种子园是林木良种繁殖的基地。因此,不仅要考虑遗传选种的问题,也要考虑诸如栽植距离,培养树冠的方法等问题。树间距离太宽是不适宜的。理由是:第一,头十年树冠较小,空地多在经济上是不利的;第二,每公顷植株少,花粉也少,对保持优良种性不利。但是,如仅考虑适合于幼龄时的距离,树冠郁闭后采集球果机械化就有困难。因此,种子园应有适应于两个时期的栽植距离。在幼龄期,单位面积上应有足够的株数,以保证良好的种性;老龄阶段,留下较少的植株,以增加产量及便于机械化采种。 Seed orchard is the seed breeding base. Therefore, not only the issue of genetic selection should be considered, but also the issues such as the planting distance and the method of cultivating the canopy should also be considered. The distance between trees is too wide is not appropriate. The reasons are: First, the crown is smaller in the first ten years and the open space is more economically unfavorable. Second, there are fewer plants per hectare and less pollen, which is unfavorable for maintaining good species. However, if only the distance suitable for young age is considered, it is difficult to mechanize the collection of cones after the canopy is closed. Therefore, the seed orchard should have adapted to the two periods of planting distance. In young, there should be sufficient number of plants per unit area to ensure good species; aging stage, leaving fewer plants to increase production and facilitate mechanized seed collection.