WOOD PHYSICAL PROPERTIES AND TRACHEID DIMENSIONS OF NON-NATIVE SOFTWOODS IN IRAN

Transcription

1 CELLULOSE CHEMISTRY AND TECHNOLOGY WOOD PHYSICAL PROPERTIES AND TRACHEID DIMENSIONS OF NON-NATIVE SOFTWOODS IN IRAN MOHAMMAD FARSI * nd MAJID KIAEI ** * Deprtment of Wood nd Pper Science nd Technology, Sri Brnch, Islmic Azd University, Sri, Mzndrn, Irn ** Deprtment of Wood nd Pper Science nd Technology, Chloos Brnch, Islmic Azd University, Chloos, Mzndrn, Irn Corresponding uthor: Mohmmd Frsi, moh_frsi@iusri.c.ir Received December 14, 2012 This study ws conducted to investigte some physicl properties (bsic density, volumetric shrinkge), trcheid dimensions (trcheid length, trcheid dimeter, lumen dimeter, nd cell wll thickness) nd biometricl properties (flexibility coefficient, slenderness coefficient nd Runkel coefficient) of 9 species of non-ntive softwoods of the world imported to nd grown in the northern region of Irn. For this purpose, 27 helthy trees from scots pine species with seed origins in Spin, Serbi (prt of former Yugoslvi), Armeni, spruce species with seed source in Serbi, Ljim nd Kelrdsht, nd species of blck pine, yellow pine nd lrch from Vnemek-Nek site in northern Irn were selected rndomly nd disk ws cut from ech one t brest height. Test smples were cut from the disks to mesure physicl properties (bsed on the ISO stndrd), trcheid dimensions (using the Frnklin method) nd biometricl indexes. The ANOVA results showed significnt difference mong softwood species in terms of physicl properties, trcheid dimensions nd biometricl properties. There ws no significnt difference in Runkel coefficient. Seed source hd some meningful effects on the physicl properties, trcheid dimensions nd biometricl properties of scots pine (except flexibility coefficient nd Runkel coefficient) nd spruce wood (except bsic density nd Runkel coefficient). The reltionship between vrious wood properties nd quntittive fetures (survivl, height nd dimeter) of the trees showed no significnt correltion between these mentioned trits in non-ntive softwood species. All of the investigted species presented importnt indictors for the production of pper in terms of biometricl coefficients. However, plnting scots pine with seed origins in Serbi nd Armeni seems to be more suitle due to higher wood production over short time period nd better comptibility with the site conditions. Keywords: softwood species, seed source, physicl properties, trcheid dimensions, biometricl properties INTRODUCTION In terms of softwood species, Irn is considered one of the poorest countries of the world, with only out 0.5% of its forests in the north being covered with coniferous species. The min ntive softwood species in Irn re cypress nd juniper. Rpid growth, proper dptility to different hitt conditions nd proper ppliction of softwoods in wood nd pper industries determined the cultivtion of these prticulr pine species. Besides, since 1956, out 48 species of softwoods hve been imported to Irn nd plnted in different regions, 1-2 including yellow pine, lrch, scots pine, blck pine nd spruce species. Yellow pine ( ponderos) is ntive to the northwest of the U.S.A. nd is geogrphiclly spred from 31 to 51 degrees ltitude in the north. Yellow pine is one of the most widespred species of pine mong the ntive Americn pines, so tht its distribution rnges from the north, from Albert nd British Columbi t Cnd border, to Wshington Stte, Oregon, nd southern Cliforni, nd extends towrds the Est to New Mexico. Scots pine ( ) is Euro- Asin species nd covers vst lnds in the high ltitudes of the northern hemisphere nd it hs spred from Siberi in Asi to Europe, nd mong pine species, it hs the highest levels of nturl spred. Lrch (Lrix decidus) is lso ntive to Cellulose Chem. Technol., 48 (5-6), (2014)

