Proizvodnost in stroški dela pri redčenju gorskih sestojev listavcev

Group work was researched for felling, processing, skidding and quality inspection activities in mountainous broadleaf thinning stands with approximately the same terrain and stand conditions. The stands were 55 and 70years old. In the forest communities of the mountainous beech forest with dead nettle (Lamio orvale - Fagetum sylvaticae/Ht. 1938) and the forests of the sessile oak and horn beam with beech (Epimedio - Carpinetum betuli var. Fagus sylvatica/Ht. 1938/Borth.1963), the main tree species are beech and sessile oak with the addition of other broadleaf species. Productivity was examined in two groups. The first comprised of five workers (A) and the secondof four workers (B). The first group was equipped with two tractors and three chain saws while the second used two tractors and two chain saws as wellas other necessary equipment. The effective time of the cutters spent on felling ranged from 36 to 42.9%, finishing and measurement took up 21%, while the effective time for the tractors ranged from 42.4 to 59%. The effective time per tree ranged from 3.62 to 3.77 minutes, i.e. from 8.46 min/m3 to 12.91min/m3 per unit. The daily output achieved by the Ecotrac and Torpedo tractors at a distance of 300 meters was 20.77.m3/day for group A, while the optimised output was 67.02 m3/day. The output achieved by both tractors in group B was 17.25 m3/day while the optimised output was 30.72 m3/day. The average performance per worker in group A was 4.15.m3/day while the optimised performance was 8.38 m3/day. For group B the average performance per worker was 4.31.m3/day and the optimised performance was 7.68 m3/day. The optimisation of the groups lowered the unit cost of production (300 m distance) for group A from 21.36 EUR/m3 to 6.62 EUR/m3, and for group B from 22.09 EUR/m3 to 12.41 EUR/m3.V raziskavi skupinskega dela v gozdarstvu smo se osredotočili na posek, izdelavo sortimentov, spravilo in nadzor kakovosti pri redčenju gorskih sestojev listavcev, ki rastejo na približno enakem terenu in v primerljivih sestojnih pogojih. Raziskava je bila opravljena v sestojih, starih 55 in 70 let. V gozdnih združbah gorskega bukovja z velecvetno mrtvo koprivo (Lamio orvale - Fagetum sylvaticae/Ht. 1938) in gozdovih gradna in navadnega gabra ter bukve (Epimedio - Carpinetum betuli var. Fagus sylvatica/Ht. 1938/Borth.1963), prevladujeta bukev in hrast ter druge drevesne vrste listavcev. Produktivnost smo preučevali na podlagi dela dveh skupin. Prvo skupino je sestavljalo pet delavcev (A), drugo skupino pa štirje delavci (B). Prva skupina je bila opremljena z dvema traktorjema in tremi motornimi žagami,druga skupina je uporabljala dva traktorja in dve motorni žagi ter drugo potrebno opremo. Efektivni delovni čas, ki so ga sekači porabili za posek dreves, je bil med 36 % in 42.9 %, dodelava in merjenje zavzemata 21 % časa na delovišču, traktorji pa so na delovišču efektivno delali med 42.9 in 59 %. Efektivni čas na drevo je bil od 3.62 do 3.77 minut, to je od 8.46 min/m3 do 12.91 min/m3 na enoto proizvoda. Dnevni učinek, ki so ga traktorji Ecotrac in Torpedo dosegli pri spravilni razdalji 300 metrov, je bil 20.77 m3/dan na delovišču A, optimizirani učinek pa 67.02 m3/dan. Dnevni učinek obehtraktorjev skupine B je bil 17.25 m3/dan, optimizirani učinek pa je znašal30.72 m3/dan. Povprečni doseženi učinek posameznega delavca v skupini A je bil 4.15 m3/dan, optimizirani učinek pa 8.38 m3/dan. V skupini B je povprečni delovni učinek posameznega delavca znašal 4.31 m3/dan, optimizirani učinek pa 7.68 m3/dan. Z optimizacijo skupin so se stroški proizvodnje na enoto (na razdalji 300 m) zmanjšali z 21.36 EUR/m3 na 6.62 EUR/m3 za skupino Ater z 22.09 EUR/m3 na 12.41 EUR/m3 za skupino B

University of Zagreb – Faculty of Forestry and Department of Forest Engineering in the Bologna Process

