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8CIENCl!
EI.SEVIER
@
Forest Ecology
and
Management
DIABCT•
Forest Ecology and Management 186 (2003) 339-348
www.elsevier.com/locate/foreco
3
Influence of ·Bravo fungicide applications on wood density and
4
moisture content of Swiss needle cast affected Do g,,as-fir trees
/{
G.R. Johnsona·*, Barbara L. Gartnerb, Doug Maguirec, AI1<ii.
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{.:
form 24 February 2003; accepted 18 Ju
Received 12 January 2003; received in revised
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e 2003
: : · ' > ..: ::.;-'_/
': \ ·:.:::
.
Abstract
Wood density, moisture content, tracheid width and cell wall size were examln .in1t ees from plots that were sprayed for 5
years with chlorothalonil (Bravo®) fungicide to reduce the impact of Swiss needle.' st (SNC) and from trees in adjacent
unsprayed plots. The unsprayed (more heavily diseased) trees had significantly n_an:_ower sapwood, narrower growth rings, lower
sapwood moisture content, and narrower tracheid cell wall thickness th nrdia·:
sprayed (less heavily diseased) trees.
Moreover, unsprayed trees had altered earlywood denslty-earlywood widt -,r latlqilshlps, higher latewood proportion, and
higher overall wood density than the sprayed trees. We hypothesize: (1) U,at the decreased moisture content of diseased trees
results from their poor carbon economy resulting in insufficient energy (photosyn te) to reverse sapwood embolisms, and (2)
SNC decreases wood density relative to growth rate.
'
<1
© 2003 Published by'Elsevier B.V.
/J.
r;·: L ;;'
Keywords;
) r
1.
.,
.
l.;-;' -
Wood density: Growth rate;
. Swiss needle cast; Xylem embolism; Chlorothalonil
.1:
1'f,
ll
26
aski ed
_
97331, USA · .\
bDepartment of Wood Science and Engineering, Oregon State University, Corvallis, OR 97331/ USA cDepartment of Forest Science, Oregon State University, Corvallis, OR 9 J.3l:·:·ysA-;/
dOregon Department of Forestry, 2600 State Street, Salem, OR 97310,'"l]Sk�\ "USDA Forest Service, 3200 SW Jefferson Way, Corvallis, OR
6
7
8
9
II
If
/'')
)."
;-;:-;,/-I•
•
1/ 1Y,12000)
have been reported, there is very little informa­
//
Introduction
l (
' '.: ..!/,ti'?i:i' available about its effect on wood properties.
.
Since the late 1980s, Swiss needle cast (SN q, > · ·-Anecdotal observations suggest that SNC increases
caused by the native pathogen Phaeocryptopus
=·'the proportion of latewood relative to earlywood; this
.. shift in early/Iatewood proportion would• be a logical
mannii (Rohde) Petrak, has become increasingly
severe in plantations of Douglas-fir (Pseudotsug'g. . outcome given that previous experimental work has
demonstrated that the earlywood production is mostly
menziesii (Mirb.) Franco) in coastal Oregoh.. aQci·
dependent on old foliage and the latewood mostly on
Washington, USA. More recently, this foliar disease-1
the new foliage (Onaka, 1950). Because SNC causes
has intensified in older, naturally establishe :stands" s
well. Whereas effects on growth (Hansen et 'al,, 209p;
premature loss of the older foliage, one would expect a
larger reduction in the earlywood than latewood incre­
Maguire et al., 2002) and physiology (Manter°'efal.,
U
ment. Studies in balsam fir and eastern larch have
\ ,
)ti
shown that defoliation can affect other wood proper­
•Corresponding author. Tel.: +1-541-750-7290;'"· '-:_-: ::J
ties as well (Filion and Cournoyer, 1995; Krause and
·
· ·:'::::.'-:-..
fax: +1-541-750-7329.
'
Morin, 1995). Information on the effects of SNC on
E-mail address: randyjohnson@fs.fed.us (G._R: Jotins;j n)
ga - /
...
.
··
''
·
·
..
1
2
c·::: :::.::.;-
0378-1127/$ - see front matter© 2003 P bllshed.by Elsevier B.V.
·,;
doi:l0.1016/S0378-1127(03)00305-0
·•.
