Effects of Four Afforestation Stands on Some Physical, Chemical and Biological Properties of Soil in Northern Iran

Selected species for afforestation have different effects on soil quality in addition to differences in their growth. The aim of current study was to investigate the effects of afforestation with four tree species, including chestnut-leaved oak, loblolly pine, black alder and Persian maple on the soil properties in the northwest of Iran. For this purpose, eight sample plots of 400 m 2 were conducted in the study area and diameter and total height of the trees were measured. Then, eight soil samples were taken from a depth of 0 to 30 cm of each stand and transferred to the soil laboratory to be investigated some physical, chemical and biological properties of the soil. Hence, a total number of 16 different soil parameters of the four stands were measured and compared using ANOVA. Besides, the correlation between different soil properties and their relationship with tree species was analyzed, using principal components analysis (PCA). The results showed that among the studied stands, the loblolly pine had a higher mean diameter, mean height, basal area and volume. Regarding soil properties, alder stand possessed the highest porosity and the lowest bulk density. The pine stand, however, was estimated to possess the highest value of basal respiration, substrate induced respirations, microbial carbon biomass, organic carbon, total nitrogen, C/N ration, absorbable potassium and the lowest pH value. Finally, the maple stand possessed the highest amount of absorbable phosphorus. Based on the results of this study, pine species due to its high diameter growth and positive effects on most soil properties is recommended for afforestation in Hyrcanian region and similar habitats in west Asia.