2 MOHAMMAD FARSI nd MAJID KIAEI centrl Europe nd its mjor hitts re the Alps, Crpthins, Souderton, southern nd centrl Polnd. It needs humid climte nd grows poorly in high cly soils. It cn tolerte this kind of poorly drined soils nd grows better in cidic recting soil thn in neutrl one. Blck pine ( nigr) is ntive to the west Mediterrnen Se nd to the zone from the Blck Se to Austri. This species is highly resistnt to cold nd dry climtes nd requires Mediterrnen climte, low soil moisture being limiting fctor for its growth. Spruce (Pice Abies) is ntive to Europen elevtions extending from the Blkns to Russi. It grows best in cold nd humid climtes nd on well drined lomy sndy soils. This species is tolernt of shde nd is sensitive to northern slope shde, low nd wet plces nd soils tht re drined poorly. 1-3 Wood density is n importnt feture of wood qulity, which cn ffect wood strength properties, wood shrinkge nd pper pulp yield. 4 In softwoods, the incresed growth rte by chnging the mount of lte wood cuses reduced density nd mechnicl properties of wood. Wood density of softwoods in the rdil xis of the tree increses from center to brk nd decreses in longitudinl xis from the bottom to top of the tree Scots pine growing in the centrl prt of Lithuni hs lower density, higher mount of lignin, nd more extrcts thn Contort, but equl contents of cellulose nd sh. 11 In study on the effect of seed source on the wood density of rdit grown in two sites in Greece, it hs been reported tht the effect of seed source (Austrli, New Zelnd nd Spin) on the wood density of rdit ws not significnt, while the independent effects of site nd the interctions between seed source nd site on the density were noteworthy. 12 The chrcteristics of wood fibers re importnt fctors ffecting the pulp nd pper industry, s well s other cellulosic industries. By studying the mentioned chrcteristics, the suitility of woody nd non-woody species for pulp nd pper industry cn be predicted. The strength chrcteristics of pper produced from the wood of trees from different regions my vry due to ntomicl vrition. Fibers tht hve thick wlls re corser; therefore, there will be more empty spce between them, but, on the contrry, the fibers tht hve brod fiber cvity nd thin wlls hve higher tendency to strip when they re beten nd, s result, the connections between fibers nd, nturlly, the tensile strength nd resistnce will improve. Burst strength nd tensile strength re two fetures tht re significntly ffected by both length nd wll thickness of the fibers; hence, flexibility coefficient hs significnt effect on the mentioned resistnces. 5,13 Forests nd Rnge Reserch Institute (FRRI) implemented project in 1997 on the dpttion of nine different species of softwoods (yellow pine, scots pine, spruce, blck pine nd lrch) in three high regions in Mzndrn nd Giln forests, northern Irn (3 ltitude clsses in ech region). Now, nerly twenty yers fter the project implementtion, it is essentil to exmine the vrious non-ntive wood species properties. The objectives of this reserch were ) to exmine the physicl properties, trcheid dimensions nd biometricl properties of mjor non-ntive softwoods grown in the north of Irn (yellow pine, scots pine, spruce, blck pine nd lrch), b) to investigte the effect of seed source on the physicl properties, trcheid dimensions nd biometricl properties of scots pine (with seed origins from Spin, Armeni nd Serbi) nd spruce (with seed origins from Ljim, Kelrdsht nd Serbi) nd c) to determine the reltionship between physicl properties, trcheid dimension nd biometricl indexes, nd tree quntittive chrcteristics (height, dimeter nd survivl). EXPERIMENTAL Mterils The reserch project site ws Vnemek-Nek in the north