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G.R. Johnson et al. I Forest Ecology and Management xxx (2003) xxx xxx
-
wood properties is critically important because Dou­
on a stand that was experiencing very severe SNC. The
stand is located approximately 10 km from the coast,
glas-fir forms the base of an industry in the Pacific
Northwest focused primarily on structural lumber.
in the "fog belt" that typically has high levels of SNC.
Site index (age 50) for the stand was estimated to be
In severely damaged stands, symptoms of SNC
36 m. Three paired 2.02 ha (5-acre) plots were estab­
infection include yellowing and premature loss of
lished; one plot in each pair was aerial sprayed with
foliage. Average annual volume growth loss asso­
Bravo fungicide for five consecutive years (1996­
dated with SNC in young Douglas-fir plantations
2000). The other plot in the pair was an unsprayed
on the north Oregon Coast was estimated to be
23% in 1996, with some plantations suffering more
control and was located within 100 m of the sprayed
than 60% volume growth loss (Maguire et al., 2002).'
plot. Each year, the fungicid :"'as;applied twice at a rate
The disease impedes gas exchange in the needles by of 6.41/ha (5.5 pints/acre)
<.helicopter. The first
application was applied iwMC!y.When the new foliage
occluding stomates with fruiting bodies (pseudothe­
cia) (Manter et al., 2000). New needles become
had expanded to a length'of 2-5
on 40% of the trees.
infected in the spring and early summer shortly after
The second application was_applied
when expansion
....__.
rates had attained thi level
on
90%
of . the trees;
they emerge from buds. The fungus grows in the
't\
.
!/
approximately 10-1 , days er the first spray.
intercellular spaces of the needle and eventually forms
· ' - - .-'/
pseudothecia. The pseudothecia emerge through the
2.2. X-ray densi�6in,e; _fi Ld and lab procedures
stomates and release spores in the spring arid early
summer. The amount of fungus and number of pseu­
1
I/ In the fall o(-2Q O ·when the stand was 20 years old,
dothecia increase with age of the needle until the needle
growth plo
is dropped (Hansen et al., 2000). In heavily infected e,f� established within each of the six
stands, first-year needles become chlorotic the follow­
plots (three spraye,!i and three unsprayed). Trees were·
felled and breasi::iieight disks were removed from
ing spring and drop from the tree during the second approxi ately:_- O trees in each plot for a total of 58
growing season. The loss of foliage and the impaired
function of needles remaining on the tree combine to
disks. T «? pitI;.7
to-bark samples from each disk were examiried·ring
by-ring using X-ray densitometry. An
reduce tree growth and vigor. Typically, healthy Dou. ,
/'
glas-fir retain needles for at least 5 years (Hood, 1982)
air-dried.fadial
strip
was sawn
from each disk and line­
'..
;I
/I
,
1th a direct-scanning X-ray densitometer,
scl1"ne
but stands on the north Oregon Coast commonly retain
'Y.fth one value every 100 µm along the 100 µm wide
needles for 3 years or less (Maguire et al., 2002). In
severely damaged trees, only the current year's foliage scan::Data were deconvoluted using standard methods
/<following the Lambert-Beer law (e.g., Liu et al., 1988)
is retained by the end of the growing season.
The objectives of this paper were to: (1) test the A to giv'e a curve, each point of which is linearly propor­
hypothesis that reducing infection by P. gaeumannii
".tti !Jaf to density of the wood at a position along the
with aerial application of fungicide caused a change in
;;s ple. The previously determined curve for each strip wood properties relative to the untreated trees; and (2):.'.;; { was adjusted separately such that its mean density quantify the effect of SNC on several growth para" >:, ··,.tequaled the measured oven-dried density of the strip.
meters and wood quality attributes. We then inteqfreti,!:...:.;;:'.;'.'.' DendroScan software (Varem-Sanders and Camp­
these results in terms of wood value and utilizatlori!!,, bell, 1996) was used to find the boundaries between
.:.. -':> growth rings (the steepest point between the maximum
i.
latewood density of 1 year and the minimum early, __
2. Materials and methods
wood density of the next year) and between earlywood
. <.
: ,_··
,!
