桥山栎林群落结构特征与物种多样性相关关系分析

为了解森林群落结构特征与物种多样性之间的相关关系,以黄土高原桥山林区典型麻栎纯林、麻栎阔叶混交林和麻栎油松混交林为研究对象,调查分析了群落结构特征,计算物种重要值及物种多样性,并进行了冗余分析,结果表明:(1)麻栎油松混交林主要以乔木层胸径、树高、枝下高等最高;麻栎阔叶混交林以灌木层盖度、地径、冠幅、高度等最高;麻栎纯林以草本地径、草本盖度及草本冠幅最高。(2) 3种类型林分乔木层重要值最高的均为麻栎(Quercus acutissima),灌木层为狼牙刺(Sophora viciifolia)、南蛇藤(Celastrus orbiculatus)、胡枝子(Lespedeza bicolor),草本层为苔草(Carex tristachya)。(3)麻栎油松混交林乔、灌层物种多样性较高,麻栎阔叶混交林以草本层物种多样性最高。(4)不同类型麻栎林群落结构特征与物种多样性关系有差异。松栎混交林中,对物种多样性影响最大的为乔木胸径、新稍长及灌木高度;麻栎阔叶混交林对物种多样性影响最大的为灌木层高度及冠幅;麻栎纯林中,对物种多样性影响最大的为乔木胸径。(5)麻栎油松混交林、麻栎阔叶混交林的胸径、树高、物种多样较麻栎纯林高,具有较高木材生产能力和生态防护功能,是未来森林经营培育的方向。

Differences in community characteristics, species diversity, and their coupling associations among three Quercus acutissima forests in Qiaoshan

To understand the coupling relationship between forest community characteristics and species diversity, three typical communities (pure forest of Quercus acutissima, mixed forest of Q. acutissima with various broad-leaved trees, and mixed forest of Q. acutissima with Pinus tabuliformis), were selected at Qiaoshan, southern Loess Plateau, to measure the community characteristics (height, diameter at breast height, and coverage). According to these indices, important values and species diversity were calculated, and redundancy analysis (RDA) was performed. The results showed that (1) the height and diameter at breast height and clear tree bole height of the arbor layer of Q. acutissima with P. tabuliformis were the highest in the mixed forest; the shrub height, shrub crown width, shrub ground diameter, shrub coverage were the highest in the mixed forest of Q. acutissima with various broad-leaved trees; and the herb ground diameter, herb coverage, and herb crown width were the highest in pure forest of Q. acutissima. (2) In three different forests, the important value of Q. acutissima in the tree layer was maximal, and the dominative species in the shrub layer were Sophora viciifolia, Celastrus orbiculatus, and Lespedeza bicolor, and that in the herb layer was Carex tristachya. (3) The biodiversity index of trees and shrubs in the mixed forest of Q. acutissima with P. tabuliformis were the highest, while the diversity index of herbs in the mixed forest of Q. acutissima and various broad-leaved trees were the highest. (4) There were differences in the relationships between the community structure characteristics and species diversity of different types of Q. acutissima forests. In the mixed forests of Q. acutissima with P. tabuliformis, the DBH, new twig length, and height of the shrub had the highest impact on species diversity. In the mixed forests of Q. acutissima with various broad-leaved trees, the height and crown width of the shrub had the highest impact on species diversity. In the pure forests of Q. acutissima, the DBH had the highest impact on species diversity. (5) Tree diameter breast height, tree height, and species diversity in the Q. acutissima with P. tabuliformis forest and in the mixed forest of Q. acutissima with various broad-leaved trees were higher than that in the pure forest of Q. acutissima. We can conclude that these two forest types have high wood productivity and ecological protection capacity, and can be the direction of future forest management.