of Irn, locted t 760 meters ove the se level (ltitude) nd t n verge grdient of 10%. The most importnt hereous species covering the project re re Crex brunnr, Pennyroyl, Juncos cutus, Sweet Bsil, Hypericum ndrosemum nd elderberry. Determining the physicl nd chemicl properties of the soil ws done by drilling profile with the dimensions of 75 cm by 5.1 m nd by 2 m in depth in the tenth yer of implementing the reserch project. The soil of the region is deep to very deep, nd the greter the soil depth the higher the cly mount nd the hevier the soil texture in the lower horizons. In terms of soil fertility, the studied re hs fvorle conditions for tree growth. Also, the soil is ctive limefree. 2 The results of ten yer climte dt obtined from Vnemek meteorologicl sttions, from 1990 to 1999, showed tht the solute mximum temperture (July) ws 42 C, the minimum temperture (Jnury) ws - 12 C nd the men nnul temperture ws 15.7 C. The totl men rinfll over the ten yers ws 1186 mm, fluctuting between 765 mm in 1995 nd 1923 ml in According to the performed investigtions 446

3 Softwood bsed on the climgrm of Emberger s formul, this region is plced in the cold nd wet climte ctegory with very cold winters, nd bsed on De Mrtonne s clssifiction, it is locted in very wet climte. In the reserch by Kisri et l. on this region, it is shown tht the conditions of the re re best for scots pine originting from Serbi nd Armeni, nd worst for lrch, in terms of survivl. Scots pine with Serbin seed source hs the highest vlues in terms of height nd dimeter t brest height (Tle 1). 2 In this study, 27 norml trees of nine exotic softwood species (yellow pine nd scots pine with seed origins in Spin, Armeni, Serbi, species of spruce with seed origins in Ljim, Kelrdsht nd Serbi, nd species of blck pine nd lrch) (Tle 2) grown in the Vnemek-Nek site in northern Irn were chosen nd disk ws cut from ech of them t brest height. Becuse of the smll dimeter of the trees, it ws not possible to obtin smples long rdil xis from the pith to the brk. Therefore, first the centrl prt ws isolted from the disks, then smples from the disk surfce were obtined. Methods Physicl properties After prepring the smples (bsed on the stndrd ISO-3131), the experiments, which included weighing nd mesuring dimensions, were done. In the first step, the volume nd weight of the smples (fter cutting the smple) were mesured. In the second step, the smples were plced in wter for 48 hours, so tht ll the smples were submerged nd/or sturted with wter. The weight nd volume of the sturted smples were determined using digitl scle nd cliper. In the third stge, the smples were plced in n oven for 48 h, t 103 ± 2 C, until the smples dried completely. The volume nd weight of the smples were mesured in dry stte. Specil bsic density is the most importnt intrinsic property of wood nd is obtined from dry weight divided by the sturtion volume. Shrinkge chnges the dimensions of the wood, which occurs by the influence of vrious phenomen nd moisture chnges between the two limits of fiber sturtion point nd dry mode of the wood nd is obtined by the reltion below (where β ν : volumetric shrinkge, v s : sturtion volume nd v 0 : dry volume). The number of smples for mesuring physicl properties ws 50 for ech species of softwood. Trcheid dimensions The number of smples for mesuring trcheid dimensions ws 15 smples for ech species of softwood nd 30 trcheids were mesured for ech prepred smple (450 trcheids for ech kind of wood). Frnklin method (1954) 14 ws used for seprting fibers. In this method, rtio of 50 to 50% of cetic cid nd hydrogen peroxide ws used. First, the smple wood picks were plced inside microqunt, then preprepred cetic cid nd hydrogen peroxide were poured on the wood