DETERMINATION OF TRANSITION RATES FOR THE ENERGY BIOMASS CALCULATIONS IN SPRUCE STANDS IN LATVIA

Transcription

1 Austro2007/FORMEC 07: Meeting the Needs of Tomorrows Forests New Developments in Forest Engineering, Otober 7 11, 2007, Vienna and Heiligenkreuz Austria DETERMINATION OF TRANSITION RATES FOR THE ENERGY BIOMASS CALCULATIONS IN SPRUCE STANDS IN LATVIA Imants Liepa*; Teodors Blija Department of Silviulture Forest Faulty, Latvia University of Agriulture 11 Akadēmijas Street, Jelgava, LV 3001 Imants.Liepa@llu.lv / Teodors.Blija@llu.lv Abstrat: The Balti Sea region with its forest resoures has a big potential in order to ahieve EU goals in the use of biomass in heating and energy prodution. Insuffiient knowledge about the potential involved in energy prodution holds bak a sustainable development of bio-energy. There is no alulation methodology worked out up to now for energy prodution for determination of the available biomass volume. There are no preise data at our disposal about how muh wood tree branhes and roots ontain. Aording to foreign literature, the mass of branhes and roots an reah more than 40% of the total amount of wood. The aim of researh is to estimate the amount of biomass aumulated and available in Latvia s fir stands, as well as the management possibilities of it. For this aim, it is neessary to alulate the fir stand timber volume, the biomass transition rates and the biomasses of rowns, roots and stubs. There were olleted sample-tree data during the field work season. The rown biomass of every sample-tree was dividend in separate frations and then in green ondition weighed. The rown frations: 1) large branhes (the thin end in average d(l) > 6.0 m); 2) medium branhes 3.0 d(m) 6.0 m; 3) thin branhes d(t) < 3.0 m; 4) needles. The root biomass was dividend in three frations: 1) large roots (the thin end in average d(l) > 6.0 m); 2) medium roots with 3.0 d(m) 6.0 m; 3) thin roots with d(t) < 3.0 m. After unearthing, the parts of stubs and the roots of every sample-tree were washed in a plasti bath of appropriate dimensions and dried after that. All the frations were weighed after the proessing. The biomass transition rate is a proportion between the biomass of the relevant part of the sample-tree, and the stem volume. When alulating, the transition rates of the rown, stub and root biomass were determined, namely C, S and R, as well as Σ i. It is easy to perform alulations by means of these transition rates for determination of non-stub fration biomass amounts in fir stands. 1. Introdution The Balti Sea region with its forest resoures has a big potential in order to ahieve EU goals in the use of biomass in heating and energy prodution. Insuffiient knowledge about the potential involved in energy prodution holds bak a sustainable development of bio-energy. There is no alulation methodology worked out up to now for energy prodution for determination of the available biomass volume. There are no preise data at our disposal about how muh wood tree the branhes and roots ontain. Aording to foreign literature, the mass of branhes and roots an reah more than 40% of the total amount of wood. By the term wood biomass, the mass of tree group of a stand per one square unit is meant (Helms, 1998). For the sake of data omparability in forest eology it is ommonly expressed also as t ha -1. Biomass struture is formed by its separation in stand omponents (belonging of trees to ertain hybrid speies, Liepa, I.; Blija, T. 1 / 7

