Constructive Species’ Coexistence Mechanisms of Pine Oak Mixed Forest in Qinling Mountains Based on the Niche Differentiation

Based on the 15 plots of Pinus tabuliformis and Quercus aliena var. accuteserrata mixed forest in Qinling Mountains, we analyzed this community’s characteristics from the aspects of species composition, niche width and diameter class, also, we used the Canonical Correspondence Analysis to explore the effects of environment on plants’ distributions and conductive species’ morphological characteristics, the main results were as follows: (1) Fifteen plots record 139 vascular plants, belonging to 53 families 102 genera, the families which possessing higher richness were Rosaceae, Asteraceae, Liliaceae and Poaceae; (2) The niche widths of Ptabuliformis (Bi=2674) and Q var. accuteserrata (Bi=2679) were all higher than other accompanying plants, and there was little niche overlap value (< 01) between them; (3) Organic matter, total nitrogen, elevation and slope mainly effected plant’s distributions; (4) Four morphological characteristics of constructive species in CCA diagram presented a opposite distribution patterns, while elevation, slope position and available nitrogen were the main induced factors; (5) Community stability of this pine oak mixed forest was relatively higher based on Godron index, and two conductive species’ diameter class were all growing type. In conclusion, high habitat heterogeneity of terrain and soil nutrient brought niche differentiation and promoted species coexistence of pine oak mixed forest in Qinling Mountains.