Abstract: Three types of forest community (Fraxinus mandshurica, Quercus mongolica, and Ulmus macrocarpa) were investigated to explore the population distribution patterns of dominant species in Daqinggou Nature Reserve in Inner Mongolia. By using theoretical distribution model and aggregation intensity index, the distribution patterns of F. mandshurica, Q. mongolica, and U. macrocarpa under different developmental stages and at different spatial scales were analyzed. The results showed that the population of dominant species generally presented a clumped distribution. However, populations in Ⅱ (4 cm≤DBH<8 cm) and Ⅳ (DBH≥24 cm) developmental stage of F. mandshurica and those in Ⅲ (8 cm≤DBH<24 cm) and Ⅳ developmental stage of U. macrocarpa showed random distributions. The clustering intensity of all three populations decreased with the increasing stem age (DBH) or developmental stage. F. mandshurica and U. macrocarpa showed random distributions but Q. mongolica presented a clumped distribution with the developmental stage. The clustering intensity of the same population and developmental stage decreased with increasing study scale. Our study proved that both the distribution pattern and clustering intensity of the three populations were affected by the developmental stages and spatial scales.

Key words: dew condensation time, dew occurrence frequency, loess hilly region, meteorological factors.