A. Goleij, H. Jalilvand, M. R. Pormajidian, M. Tabari, K. Mohammadi Samani,
Volume 11, Issue 41 (fall 2007)
Abstract
In order to investigate the success of natural regeneration and to determine the best area for regeneration settlement, 12 gaps with the areas ranging from 50-100, 150-300, and 400-600 m2 and 4 replicates equal elevation level were selected. For measuring frequency, height, and collar diameter of regenerated seedlings, a certain number of 2 m2 subplots were carried out inside the gaps, along the bigger diameter, and related to each gap’s area. Results showed that the number of seedling varies from 5 (in big gaps) up to 28 (in small and moderate gaps) per square meter. Furthermore, there was not a significant difference between the number of seedlings in small and moderate gaps. In contrast, the number of seedlings in small and moderate gaps was significantly different from those in large gaps (at 1% Probability). This finding demonstrates that natural regeneration would be limited in large gaps (400-600 m2) but it shows a better result in smaller gaps, associated with single- tree harvests. The final result of this study shows that the most appropriate area for selective cuting in such an area is up to at most 300 m2.
P. Rostamizad, V. Hosseini, K. Mohammadi Samani,
Volume 22, Issue 2 (Summer 2018)
Abstract
Trees crown can be regarded as main factor contributing to the conservation and support of soil in many ecosystems including semiarid forests in Zagross. The aim of this study was to find out the effect of tree crown of pictachio (Pistacia atlantica Desf) on N, OC, P, pH, EC and the texture of the soil. Soil samples were collected in and outside the crown of 5 single pistachio trees on four directions of each tree in a northern slope from the 0-5 cm depth of soil in the Sarvabad region, Kurdistan. The results of this study showed that the amount of the soil organic carbon was decreased from 6.71% in the soil inside tree crowns to 4.73% in the soils outside the tree canopies. The soil inside trees had a higher concentration of soil nitrogen (0.406%) than the one outside (0.224%) the tree crown; the concentration of phosphorus was measured to be 32.7 mg/kg in the soil inside canopy, while it was 21.1 mg/kg in the soil of outside the tree canopy. EC under the tree crowns was more than that outside the canopy. The results, therefore, showed that soil texture was lighter inside the canopy, as compared to outside; however, the acidity of the soil was not affected by tree crowns and no significant differences were observed in different areas of the crown. Therefore, Persian turpentine trees have positive impacts on the soil properties in Zagros forests and eliminating them will lead to the significant loss of soil fertility and greater soil erosion.
