Abstract
Yield of stand affected by different characteristics of a tree or the stand , correspondingly ,the height is one of the important factor effects the quality and quantity of the yield , for that this investigation was conducted in order to estimate growth of height for Populus nigra stands grown at Zakho Region depending on age ( A) , diameter at breast height (dbh) and density of stand . Forty five samples will be selected randomly from stands with different densities and ages . Data analyzed and mathematical models driven for many equations connect the studied variable of stands with the height by using regression system then constructing on the resulted precision measurements of the equation , the followings were selected:
H =-12.12 + 8.50(A) 0.5
H = -2.08 + 1.74(A) + 0.14(SP ) 2
H = 1.27 + 2.132(D) – 0.75EXP(SP)
The coefficient determination coefficient (R2) of above equations were (90.3, 91.02 ,91.33) with standard error (0.88,0.86,0.84) respectively. Resulted equations enable us to estimate average stand height at any age or density then different tables and graphics prepared to illustrate the development of stand height growth which is widely used by forest managers in order to predict the mean stand height also to estimate average growth annual growth in the height of stand through first driven of equations links the height with the age .
