Abstract: Effect of topographic factors on the distribution of understory plant species was investigated in the montane forest communities in Nanling National Nature Reserve,Guangdong,China.The montane evergreen broadleaved forest communities sampled from 3 elevations had diverse species composition and abundance,but with great heterogeneity in spatial distribution.255 vascular plant species from the understory,with a total abundance of 3228 stems,were recorded in 450 subplots(4 m²each)within the total plot area of 9000 m²,which belonged to 95 families and 181 genera.The result of Multi-Response Permutation Procedures(MRPP) showed that aspect,elevation(p<0.0001) and slope(p<0.05) had a significant influence on the distribution of understory species,with the magnitude of influence in the following order:elevation>aspect>slope.Furthermore,Indicator Species Analysis(ISA) identified the indicator species with a significant indicator value ≥50 under different topographic conditions.This study indicated that a community might be affected by several topographic factors in the meantime.Therefore interactions and compensation among topographic factors should be taken into account when assessing the effect of a single topographic factor on the spatial patterns of understory vegetation.The two statistical programs,MRPP and ISA,are robust in demonstrating relations of spatial heterogeneity of plant distribution to environmental factors,and in identifying indicator species,which has significant implications for plant biodiversity conservation,forest restoration,and silvicultural applications.