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Physical and mechanical properties of paulownia tomentosa wood planted in hungaria

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Szabolcs Komán at University of Sopron
Szabolcs Komán
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S. Feher
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Andrea Vityi at University of Sopron
Andrea Vityi
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The Paulownia tree (or to its well-known name Chinese empress tree; Paulownia tomentosa) is classified among the most variable wood species of the world concerning usability. Its cultivation in Hungary in form of research plantations has just started in the last decade, first of all for the investigation of energetic properties. Due to this the information related to the physical-mechanical properties of the wood was still not determined, from which aspect this study is essential. The investigated wood with an air-dry density of 0.3 g·cm⁻³ has shown low bending (42 MPa), compressive (22 MPa), shear (7 MPa), tensile (33 MPa) and impact strength (1.6 J·cm⁻²) values, based on which its wooden material properties can be compared to poplars considering tree species in the region.
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335
WOOD RESE ARCH
62 (2): 2017
335-340
Short note
PHYSICAL AND MECHANICAL PROPERTIES OF
PAULoW nIA t oMe ntoS A WOOD PLANTED IN
HUNGARIA
S K, S F
U  S, I  W S
S, H
A   V
U  S, I  F  E T
S, H
(R A )
ABSTRACT
The Paulownia tree (or to its well-known name Chinese empress tree; Paulownia tomentosa) is
classified among the most variable wood species of the world concerning usability. Its cultivation
in Hungary in form of research plantations has just started in the last decade, first of all for
the investigation of energetic properties. Due to this the information related to the physical-
mechanical properties of the wood was still not determined, from which aspect this study is
essential. The investigated wood with an air-dry density of 0.3 g.cm-3 has shown low bending
(42 MPa), compressive (22 MPa), shear (7 MPa), tensile (33 MPa) and impact strength
(1.6 J.cm-2) values, based on which its wooden material properties can be compared to poplars
considering tree species in the region.
KEYWORDS: Paulownia tomentosa, physical properties, mechanical properties, density,
INTRODUCTION
In Asia and in some European countries Paulownia species are preferred in tree cultivations
or agro-forestry plantations of industrial wood purpose, in the latter typically in combination of
industrial wood/agricultural crop plant, rarely in mixed culture of other purpose (e.g. energy).
For example in the Chinese agriculture Paulownia is cultivated as intermediate plant on almost
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WOOD R ESEARC H
1.3 million hectares. The reason for this is that one manages meagre property assets in China, so
food production and industrial wood cultivation can be realized on the same ground (Vityi and
Marosvölg yi 2012).
Literature data and the results of Hungarian investigations performed present that individual
Paulownia species are basically undemanding, have a great yield and can be cultivated relative
simply. It can be well reproduced from grain, root cutting (according to some sources also from
shoot cutting), under favourable conditions it can reach a trunk diameter of 30-40 cm, the height
of 10-12 m and the wood yield of 0.2-0.6 m-3 by the age of 10 years. (Under ideal cultivation
conditions its growth can be even quicker). (Yang 2004).
Its wide utilization spectrum ranges from industrial applications (furniture and building
timber, base material for paper industry, biomass for energy purposes etc.) through apiculture and
medical industry (bark, leaf, f lower cluster) to decoration function (park tree, base material of
exquisite wood-carving). Owing to its machinable timber of decorative texture it is used in Japan
as traditional timber, where a high quality log counts as valuable base material. The less valuable
base material can be utilized on other areas such as for example chipboard (Kalaycioglu 2005),
however it is applied as heat and electric insulation material (AFBI 2008) respectively. From
the properties of a wood density is most essential concerning utilization. From this information
one can conclude on the strength properties (Kiaei 2013). Typically there is a strong correlation
between density and MOR and MOE resp (Zhang 1997). The basic density relates closely to
the quality parameters of the final usage, such as e.g. cellulose yield and strength of construction
materials (Harvald and Olesen 1987). The tree species of higher density generally have more solid
wood than the ones of lower density (Walker and Butterfield 1996).