smples by clibrted pipette nd the microqunt ws plced in n oven nd heted for 48 h t 64 C. After whitening, the smples from the microqunt were wshed 4 to 5 times by clibrted pipette with distilled wter until the odor of hydrogen peroxide nd cetic cid ws completely removed. To exmine trcheid dimension, n Imge Anlysis System ws used. Biometricl properties include flexibility coefficient, slenderness coefficient nd Runkel coefficient. Flexibility coefficient shows the resistnce of the pper ginst rupture nd burst nd if flexibility coefficient increses, the resistnce of the pper will increse; this coefficient is obtined from the lumen dimeter divided by the trcheid dimeter. 15 Slenderness coefficient shows the qulity of the pper nd is obtined from the trcheid length divided by the dimeter of the fibers. 16 Runkel coefficient shows pper resistnce ginst rupture nd is obtined from the two-cell-wll thickness divided by the fiber dimeter. 17 Tle 1 Tree sttus of the mjor world softwoods plnted within the project in Vnmk-Nek Softwood species Tree sttus Tree ge Seed source Plnttion (Scots pine) Potted 3 yers (2+1) Armeni Aslem (Scots pine) Potted 3 yers (2+1) Spin Aslem (Scots pine) Potted 3 yers (2+1) Serbi Chlmrdy nigr (Blck pine) Potted 3 yers (2+1) Austri Kelrdsht Pice ies (Spruce) Potted 3 yers (2+1) Kelrdsht* Kelrdsht Pice ies (Spruce) Potted 3 yers (2+1) Ljim* Ljim Pice ies (Spruce) Potted 3 yers (2+1) Serbi Pjet ponderos (Yellow pine) Potted 4 yers (3+1) USA Kelrdsht Lrix decidus (Lrch) Potted 3 yers (2+1) Serbi Pjet *The min source of these trees is Serbi, but fter nturl regenertion in Kelrdsht nd Ljim regions in Irn, the source nmes chnge to Kelrdsht nd Ljim, respectively 447

4 MOHAMMAD FARSI nd MAJID KIAEI Tle 2 Averge quntittive fetures of softwoods from Vnmk-Nek region Softwood species Source Survivl (%) DBH (cm) Height (m) Scots pine Armeni Scots pine Spin Scots pine Serbi Blck pine Austri Spruce Kelrdsht Spruce Ljim Spruce Serbi Yellow pine USA Lrch Serbi The ge of the trees ws yers old for ll studied species; DBH: tree dimeter t brest height Sttisticl nlysis In this study, the effect of treting the softwood smples on their physicl properties, trcheid dimensions nd biometricl properties nd the effect of seed origin on the mentioned properties of scots pine nd spruce were studied. Vrince nlysis test ws used to determine significnt differences nd Duncn's tle ws used for grouping the mens. Also, the reltionship between physicl properties, trcheid dimensions nd biometricl indexes, nd the quntittive chrcteristics of trees growing in Vnemek-Nek site, t softwoods species level, ws evluted using Person mtrix correltion. RESULTS AND DISCUSSION Bsic density The results of vrince nlysis (ANOVA) indicted tht the effect of softwoods tretment ws significnt on bsic density, so tht the mximum vlue of bsic density ws obtined for lrch species (0.498 g cm -3 ) nd its minimum vlue for Kelrdsht spruce wood (0.332 g cm -3 ). The effect of seed source on scots pine wood density ws meningful, while it ws insignificnt on spruce wood density. Among the scots pines, the bsic density ws higher for Spnish seed origin (0.443 g cm -3 ) nd lower for Armenin seed origin (0.396 g cm -3 ). In ddition, the bsic density of spruce wood with Ljim seed source (0.351 g cm -3 ) ws slightly higher thn those with Serbin nd Kelrdsht seed origin (0.343 g cm -3 ) nd (0.332 g cm -3 ), respectively (Fig. 1). Figure 1: Averge bsic density of non-ntive softwood species 448