·
1•
and latewood (the point within a growth ring that has
2.1. Study site
the average density between minimum earlywood and
maximum latewood densities). These boundaries were
iThe Oregon Department of Forestry{estabi hed a
then verified by comparison of graphs to samples.
. 4 5W) to
These definitions of the boundaries between growth
trial near Beaver, Oregon (45°18'N..t. 'i23
rings and between earlywood and latewood are fixed
examine the effectiveneSs of BraVo -....._fungicide
within the software, but they matched our visual
(Chlorothalonil) in controlling SN6::.orF·Dbuglas-fir
__
,'
. ••.
·
90 92
93
94
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134 135 136 137
138 139 140
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G. R . Johnson et al.I Forest Ecology and Management xxx (2003) xxx-xxx
145
determinations (by color) well. Data then were sum­
marized for each groWth ring to give the following
values: growth ring density (total, earlywood, late­
wood), growth ring width (total, earlywood, and late­
wood), and latewood proportion.
146
2.3. Cell dimension measurements
141
142
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·
.
,
3
of color and weighed to the nearest 0.001 g. Core
length was measured to the nearest mm in order to
obtain green volume. Time of collection and time of
weighing were noted for each core. Approximately
half of the cores were weighed within an hour of
collection on site, the remaining half were divided and
weighed the same day or the following day (Septem­
ber cores only) in the lab.
Density and moisture contel,lt were determined by
obtaining green (fresh) mas f,,bv; ndry mass and core
length. By using a wood deftsi y; onversion factor of
1.53 g/cm3 for pure cell all m<iterial (Kellogg and
Wangaard, 1969; Siau, (984), the volume of wood,
water and gas in the wooti:. ere:estimated as follows:
'
Core volume (cm3); ;;
ength x n x (0.25).
From the same sample of trees analyzed by X-ray
densitometry, three trees were randomly selected from
each plot (18 trees total) and examined to determine
tracheid width (lumen diameter) and double cell wall
thickness. Transverse sections were made with a
sliding microtome, then stained with safranin, and
mounted permanently for analysis. The sections
included the second growth ring (1999 growing sea­
son) inward from the cambium. The 1999 growth ring
was chosen because it had been impacted by the
spraying and would not have been affected by the
removal of the bark from the sample. For both the
earlywood and latewood in the 1999 ring, 15 tracheids
from three separate regions (45 tracheids from the
earlywood and 45 from the latewood) were measured
in the radial direction for tracheid width and double
cell wall thickness for each of the 18 trees. Values for
double cell wall thickness were divided by 2 and are
reported as cell wall thickness. The first and last­
formed tracheids were avoided for measurements
because they are often anomalous.
•
•
•
•
•
186
187
188
189
190
191
192
193
194
195
196
197
i
!
e on an ovendry mass
Moisture content (p__er'.
basis) 100 x :[ (gr;een-iriass - dry mass)/dry
,.. ,
j
mass].
1? . !;-:.:::z.-.1
.
Green density:(g ¢°'3) green mass/green
Volume . ,1-,::_-1,,
-----·>
' )•\
Basic density,(g/cm3) dry mass/green volume.
Percentage wafer:(by volume) 100 x [(green
mass -Ar.ymass)/green volume].
Percentage'6r : )Vood (by volume) 100 x [(dry
!
mas!:>/1:5 )/gi'een volume].
Per enJ gepf gas (by volume) 100 - percen­
tage.qfl\va(er - percentage of wood.
=
•
185
202
_,
203
=
205
=
=
208
=
=
t';'
''-.,C .}/
210
·
212
213
.
!:.-' <--..
2!$. Companion study
:
,; :-:-1 "
fJ
214 .
