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ŠUMARSKI LIST 13/2011 str. 115     <-- 115 -->        PDF

A. P. B. Krpan, Ž. Tomašić, P. Bašić Palković :BIOPOTENCIJALAMORFE (Amorpha fruticosa L.) – DRUGA... Šumarski list – Posebni broj (2011), 103-113


survey, sampling and data processing are described in the chapter Materials and Methods.
The results of the field measurements on the plots are shown in Figures 1 to 4, in
which positions of Indigobush stumps and values related to Indigobush sprouts can be
seen.The number of annual sprouts on plots nr.1 ranges from 276 to 455 and two-yearold
sprouts on plots nr. 2 ranges from 265 to 432. Converted to hectares, number of
sprouts is 106,000 to 182,000.Medium height of annual sprouts on plots nr.1 is from


2.13 m to 2.25 m, and heights of two-year-old sprouts on plots nr. 2 are form 2.28 m to


2.58 m. The mean diameter of sprouts on plots nr. 1 ranges from 7.0 mm to 7.6 mm, and
on the plots nr. 2 it ranges form 9.1 mm to 10.5 mm.At the annual sprouts the largest
diameter recorded was 14 mm and maximum height was 3.4 m, and at the biennial
sprouts it was 20 mm for maximum diameter and 3.7 m for maximum height. In proportion
to the number and size of the Iindigobush sprouts mass of wood substance on
plots nr.1 ranges from 23.29 kg to 38.14 kg, on the plots nr.2 from 54.34 kg to 78.55 kg.
Given the uniformity of height and diameter growth and increment, we find that the
production of Indigobush biomass is in direct correlation with the number of sprouts
per unit area.In the second year, height increment is reduced (compared to the first
year), the mean diameter increases from 2 to 3 mm, stem branches, starts flowering
and fruiting.Table 1 shows green mass on the surface, green mass per hectare, the proportion
of moisture or dry weight in green mass and dry wood substance produced on
the plot and per hectare for plots 1 and 2 in the field experiment. In two-year-old Indigobush
stand, production of green and dry biomass is twice as high (24.52 to 11.96 t/ha
or 16.39 to 7.87 t/ha) compared to the biomass of annual stand of other vegetation.In
the first vegetation period, after felling old Indigobush, the annual production of green
biomass was 15.20 t/ha (Krpanand Tomašić2009), and in the second period was


11.96 t/ha or 3.24 t/ha less, indicating a decrease of Indigobush’s biopotential at repeated
annual cutting on the same surface.One third of the green mass goes to moisture
and two thirds go to dry matter, which places Indigobush, cut out of vegetation
period, commercially favorable for biomass energy.


In Table 2, data on seed collection from the plots number 2 of field experiments
from 1 to 4 is shown. On the plots it was collected from 3.20 kg (field 3) to 4.94 kg
(field 1) or an average of 3.97 kg, so the weight of seed per hectare at the time of collection
ranged from 1.280 kg to 1.976 kg or an average of 1.589 kg.Seed moisture content
ranged from 14.3 % to 15.7 % or an average of 15.2 %, a mass of dry seeds
ranged from 1,082 kg/ha to 1,674 kg/ha, or an average of 1,348 kg/ha.First crop confirmed
earlier findings of an abundant yield of Indigobush. Table 3 shows data of green
and dry mass of Indigobush wood on plots nr. 2, for which the values of wet and dry
seed mass have been added. With moisture content W = 34.2 % the energy value of Indigobush
biomass is 12.727 MJ/kg, and at W0 = 20.259 MJ/kg (Marosvölgyiet al.
2009).Very close mean values of moisture content obtained in our study (Table 1) and
data of produced biomass (Tables 1 and 3) show us ability to assess the energy value of
Indigobush biomass.ld be noted that the Indigobush biomass in our lowland forests
forms naturally without any agricultural practice and associated costs. Including Indigobush
biomass into alternative energy flows brings multiple benefits and development
opportunities. We think that this would significantly increase the amount of
available forest biomass in Croatia, would have widened the range of forestry products,
would reduce the cost of regeneration of lowland forests, and residents of rural
and urban gives up the possibility of earning an income related to the cultivation and
harvesting of Indigobush biomassas well as introduction of biomass power plants.


Key words: Indigobush, bioproduction, energy value, lowland forest ecosystems,
Croatia