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ŠUMARSKI LIST 1-2/2009 str. 16     <-- 16 -->        PDF

V. Topić, L. Butorac, G. Jelić: BIOMASA U PANJAČAMAPLANIKE(Arbutus unedoL.) NA OTOKU BRAČUŠumarski list br. 1–2, CXXXIII (2009), 5-14
Research on strawberry coppice trees are done on experimental plots in
Gornji Humac on the northeast part of the island Brač, dominated by un mi x ed
and mixed evergreen oak forests. The plots have an area of 1 ha, the subplots
19 and 20, 25 m2(table 1). The canopy on subplots amounts to 84,79 %
(subplots 19), to 98,41 % (subplots 20), the medium height of sprout of strawberry
tree is 3,60, that is 4,01 m (maximum 4,50 m).


Biomass of wood and foliage on experimental plots was measured separately
for every sprout as weight and volume, the independable estimatiors
were the diameter od sprout on the height of 50 and 130 cm above ground,
height of sprout and diameter of crown of the sprout. The weight of wood and
leaves were measured in kg, volume in m3, diameter of sprout in cm, height of
sprout and diameter of crown in m. Wood volume in coppice forests, on the
area of 25 m2, varies from 0,276 to 0,405 m3, the leaf volume from 0,044 to
0,066 m3. The volume depends on the degradation stadium of coppice, that is
on the dimension of species they consist of, their number on the unit of area,
the way of grouping and the stand. The important part of the research is the
model for quick and reliable estimation of biomass is forest ecosystems.
General linear modelling is used for the development of the model. The
research results showed that the wood and foliage volume in strawberry tree
coppice is in strong, very strong and extremely strong linear dependance on
the diameter of sprout, height of sprout and crown diameter of sprout. The
correlation coefficients are between 0,599 and 0,961. The greatest correlation
ceofficient has the relation of wood weight and sprout diameter at 50 cm
height above ground level (r = 0,961).


By univariate regression analyisis biomass above soil level in coppice
strawberry trees can at best be estimated on the basis of sprout diameter,
although the other independable variables also explain this regression model
(table 4, figure 1). Diameter of sprout at 50 cm above ground explains 92,3 %
of variability of wood weight, 72,6 % of leaf weight, while the crown diameter
of the sprout explain 76,7 % of variability of wood weight and 75,9 % of
weight and leaf volume.


Multivariate regression models do not give much better results than univariate,
especially at sprout diameter, as the best independable estimator,
where values are equal. The diameter of sprout, its height and crown diameter
of the sprout explain 87,9 % of variability of wood weight, 76,9 % of weight
and leaf volume.


Diameter of the sprout explains best this regression model for weight and
wood volume, by weight and leaf volume of the crown diameter (table 5).


All models can be used for quick and reliable estimation of biomass of
each unit (wood and leaf) in strawberry tree coppice, especially with variable
of sprout diameter.


Key words:biomass, strawberry tree coppice, weight and volume of
wood, weight and foliage volume, sprout diameter, height of sprout, crown
diameter of the sprout