5 Softwood 16 Volumetric shrinkge (%) c e de cd b 4 2 Trcheid length (mm) 0 ponderos nigr Yugoslvi Spin Armeni Pice ies Ljim Pice ies Keldsht Pice ies Yugoslvi Lrix decidus Figure 2: Averge volumetric shrinkge of non-ntive softwood species e d d d c Spin ponderos Armeni nigr Pice ies Pice ies Pice ies Yugoslvi Yugoslvi Ljim Keldsht Lrix decidus Figure 3: Averge trcheid length of non-ntive softwood species Volumetric shrinkge Vrince nlysis (ANOVA) showed tht the effect of softwoods tretments on volumetric shrinkge ws significnt, so tht the gretest mount of volumetric shrinkge ws chieved for blck pine wood (11.53%) nd the lowest for the Serbin spruce wood (6.12%). The effects of seed origin on the shrinkge of scots pine nd spruce ws meningful. Among scots pines, shrinkge ws more thn 10.70% for the Spnish seed source nd less thn 7.11% for the Serbin seed origin. Among spruce woods, mximum nd minimum mounts of volumetric shrinkge were observed for Kelrdsht (10.60%) nd Serbi (6.12%) seed sources, respectively. Despite the high density, lrch species hve good dimensionl stility (Fig. 2). Trcheid dimensions Trcheid length The results of vrince nlysis showed tht the effect of softwoods tretments on trcheid length ws significnt, so tht the mximum mount of trcheid length (3.3 mm) ws obtined for Spnish scots pine, while its minimum mount ws recorded for Serbin spruce wood (2.22 mm). The effect of seed source on the trcheid length of scots pine nd spruce ws significn; mong scots pines, trcheid length ws higher for scots pine with seed sources in Spin nd ws lower for seed sources in Armeni (2.78 mm). Moreover, the vlue of this property in Ljim spruce (2.92 mm) ws greter thn those of spruce with Kelrdsht (2.37 mm) nd Serbin seed origins (Fig. 3). Trcheid dimeter Vrince nlysis results showed tht the effect of softwoods tretments on trcheid dimeter ws significnt: the mximum trcheid dimeter ws found in the scots pine of Serbi (42.34 µm) nd the lest one in yellow pine (29.78 µm). The effect of seed source on the trcheid dimeter of scots pine nd spruce ws significnt, so tht mong scots pines, the trcheid dimeter of scots 449

6 MOHAMMAD FARSI nd MAJID KIAEI pine of Serbin origin ws more thn µm, while for tht of Spnish origin it ws less thn µm. Also, the vlue of this property in Kelrdsht spruce (34.84 µm) ws higher thn tht for spruces with seed origins of Ljim (31.21 µm) nd Serbi (31.42 µm) (Fig. 4) ef de f Trcheid dimeter (µm) cd 10 0 Spin ponderos Armeni nigr Yugoslvi Pice ies Yugoslvi Pice ies Ljim Pice ies Keldsht Lrix decidus Figure 4: Averge trcheid dimeter of non-ntive softwood species c b b Lumen dimeter (µm) Spin ponderos Armeni nigr Pice ies Pice ies Pice ies Yugoslvi Yugoslvi Ljim Keldsht Lrix decidus Figure 5: Averge lumen dimeter of non-ntive softwood species Lumen dimeter Vrince nlysis results showed tht the effect of softwoods tretments on lumen dimeter ws significnt: the mximum lumen dimeter (31.74 µm) ws in Serbin scots pine nd the minimum in yellow pine (21.31 µm). The effect of seed source on the lumen dimeter of scots pine nd spruce ws lso significnt: mong scots pines, the lumen dimeter of scots pine wood with Serbin origins ws greter thn tht of the others, while tht of scots pine with Spnish seed sources ws the lowest (23.19 µm). Moreover, the vlue of this property in Kelrdsht spruce ws greter (27.80 µm) thn those for spruce with Ljim (22.95 µm) nd Serbin (22.64 µm) seed origins (Fig. 5). Cell wll thickness Vrince nlysis (ANOVA) results showed tht the effect of softwoods tretments on cell wll thickness ws meningful: the mximum cell wll thickness (5.72 µm) ws observed in Armenin scots pine nd the minimum in Kelrdsht spruce wood (3.52 µm). The effect of seed source on the cell wll thickness of scots pine nd spruce ws lso significnt, mong scots pines, cell wll thickness ws higher in Armenin nd lower in Spnish (4.765 µm) scots pine wood. 450

