Effects of slope orientation on tree species composition, structure and diversity in temperate forests of Durango, Mexico

Silvicultural treatments in temperate forest ecosystems can influence tree species composition and diversity, depending on both management intensity and site-specific environmental conditions. Among these conditions, slope orientation plays an important role by regulating microclimatic factors such as solar radiation and soil moisture. Therefore, this study evaluated the effect of slope orientation on tree species composition and diversity in a temperate forest under the Mexican Method for the Management of Irregular Forests (MMOBI), which applies selective harvesting of mature trees. An ecological analysis was conducted using the Importance Value Index (IVI), Margalef species richness index (DMG), and Shannon diversity index (H′). The IVI showed that the genus Pinus dominated north-, south-, west-facing slopes and the zenith area, with values of 49.67%, 57.58%, 50.41%, and 44.16%, respectively, whereas Quercus dominated east-facing slopes (70.58%). Shannon diversity values ranged from 0.47 to 1.02, with the highest value observed on north-facing slopes and the lowest on west-facing slopes. Margalef richness values ranged from 0.56 to 0.80, with the lowest richness recorded on south-facing slopes, which differed significantly from the other orientations. These results indicate that tree species composition and diversity vary according to slope orientation, reflecting the combined influence of forest harvesting practices and microclimatic variation associated with topography. The findings highlight the importance of considering slope orientation as an ecological factor in forest management and planning in temperate forests.