,
2.4. Moisture content field and lab procedures
\- A cqmpanion study examined the percentage of
Moisture content of the sapwood and heartwood
"wp(_)d·,iwater and gas in earlywood and latewood. Fifwas examined on 30 May 2001 (120 trees total) and 10
,teen dominant trees were cored with I 0 mm increment
September 2001 (116 trees total) from a separate · _._,_./_cor sfrom a 23-year-old plantation in McDonald-Dunn
sample of trees. Approximately 20 dominant trees-;· .. · ·Experimental Forest located outside of Corvallis, OR
in each of the six plots (three sprayed and three ,:_'< - (44°29'N, 123°16'W). Cores were wrapped individuunsprayed controls) were cored with a 5 mm inct&- ,"?.> ally in plastic wrap immediately after removal from the
, -..,.__
""-.:"><,
ment borer from bark to pith. Cores were col!ecte . : tree and placed into a cooler. They were returned to the
from both treatments simultaneously in a block.:'!l'.!: t
lab within 3 h and processed. The last growth ring was
ments were randomly assigned to each of , - "<><>
removed and the next two growth rings (growing
persons coring the trees. Immediately after,rremoval,
seasons 1999 and 2000) were divided into earlywood
each core was wrapped tightly in plastic wr p_. Cor s
and latewood with a razor blade. Demarcation of earwere carried to the cooler after 10 core ,)ver ak n.
lywood and latewood was based on color change. Green
mass was measured and volume obtained by submerand then again after the second 10 core were':!aken
sion in mercury following ASTM 2395-93, method D
from each plot. A third person began s i>iirati g and
f>
(ASTM, 1999). Ovendry mass was obtained after 48 h ·
weighing cores once the first set was recelv.Et · Cores
were divided into sapwood and heaJ1\\'.«?0dnn.the basis
at 103 °C. From these measurements the wood proper1 '
__ , -
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.
234
ties of the earlywood and latewood were calculated
(moisture content, basic density, and volumetric per­
centage of water, wood, and gas).
235
2.6. Statistical models
233
236
237
238.
239
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G. R. Johnson et al. I Forest Ecology and Management xxx (2003) xxx-xxx
4
232
.
where h's are the regression coefficients for collection
time and measurement time (i.e. covariates), and . the
other independent variables are the same as in Eq. (1).
Means and standard errors were computed with the
least-square means option of the MIXED procedure of
SAS (1999).
Examination of the growth increments indicated
that the fungicide treatmerits had affected growth
primarily in the last 3 years. Therefore, only the
overall means of the last three rings were sub4ected
to statistical analyses for the density and growt data
obtained from X-ray densitometry. The regression
analyses used the MIXED procedure of SAS (1999) assuming the following statistical model:
3. Results
1
3.1.
r
·
with Bravo
appeared to have recov r_ed. Ji a "normal" rate by 1998 (after 2 years ,9FS·p �:Yfng) (Table 1). Growth
Wood property;jk µ+Block; + Treatmenlj
,
during the last 3 Yf? rs was) significantly reduced in
+ Block x treatmentv + evk (1)
both the earlywood and.l(!t wood growth rings of the
where Wood property;jk is the value of the wood prop­
unsprayed trees tfah!e. 2), with the greatest difference
erty for the kth tree in the ith block ofjth treatment,µthe
in the earlywoo .. Tliis ·pattern resulted in a higher
overall mean, Block; the random effect of the ith block,
proportion ofJl!t ooq.in the unsprayed plots than the
i.e., which pair of plots, Treatmentj the fixed effect of
sprayed plot$' (table 2, 52 vs. 41%, P < 0.0001),
thejth treatment (unsprayed control or Bravo-sprayed),
which in tiirnr in.creased the ring density in the
Block x treatmentv the random effect interaction of the
unsprayed plots {0:589 vs. 0.524, P 0.1025). The
ith block and the jth treatment, and e1jk the residual
unadjus drneans of earlywood and latewood density
variation associated with the among tree variation
were not__ statistically different between the tre t­
within each block-treatment subplot.
ment ; · - · .
The appropriate error term for the treatment effect
Ri;iig 1 en ity and earlywood density in the outer
was the block x treatment interaction with only 2
three:i'ings.were correlated significantly (P < 0.0001)
degrees of freedom. If the block effect was not sig­
with ring width and earlywood width (r = -0.67 and
.2o. 56;r spectively). Latewood density did not have a
nificant, the block. effect was pooled with the interaction to bring the denominator degrees of freedom for
.<signi cant correlation with lat wood width for these
the F-test to 4.
: ; three rings (r -0.08, P 0.56). Regression ana­
Earlywood density and latewood density were also ,,., \ ly s-&emonstrated a statistically different (P 0.01)
subjected to a covariate analysis where earl ood / re tionship between earlywood width and early­
; ,J '
width and latewood width were used as covanates ( ;j w od density for the two treatments; different equa­
Analysis of covariance facilitated assessment of t, - " ''·":::lions were needed to represent the relationship
marginal effect of SNC on wood density for a g!yen,J,b:;!J:between earlywood width and earlywood density
growth rate.
