Attached
Timber volume is the most crucial variable in commercial forest plantations. Therefore
model construction for Eucalyptus grandis to predict the main stem volume for individual
trees precisely.
The study was carried out in Pedruthalagala area in Nuwara Eliya district because the
selected plantation is well matured and at the felling age. The circular sampling plots of
0.02 hectare were decided to obtain the required tree measurement.
Diameter at breast height, total height, diameter at different height levels were taken by
usingthe instruments such as diameter tape, Blume Leiss altimeter, and Spiegel relaskop.
All together 14 such plots were used to take the measurements.
The basic relationship was developed using the equations volume = form factor * basal
area
* height. Because form factor is difficult to quantify, it was tried to replace it by
usingthe plantation attributes such site quality, age etc.
At the first phase of this study 12 equations were selected and after a series of rigorous
testing, such average model bias, efficiency, residual distribution and R2, two models
were selected for the use in the field. These models are follows
1. vol=O.147(g*h)+O.00839top
2. vol=O.147(g*h)+O.637topiage
Where:
g*h = basal area
tpp = top height
to/age = top height / age
g = diameter