7 Softwood Moreover, the vlue of this property ws greter in Ljim spruce (4.125 µm) thn in Kelrdsht (3.52 µm) nd Serbin (4.385 µm) spruce (Fig. 6). 9 8 d d cell wll thickness (µm) d c cd c Spin ponderos Armeni nigr Yugoslvi Pice ies Yugoslvi Pice ies Ljim Pice ies Keldsht Lrix decidus Figure 6: Averge cell wll thickness of non-ntive softwood species Tle 3 Averge biometricl indexes of exotic softwood species grown in Vnmk-Nek site Softwood species Flexibility coefficient Slenderness coefficient Runkel coefficient Spnish scots pine c 0.45 Yellow pine b 0.41 Armenin scots pine Blck pine Serbin scots pine Kelrdsht spruce b Serbin spruce Ljim spruce c 0.40 Lrch Biometricl coefficients Vrince nlysis results showed tht the impct of the softwood species on the flexibility coefficient ws significnt. The mximum flexibility coefficient ws observed in Kelrdsht spruce (79.04%) nd the lowest in Spnish scots pine (70.66%). The effect of seed origin on the flexibility coefficient of spruce ws significnt, while it ws not significnt in scots pine. Among the species of spruce, the mximum flexibility coefficient ws found in Kelrdsht spruce (79.04%) nd the minimum in Ljim spruce (71.82%) (Tle 3). Vrince nlysis results showed tht there ws significnt difference between softwood species in terms of slenderness coefficient. The highest slenderness coefficient ws observed in the scots pine with seed origin from Spin (102.83) nd the lowest coefficient in blck pine (66.56). The impct of seed source on the slenderness coefficient of scots pine nd spruce ws significnt: mong scots pines, the highest slenderness coefficient ws found in Spnish scots pine species (102.83) nd the lowest in Serbin scots pine (70.78). In spruce species with different seed origins, the mximum nd minimum vlues belonged to spruce with seeds from Ljim (95.23) nd Kelrdsht (69.19), respectively (Tle 3). Vrince nlysis results showed tht the effect of softwood species on Runkel coefficient ws significnt, while the effect of seed sources on Runkel coefficient of spruce nd scots pine wood ws not significnt. In generl, the highest nd the lowest Runkel coefficients were observed in the scots pine of Spin (0.45) nd spruce of Kelrdsht (0.28), respectively (Tle 3). The Runkel coefficients of ll types of imported nonntive softwoods were below one. The reltionship between physicl properties 451

8 MOHAMMAD FARSI nd MAJID KIAEI (bsic density nd volumetric shrinkge), trcheid dimensions (trcheid length, trcheid dimeter, lumen dimeter, cell wll thickness) nd biometricl properties (flexibility coefficient, slenderness coefficient nd Runkel coefficient), nd the quntittive chrcteristics of the mentioned trees (survivility, dimeter nd height) showed no significnt differences mong the mentioned properties of the nine imported softwood species. The reltionship between fiber dimensions nd survivility ws positive, while between fiber dimensions nd tree height it ws negtive. Vritions mong species, within the sme species (from tree to tree) nd within tree (chnges in tree height nd rdil chnges from the pith to the brk), s well s chnges in the rings (erly wood nd lte wood) re fctors tht cn ffect the properties of wood. These vritions re incresed by the hitt, climte nd seed source fctors. 13,18 The present study indicted significnt differences between softwood species in terms of physicl nd biometric properties, which my be cused by vritions within species, even though ll the investigted species belong to the pine fmily. The effect of seed origin on trcheid length of scots pine nd spruce nd on the bsic density of scots pine is significnt, while it is insignificnt s regrds the bsic density of spruce wood. Also, the reltionship between the physicl nd biometric properties nd the quntittive fetures of trees showed tht there ws no significnt correltion between the