U radu je prikazan tijek i sadašnji doseg reforme visokoobrazovnog sustava na Šumarskom fakultetu, Zagreb kao čimbenika uključivanja Fakulteta u Europski prostor visokog obrazovanja (EHEA) i Europski istraživački prostor (ERA). Prihvaćen je trostupanjski obrazovni sustav te su izrađeni obrazovni programi za preddiplomske, diplomske i poslijediplomske studije u shemi 3 + 2 + 3 (2) odnosno 180 + 120 + 180 (120) ECTS bodova. Uspostavljena su tri preddiplomska studija i to Šumarstvo, Urbano šumarstvo, zaštita prirode i okoliša i Drvna tehnologija, po kojim se programima obrazuje već treća generacija studenata. Razvijeni su programi diplomskih studija Šumarstvo i Urbano šumarstvo, zaštita prirode i okoliša te programi Drvnotehnološki procesi i Oblikovanje proizvoda od drva. Diplomski studij Šumarstvo ima dva smjera i to: Uzgajanje i uređivanje šuma s lovnim gospodarenjem i Tehnike, tehnologije i menadžment u šumarstvu. Razvijen je poboljšani prijedlog doktorskog studija Šumarstvo s tri smjera (Uzgajanje šuma i lovno gospodarenje, Tehnike, tehnologije i menadžment u šumarstvu, Urbano šumarstvo, zaštita prirode, uređivanje i zaštita šuma) te program doktorskog studija Drvna tehnologija. Specijalistički poslijediplomski studiji razrađeni su u deset programa.The paper presents the past course and achievements of the reform of the higher educational system at the Faculty of Forestry of the University of Zagreb. The reform is part of the effort undertaken in order to include the Faculty in the European Area of Higher Education (EHEA) and the European Research Area (ERA). A three-cycle educational system has been adopted and the curricula for undergraduate, graduate and postgraduate studies have been devised on a 3 + 2 + 3 (2) or 180 + 120 + 180 (120) ECTS points basis. Three undergraduate studies have been established: Forestry, Urban Forestry and Wood Technology, whose programmes are already followed by two generations of students. The following graduate study programmes have been developed: Forestry and Urban Forestry, Nature and Environment Protection and Wood Technology Processes and Design of Wood Products. Graduate studies in the Forestry department contain two programmes: Silviculture and Forest Management with Wildlife Management and Techniques, Technologies and Management in Forestry. An improved proposal for doctoral study has been developed in the Forestry Department consisting of three programmes (Silviculture and Wildlife Management, Techniques, Technologies and Management in Forestry, and Urban Forestry, Nature Protection, Forest Management and Protection), as well as a doctoral study programme Wood Technology. Specialist postgraduate studies have been devised in ten programmes

Productivity of C Holder 870 F tractor with double drum winch Igland 4002 in thinning beech stands

Research of productivity of C Holder 870 F tractor in thinning beech stands was performed in the area of Forest Administration Bjelovar, Forest Office Velika Pisanica in the compartment 87a of the management unit Bilo Jezero. Timber was skidded uphill. Time study of a cycle was carried out by using collected data and by mathematical–statistical analysis, and it was shown that effective time accounted for 72.98 % and additional time accounted for 27.02 %. Additional time coefficient is 1.37. Time standard for skidding distance from 25 to 250 m ranges between 22.23 and 34.29 min/m3, and daily output, at mean load volume of 0.76 m3, is 21.59 m3/day for skidding distance of 25 m, i.e. 14.00 m3/day for skidding distance of 250 m. Based on official calculation of Hrvatske šume d.o.o. Zagreb for the year 2000 and daily output, the daily unit cost of C Holder 870 F tractor was established and it ranges from 69.16 kn/m3 for skidding distance of 25 m to 106.66 kn/m3 for skidding distance of 250 m

The Problem of Establishing the Assortment Structure of Even-Aged Beech Stands