Paulownia is mainly cultivated on areas with hotter climatic conditions of the world (mainly
on the extended plantations of China and USA), where the usage of P. elongata has spread. For
this reason there is lot of information about this tree species, while one can find much less data
related to P. tomentosa tolerating also more moderate climatic conditions. The purpose of this
research is the discovery of the properties of the wooden material cultivated in Hungary, which
is the essential condition of applicability on some utilization areas.
MATERIALS AND METHODS
The Hungarian cultivations were established first of all for the purpose of plantation
experiences and energetic researches, for this reason older, more mature wood was not available
for investigation. The tree-trunk serving as base material for the specimen required for the
examination is situated at an altitude of 70 m; the average annual temperature ranges between
11-12°C, and the long-term total annual precipitation is approx. 608 mm. The examinations have
covered the following properties in accordance with the relevant standards:
- Annual ring structure
Based on the picture made of the disc cut from the trunk by means of the program Image Pro
Plus the annual ring width was determined along the smallest and biggest radius.
- Physical-mechanical properties
From the examined trunk the following properties were defined based on the relevant
standards: Density (DIN 68364:2003), Shrinkage and swelling (DIN 52184:1979), Compression
strength (DIN 52185:1976), Tensile strength (DIN 52188:1979), Shearing strength (DIN
52187:1979), Static bending streng th (DIN 52186:1978), Modulus of elast icity (DIN 68364:2 003).
Impact bending strength (DIN 52189:1981), Brinell hardness (MSZ EN 1534:2000).
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Vol. 62 (2): 2017
The examination were performed under standard climatic conditions (T=20°C; φ=65%)
- until equilibrium moisture content - on stored specimens. The strength examinations were
carried out with universal material examining device type Instron 4208 and Charpy-impact tester
on specimen series of 25 pcs. each.
RESULTS AND DISCUSSION
Due to the eccentric structure of the examined disc along the biggest radius the growth is
wider by approx. 30% than the value of the smallest radius. The increase cycle becomes constant
beginning from the 5th year (Fig. 1) under the growth ring width value of 1 cm. In the previous
years significantly bigger values can be found. The average growth ring width is 14.7 mm along
the biggest radius, while 8.3 mm in the direction of the smallest radius .
Fig. 1: Growth per year.
Density
Paulownia tomentosa has an expressly light, soft wood, which is proven by the measured
density values. The air-dry density (Tab. 1.) received corresponds with the average of the values
in the literatures (Kanehira 1933, Senelwaa and Sims 1999, Flynn and Holder 2001, Kalaycioglu
2005, Akyildiz 2010). This low density does not even exceed that of the poplars for example.
Tab. 1: Values of the measured densities (kg.m-3).
Density type Average Min. Ma x. St . dev.
Air-dry (u=12%) 300.18 262.33 360.18 26.59
Oven-dry (u=0%) 275.46 240.00 328.15 23.52
Basic 264.2 224.39 309.09 23.04
Shrinking-swelling
In case of the Paulownia tree we have received favourable results (Tab. 2.) from aspect
of dimensional change caused by moisture. Firstly the radial and tangential values are very
favourable, which almost completely comply with the ones communicated by Meier (2015).
However related to the dimensional change of volume higher literature values by more than
20-30% can be found as well (Akyildiz 2010).
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WOOD R ESEARC H
Tab. 2: Values of the measured densities.
Longitudinal Radial Tangential Volu met ric
Shrinkage 0.69 2.20 3.89 6.94
Swelling 0.68 2.17 3.73 6.28
Strength
From the low density value of the wooden material it is inferred that the different strength
values are not high as well. It is proven by the results received (Tab. 3.), which often have not
reached that of the poplars with similarly soft wooden material.
Tab. 3: Mechanical properties (parallel to the grain (MPa)).
