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Biopotential of Indigobusch (Amorpha fruticosa L.) – Second Year of Investigation

Ante P. B. Krpan ; Hrvatski šumarski institut Jastrebarsko
Željko Tomašić ; Hrvatske šume d.o.o. Zagreb
Pavao Bašić Palković ; Hrvatski šumarski institut, Centar za nizinske šume Vinkovci

Sažetak

Recent studies of biomass in Croatia were directed towards commercial forest species. Besides trees, building elements of our natural forests are also various shrubs and ground vegetation. It is assumed that, because of the increasing market demand, the biomass of trees but also some of the other components of forest biomass will be commercially interesting in the near future. One of them is Indigobush (Amorpha fruticosaL.), a North American shrub, which can be found, in the areas of our lowland forest ecosystems since year 1900, making natural regeneration of stands even more difficult or often preventing natural regeneration. Today, Indigobush expands to the habitat of lowland forests and in riparian forest of oak and broom (Genisto elatae-Quercetum roboris Ht. 1938), especially in sub associations with trembling sedge (Genisto elatae-Quercetum roboris caricetosum brizoides Ht. 1938) and remote sedge (Genisto elatae-Quercetum roboris caricetosum remotae Ht. 1938) (Matić2009). According to present research, Indigobush is the most common in the Posavina region.
This paper shows the results of the second year of study in Indigobush biopotential as a part of six-year-long experiment in a natural stand of Indigobush in the forest Management Unit Posavina, Department 126a, Forestry Sunja, FA Sisak.On the harvested area in the year 2008, four field experiments were established with six plots measuring 5 x 5 m each.Plots are marked form1 to 6.Numbering indicates the length of rotations for Indigobush as well as rhythm of measurements and harvesting on the plots. In the second year of the project survey sample plots 1 and 2 were included, which position in the experimental fields can be seen in Figure 1. Ways of filed 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.

Ključne riječi

Indigobush; bioproduction; energy value; lowland forest ecosystems; Croatia

Hrčak ID:

72318

URI

https://hrcak.srce.hr/72318

Datum izdavanja:

14.10.2011.

Podaci na drugim jezicima: hrvatski

Posjeta: 3.548 *