U radu je istraživana vjerojatnost pojave drvnih sortimenata tehničke oblovine u bukovim stablima s obzirom na vrstu sijeka, kao i razlike između postotnih udjela drvnih sortimenata tehničke oblovine po debljinskim stupnjevima i vrsti sijeka. Postotni udjeli tehničke oblovine određeni ovim istraživanjem uspoređeni su s planskim vrijednostima (sortimentnim tablicama) koje se primjenjuju u šumarskoj operativi. Na temelju rezultata istraživanja izrađene su nove sortimentne tablice prema Hrvatskim normama proizvoda iskorištavanja šuma od 1995. godine. Istraživanja su provedena na uzorku koji obuhvaća 787 stabala u proredama, 1025 stabala u pripremnim, 606 stabala u naplodnim i 583 stabala u dovršnim sjekovima. Sveukupno je istraživanjima obuhvaćeno 3001 primjerno stablo. Starost istraživanih sječina iznosila je od 59 do 91 godinu kod prethodnog prihoda (proreda), od 94 do 110 godina kod pripremnog sijeka, od 100 do 112 godina kod naplodnog sijeka te od 98 do 112 godina kod dovršnog sijeka. Dosadašnji je pristup određivanju sortimentne strukture jednodobnih bukovih sastojina u velikoj mjeri pogrešan. Operativne sortimentne tablice daju previsoke procjene za najkvalitetnije drvne sortimente svih vrsta sjekova osim zadnjih sjekova oplodnih bukovih sječina. Tablice šumskih drvnih sortimenata koje uvažavaju vrstu sijeka kao jedan od ulaza, omogućuju pouzdaniju procjenu sortimentne strukture sječine i preciznije planiranje sječivog etata. Pri tome su kao čimbenici razdvajanja uzeti kriteriji selekcije prilikom doznake stabala za sječu koji se primjenjuju do uključivo pripremnog sijeka. Iz tih su razloga tablice šumskih drvnih sortimenata izrađene zasebno za prorede i pripremni sijek, a zasebno za naplodni i dovršni sijek.The subject of research was probability of appearance of technical roundwood timber assortments in trees according to type of felling, as well as the difference between shares of technical roundwood timber assortments according to diameter class and type of felling. The percentages of technical roundwood established in this research were compared to the planned values (assortment tables) which are applied in forestry operational bodies. Research was carried out on a sample consisting of 787 trees in thinning felling, 1025 trees in preparatory felling, 606 trees in seeding felling and 583 trees in final felling. An overall number of 3001 exemplary trees were included in the research. The age of the felling areas studied was between 59 and 91 years in the preliminary yield (thinning), 94 to 110 years in preparatory felling, 100 to 112 years in seeding felling, and 98 to 112 years in final felling areas. We think that the approach to establishing the assortment structure of even-aged beech stands taken so far is to a large extent wrong. The operative assortment tables give too high estimates of top quality timber assortments of all types of felling, except the final felling of seeding beech felling areas. Timber assortment tables that take into consideration the type of felling as one of the inputs, enable a more reliable estimate of assortment structure of the felling area and more precise planning of timber mass marked for felling. In this case, as a distinguishing factor, we took the selection criterion for marking trees for felling which is applied for the types up to, and including, the preparatory felling. For that reason, timber assortment tables were made separately for thinning and preparatory felling, and separately for seeding and final felling. On the basis of the research results, new assortment tables were made according to Croatian Standards of Forest Exploitation Products from 1995. Seeding and final felling show by ca 8–14 % higher shares of top quality timber assortment (F and L) than thinning and preparatory felling. On the other side, thinning and preparatory felling show by ca 4–15 % higher shares of technical roundwood assortment of lower quality (second-class and third-class) than seeding and final felling

STUDY OF BIOPRODUCTIVE AND ENERGY POTENTIALS OF INDIGOBUSH (Amorpha fruticosa L.)

