Effect of spacing on degree of taper and preparing taper table for even aged stand of Populus nigra L.

الملخص EN

A taper equation was developed for poplar trees growing at four initial spacing (0.5 × 0.5, 1 × 1, 1 × 2, and 2 × 2 m) at age 4 years.

In this study, Data came from 160 trees of Populus nigra L.

plantations collected from two sites Semel and Zakho districts.

Total tree height, diameter at breast height, height limit and diameter limit at one meter interval were recorded for each tree.

From five candidate equations, equation (1) gives the best performance for estimating tree taper depending on the values of test statistics.

This equation can be used to construct taper table to show diminution of diameter along the stem.

Total tree volume is obtained by integrating the area from equation (1) at each infinitesimal stem diameter along the entire height of the tree.

Under all spacing, the results of statistical analysis showed that increasing in spacing from (0.5×0.5 to 2×2 m) significantly (P < 0.01) increased the average diameter at breast height from (4.5275 to 7.4560 cm), but spacing regime had no significant effect (P >0.35) on tree height.