chinensis var. mairei seed. The results showed that the methanol extract from middle spermoderm, endopleura and endosperm of T. chinensis var. mairei seed had the inhibitory effects on the percentage germination, height and root growth of Brassica campestris seedling. Moreover, the higher the extract concentration was the more obvious the inhibitory effect were Also, it was first time that many organic compounds were identified from different parts of T. chinensis var. mairei seed, and the inhibitors and their relative content were mensurated, these inhibitors included the reported heptanoic acid, nonanoic acid and acetic acid. It is concluded that the seed of T. chinensis var. mairei contains some germination inhibitors.