2 stages) and frations (stems, branhes, needles (leaves), stumps, roots), but in the groups of stands - also by the site quality index and age lasses, thikness and other groups of stands. A demand for stem fration evaluation in volume units has been existing through enturies, usually it is m³ ha -1. Therefore, many onvenient and preise methods of determining the volume of separate tree stems and the stand total volume of tree groups have been developed in forest inventory (Philip, 1994). Then, knowing the wood density values offered by wood siene (Уголев, 2001), it is possible to re-alulate the volume into mass units. The situation is radially different in determination of the non-stem fration biomass, where this methodologial solution is not suitable due to the non-fration volume alulation diffiulties. It is generally known that forests are the main produer of wood among the land eosystems. The nonstem fration biomass ontains a onsiderable part of tree stand wood that an reah 40% and more. However, the methodology of determining this part of biomass has been worked out inompletely by now. The relatively small use of the non-stem biomass up to now has not failitated obtaining of more preise data on this part of tree stand. It is why the information being at the disposal of many ountries inluding Latvia, relating the volume of this forest resoure, ould be onsidered as fragmentary. The aim of this work is to fill up the gap by ompleting the following tasks: evaluation of the fir stand total volume; determination of the transition rate of non-stem fration biomass; alulation of the biomass of stems, branhes, needles, stumps, roots and the total fir stand biomass. 2. Methodology and material Stem fration biomass is expressed by formula (1) M st = ϕ V (1) where M st, φ and V are the stem fration biomass in t, the wood density rate in t m -3 and the total volume in m³. Fir stand total volume of the state level is taken from the forest inventory data of available at State Forest Servie of Ministry of Agriulture (Боровиков and Уголев, 1989). Wood density depends on moisture in wood. In our ase, the density of freshly ut wood is apliable, for fir whih is φ = 0.794, t m -3 (Уголев, 2001). For the alulation of non-stem fration biomass, the transition rates i have been used. The transition rate is i-proportion of that fration biomass M i and the total volume V, whih is expressed by t m -3. Therefore, multipliation of the rate i with stem volume or the total stand volume is biomass of the relevant tree or part of the stand, expressed in mass units. Values of i for Latvia s onditions have been unknown so far. Therefore, we have determined them empirially by the sample tree method, separating biomass in the frations of branhes, needles, stumps and roots. Volume of the sample tree stems v has been alulated by formula (2) (Forest Setor in Latvia, 2005): v = ψ h α d β lg h+ ϕ (2) Where v, d and h are the stem volume in m³, the breast-height diameter in m and the height in m. Ψ, α, β and φ are the stem apaity rates for fir: Ψ = ; α = ; β = ; φ = Branh fration inludes also the green and the dry branhes. After sorting, all the branhes were paked and weighed by using the movable hanging sele KERN HCB 100K200 with weighing possibility range Liepa, I.; Blija, T. 2 / 7

3 from 0.2 up to kg. The green branhes were weighed together with needles. The diferene between this total mass and the needles mass is the green branhes mass. Needle mass was determined indiretly by using the sample branh method. 5 sample branhes were ut from eah sample tree, whih have been weighed before, and for the purpose of the ontrol also after de-needling. Needles of the sample branhes were weighed by using the sale KERN MH 5K5 with digit value 5 g. When seleting the sample branhes, the ondition stritly observed was the branhes should have been ut from the upside of the ut-down tree, on the line that was parallel to the tree growing line. Attahment plaes of the sample branhes: attahment plae of the first branh is in the distane of 0.2l from the beginning of the first green branh (l = rown length in m); plae of the seond branh in the distane of 0.2l from the top bud; plae of the third branh exatly in the middle of the rown; plae of the forth branh midpoint between the first and the third branh; plae of the fifth branh - midpoint between the third and the seond branh. Needle mass of the whole rown was alulated proportionally to the total mass of green branhes by using the total mass of non-needled sample trees and the needles masses of these branhes. Unearthing of roots is tehnially the most ompliated stage of researh exeution. It demands long and areful work in order to minimize amount of roots left in soil. Fir has a superfiial and large roots system whih extends the rown projetion boundaries far away. A omplete unearthing of roots system is not effiient due to the onsiderable time and labour onsuming. A high probability is that a small part of the minor roots would be left in soil. Roots of the sample trees were unearthed by traking them individually. Stem onsists of the superfiial part and the part in earth. By the last one, the monolithi part, undifferentiated in separate roots, is meant. After unearthing, the part of stem and the roots previously being in earth of every sample tree were arefully washed in a plasti bath of appropriate size, then dried and weighed. For mathematial proessing of the empiri material the graphial and analytial methods were used (State Forest Servie Riga, 2005) by taking opportunities of the omputer program MS Exel (Liepa, 1996). The material of sample trees have been olleted in sprue stands (Oxalidosa, Myrtyllosa-Polytrihosa and Myrtyllosa mel) thus representing the most ommon fir growing ondition types. It should be emphasized that no diferenes have been notied during the whole season of field works. The total number of sample trees 21, so in different growing onditions 7. This number results from a onlusion that at least 7 orelogram points are needed for a quantitative desription of biomass grouping speifis of various size trees of one stand in a form of regression equation, and these points are more or less evenly distributed in the definition area empirially represented by the argument. Loation area of sample trees regions of Dobele, Jelgava and Bauska and the middle part of Latvia. Site quality index of stands - I a, I and II, thikness , age middle age, maturity stands and adult tree stands, and hybrid and layering various. Trees of the first and the seond layer as well as trees of different G. Craft lasses are represented by the sample trees. The foreign authors researh and our previous researhes in Latvia show that the total tree biomass and its frational separation is determined mainly by the tree breast-height diameter. So the seletion of sample trees in eah stand has been arried out in the interval d min d j d max, trying to represent the I, II and III G. Craft lasses (utmost in proportions 2:3:2). The onlusion on dependene of the tree biomass volume on the breast-height diameter has been used also in order to hek the quality of field works (Figure 1). Liepa, I.; Blija, T. 3 / 7