U radu su prikazani rezultati treće godine istraživanja vezanih za biopotencijal i energetske značajke amorfe. Cjelokupno istraživanje planira se završiti unutar razdoblja od 6 godina. Prema utvrđenome godišnjem planu, istraživanja su provedena na plohama 1 i 3. Istraživački blok poligon postavljen je u trinaestogodišnjoj amorfi u odjelu 126a u Gospodarskoj jedinici Posavske šume, Šumarija Sunja, UŠP Sisak. Istraživanja se provode na temelju protokola projekta i godišnjih planova rada na četiri pokusna polja, svako sa po šest pokusnih ploha veličine 5 x 5 m. Temeljna zadaća znanstveno-istraživačkog projekta je utvrđivanje trendova kretanja bioproizvodnog, odnosno bioenergijskog kapaciteta u od prirode zakorijenjenoj amorfi pri ponavljanim sječama. Vremenski ritam istraživanja određen je pripadnim brojem plohe, definiran uz to projektnim protokolom i godišnjim planovima rada.Na plohama 1, koje se sijeku svake godine po završetku vegetacije, utvrđeno je da godišnja bioproizvodnost zelene i suhe biomase varira. Nakon prve vegetacije 2008. suha je tvar iznosila 12 t/ha (Krpan i Tomašić 2009), nakon druge (2009) 7,87 t/ha (Krpan et al. 2011b), a nakon treće (2010) 9,79 t/ha, pa se može zaključiti da je trend bioproizvodnje amorfe u opadanju u odnosu na prvu vegetaciju. Godišnja prosječna proizvodnja u dvogodišnjoj ophodnji amorfe je 8,19 t/ha, a u trogodišnjoj 7,03 t/ha. Zelena biomasa amorfe svedena je na suhu, prema udjelima mokrine drva koja u uzorcima u trenutku sječe varira ne prelazeći 35 %.Bioproizvodnost amorfe iz panja ovisi o broju izdanaka i njihovim dimenzijama, na što će utjecati vanjski utjecaji poput hranidbenog potencijala tla te prevladavajućih klimatskih čimbenika u vrijeme vegetacije. Na plohama 1 srednji prsni promjer izdanka amorfe je 7,99 mm, a srednja visina 2,37 m, a na plohama 3 srednji je prsni promjer 11,61 mm, a srednja visina 2,79 m.Prema rezultatima dosadašnjih istraživanja, unatoč utvrđenim trendovima opadanja bioproizvodnosti, amorfa zadržava konkurentnost u području obnovljivih izvora energije. Posebice iz razloga potpune prirodne pojavnosti i razvoja bez ikakvih agrotehničkih mjera i troškova (osim troškova pridobivanja i manipulacije), bez kakvih nije zamislivo podizanje i gospodarenje energetskih nasada kratkih ophodnji poznatih brzorastućih vrsta drva.The paper shows the results of the third year of research into biopotential and energy properties of indigobush. The research is planned to last for 6 years. According to the annual plan, the experiments were done in sample plots 1 and 3 in the third year of research. A research block polygon was established in a thirteen-year-old natural stand of indigobush in the compartment 126a of the Management Unit Posavske Šume, Sunja Forest Office, Sisak Forest Administration. The research is based on a project protocol and annual work plans and is carried out in four experimental fields, each containing six 5 x 5 m experimental plots. The basic task of the scientific-research project is to determine trends in bioproductive or bioenergy capacity in naturally planted indigobush at repeated felling operations. The time rhythm of the research was determined by the number of the plot, in combination with the project protocol and annual work plan.Indigobush, particularly in the lowland systems of the Posavina region, covers large areas of forest soil. In some of these areas indigobush is so widespread that its shade prevents natural regeneration of stands of valuable autochthonous tree species. As a species of light, indigobush invades forest areas after tree cutting and overshadows the desired autochthonous young growth with its dense canopy. For this reason, it is perceived as an aggressive plant and a very dangerous weed, since not only does it considerably hinder the regeneration of Croatia’s most valuable lowland forests but also makes it more costly.The possibility of using indigobush biomass for energy is limited by a number of factors. The most important ones include the quantity of biomass per surface unit and the profitability of its harvesting, chipping, transport to the user, storage and drying to the desired level of moisture. The energy value of indigobush wood has been firmly confirmed by various literary sources. Extensive research into bioenergy potentials of different plant species, including indigobush, has been conducted in Hungary. According