Estimation of tree and stand volume is a key calculation for productive forest
management (de Miguel et al., 2012). A precise estimation of tree volume needs to take the
variation in bole forms into account while calculation, this can be done by es
timating tree
form factor.
This study aims to construct a mathematical model to calculate the form factor of
brutia pine trees grown in the regions of Rabiaa in northern Latakia. The form factor model
can help foresters to precisely estimate the volume of tree and forest stands.
During the period 2008-2011, 72 pine trees of various ages and sizes, located in
natural stands of different densities and site qualities, were felled.
Diameters at different heights of the felled trees were measured; trees volumes and
volumes of equivalent cylinders were calculated, and consequently the values of tree form
factor were computed. The dataset was randomly split into two parts, 75% (55 trees) of the
data for constructing form factor model and 25% (17 trees) for model validation.
A form factor model was obtained using the non-linear regression equations in the
statistical program SPSS. Value of the coefficient of determination adjusted (R²adj) was
about 0.81. The model has been validated using several statistical methods, the relative
bias ( e%) was ca. 17.9%, while the value of model accuracy ) % x m ) was 22.9 %. In
order to obtain lower value of model relative bias and higher value of accuracy it’s
recommended to use a larger database comprising all distribution areas of pine in Syria.
This study aims to construct a mathematical model to calculate the form factor of
Palestine Oak Maquis grown on the eastern versants of coastal mountains. The form factor
model can help foresters to precisely estimate the volume of tree and forest
stands.
In the year 2014, 129 oak shoots of various ages and sizes, located in natural stands
of different densities and site qualities covering all conditions of region grown on, were
felled.
Diameters at different heights of the felled shoots were measured; shoots volumes
and volumes of equivalent cylinders were calculated, and consequently the values of shoot
form factor were computed. The dataset was randomly split into two parts, 70% (90
shoots) of the data for constructing form factor model and 30% (39 trees) for model
validation.
Several form factor models were developed using the non-linear regression equations
in the statistical program SPSS. Best fit to the data was selected and value of the
coefficient of determination adjusted (R²adj) was about 0.77. The model has been validated
using several statistical methods, the relative bias of the best model ( e%) was ca. -3.6 %,
while the value of model accuracy ) % x m ) was 15%. In order to obtain lower value of
model relative bias and higher value of accuracy, it’s recommended to use a larger
database comprising all distribution areas of oak Maquis in Syria.
This research aimed to evaluate the growth and productivity of planted Pinus pinea
in pure stands at "DAHR AL SORANI" forest site. The site is about 50 km north east of
Tartous city, which is located in Temperate-Humid Bioclimate Zone.
Results sho
wed that the stands were not equivalent in growth indicators; this was due
to many factors affecting growth like site characteristics and trees density…etc. In spite of
the mediocre values of form factor, the volume and mean of annual increment was not
influenced.
Results revealed that the mean values of tree density was 851 trees/ha and ranged
between 350 - 1975 trees/ha, woody volume was averaged at 116.337 m3/ha and
ranged between 51.6519 - 215.3635 m3/ha; annual increment had also an average of 4.4548
m3/ha/year and ranged between 1.9866 - 7.9764 m3/ha/year.
The study showed a high straightness of pine. Pinus pinea trees had very rarely
forked boles.
This research was aimed at evaluation of growth and productivity of two
pine species; namely, Maritime Pine Pinus pinaster Sol. and Brutia Pine P.
brutia Ten. at the Cool-Humid Bioclimate Zone in the Mid Altitudes of the
Coastal Mountain Ranges. T
he study revealed that, height growth was not
significant between the two species. Although average diameter at breast
height was significantly superior in Brutia pine to that of Maritime pine, this
was not reflected on productivity of trees, wood volume, or the annual growth
rate due to great differences in growth forms of the two species.
