A study on the dimensional characters of even-aged and Mixed Fraxinus excelsior stand (case study: Chelir District, Kheyrud Forest)

Knowing and conducting studies on size characters of trees is essential for assessing the tree volume and/or other statistical parameters and also forest management. The characteristics of 529 trees including diameter at breast height (DBH) and total height were measured in an even aged Fraxinus stand for two periods from 2005 to 2012 in Chelir district, a part of experimental Kheyrud forest. Results showed that there are statistical correlations among the size characters of ash trees, therefore, mathematical-statistical equations could be developed among these characteristics This relationship was calculated for all trees in the stand as even-aged stand and then calculated for Fraxinus trees in the stand. There is an increasing power relationship between DBH and total height of all trees in the stands in two periods which is used for estimating the growth of total height of trees in next period. There are power relationships between size characteristics of Fraxinus trees in stand. The relationships between DBH and slenderness index for the first and second period are 0.014 1.475 dbh h d e and 0.006 1.210 dbh h d e , respectively. The vitality percentage curve was prepared for stand trees in diameter classes and the results showed that the periodic annual increment for Fraxinus tree is 3 mm. The research in natural forest stands and investigating their changes in a period, will show the path and proper method of management in accordance with the nature of the forest stands for maximum and sustainable production.