to Marosvölgyi et al. (2009), experiments related to naturally grown indigobush and energy plants showed that indigobush is an exceptionally suitable material for energy production. Initial moisture of one-year-old sprouts during one-month storage dropped from 47.0 % to 34.2 %. The measured fuel value at W = 34.2 % was 12.7 MJ/kg. In dry condition, the energy value of indigobush is 20.2 MJ/kg. In comparison, dry pine sawdust has a slightly lower value of 19.7 MJ/kg. Moreover, the ash content in indigobush was found to be 1.5 %, while the content of volatile materials was relatively higher. Puljak (2005) burned indigobush in a biomass energy plant in Ogulin to confirm its energy value as fuel by monitoring the temperature of the firebox, smoke gases and water, which satisfied the set criteria.Figures 2 and 3 show the data for plots 1. A spatial arrangement of the stumps, their form and surface size are shown in the layout. There are from 12 to 20 stumps in the plots. The number of the stumps is not an indicator of indigobush productivity (the case with a plot in field IV with the lowest number of stumps and field 1 with the highest). As seen from table data, indigobush productivity correlates with the number of the sprouts and their dimensions. The number of the sprouts in the plots varies from 278 pcs/plot (111,200 pcs/ha) to 389 pcs/plot (155,000 pcs/ha). The mean heights in the plots range from 2.23 m to 2.48 m and the mean diameters vary from 7.35 mm to 8.58 mm. The lowest sprout mass of 11,000 kg/ha was recorded in sample field IV, and the highest of 18,400 kg/ha was found in field III. The mean value of green biomass bioproduction during one vegetation season amounts to 14,776 kg/ha of green indigobush mass per hectare.Sample plots 3 were measured for the first time. The results of measurements are given in Figures 4 and 5. The number of the stumps ranged from 13 to 21, and that of the sprouts from 254 pcs/plot to 292 pcs/plot, or from 101,600 pcs/ha to 116,800 pcs/ha. The mean heights in the plots were from 2.69 m to 2.88 m, and the mean diameters were from 10.60 mm to 12.43 mm. The sprout mass ranged from 61.50 kg/plot or 24,600 kg/ha to 89.30 kg/plot or 35,720 kg/ha. The average overall green mass production in plots 3 amounts to 30,700 kg/ha, and the average annual production amounts to 10,233 kg/ha.Variance analysis was used for indigobush breast diameters and sprout heights in plots 1 and 3. The results are given in Table 1 and 2, and mean values are presented graphically in Figures 6, 7, 8 and 9. It can be concluded from Table 1 and variance analysis that there is a statistically significant difference in mean breast diameters between the analysed sample fields (F = 9.597; df = 3; p < 0.001). The Tukey post hoc test showed a statistically significant difference between field III and fields I and IV, as well as between field I and field II and III. The statistically significant highest breast diameter of 8.58 mm was found in sample field III.Variance analysis found a statistically significant difference in the average height values for the analysed sample fields (F = 17.38; df = 3; p < 0.001). The Tukey post hoc test showed that sample fields I and IV differed statistically significantly from fields II and III, whereas the former (I and IV) and (II and III) did not differ from one another.According to the Tukey post hoc test, there was a statistically significant difference among the average values of breast diameters in the three-year-old stand (Table 2) between experimental fields 1 and 4, as well as between 2 and 4. The mentioned average values between exp. fields 3 and 4 did not show any statistically significant difference.Related to the analysis of the average height values, a statistically significant difference was also found between the sample fields (F = 10.39; df = 3; p < 0.0001). According to the results of the Tukey post hoc test, the average height value in sample field IV was found to differ statistically significantly from the average values in all other sample fields. These values did not differ statistically significantly in sample fields I, II and III.Table 3 shows data of indigobush bioproduction analysis, both green and dry mass, in plots 1 and 3 in the sample fields, as well as data calculated per surface hectare. Data are also given of the percentage share of moisture calculated on the basis