Test type Average Min. Ma x. St .dev.
Compressive 22 .14 19.63 25.24 1.78
Tensile 33.23 21.86 52.96 8.90
Shearing 7.0 3 6.08 8.00 0.52
MOR (3 points) 41.51 28,65 48.65 4.68
MOE (3 points) 3492 2595 4142 472
Brinell
Cross 26.74 20.78 31.89 3.22
Tangential 9.13 5.59 13.61 2.16
Radial 9.51 6.53 13.39 2.17
Impact bending strength
(J.cm-2)1.59 1.27 1.90 0 .17
The strength values of the investigated paulownia correspond in some cases, while in other
cases these deviate more or less from the ones indicated by others. The values of bending strength
as maybe the most important strength property are practically identical with the values found in
some literatures (Akyildiz 2010, Meier 2015, Shim 1948). However regarding flexibility we have
received significantly lower values than communicated by other sources (Akyildiz 2010, Meier
2015, Shim 1948).
Regarding compressive strength the average 22 MPa value can be considered as very low,
which is however connected to favourable deviation values. The average shear strength value
received can be higher by even 20% compared to some earlier researches (Shim 1948, Barton
2007).
The determination of the tensile strength values is generally performed rarely in case of
wooden material examination, contrary to e.g. bending or compressive strength. In this case the
very high deviation value was connected to relatively low (33 MPa) strength.
The determination of the impact-bending strength – which is already a dynamic strength
property - is performed also relative rarely, for this reason values in this regard were not available.
The values received are extremely low, even in case of wood species with similar low density.
The Brinell hardness values measured in the main anatomical directions of the wood have
produced similar values as the similarly soft poplars. The axial hardness is almost the triple of the
side hardness values, which are practically the same.
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Vol. 62 (2): 2017
CONCLUSIONS
The wooden material properties of Paulownia tomentosa cultivated in Hungary do not show
any significant deviation related to the ones cultivated in other parts of the world. Due to its
low density (air-dry: 300 kg.m-3) and strength values it is not suitable for structural purposes;
however it can be a serious competition for broad-leaf tree species, f irst of all due to its growth
characteristics. Based on our investigations its properties can be compared first of all to hybrid
poplars. The density of hybrid poplars wood is between 300-400 kg.m-3. The cultivation
experiences and the current research related to the physical-mechanical properties of wooden
material can establish the more significant extension of the species in the region.
REFERENCES
1. AFBI, 2008: Paulownia as a novel biomass crop for Northern Ireland? A review of
current knowlwedge, Occasional publication No. 7. Agri-Food and Bioscience Institute,
Hillsborough.
2. Akyildiz, M.H., Kol, S.H., 2010: Some technological properties and uses of paulownia
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grain
6. DIN 68364, 2003: Properties of wood species - Density, modulus of elasticity and strength
7. DIN 52186, 1978: Testing of wood - Bending test
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grain
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S K*, S F
U  S
I  W S
B Z. S. 
H- S
H
Corresponding author: koman.szabolcs@uni-sopron.hu
A   V
U  S
I  F  E T
S
H
... (0.038) and the highest CV of 0.042 for the panel bonded with PUR. It can be observed that the density values for the single-layered panels are consistent with the raw density of Paulownia wood in results from studies concerning plantation wood from Spain, Serbia and Bulgaria [11,14] and Hungary [13,27]. The three-layered SWPs had increased density due to the adhesive application and there was no difference regarding the extraction of samples parallel or perpendicular to the direction of production/or the grain. ...
... These boards had similar CVs (about 0.09) when tested in both kg/m with a minimum of 264 kg/m and a maximum of 300 kg/m , with the smallest CV for the panel with MUF application (0.023), followed by the panel with PVAc application (0.038) and the highest CV of 0.042 for the panel bonded with PUR. It can be observed that the density values for the single-layered panels are consistent with the raw density of Paulownia wood in results from studies concerning plantation wood from Spain, Serbia and Bulgaria [11,14] and Hungary [13,27]. The three-layered SWPs had increased density due to the adhesive application and there was no difference regarding the extraction of samples parallel or perpendicular to the direction of production/or the grain. ...
