=Paper=
{{Paper
|id=Vol-2030/HAICTA_2017_paper70
|storemode=property
|title=Tree-ring Widths and Wood Density Variability of non-Native Species: A Case Study of Douglas-fir Growing in Central Europe
|pdfUrl=https://ceur-ws.org/Vol-2030/HAICTA_2017_paper70.pdf
|volume=Vol-2030
|authors=Kyriaki Giagli,Lukáš Timko,Vladimir Gryc,Marek Fajstavr,Hanuš Vavrčík
|dblpUrl=https://dblp.org/rec/conf/haicta/GiagliTGFV17
}}
==Tree-ring Widths and Wood Density Variability of non-Native Species: A Case Study of Douglas-fir Growing in Central Europe==
https://ceur-ws.org/Vol-2030/HAICTA_2017_paper70.pdf
Tree-ring widths and wood density variability of non-
native species: a case study of Douglas-fir growing in
central Europe
Kyriaki Giagli1, Lukáš Timko1, Vladimír Gryc1, Marek Fajstavr1, Hanuš Vavrčík1
1
Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemĕdĕlská 3, 61300
Brno, Czech Rupublic, e-mail: giagli@node.mendelu.cz
Abstract. The aim of the present study was to analyze the wood density
variations along the stem radius of non-native Douglas-fir (Pseudotsuga
menziesii (Mirb.) Franco) growing in Central Europe. Sample logs (0.5 m;
breast height) were obtained from five Douglas-fir trees growing in the Czech
Republic, to analyse the tree-ring widths (TRW) and the oven-dry wood
density intra-species variability. The first 15 tree rings (close to the pith) were
found to be 5.14 ± 1.68 mm wide, while the average TRW gradually
decreased. The average oven-dry density of wood produced by non-native
Douglas fir growing in the Czech forest was 542.9 ± 66.3 kg m-3, which is
notably higher than the home-grown Douglas-fir wood. Along the stem radius,
from pith to bark, oven-dry wood density showed an upward trend.
Keywords: oven-dry wood density; Pseudotsuga menziesii; latewood
proportion; earlywood width.
1 Introduction
Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) lies among the most
environmentally and commercially promising non-native species in several European
countries i.e., Germany, France, United Kingdom (Gartner et al. 2002, Šindelař and
Beran 2004, Blohm et al. 2016). In the Czech Republic, recent forestry studies has
been focused on partly replacing native tree species with Douglas-fir, mostly
targeting on great biomass yield and high lumber production (Menšík et al. 2009,
Kubeček et al. 2014, Remeš and Zeidler 2014, Podrázský 2015, Podrázský et al.
2016). Within this frame, estimating intra-species wood variability is a handy tool for
the wood industry (Taylor and Wooten 1973).
Wood density varies within the tree from base to top, from pith to bark along the
stem radius, from earlywood to latewood within tree-rings (Jozsa et al. 1989,
Kennedy 1995, Gartner et al. 2002, Acuna and Murphy 2006). Namely, wood density
changes dramatically along the stem radius from the juvenile (close to pith) to mature
(close to bark) wood (Gartner et al. 2002). The distinction between juvenile and
mature wood was developed mostly for practical rather than biological reasons.
Within this frame, the transition threshold was defined around 10–20 years, since the
changes in properties were negligible by this age (Acuna and Murphy 2006). In line
571
with this, Blohm et al. (2016) found that mature wood began to form around the age
of 18 in Douglas-fir trees growing in plantations in Southern Germany. Wagenfür
(2000) reported that Douglas-fir oven-dry wood density was 470 kg.m-3 while
according Rijsdijk and Laming (1994) it was higher (492 kg.m-3). Nevertheless, the
homegrown Douglas-fir oven-dry wood density was 419.7 kg.m-3, in the USA (Pong
et al. 1986).