of laboratory research into indigobush wood samples and dry matter, expressed as a difference between the percent share of moisture and 100 % amount. The moisture content of indigobush wood at the moment of harvesting is important in terms of price, which depends on water content and a possible need to dry the chips in the storehouse until they reach the optimal water content. In exp. plots 1 the indigobush wood moisture percentage ranges from 32.78 % to 34.50 % (33.71 % on average), meaning that all percentages are lower than 35 %. Exp. plots 3 contain even lower values, which oscillate from 30.09 % to 31.90 (31.33 % on average). Dry wood matter in plots 1 ranges from 18.21 kg to 30.46 kg, with the mean value of 24.47 kg, and in plots 3 from 41.88 kg to 60.97 kg, with the mean value of 52.77 kg. Dry wood matter in plots 1 is from 7.28 t/ha to 12.18 t/ha, with the mean value of 9.79 t/ha, and in plots 3 from 16.75 t/ha to 24.38 t/ha with the mean value of 21.09 t/ha.In plots 1, which are harvested every year at the end of vegetation, bioproductivity was found to vary. After the first vegetation in 2008, dry matter amounted to 12 t/ha (Krpan and Tomašić 2009), after the second (2009) it came to 7.87 t/ha (Krpan et al. 2011a,b), and after the third (2010) it was 9.79 t/ha. It can therefore be concluded that, in relation to the first vegetation, bioproduction manifests a downward trend. The average annual production of two-year-old indigobush is 8.19 t/ha, while that of three-year-old indigobush is 7.03 t/ha. Hence, a downward trend in bioproduction is present here as well.A quantity of 2.68 kg seed or 1,073 kg/ha was collected in exp. plots 3. This result is tentative because a large amount of seed naturally falls off by the time of collection, as well as during collection due to shaking caused by bending the branches. According to our estimates, seed loss may amount to over 50 %. To avoid the possibility of incorrect evaluation, seed loss will not be analysed in more detail here. It is evident from the above that almost all the seed is lost during harvesting after vegetation, handling, chipping and transport and that it cannot be expected to accompany the leaves in the combustion process in energy plants.The results of indigobush research in the third year of the project show that, despite the established downward trends in bioproductivity, the plant still retains its competitiveness in the field of renewable energy sources, particularly because it occurs and develops naturally. It does not require any agrotechnical measures, nor does it incur any costs (except for harvesting and handling costs), which are otherwise indispensable when establishing and managing energy cultures and short rotation orchards of well-known fast growing tree species

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

U radu se prinose rezultati druge godine istraživanja biopotencijala amorfe (Amorpha fruticosaL.) u šestgodišnjem pokusu postavljenom u prirodnoj amorfi u odjelu 126a, u gospodarskoj jedinici Posavske šume, šumarija Sunja, UŠP Sisak. Na posječenoj su površini 2008. osnovana četiri pokusna polja sa po šest ploha dimenzija 5 x 5 m svaka. Plohe broj 1 su mjerene drugi put, a plohe broj 2 prvi put. Srednje su visine izdanaka u drugoj jednogodišnjoj vegetaciji na plohama 1 od 2,13 m do 2,25 m. Najveća izmjerena visina je 3,4 m. Srednji je promjer izdanaka u prsnoj visini u rasponu od 7,0 mm do7,6 mm, a najveći 14 mm. U proporciji s brojem i dimenzijama izdanaka na plohama 1, proizvedena je zelena biomasa od 23,29 kg (9 316 kg/ha) do 38,14 kg (15 256 kg/ha). Visinski se prirast na plohama 2 u drugoj vegetaciji znatno smanjuje u odnosu na prvu godinu. Srednje vrijednosti visina su od 2,28 m do 2,58 m, a najveća je 3,7 m. Srednji promjer izdanaka je u rasponu od 9,1 mm do 10,5 mm, uz najveći izmjereni od 20,0 mm. Proizvedena je zelena biomasa na plohama 2 od 54,34 kg (21 734 kg/ha) do 78,55 kg (31 418 kg/ha). K tome je sakupljeno od 3,20 kg (1 280 kg/ha) do 4,94 kg (1 976 kg/ha) ili prosječno 3,97 kg (1 589 kg/ha) sjemena. Udjeli mokrine drva u plohama 1 i 2 u trenutku sječe su niski i iznose 34,23 %, odnosno 33,12 %. Mokrina sjemena je 14,3 %. Prosječna jednogodišnja produkcija suhe biomase je 7,87 t/ha, a u dvogodišnjoj amorfi s pridodanim sjemenom 17,73 t/ha. Energetski ekvivalent zelene biomase jednogodišnje amorfe je 152,2 GJ/ha, a suhe 159,4 GJ/ha. U dvogodišnjoj amorfi energetski ekvivalent zelene biomase je 332,2 GJ/ha, a suhe 359,1 GJ/ha.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