mentioned properties, which grees with the results obtined by the world s leding reserchers, 12,19 who stted tht the density of rdite presented wek negtive correltion with the dimeter t brest height, property which is not dependent on the height of trees. Since ll the mechnicl properties of wood hve strong reltionship with density, while some of the resistnce properties of wood hve stronger reltion with density, it is expected tht high density lrch species would hve higher resistnce thn others, which is very importnt in the design of wood structures. The dependence between wood density nd mechnicl properties of wood for mny species of softwoods hs been demonstrted. 2,18 Also, mny of the mechnicl properties of wood re dependent on the trcheid dimensions including the length nd dimeter of trcheid. 5 Tle 4 Reltionship between physicl nd biometric properties nd quntittive fetures of imported softwood species Person correltion Survivl DBH Height Bsic density Volumetric shrinkge Trcheid length Trcheid dimeter Lumen dimeter Cell wll thickness Flexibility coefficient Slenderness coefficient Runkel coefficient All reltionships between wood properties ren t significnt; DBH: tree dimeter t brest height Since the lrch species hve the most bsic density of the other species, therefore, these fctors my ffect the production of pulp. In equl digester volume, lrch wood species produced more pulp thn others. Therefore, greter pper strength is expected from lrch wood. As known, there is positive reltionship between wood density nd opticl properties, on the one hnd, nd between wood density nd ter resistnce, on the other hnd, nd negtive reltionship between wood density nd the tensile strength of pper. 11,20 Wood with bsic density of g cm -3 is suitle for the production of pper pulp. 21 This property is observed in scots pine species with seed sources from Serbi, Armeni (roughly) nd Spin, blck pine nd lrch. The bsic density of scots pine with seed origins from Spin is g/cm 3, which is lmost equl to the bsic density of the wood plnted in Spin 9 (0.443 g cm -3 ) nd in southern Finlnd (0.443 g cm -3 ). 8 Bsed on IAWA clssifiction, the fibers of ll 452

9 Softwood mjor softwood species of the world, grown on Vnemek-Nek site, re considered long, nd from the softwood species fmily, the longest fibers belong to the scots pine of Spin (3.3 mm). In generl, the higher the fiber length of specific species, the more suitle it is for the production of pper. But reserches hve shown tht the suitility threshold of trcheid length is 2 mm, for producing krft pper with good ter strength, nd fter this threshold, longer cells hve little effect on the qulity of the finl product. It hs been lso reported in other studies tht lrger cells hve no significnt effect on incresing the tensile strength of pper, 13 which my pply to ll the ove-mentioned species, since the trcheid length of the studied species ws found to be higher thn 2 mm. In terms of flexibility coefficient, fibers cn be clssified into four groups: 1) very flexible fibers with flexibility coefficient higher thn 75; 2) flexible fibers with flexibility coefficient of 50-75; 3) hrd nd rough fibers with flexibility coefficient of 30-50; nd 4) fibers with high stiffness nd flexibility coefficient lower thn According to this clssifiction, Kelrdsht spruce softwoods belongs to the first group nd the remining species to the second group. Very flexible (first group) nd flexible (second group) fibers, present in ll the investigted species, re suitle for pper production. Of course, hrd nd rough fibers with flexibility coefficient of re not suitle for the mnufcture of pper nd re mostly used for pperbord products. 