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Full-text available
  • Jun 2023
The forest raw material base of Ukraine needs a long-term recovery, caused by current shortage of wood and in the long-term perspective, as well. One of the ways to solve this problem is to create plantations of Paulownia tomentosa (Thunb.) Steud., which are able to accumulate in a very short time a significant stock of wood, suitable for industrial use. Determination of the physical and mechanical properties was carried out on samples of standard sizes. It has been established that the density of paulownia wood, grown under the conditions of the Western Forest Steppe of Ukraine, ranges from 329-342 kg·m-3 (sapwood, heartwood) to 416 kg·m-3 (middle part between the sapwood and heartwood). Under the conditions when only air moisture influences the wood, the moisture content increases up to 12.9 %. Static bending strength, compressive strength parallel to grain, static hardness, modulus of elasticity of sapwood and heartwood parts of the trunk are characterized by minimum values, and the middle part (between the sapwood and heartwood)-by maximum ones. Therefore, in terms of appearance and texture, the wood has the most similarity with the wood of common ash; considering its density value, paulownia wood resembles the wood of Norway spruce and silver fir, but due to lower moisture absorption and the content of tannins, it is more resistant to decay than the mentioned species; the middle part according to some mechanical indicators is close to common pine wood, therefore, it can be widely used in building industry. Paulownia tomentosa wood is advisable to be used as a promising material for the production of firewood and wood pellets. The data we have obtained can be taken into account by specialists in the woodworking, furniture and agricultural industries when planning the creation of plantations and the use of its wood.
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Estudio comparativo de módulos de rigidez de tres maderas mexicanas y tres maderas japonesas
Article
Full-text available
  • Feb 2024
RESUMEN El objetivo de la investigación fue determinar las densidades y los módulos de rigidez en tres maderas japonesas y tres maderas mexicanas. La unidad experimental consistió en 210 especímenes agrupados en muestras de treinta y cinco probetas de cada una de las seis especies. Se determinaron el contenido de humedad y la densidad, y se midieron las frecuencias naturales de vibración en pruebas de torsión dinámica. Las magnitudes de los módulos de rigidez son comparables con los de investigaciones anteriores. Sin embargo, existen diferencias estadísticamente significativas entre las densidades y los módulos de rigidez de las seis especies. ABSTRACT The objective of the investigation was to determine the densities and stiffness modules in three Japanese woods and three Mexican woods. The experimental unit consisted of 210 specimens grouped in samples of thirty-five specimens of each of the six species. Moisture content and density were determined, and natural vibration frequencies were measured in dynamic torsion tests. The magnitudes of the modules of rigidity are comparable with those of previous investigations. However, there are statistically significant differences between the densities and modules of rigidity of the six species.