In the Czech Republic, the biggest research interest has been recently focused on
the environmental parameters (drought tolerance, soil quality) and the high
production volumes of the species (Menšík et al. 2009, Viewegh et al. 2014, Kubeček
et al. 2014, Podrázský 2015). Nevertheless, to our knowledge, the quality traits of
Douglas-fir wood currently produced in the Czech Republic still need to be
elucidated. In this study we aimed at outlining the oven-dry wood density variability
along the stem radius of the non-native Douglas-fir (Pseudotsuga menziesii (Mirb.)
Franco) growing in the Czech Republic.
2 Materials and Methods
The research plot was located in the University Forest Enterprise in Křtiny –
Vranov, Czech Republic. The research was conducted on Douglas-fir trees growing
in a mixed forest stand (Norway spruce 6 %, larch 29 %, Scots pine 6 %, Douglas-fir
22 %, European beech 19 %, lime 14 %, sessile oak 3 % and hornbeam).
Five healthy co-dominant 76-year-old Douglas-fir trees were selected and felled.
Logs (50 cm) were cut at breast height (1.3 m) from each tree. A central plank (6 cm
thick) including the pith in the axis was produced from the each log. Tree-ring width
(TRW) were analyzed along the stem radius (from A-pith to J-cambium).
Additionally, the early- and latewood proportions were calculated per tree ring.
Samples of 2×2×3 cm for oven-dry wood density testing were obtained radially
from bark to pith. In total, 336 samples were obtained from all 5 trees. The samples
were dried up to 0% moisture content in a programmed oven (at 103±2 °C). Each
oven-dried sample was measured in three anatomical directions and then weighed.
Oven-dry wood density denotes the oven dried weight (0% moisture content) in
relation with the respective volume, i.e. at 0% moisture content, calculated as:
!!
𝜌! = (1)
!!
where ρk: oven-dry wood density (kg.m-3), m0: mass of wood (kg) at oven-dry
moisture content and V0: volume of wood (m-3) at oven-dry moisture content.
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3 Results and Discussion
2.1 Tree rings
The close to the pith (1-15 tree-rings) the average TRW was 5.14 ± 1.68 mm,
getting promptly narrower (3.61 ± 1.55 mm) in the next set of 15 tree-rings.
Nevertheless, average TRW gradually decreased and conceivably held steady
approaching to cambium (Table 1, Fig 1). Blohm et al. (2016) reported that juvenile
wood average TRW was 6.2 mm while the respective value for mature wood was 4.8
mm for Douglas-fir grown in Germany. This is not in line with our findings,
considering the mature wood TRWs. Surely, according several studies on Douglas-
fir, the transition threshold from the juvenile to the mature might vary due to
variability per individual tree (Di Lucca 1989, Fabris 2000), genetic predisposition
(McKimmy and Campbell 1982, Vargas-Hernandez and Adams 1991, Abdel-Gadir
and Krahmer 1993), or just the sampling height (Fabris 2000, Gartner et al. 2002).
Table 1. Average tree-ring widths along the stem radius.
Interval of tree-rings from pith to cambium
Tree rings 1–15 16–30 31–45 45–60 61–76
Average (mm) 5.14 3.61 2.65 2.45 2.24
Standard deviation
1.68 1.55 1.32 1.21 1.17
(mm)
Coefficient of
28.26 42.78 50.03 49.37 52.23
variation (%)
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12
10
Tree ring width (mm)
8
6
4
2
0
0 10 20 30 40 50 60 70 80
Age
1 2 3 4 5 Mean PPolynomial
olynomická (Mean )
function
Fig. 1. Tree-ring widths along the age depicted per tree (1-5) and mean values.
The average width of earlywood behaved similarly to the average TRW along the
stem radius. The average width of the latewood remained almost invariable as the
tree was aging, besides a slight increase noticed around the age of 60. Diametrically
opposed trend showed the proportion of the late-wood which steadily increased with
the age (Fig 2).
