乳源木莲优质干材混交培育的研究

CULTIVATING HIGH-QUALITY STEMWOOD OF MANGLIETIA YUYUANENSIS BY MIXING WITH CUNNINGHAMIA LANCEOLATA

研究证实 ,乳源木莲生长迅速 ,树干通直圆满 ,较少病虫害 ,其木材密度超过同龄的杉木。乳源木莲早期生长缓于混交树种杉木 ,1 0a生左右进入干材速生期 ,1 6a生时干材材积接近杉木的 3倍 ,这说明通过与杉木混交可以培育优质的大径阔叶材。乳源木莲侧枝形成分叉特性显著 ,适时的除萌修枝方能保证高质量干材的培育。研究发现 ,在南方低山丘陵区 ,影响混交乳源木莲干材生长的主要生育地因子是坡度 ,缓坡地土层深厚 ,立地条件较好 ,乳源木莲干材生长量大 ,枝下高长。生长在下坡和半阴 (阳 )坡的乳源木莲之高径生长有高于其它坡位和坡向的趋势。根据林分密度和杉莲比之于乳源木莲干材培育的作用机理 ,应适当降低混交林的初植密度和单位面积乳源木莲的株数 ,采用 3∶1或更高的杉莲比混交造林 ,并通过适时的间伐 ,以达到枝下高长。

The results proved that Manglietia yuyuanensis was an excellent broadleaved tree species with fast growth rate, high-quality stem form, less diseases and pests and higher wood density.And after slower early growth period, M.yuyuanensis begin to enter a rapid growth phase of stemwood at 10 years old. Individual stemwood of M.yuyuanensis at age 16 was nearly as three times as Chinese-fir, suggesting that interplant with Chinese fir would be a effective way of cultivating high-quality and large-diameter broadleaved wood. Because of marked stem forking, it was important for cultivating high-quality stemwood of M.yuyuanensis to remove or prune sprouts in time. The results indicated that hill slope was a major site factor affecting stemwood growth of M.yuyuanensis in the mountain areas in South China with lower elevation. Gentle slope means deeper soil and better site, resulting in greater stemwood and longer clear bole height. There existed some trend of great height and DBH growth for M.yuyuanensis planting lower position and semi-shade (or semi-sun) aspect.Based on the mechanism of stemwood cultivation, initial planting density and M.yuyuanensis trees per hectare should be reduced properly and higher ratio of Chinese fir to M.yuyuanensis adopted in order to cultivate longer clear bole height and large-diameter broadleaved wood.