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Peculiarities of plant growth, development, and chemical composition of the Paulownia biomass
Article
  • Oct 2023
Purpose. To establish the peculiarities of plant growth, development, and chemical composition of the paulownia biomass of two species in the Right Bank Forest Steppe of Ukraine. Methods. Field, laboratory, measuring and weighing, mathematical and statistical. Results. The biological properties of two Paulownia species, namely Clone in vitro-112 and Paulownia tomentosa, were studied. The maximum number of leaves per plant at the end of the vegetation season was 24–26 in Clone in vitro-112 and 22–24 in Paulownia tomentosa. Leaf area per plant was 5.0–5.5 m2 and 4.0–4.5 m2, respectively. The main period of wood accumulation falls during the first three years of vegetation, and during this period, biomass productivity indicators are the highest. Five-year wood yield per tree was about 0.35 m3 in Clone in vitro-112 and 0.24 m3 in Paulownia tomentosa. The research determined the optimal content of nutrients, the lack or excess of which negatively affects biomass quality. Nitrogen is mostly concentrated in leaves (2.3–2.6%) and petioles (0.67–1.1%). The content of phosphorus was quite low: 0.33–0.36% in leaves and 0.22–0.23% in petioles. Plants contain a significant amount of potassium in the leaves: 1.25% in Clone in vitro-112 and 0.75% in Paulownia tomentosa. Conclusions. Clone in vitro-112 can be recommended for cultivation in the Right Bank Forest Steppe Zone of Ukraine. One hectare can produce 200–250 m3 of industrial wood and the same amount of branch biomass for 5–6 years. Branches are suitable for the production of fuel pellets and chips with low ash content (0.8–1.5%). At the same time, leaves and petioles of paulownia have an increased ash content (3.9–7.1%) due to the higher content of nutrients, in particular nitrogen. Therefore, it is not advisable to use them as feedstock for the production of solid biofuel, but they are suitable for the production of biogas.
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ПЕРСПЕКТИВИ ВИКОРИСТАННЯ ДЕРЕВИНИ ПАВЛОВНІЇ ПОВСТИСТОЇ PAULOWNIA TOMENTOSA (THUNB.) STEUD.
Article
Full-text available
  • Sep 2023
Узагальнено дані літературних джерел та наведено результати досліджень біолого-екологічних властивостей Paulownia tomentosa (Thunb.) Steud. в умовах Західного Лісостепу України. Досліджено механічні властивості деревини павловнії, вирощеної шляхом плантаційного вирощування в Україні. Об’єкт дослідження – деревина павловнії повстистої, вирощена в умовах Західного Лісостепу України. Предмет дослідження – механічні властивості деревини павловнії повстистої. Мета роботи – узагальнити відомості та систематизувати наявні наукові дані щодо таксономічної характеристики, морфологічних та екологічних особливостей павловнії повстистої в Україні, дослідити механічні властивості деревини за плантаційного вирощування та зробити оцінку щодо придатності її використання в промисловості. Основні завдання дослідження: визначити міцність деревини павловнії; зробити порівняльну оцінку механічних властивостей деревини павловнії та автохтонних порід; проаналізувати можливість використання деревини павловнії в різних галузях промисловості. Наукова новизна отриманих результатів дослідження – про механічні властивості деревини павловнії повстистої, вирощеної в Україні, інформація в проаналізованих нами друкованих та електронних виданнях відсутня. Серед механічних властивостей досліджено: міцність деревини при стиску вздовж волокон, міцність при статичному згині, торцеву твердість, модуль пружності. Встановлено, що для павловнії характерна різка зміна механічних властивостей деревини в межах діаметру стовбура. Показники основних механічних властивостей серцевинної та заболонної частини стовбура характеризуються мінімальними значеннями, а серединної частини стовбура (між серцевиною і заболонню) – максимальні. Так, якщо за своїми основними усередненими характеристиками деревина павловнії повстистої близька до деревини осики, то деревина серединної частини стовбура за окремими показниками наближається до деревини хвойних порід, які мають досить широке використання у будівництві. Практична значущість результатів дослідження – отримані нами дані можуть враховуватися фахівцями деревообробної, меблевої та аграрної галузі при плануванні створення плантацій та використання деревини павловнії повстистої.
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Some of the properties of particleboard made from Paulownia
Article
Full-text available
  • Aug 2005
The objective of this study was to determine some of the properties of experimental particleboard panels made from low-quality paulownia (Paulownia tomentosa). Chemical properties including holocellulose, cellulose, lignin contents, water solubility, and pH level of the wood were also analyzed. Three-layer experimental panels were manufactured with two density levels using urea–formaldehyde as a binder. Modulus of elasticity (MOE), modulus of rupture (MOR), internal bond strength (IB), screw-holding strength, thickness swelling, and surface roughness of the specimens were evaluated. Panels with densities of 0.65 g/cm3 and manufactured using a 7-min press time resulted in higher mechanical properties than those of made with densities of 0.55 g/cm3 and press times of 5 min. Based on the initial findings of this study, it appears that higher values of solubility and lignin content of the raw material contributed to better physical and mechanical properties of the experimental panels. All types of strength characteristics of the samples manufactured from underutilized low-quality paulownia wood met the minimum strength requirements of the European Standards for general uses.