,''·;;;:·::�,
for each treatment group. The different relationship
Moisture content can be affected by collecti 9-tipie _., for each treatment group was true whether the rela_,,
e··and, if drying occurs after core extraction,
tionship was modeled as a simple linear function or as
between collection and measurement. To xa
a negative exponential function. The negative expo­
,
. ,
these effects, the model for analyzing moist recont nt
nential function relationship was close to linear for the
was modified to
data if separate models were generated for each
»-.:....
//
' - ·
treatment group, therefore, the simple linear relation,
f:l
Moisture contentijk
tr'
ship for the controls and Bravo-sprayed trees is shown
'.\
(b1 x Collection time)
1:� , / '
in Fig. 1. The range of earlywood widths differed for
+ (b2 x Measurement time lag) +'-&l!> k[;:,·
the two groups as well, and had very little overlap
k
+ Treatmentj +Block x treat eQt;/
(2)
(Fig. 1).
,,,
=
=
·
/
=
....
.
=
.
1§
277
278
279
280
281
282
.
[·
X- ay densitometry da1v
ta.:_'1!___
<'""'.:.; ''-l:r
Radial growth of t�e' tre s;'sprayed
h
'
=
=
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
��--
310
.
314
,...·
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G.R. Johnson et al. I Forest Ecology and Management
xxx
(2003)
5
xxx-xxx
Table l
Average earlywood, Iatewood a d total ring widths (cm) and latewood proportion by annual ring, as determined from growth plot disks,
without (control) and with chloranthalonil spraying (Bravo) for approximately 30 sample trees In each treatment
Ring year
Earlywood width
Ring Width
Latewood width
Latewood percentage
Control
Bravo
Control
Bravo
Control
Bravo
0.59
0.60
0.66
0.58
0.47
0.53
0.54
0.65
0.59
0.47
0.26
0.27
0.34
0.26.
0.23
0.21
0.22
0.32
0.27
0.21
0.33
0.34
0.32
0.32
0.24
0.32
0.32
0.33
0.32
0.26
Annual spraying begins
0.36
1996
0.40
1997
0.40
1998
0.33
1999
0.30
2000
0.34
0.47
0.63
0.60
0.65
0.14
0.16
0.20
0.15
0.14
0.12
0.18
0.39
0.35
0.39
0.23
0.24
0.19 0.17 0.16 No spraying
1991
1992
1993
1994
1995
Control
58
57
" 49
1 1
;53
: r
{
Bravo
61
60
53
56
57
66
62
40
43
41
,..-
,
·:.
_ .-
....-."
Table 2
; '·
i/
.
Wood properties averaged for the outer three rings of trees that were ·unsprayed (control) and0'thoi1t1qprayed with chloranthalonil (Bravo)
'·'J
fungicide (means, standard errors, and level of statistical .difference (P-value))"
{: _,;_'.;;,
..
Control
P-value
Bravo .
_
Mean
S.E.
S.E.
,
Ring width (cm)
EW width (cm)
LW width (cm)
LW percentage
Ring density (g/cm3) EW density (g/cm3) LW density (g/cm3) EW tracheld diameter (µm) LW tracheid diameter (µm) EW celi wall thickness (µm) LW cell wall thickness (µm) 0.333
0.164
0.170
52.0
0.589
0.376
0.777
32.33
11.05
3.18
5.70
}
/(_' J )
/! :- 2S()!
0.077
0.62 \
0.053
'";?0.313,1/
0.025
/;/ i 41.4'"
1.9
f
1.
· : i, 0:524
0.016
!'>
- ·0:362
0.016
/;.-:': -· . 0.775
0.009
" ·34.83 .
1.63
t'
7.28
0.58
'
0 36 t'
5 35
0 22n ·::;:;-·r;:r:/J
5 62
r.
