杉莲混交林中乳源木莲生长形质、空间利用能力的混交比例效应

【目的】针阔混交林以其有效改善针叶纯林树种结构简单、生态功能低效、生产力低下局面的特点而被广泛推广。杉木乳源木莲混交林(简称为“杉莲混交林”)是中国南方林区重要的混交林类型,系统分析各混交比例类型下乳源木莲生长性状、干形形质以及空间利用能力和综合表现的效应与规律,为科学构建杉莲混交林提供理论依据。【方法】以福建省沙县12年生不同混交比例杉莲混交林和纯林中的乳源木莲为研究对象,调查乳源木莲的生长形质和空间利用能力等系列性状表现,分析乳源木莲在各混交类型中生长、干形形质、空间利用能力等系列性状的差异变化;应用主成分分析法综合有显著混交比例类型效应的乳源木莲生长形质和空间利用能力表现,揭示乳源木莲生长、干形形质、空间利用能力综合表现的混交比例类型效应和变化规律,并基于总体表现进行混交比例类型的评价与优选。【结果】乳源木莲各项生长指标均有显著的混交比例效应,胸径、树高、单株材积随混交比例减少而逐渐增加;乳源木莲尖削度和胸高形数随混交比例减少而逐渐减少,枝下高则随混交比例减少而逐渐增加;乳源木莲冠高、树冠体积、树冠表面积及生长空间指数随混交比例减少而逐渐增大,但树冠圆满度则随混交比例减少而逐渐减小,乳源木莲在生长形质及空间利用能力的综合得分值呈现随混交比例减少而逐渐增大;混交比例对乳源木莲的冠幅和枝下高比例无显著影响。【结论】混交比例类型显著改变杉莲混交林中乳源木莲生长、干形形质和空间利用能力及其综合表现,合理混交比例类型可显著提高其生长、干形形质和空间利用能力,乳源木莲生长、干形形质和空间利用能力等性状有着不同的混交比例效应,开展综合评价十分必要。综上,杉莲混交林在密度为2 500株/hm²时,以2杉1莲混交模式下乳源木莲生长形质及空间利用能力表现最好。

Effects of mixing proportion on the growth,stem form quality and spatial utilizataion ability of Manglietia yuyuanensis in mixed forests with Cunninghamia lanceolata and M. yuyuanensis

【Objective】Coniferous-broad-leaved mixed forests have been widely promoted for their functions in improving the simple structure,low ecological function,and low productivity of pure coniferous stands.Cunninghamia lanceolata and Manglietia yuyuanensis mixed forest is an important type of mixed forest in southern China.The effects and laws of growth,stem form as well as quality,spatial utilization ability,and comprehensive performance of C.lanceolata and M.yuyuanensis mixed forest under different mixing proportions were systematically analyzed,to provide a theoretical basis for the scientific construction of C.lanceolata and M.yuyuanensis mixed forests.【Method】M.yuyuanensis trees from 12-year-old C.lanceolata and M.yuyuanensis mixed forests under different mixing proportions and M.yuyuanensis pure stands in Shaxian County of Fujian Province were selected as the research objects.The growth quality,stem form and space utilization ability of M.yuyuanensis were investigated,and differences as well as changes in growth,stem form quality,and spatial utilization ability of M.yuyuanensis under different types were analyzed.Based on the characteristics of growth,stem form quality,and spatial utilization ability,a principal component analysis was applied to the performance of growth form and spatial utilization ability of M.yuyuanensis,revealing the mixed proportion effect and change rule of comprehensive performance of growth,stem form quality,and spatial utilization ability of M.yuyuanensis and evaluating and optimizing the mixed proportion type based on the overall performance of M.yuyuanensis.【Result】The height,DBH(breast-hight diameter)and individual volume of M.yuyuanensis presented a significant mixed proportion effect.The DBH,height and volume of individual trees increased with the decrease in mixed proportion.Mixed proportion significantly affected tip sharpness,under-branch height,and shape of breast height.The sharpness and form factor of breast height decreased with the decrease in mixing proportion,while the under-branch height increased with a decrease in the mixing proportion.The spatial utilization ability,such as crown length,crown fullness,crown volume,crown surface area,and growth spatial index of M.yuyuanensis were significantly affected by the mixing ratio.The crown length,crown volume,crown surface area,and growth spatial index of M.yuyuanensis increased as mixing ratio decreased,while its crown fullness increased.The mixing proportion significantly affected the comprehensive performance of growth and form quality and spatial utilization ability of M.yuyuanensis.The comprehensive score value increased gradually with a decrease in the mixed proportion.Mixing proportion had no significant effect on crown width and under-branch height of M.yuyuanensis.【Conclusion】Mixing proportions can significantly change the growth,stem form quality,spatial utilization ability and comprehensive performance of M.yuyuanensis in C.lanceolata-M.yuyuanensis mixed forests.Rational mixed proportion types can significantly improve the growth,stem form quality,and spatial utilization ability of M.yuyuanensis,which is very important.In the mixed forest of C.lanceolata-M.yuyuanensis,the growth,stem form quality,and spatial utilization ability of M.yuyuanensis present different mixed proportion effects;therefore,comprehensive studies are needed.At a density below 2500 plants/hm^2 in C.lanceolata-M.yuyuanensis mixed forests,the growth quality and spatial utilization ability of M.yuyuanensis performed the best under the model of two C.lanceolata to one M.yuyuanensis.