4 Non- stem biomass,kg y = x R 2 = Breast hight diameter,m Figure 1: The quality ontrol for non-stem biomass data olletion. As the empiri points exluding two of them, are grouping densily along the adjustment urve, it may be onsidered that the data of sample trees have been olleted stritly observing the methodologial rules. Separation of the hosen sample trees and the evaluation data are shown in Table 1: Table 1: The harateristi of sample trees Branhes without needles, kg total green dry Needles, kg Stumps, kg Roots, kg No. d, m h. m It follows out of the Table that the breast-height diameter of the sample trees is represented in the interval of d min = 8.0 m and d max = 42.7 m, height h min = 9. 6 m and h max = 31.3 m. Liepa, I.; Blija, T. 4 / 7

5 3. Results and disussion The transition rate values of branhes, needles, stumps, roots ( Z, Sk, C C, C S ) and the total non-stem biomass (ΣC i ) are shown in Table 2. No. v, 3 m Table 2: Biomass expansion fators Z Sk Fators i The transition rates sum ΣC i of the sample trees biomass fration and the breast-height diameter (Figure 2) are mutually independent features (this refers also to the rates of partiular frations). Dispersion of the empiri points in orelogram is relatively wide. It is explained by the dendrometri, phytoenoti and edaphi variety harateristi to the sample group of sample trees whih was hosen on purpose in order to represent Latvia s fir stands as muh appropriate as possible. A onlusion following out of the Fig 2 allows using the mean values of transition rates in the non-stem biomass alulation of stands and its groups, whih onsiderably simplifies evaluation of the biomass of stands, beause only one initial parameter total volume of the relevant stand or the group of stands - is needed to determine the total biomass or the biomass of its partiular frations. C S Σi Liepa, I.; Blija, T. 5 / 7

6 y = x R 2 = d, m Figure 2: Correlation between an expansion fators sum and stem diameter Biomass alulation of fir stands in Latvia aording to site quality index lasses is shown in Table 3. Table 3: The volume and biomass of sprue forests in Latvia mlj.t Site quality Volume index. 3 Biomass, m stems branhes needles stumps roots total I a I II III IV V V a Total % The total biomass volume in Latvia is million t, from whih million t or 60.2% is the stem fration part, and million t or 39.8% - non-stem fration part. As the total area of fir stands in Latvia is ha (Уголев, 2001), so 227,2 t of biomass per 1 ha in average have been aumulated. The branhes ontain 10.3%, needles -10.6%, stems 5.3% and roots 13.6% of the total biomass volume (Table 3), whih is a potential reserve of the eonomi use of forest resoures. Currently, more easily aessible biomass parts branhes and needles, whih make 20.9%, - are being involved in produing woodhip in Latvia. The performed researh allows planning the biomass volume potential for energy obtaining. So it is possible to determine the potentially usable biomass volume for obtaining of energy by planning of logging and determining the utable wood amount in a sprue stand. 4. Conlusions The transition rate i values for sprue non-stem biomass fration (branhes, needles, stumps, roots) and the volume orrelation between the relevant fration biomass and stem volume (mean value ± standard error) have been alulated: branhes Z = ± ; needles Sk = ± ; stems C = ± ; roots S = ± ; non-stem frations altogether ΣC i = ± Liepa, I.; Blija, T. 6 / 7

7 The total biomass volume of Latvia s fir stands are million t, from whih million t or 60.2% is the stem fration part, and million t or 39.8% - non-stem fration part. The branhes ontain 10.3%, needles -10.6%, stumps 5.3% and roots 13.6% of the total biomass volume. The performed researh allows planning the biomass volume potential for obtaining of energy. 5. Referenes John, A. Helms (1998) The Ditionary of Forestry. The Soiety of Amerian Foresters, Bethesda, 210 pp. Mihael, S. Philip (1994) Measuring Trees and Forests. Seond Edition.CAB. International. Department of Forestry. University of Aberdeen, 310 pp. Уголев, Б. Н. (2001) Древесиноведение с основами лесного товароведения. Изд. третье. Москва, МГУЛ., 340 с Боровиков, А. М., Уголев, Б. Н. (1989) Справочник по древесине. - Москва: Лесная промышленность., 296 с. Forest Setor in Latvia (2005). Rīga, 32 pp. Growth Ring. ( 2005) State Forest Servie, Riga, 28 pp. Liepa, I. (1996) Pieauguma māība. LLU, Jelgava, 123 lpp. Zar, J. H. (1999) Biostatistial Analysis. Fourth edition. Prentie Hall International, Northern Illinois University, USA, 663 p. Arhipova, I., Bāliņa, S. (2003) Statistika ekonomikā. Risinājumi ar SPSS un Mirosoft Exel. Datorzinību entrs, Rīga, 352 lpp. Liepa, I.; Blija, T. 7 / 7