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Propagation method influences first year field survival and growth of Paulownia
Article
Full-text available
  • Nov 1998
Field trials at three locations were used to evaluate survival and early growth of Paulownia elongata, P. fortunei, and P. ''Henan 1'' plants produced from seeds, shoot cuttings, and micropropagated shoots. One year after field establishment, trees produced by either vegetative propagation method survived with higher frequency and were taller and of greater diameter breast height than trees grown from seed. The influence of propagation method was more pronounced in P. elongata and P. fortunei than in P. ''Henan 1''. Survival frequency was similar for each species/hybrid, but both species were taller than P. ''Henan 1'' across propagation method and site. Field site had a pronounced influence on tree survival and height. Species/hybrid differences were not detected at the site that promoted the greatest tree growth, but P. elongata outperformed P. fortunei and P. ''Henan 1'' at the two sub-optimal sites. Clones within species/hybrid produced through micropropagation differed in survival frequency, height, and diameter breast height. Under the conditions used for this study, Paulownia field survival and early growth in central North Carolina was improved by using P. elongata or P. fortunei produced by rooting shoot cuttings or micropropagated shoots. Significant variation among clones within these species demonstrated the potential benefit of identifying superior clones to improve first year field survival and growth.
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Some technological properties and uses of paulownia (Paulownia tomentosa Steud.) wood
Article
Full-text available
  • May 2010
The aim of this study is to determine some physical and mechanical properties of Paulownia tomentosa wood grown in Turkey. The samples trees harvested from Kargi in Corum. Physical properties including air-dry density oven-dry density basic density swelling, shrinkage and oven-dry and air-dry thermal conductivity coefficients; mechanical properties including bending strength, modulus of elasticity in bending, compression strength parallel to grain, hardness, bonding strength were analyzed. Paulownia tomentosa wood's air dry and oven dry densities were determined as 0.317 and 0.294 g cm(-3); basic density was determined as 0.272 g cm(-3); volumetric shrinkage and swelling were determined as 7.78 and 8.41%; tangential, radial and longitudinal air-dry thermal conductivity coefficients were determined as 0.089, 0.090 and 0.133 kcal/mh degrees C, respectively. Fiber saturation point (FSP) was found 28.79%; bending strength, Modulus of elasticity in bending, compression strength parallel to grain and Brinell hardness values (parallel and perpendicular to grain) were determined as 43.56 N mm(-2), 4281.32 N mm(-2), 25.55 N mm(-2), 2.01 kgf mm(-2) and 0.88 kgf mm(-2), respectively. Consequently paulownia wood can be widely used for various purposes such as house construction, furniture making, pulp and paper and handicrafts.
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Radial variation in wood static bending of naturally and plantation grown alder stems
Article
  • May 2013
  • CELL CHEM TECHNOL
This study was carried out to determine radial variation of wood density, modulus of elasticity (MOE), modulus of rupture (MOR) and stress at elastic limit in plantation and natural alder forests in the north of Iran. Testing samples were taken at breast height of the stem and in three radial positions (10, 50 and 90% of radius) from natural and plantation forests to determine wood mechanical strength properties, according to the ASTM standard. The analysis of variance indicated that planting conditions (natural and plantation forests), radial position and their interaction had no significant effects on the modulus of elasticity (MOE), modulus of rupture (MOR) and stress at elastic limit in alder wood, while only radial position had a significant effect on wood density. Wood density was increased along radial direction from the pith to the periphery for both planting conditions. Overall, the mechanical strength properties in the plantation forest were slightly higher compared to the natural forest. The relationship between wood density and mechanical properties were analyzed by linear regression. A positive relationship was found between wood density and mechanical properties for both planting conditions. This relationship was stronger in plantation grown, compared to naturally grown trees.
