Ecological Relationships of Slope and Elevation with Rowan (Sorbus aucuparia L.) in Arasbaran Forests

Rowan or mountain ash (Sorbus aucuparia) has been studied less in terms of biological and silvicultural characteristics. Given the little information about the rowan species and the high ecological importance of this species and the lack of information about the habitats of this species in Arasbaran and the quantitative characteristics of this species, this study aims to address the lack of information required about this species to provide management solutions and improve the habitat of this species.

In the study area, 18 half-hectare sample plots with dimensions (50 × 100 meters) and a total of nine hectares were selected and surveyed. The selection of sample pieces was systematic randomized so that the first sample pieces were randomly and the next sample plots were selected at a distance of 800 m from each other in the eastern direction. All trees in the sample plot were surveyed in order to determine the percentage of rowan species compared to other species in the sample plots.

Results showed that there were 20 species in the sample plots. Quercus macranthera (1018 stems per hectare), Viburnum lantana (290 stems per hectare) and Carpinus orientlais (226 stems per hectare) were the three most important species in terms of abundance in the study area. Sorbus aucuparia species was observed along with the mentioned species in the region and showed the fourth rank in terms of average density per hectare (142 stems per hectare). The average diameter at the breast height (DBH) and height of the measured tees stems were 9.8 (±6) cm and 4.4 (±1.8) meters, respectively. The highest number per hectare was observed on slopes less than 40% and at altitudes above 2200 meters above sea level. There was a significant statistically difference in the values ​​of DBH with slope classes. There was no significant difference between the height of trees and the frequency per hectare with the slope of the land.

According to the results, considering the role of rowan in the stability of sloping areas and reducing erosion, by increasing the conservation period and exclosure of valuable forest species, including various species of Sorbus sp, long-term results will be accessible in the protection of Arasbaran plant ecosystem.