Comparing the growth of Paulownia fortunei and Populus deltoides plantations under different spacing in northern Iran

This study was carried out to investigate poplar and paulownia’s growth under different spacing in a 5-year plantation located in Mazandaran wood and paper company’s fields in Sari-Iran. The trees were planted in three different spacing: 3×3m, 4×4m, and 5×5 m, each established in 3 replications. The quantitative parameters including DBH and Height were measured and a comparison was made between the stands height and diameter growth. Survival percentage was also calculated across the stands. The averages were statistically compared in a randomized block design in two forms: 1) two species were separately compared in their threefold spacing, and 2) two species were crossed in each spacing. Tukey’s test was used to compare the averages. Results showed a promising rate of survival over the stands. Moreover, the growth was significantly different amongst different spacing of the stands, representing the best growth in 3×3m spacing. In addition, the height of poplar was significantly more than those of paulownia, though the diameter growth assessment showed a reverse trend between the stands.