In Germany, lower latewood percentage (34%) was reported in the juvenile wood
compared with the mature wood (Blohm et al. 2016). In our study, we found that the
late-wood proportion of the TRW was around 30% in the juvenile wood, whereas it
reached almost 50% in the mature wood (ca. 76 years). This can provide us
information on wood density since Wimmer (1995) reported that in conifers, the tree-
ring density was mainly influenced by the radial diameter and cell-wall thickness of
latewood tracheids.
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7 70
6 60
Width of TRW / E W / LW (mm)
P roportion of late-wood (% )
5 50
4 40
3 30
2 20
1 10
0 0
0 10 20 30 40 50 60 70 80
Age
tree ring width width of early-wood
width of late-wood proportion of late-wood
Fig. 2. Tree-ring widths (TRWs), earlywood and latewood trends and proportions.
2.2 Oven-dry wood density
Lausberg et al. (1995) noticed high density variation among Douglas-fir trees
from the same provenance. Other studies stated that Douglas-fir wood density was
featured by strong inter- and intra-tree-ring heterogeneity (Vonnet et al. 1995,
Rathgeber et al. 2006). We found that the oven-dry density among the trees ranged
from 517.0 ± 49.5 kg m-3 to 596.4 ± 78.7 kg m-3 (Table 2). Furthermore, the average
oven-dry wood density was 542.9 ± 66.3 kg m-3 and ranged between 402.7 and 648.9
kg m-3. This resonates well with Wagenfür (2000) and Rijsdijk and Laming (1994)
and confirms again the higher wood density of non-native Douglas-fir growing in
Europe, in comparison with the home-grown trees.
The oven-dry wood density was found low close to the pith but gradually
increased along the stem radius (Fig. 3). Douglas-fir juvenile wood density was
reported several times to be relatively low during the first 15-20 years of growth,
followed by a rapid increase around 30 years, and eventually resulted in rather
constant or even ascending wood density trend up to more than 50 years (Jozsa and
Kellogg 1986, Gatner et al. 2002, Acuna and Murphy 2006). In horizontal
distribution, from the pith to the cambium, wood density increased, culminating close
to the bark (Gartner et al. 2002, Acuna and Murphy 2006). Our results cast no doubt
on the prevalent reports on non-native Douglas-fir growing in the central Europe.
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Table 2. Average oven-dry wood density per tree and total.
Oven-dry wood density
Tree no. 1 2 3 4 5 Total
N 64 75 62 61 74 336
Average (kg·m-3) 541.6 517.0 522.0 537.4 596.4 542.9
Standard deviation
(kg·m-3) 53.9 49.5 49.9 99.4 78.7 66.3
Minimum (kg·m-3) 407.9 415.7 392.2 396.6 400.9 402.7
Maximum (kg·m-3) 619.3 621.6 635.8 666.1 701.9 648.9
Coefficient of
variation (%) 10.0 9.6 9.6 18.5 13.8 12.8
750750
700700
650650
Density (kg·m-3)
600600
Hustota (kg · m -3)
550550
500500
450450
400400
350
350 A
A B
B C
C D
D E
E F
F G
G HH II JJ
Sekce po poloměru kmene
Position along radius
Fig. 3. Oven-dry wood density along stem radius from pith to cambium (A-J).
Nevertheless, wood density can be affected by silvicultural treatments or the
growing site can affect wood density values at a given cambial age (Erickson and
Harrison 1974, Smith 1980, Jozsa and Brix 1989, Cown and Parker 1979, Fabris
2000, Gartner et al. 2002).
4 Conclusions
Douglas-fir is of great interest in forestry as it combines strong productivity and
high wood quality (Rathgeber et al. 2006). To illustrate the quality of the raw
material before use, wood density is a reliable indicator and certainly one the most
determinant wood properties (Gartner et al. 2002, Rathgeber et al. 2006). We found
576
that non-native Douglas-fir trees growing in the Czech Republic produce notably
denser wood than the homegrown Douglas-fir trees. Along the stem radius, the oven-
dry density followed an upward trend, which culminated close to the bark.
Acknowledgments. Special thanks to the University Forest Enterprise in Křtiny –
Vranov, Czech Republic, for providing us with the research material.
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