Quantitative and qualitative study and index choice to compare four eastern cottonwood (Populus deltoides Bartr. ex Marsh) stands in Gilan and Mazandaran

In order to compare the quantitative and qualitative characteristics of eastern cottonwood (Populus deltoides Bartr. ex Marsh) trees that are the most common ones for wood culture in north of Iran, four P. deltoides stands with clone of 69/55 were selected in lowlands of Gilan (Davoodmazar and Haftdaghanan) and Mazandaran (Shirkola and Chamestan) provinces. In each stand, with method of random – systematic, samples of 400 m² were designed to measure the trees and soils. Likewise, the mean annual volume increment with highest coefficient of variation (CV) was considered as Comparison Index for determining the main affecting factors on growth and yield in four Populus stands. The mean diameter of trees in Shirkola (42.9 cm) and Chamestan (39.1 cm) was greater than that in Davoodmazar (27.9 cm) and Haftdaghanan (28.7 cm). The mean volume increment of tree in two province was significantly different, whereas in areas of Chamestan (34.4 m³/ha) and Shirkola (22.5 m³/ha) was greater than that in Davoodmazar (17.17 m³/ha) and Haftdaghanan (17.03 m³/ha). The mean annual volume increment of each tree was bigger in Shirkola (0.089 m³) and Chamestan (0.074 m³) compared to Haftdaghanan (0.036 m³) and Davoodmazar (0.031 m³). It can be deduced that in areas with very humid to humid climates of Gilan and Mazandaran which have favorable conditions for growth of Populus trees, soil texture is light to moderate with a silt content of more than 47% and pH higher than neutral, Populus deltoides growth is higher. The similar investigations with other clones of Populus in northern provinces of Iran with different climates are recommended.