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The variation of the basic density within the juvenile wood of Sitka spruce (Picea sitchensis)
Article
  • Jan 1987
The variation in the basic‐density level of 45 stems of Sitka spruce from two Danish sites has been examined. It is shown that the basic‐density level, i.e. the basic density as a function of ring width, within the juvenile wood decreases with (1) increasing distance from the pith and (2) increasing height in the stem (same ring number from pith provided). Furthermore, the basic‐density level seems to decrease with increasing stand quality, which may affect the pattern of variation in basic‐density level if the stand quality class varies with age. The basic density of the juvenile wood is markedly higher in Sitka spruce than in Norway spruce, whereby the risk of stem cracks probably is reduced.
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Wood specific gravity-mechanical property relationship at species level
Article
  • Jun 1997
Based on the data set of specimen tests on 16 timber species belonging to four distinct wood categories, the specific gravity-mechanical property relationship at species level was examined, and differences in the relationship between species from distinct wood categories were discussed. The linear equation (S =a +bG) was compared with the curvilinear one (S = G) in terms of the goodness at predicting mechanical properties through specific gravity at species level. The specific gravity-mechanical property relationship, to a differing extent, varies with mechanical properties and wood categories. Among three mechanical properties studied, MOR is most closely and almost linearly related to specific gravity, followed by Cmax, whereas MOE is poorly and least linearly related to specific gravity. In general, the relationship between MOE and specific gravity in a species from the ring-porous category is stronger than in a species from the diffuse-porous category. It appears that Cmax in a species from the second softwood category and the ring-porous category is more closely related to specific gravity than in a species from the first softwood category and the diffuse-porous category, respectively. In addition, MOE in a softwood species is generally less related to specific gravity as compared to a hardwood species. Yet, Cmax in a softwood species appears more closely related to specific gravity. Overall, the curvilinear equation is better than the linear one at predicting mechanical properties (especially MOE) in a species.
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Fuel characteristics of short rotation forest biomass
Article
  • Aug 1999
  • BIOMASS BIOENERG
Fuel characteristics of biomass from 12 tree species grown under a short rotation forestry regime were analysed. E. globulus, E. nitens and A. dealbata had the biggest trees while A. glutinosa, P. tomentosa and S. matsudana×alba 1002 had the smallest trees when the trees were harvested at the age of 3, 4 and 5 years. Higher heating value (HHV) ranged from 19.6–20.5 MJ/kg for wood, 17.4–20.6 MJ/kg for bark, and 19.5–24.1 MJ/kg for leaves, with the highest values for wood and bark being obtained from Pinus radiata. Wood basic density ranged from 250–500 kg/m3; ash content, 0.7–1.4%; volatile matter content, 91.5–95.1%; fixed carbon content, 4.2–7.3%; and extractives content, 3.3–11.9%. Wood properties were significantly different from those of bark, and also different from those of leaves. Except basic density and the proportion of bark on the stem, properties of wood did not vary with either cutting age or stocking density. Wood from coppice crops did not differ from that of single stem, first harvest crops.Differences in tree size for species planted at similar plant populations determine species yields. Variations in properties between species and between tree parts have implications for feedstock handling, transport, drying, storage, and on the design of conversion systems.
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Paulownia as a novel biomass crop for Northern Ireland? A review of current knowlwedge
  • Jan 2008
AFBI, 2008: Paulownia as a novel biomass crop for Northern Ireland? A review of current knowlwedge, Occasional publication No. 7. Agri-Food and Bioscience Institute, Hillsborough.