Abstract
Consequence of the use of Non-Linear function in this study, which is believed to be in harmonic with the characteristics of tree stand, twelve trees were selected which represents different location over an area planted with Populus nigra trees ,and after data analysis of variable values , three mathematical equations were obtains which link the yield per area ,a dependent variable and age ,mean height of stand quadratic mean diameter as the independent variable , in order to obtain yield table of revocable densities for Populus nigra , selecting the best model , different measures of precision , such as , coefficient of determination, standard error of estimate and residual analysis test, so following regressions selected :
Y= 4.1356 G1.12355
R2= 0.9796 S.E=1.8
Y= 0.12788H2.27
R2= 0.913 S.E=3.54
Y= -0.64168+0.34744A2+0.063183Dq2.4
R2= 0.9674 S.E=2.29
Since there are good values of precision measures , so we will be able to use equations to prepare yield table at different densities of Populus nigra stands in Nineveh, depending on mean height or basal area per hectare or for age and quadratic mean. Nineveh.