BIOPRODUCTIVITY OF INDIGOBUSH (Amorpha fruticosa L.) IN ONE-YEAR, TWO-YEAR AND FOUR-YEAR ROTATION

U radu se razmatraju rezultati četvrte godine istraživanja bioproizvodnog potencijala amorfe, uz osvrt na europsku normizacijsku propisnost što određuje njen položaj u familiji obnovljivih izvora šumske drvne biomase za energiju. Bioproizvodnost amorfe istraživana je na tri pokusne plohe unutar četiri pokusna polja. Broj ploha ujedno označava duljinu ophodnje. Mjerenjem su utvrđeni parametri bioproizvodnosti amorfe od broja panjeva na plohama, broja izdanaka na pojedinom panju i na plohi, visine i promjera izdanaka te izmjere zelene biomase nakon sječe odvagom. Određeni parametri preračunati su na hektar.U jednogodišnjoj ophodnji zelena biomasa amorfe u četvrtom turnusu u rasponu je od 7,40 t/ha do 13,20 t/ha, a prosječna 10,15 t/ha. Uz udio vlage 35,92 % suha je biomasa 6,50 t/ha. Prosječna zelena masa jednog izdanka amorfe na plohama iznosi 0,0897 kg. Prosječna dvogodišnja proizvodnja zelene biomase u drugome turnusu dosegla je iznos od 24,52 t/ha, dok je prosječna godišnja bioproizvodnja 12,26 t/ha. Udio vlage u zelenoj biomasi je 35,71 %, što znači da je dvogodišnja bioproizvodnja suhe biomase 15,76 t/ha, odnosno godišnji je prosjek 7,88 t/ha. Prosječna masa jednog izdanka amorfe na plohama iznosi 0,2404 kg. Zelena biomasa u četverogodišnjoj ophodnji ostvarena je u rasponu 33,24 t/ha do 51,40 t/ha, s prosjekom od 42,06 t/ha. Prosječna godišnja proizvodnja zelene biomase ostvaruje se od 8,31 t/ha do 12,85 t/ha, s prosječnom vrijednošću za sve plohe 10,52 t/ha. Uz vlagu od 33,19 %, bioproizvodnja suhe biomase tijekom četiri vegetacije iznosi 28,10 t/ha, s godišnjim prosjekom od 7,03 t/ha. Prosječna masa jednog izdanka je 0,3859 kg.At the beginning of 2008, within the scope of the project Forest products and harvesting technology agreed with Croatian Forests Ltd, Zagreb, we have set up a research of biopotential, energetic characteristics and harvesting technology and use of indigobush biomass. From the above mentioned project, in 2012, a separate project Biopotential and energy characteristics of indigobush was transferred to the Academy of forestry sciences. The research ground was established in the pure indigobush stand in the forest management unit of the Posavina Forests, department 126a, Forest Office Sunja, Forest Administration Sisak. Within the block system, four test fields have been established; each with six 5 x 5 m large sub-test plots. (Figure 1)This paper shows the results of the fourth year of research of indigobush considering its bioproductivity potential with a reference to the prescribed standards, harvesting characteristics and market demands, all which determines its position within the family of renewable resources of wood biomass for energy purposes. The research has encompassed plots 1, 2 and 4, i.e. bioproductivity of indigobush in one-year, two-year and four-year rotations. Within the scope of forest biomass issues, a higher number of HRN EN standards was considered, and a critical review of the terminology related to forest biomass, i.e., hard fuels, a term unscrupulous authors use in their publications. Data of plots 1 are shown in Figures 3 and 4. In a one-year rotation per hectare, there were 87 200 to 140 400 one-year-old sprouts of indigobush. Mean height of sprouts on plots vary in a narrow range of 16 cm, taking a value of 2.07 m on the test field IV and up to 2.23 m on the test field II. The smallest mean diameter is recorded on the test field II and it amounts to 7.11 mm, while the largest was found on the test field III and it was 7.56 mm. Green indigobush mass on plots 1 ranges between 18.50 kg to 33.00 kg or in the calculation per hectare of the surface, it ranges between 7.40 t/ha and 13.20 t/ha. The difference between the smallest and the biggest value of green mass production on plots 1 is significant and it amounts to 5.80 t/ha. Average bioproduction of the green mass of indigobush on plots 1 in the fourth year of research amounts to 10.15 t/ha. Mean mass of one sprout of indigobush for all four plots is 0.0897 kg. Data of plots 2 are shown in Figures 5 and 6. Number of sprouts on plots 2 ranges from 225 on fields II and IV up