云南松天然优良林分疏伐营建母树林的研究

摘要

More than 10 years of study on the establishment of seed production stand by thinning natural superior stands of Pinus yunnanensis in western and middle part of Yunnan and their genetic increment shows thinning natural superior stands is an important technical measure to establish seed production stand. The thinning intensity (degree of closeness) of 0.3 is proper for reconstructing 16 years old natural superior stands as seed production stand, and the seed production stand will be of commitment after 2 times thinning, of which the thinning interval should be shorter than 4 years. From 1993 to 1995, the average fruit bearing per tree in seed production stand is 60 and that of per hectare is 10 329, and setting percentage reaches 95.65%, which are 5.08, 1.26 and 1.15 times those of the check respectively. 4 years as a bearing cycle, the frequency distribution of bearing amount per tree presents logarithmic normal distribution. Moreover, the bearing property is stable relatively. Both natural superior stands and progeny of seed production stand of Pinus yunnanensis have the characteristics of straight stem, small ratio of wood twisted grain and fast growing. Most properties of Pinus yunnanensis are affected heavily by gene linkage and co- effect gene, while lightly influenced by environment, therefore, they are of highly genetic stable. The genetic increment of height, diameter, stem volume and ratio of wood twisted grain of superior stands and progeny (6～10 years) of seed production stand are 5.74%～20.14%, 8.61%～40.46%, 27.88%～107.11% and 17.42%～59.79% respectively.%10余年来对滇西和滇中的云南松天然优良林分疏伐营建母树林及遗传增益的研究结果表明：疏伐是优良林分营建母树林的重要技术措施。改建16年生左右的云南松天然优良林分为母树林，以选择0．3(郁闭度)疏伐强度为好，母树林经2次疏伐后即可定型，其疏伐间隔期不超过4年。1993～1995年，母树林平均单株结球果达60个，每公顷结10 329个，结实株率达95．65％，分别是对照的5．08倍、1．26倍和1．15倍。母树的结实性状较为稳定，单株结实量的频率分布呈对数正态分布，一般以4年为1个结实周期。云南松天然优良林分和母树林子代均具有干型通直、木纹理扭转度小、生长量大的特点。云南松诸性状间较多地受基因连锁或共效基因的作用，而受环境的影响相对较小，大多数性状具有较高的遗传稳定性。在云南松种子的调拨中应注意不同种源的适生区域。云南松优良林分和母树林子代林6～10年生的树高、胸(地)径、材积和木纹理扭转度的遗传增益分别为5．74％～20．14％、8．61％～40．46％、27．88％～107．11％和17．42％～59．79％。