The mountaintop mossy dwarf forest is a community of evergreen broad-leaved forests in subtropical mountains facing extreme climatic and environmental conditions. Understanding the distribution pattern and scale of the dominant tree species in this forest can provide insights for effective management measures and an understanding of the mechanisms of community assembly in subtropical forests. In this study, we established 3 plots to explore the distribution patterns of dominant species in a mountaintop mossy dwarf forest in three directions in the Yangming Mountains in Hunan Province, China. An adjacent lattice method was used to survey dominant species (i.e., Rhododendron fortunei). At seven spatial scales, aggregation intensity indexes such as variance/mean ratio (v/m), negative binomial parameter (k), clumping index (I), mean crowding index (m^*), patchiness index (m^*/m), aggregation index (C_a), and Green index (GI) were used to analyze distribution patterns of populations. The results showed that the dominant species in the northern, southern, and eastern plots presented a clumped distribution. However, with increasing surveying scales, the distribution patterns changed from clustered to uniform, and the intensity and size of the aggregation pattern decreased. The spatial distribution characteristics at different developmental stages showed that population aggregation intensities developed from strong via weak to random. Population dominance and resultant distribution patterns were mainly caused by biological characteristics such as seed propagation and vegetative reproduction, and the influence of environmental factors, such as plot orientation and slope direction.