22 The higher the slenderness coefficient, the higher nd better pper qulity will be; however, n cceptle vlue of the slenderness coefficient for the pper industry is ove 33%. 23 These properties hve been observed in ll softwood species grown on Vnemek-Nek site. When Runkel coefficient is ove 1, fibers hve thick cell wlls nd the cellulose obtined from them is less used in the pper industry. However, when its vlue is equl to 1, fibers hve verge cell wlls nd the cellulose obtined is suitle for pper production. When the coefficient of this vlue is below one, fibers hve thin cell wlls nd the cellulose obtined such fibers is most frequently used in pper industry. 23 Thus, the fibers from ll the softwood species under study re suitle for pper production, due to the low vlue of this coefficient. CONCLUSION 1- There re significnt differences mong the imported softwood species s to physicl properties, trcheid dimensions nd biometricl indexes, except Runkel index. 2- The seed source hd significnt effect on the physicl properties, trcheid length nd biometricl indexes, except bsic density nd Runkel index in spruce species, nd flexibility nd Runkel index in scots pine species. 3- All softwood species investigted in the present study re suitle for the pper industry in terms of density, trcheid length nd biometric coefficient (Runkel coefficient, flexibility coefficient nd slenderness coefficient), but considering the desired high volume wood production in short period of time, scots pine species with seeds from Armeni nd Serbi re more suitle thn other softwood species, s in ddition to presenting suitle indictors for pper production, they chieve the desired dimeter nd length in short time. As Irn forest resources re reltively poor, the results of this study show tht the cultivtion of this species (scots pine of Armenin nd Serbin origin) is necessry nd importnt. REFERENCES 1 H. Zre, Ntive nd Imported Conifers by Irnin Ministry of Jihd-e-Agriculture, Agriculture Reserch, Eduction nd Extension Orgniztion, No271, Tehrn, Irn, M. Kiei, Turk. Agric. For., 35, 31 (2011). 3 S. M. N. Kisri, S. A. Mousvi, S. Amini, A. Borhni, B. Jfri et l., Journl of Sciences nd Techniques in Nturl Resources, 6(4), 25 (2011). 4 P. W. West, Growing Plnttion Forests, Springer Verlg, Berlin, A. Pnshin nd C. de Zeeuw, Textbook of Wood Technology, 4 th ed., McGrw-Hill, New York, L. A. Bouffier, B. L. Grtner nd J. C. Domec, Wood Fiber Sci., 35(2), 217 (2003). 7 R. Mutz, E. Guilley, U. H. Suter nd G. Nepveu, Ann. Sci. Forest., 61, 831 (2004). 8 J. Repol, Silv Fenn., 4(4), 673 (2006). 9 R. Munoz, M. Cns nd R. R. Solleiro, Ann. Sci. Forest., 65, 507 (2008). 10 M. Kiei, H. Khdemi-Eslm, A. H. Hemmsi nd A. Smrih, Cellulose Chem. Technol., 46(1-2), 125 (2012). 11 I. Sle, U. Grinfelds, A. Jnsons, L. Vikele, I. Irbe et l., Bioresource, 7(2), 1771 (2012). 12 D. I. Mtziris, Silve Genetic, 28, 104 (1979). 13 B. J. Zobel nd J. P. vn Buijtenen, Wood Vrition: Its Cuses nd Control, Springer-Verlg, Berlin, Heidelberg, New York, F. L. Frnklin, Tropicl Woods, 88, 35 (1964). 15 F. F. Wngrd, Tppi J., 45, 548 (1962). 453

10 MOHAMMAD FARSI nd MAJID KIAEI 16 M. Kiei, A. N. Sdegh nd R. Moy, Cellulose Chem. Technol., 47(1-2), 49 (2013). 17 Runkel, Ds Ppier, 3, 476 (1949). 18 S. Y. Zhng, Wood Sci. Technol., 31, 181 (1997). 19 R. Burdon nd J. Hrris, New Zel. J. For. Sci., 3 (3), 286 (1973). 20 R. Wimmer, G. M. Downes, R. Evns, G. Rsmussen nd J. French, Holzforschung, 56, 244 (2002). 21 G. M. Downes, I. L. Hudson, C. A. Rymond, G. H. Den, A. J. Michell et l., Smpling Plnttion Euclypts for Wood nd Fibre Properties, CSIRO Publishing, Melbourne, Austrli, 1997, 132 pp. 22 I. Bekts, A. Tutus nd H. Eroglu, Turk. J. Agric. For., 23, 589 (1999). 23 F. Xu, X. C. Zhong, R. C. Sun nd Q. Lu, Ind. Crop. Prod., 24, 186 (2006). 454