The effect of different soil remediation methods on growth and primary establishment of Pistacia atlantica Desf., Quercus infectoria Oliv., Melia azedarach L. and Cupressus sempervirens L. saplings in Semnan

Species selection and suitable planting methods are essential for creating plantation and green space. This is important specially in arid and semi-arid regions. The object of the present study was to investigate the growth and primary establishment of four tree species using four different soil remediation treatments in Semnan City. These treatments were applied to two-years-old saplings in three replications and five observations in each replication and the quantitative and qualitative characteristics of saplings were measured and recorded during the experimental period. The results showed that straw mulch (together with stone cover) caused the highest collar growth in all investigated species, while the usage of hydrogels and zeolites did not have a significant positive effect on the sapling growth and decreased the growth in some cases. Compared to control soil (sandy-loam), the modified soil texture treatment (loam soil) did not change the collar diameter, height and total length of lateral branches of Melia and Cupressus saplings, but it reduced the diameter growth in Pistacia and Quercus saplings. The highest rate of survival in all investigated species was observed in control and straw treatments. The results of this study showed that Pistacia and Melia had the highest and lowest survival rate, respectively. However, Melia had the highest height and collar diameter growth amongst investigated species with maximum growth under straw treatment. Contrasting other species, Quercus has experienced a significant decrease in collar diameter and height (in all treatments specially hydrogels and zeolites) after June and has progressed to shrub form.