to 303 on field I, respectively, from 90 000 pcs/ha to 121 000 pcs/ha. Minimal mean height of 2.67 m is recorded in field I, and the maximal in field II, namely, 2.81 m. Mean diameter was the lowest on plot 2 in field I and it amounts to 9.82 mm, while the largest of 11.77 mm was recorded on test field IV. After long vegetation the established production of green mass of indigobush on plots amounts from 55.50 kg to a maximum of 70.50 kg or from 22.20 t/ha to 28.20 t/ha. Average biannual production of green biomass amounts to 24.52 t/ha, respectively, average annual value amounts to 12.26 t/ha. Mean mass of one sprout of indigobush on plots assumes the value from 0.199 kg to 0.264 kg, i.e. 0.240 kg on average for all plots. The parameters of bioproduction of indigobush for plots 4 are shown in Figures 7 and 8. Mean sprout height on plots 4 varies from 2.82 m to 3.04 m, and the diameter from 11.49 mm to 13.96 mm. The accumulated green biomass of indigobush during four vegetative periods varies between 83.10 kg/plot to a maximum of 128.50 kg/plot. After four-year rotations, per hectare, we acquired from 90 800 to 131 600 or an average of 109 000 sprouts and green biomass between 33.24 t/ha and 51.40 t/ha or an average of 42.06 t/ha. Average annual production of green biomass on plots 4 ranges from 8.31 t/ha to 12.85 t/ha and the mean value for all plots is 10.52 t/ha. Mean mass of one sprout of indigobush on all plots is 0.386 kg. Table 1 and Figures 9, 10 and 11 show data of the variation analysis of diameter at breast height, and Table 2 and Figures 12, 13 and 14 show data of the variation analysis of mean sprout height of indigobush, including a discussion. Table 3 shows the production of green biomass, laboratory determined percentages of moisture ratio of green indigobush and dry biomass matter. On plots 1, the percentage of moisture of indigobush wood ranges from 35.27 % to 37.02 % with a mean value of 35.92 %, on plots 2 the range of moisture is between 35.26 % and 36.03 % with mean value of 35.71 %, while on plots 4 it ranges between 30.91 % and 35.59 % with a mean value of 33.19 %. The proportion of dry matter in the samples of indigobush wood, relevant for all tested plots, ranges from 62.98 % to 69.09 %. In average, it is lowest on plots 1 with 64.08 %; on plots 2 the average value is 64.29 %, and on plots 4 it is the highest and it amounts to 66.81 %. Absolute values of the produced dry indigobush biomass in 2011 on plots 1 ranges from 11.88 kg/plot to 21.36 kg/plot or in average 16.26 kg/plot, i.e., or 6.5 t/ha of dry biomass. On plots 1, which are harvested on a yearly basis at the end of every vegetative period, the annual level of bioproductivity of dry biomass after the first vegetation in 2008, it amounted to 12 t/ha (Krpan and Tomasic, 2009), after the second (2009) it was 7.87 t/ha (Krpan et al. 2011 –2), after the third (2010) it was 9.79 t/ha, and in 2011 it was 6.5 t/ha, and thus it could be concluded that bioproductivity of indigobush in one year rotation varies and has a decreasing trend in comparison with the first vegetation. In a two-year rotation on plots 2, it was produced between 35.64 kg and 52.30 kg, with an average of 40.99 kg/plot (Krpan et al. 2011 –2). Therefore, the mean biannual bioproductivity of dry indigobush matter amounted 16.40 t/ha or on an annual average basis it was 8.20 t/ha which increases the value of bioproductivity for 0.31 t/ha in comparison with the second biannual yield in 2011. In the four-year rotation of indigobush on plots 4, the established bioproductivity of dry biomass of indigobush has a value from 55.05 kg/plot to a maximum of 86.62 kg/plot or an average of 70.25 kg/plot, respectively, 28.10 t/ha. Mean annual bioproductivity of dry biomass in the four year rotation was 7.03 t/ha. Bioproductivity of indigobush in this paper, based on the measurements of growth and increment parameters, density of the sprouts, parameters of laboratory research, its green mass, moisture and dry matter per plot unit in one-year, two-year and four-year rotation, despite the understandable variations, shows the potential benefit of indigobush within the family of solid fuels derived from forest biomass for energy. This paper showed previous research results based on which, due to the variations in the annual biomass production, it is not possible to choose and recommend an optimal rotation