Abstract:Variations in β diversity of forest communities along an altitudinal gradient were studied in Nanling National Nature Reserve, China. A horizontal transect (10 m × 120 m) was established at each 100-m altitudinal interval from an elevation of 300 m up to 1 900 m a.s.l. Correlation analysis, regression analysis and ANOVA were used to determine altitudinal patterns of β diversity and its relationship with environmental factors. Results were as follows: the Cody index and species turnover rate βC showed linearly and significantly negative correlations with altitude (P＜0.05) in base and adjacent belt transects. Shared species of community, canopy stratum, understory stratum decreased with increasing species turnover rate βC (P＜0.05). The Cody index could better reveal the species differences along altitude among communities, canopy stratum and understory stratum, based on analysis of one-way ANOVA, Fish’s LSD and Tukey’s HSD. Compared with community dissimilarity, the Bray-Curtis index, the Morisita-Horn index, species turnover rate Sβ and species turnover rate t, the Cody index and species turnover rate βC were useful to characterize the β diversity of forest communities along an altitudinal gradient in Nanling National Nature Reserve.