/'/''1
:
·
.
rr
•
,
:
·
0.077
0.053
0.025
1.9
0.016
0.016
0.009
1.63
0.58
0.36
0.22
0.0081
0.0125
0.0876
<0.0001
0.1025
0.5857b
0.8579
0.1949
0.0377
0.0004
0.8220
Data Is from 60 tr es sampled in the growth plots, except f f 19 ile1d;:dlameter and double cell wall thickness, which are from a
subsample of 18, for the 1999 growth ring only. EW: earlywood; LW::Iatewqod.
b Differences exist between treatments In the relationship be e\!n densi and width. •
320
321
322
323
324
325
326
327
328
329
3.2. Tracheid and double cell wall thickness
fy
!/ /: ;:: "
· .-, c::'.(, 3.3.
,f-:\ .
Earlywood cell wall thickness was larger ,in .the
sprayed trees than in the unsprayed trees (I'abl : 2;.-.
3.2 µm for the unsprayed vs. 5.4 µm for thfBravo­
sprayed trees). Cell wall thickness of latewood .did n9t
differ between treatments. Earlywood !ractieif -diameters did not differ between treatments, but'f' o the
latewood, tracheid diameter was !atg r- -!-il the
unsprayed trees (Table 2, 11.l µm fof''ihe;-u sprayed
trees and 7 .3 µm for the sprayed tree ):.:· -::t>
: ,., ::. :;(/,:
-:
·
:·J
Moisture content samples
330
Time of collection and time of measurement did not
affect any variables in the May samples, but did affect
the September moisture and gas contents (P < 0.05).
The block effect was not statistically significant in
either month for any trait (P > 0.10). Therefore, the
block effect was dropped from the model and pooled
with the block x treatment interaction.
As expected, there was a large difference between
the sapwood and heartwood moisture contents
t .....
. --.., :.�,,
J:i
c:.
·
....-:-. :, "/
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G.R. Johnson et al. I Forest Ecology and Management x.u (2003) x.u-x.u
6
0.6 r 0.5 +---...0---
II)
c
GI "Cl"Cl
'Cl
0.2 T----;;=:=
-- '
c=on= o= l
s
===========
o= tr =
:;- 1.· 1 .. '..',f
=
5
p
- Den s i ty 0.462 - (0.4 9 x width), r'=0.47,
< 0.0001
.. , ·
· . ,·
.., "
e Bravo-trea ted
.rJ 0.1
s ty= 0.
- Deni
0
0
0.1
0.2
0.3
0.4
0.6___ .
' 0.5
(mm)
..
·
. ·
/;
0;7 /
.
/"'"
... '\\
//
\\
Relationship between earlywood density and earlywood width In the outer three growt,hJihgs :f9,r5Bravo-treated and control trees.
Earlywood width
Fig. 1.
/;.:..:· '\ ,.:: :
374 - (0.062 x width), r'=0.07, p=0.1533
h"\\
/i
.,),.,...".",¥
1< .. _
;:
,.
·
.
.
Sapwood d ;aooJlrea were greater in the sprayed
plots (fable ,4)'. o average, the sprayed trees had 35%
more sapwo6i:tc fea than did the unsprayed trees.
'
At both dates. ihere was significant!y lower moist­
ure cont ri.tln pwood of trees in the unsprayed plots
than tr e in ilie sprayed plots. Sapwood moisture
cont r,it k.: un prayed plots and sprayed plots was 88
and,1110}�. respectively, in May, and 84 and 104% in
Septein e (fable 4). Similarly, the volumetric per­
n
116)
of\Vater was also lower in the unsprayed trees
cdritage
7
Heartwood(September)
35
2.5
ti{3';tihe:sPrayed trees {42 and 40% vs. 50 and 47%,
t,..Tabl 4).°This reduction in moisture came as a result of
k incr ed gas because there was a statistically signifi­
(Table 3). The amount of variation associated with ,,, '�'c@t:.'fucrease in percentage of gas. but not in the
the sapwood moisture content was considerably/ i /'percentage of wood (Table 4).
greater than that associated with the heartwood;· ?- ' {;Because of the increased moisture content, the
coefficients of variation ((S.D./mean) x 100) w re :- -'green density of the sapwood was higher in the
three times larger for the sapwood than the heartw«;)bd/;;.:, ''"'Bravo-sprayed trees (fable 4). However, sapwood
(Table 3).
,.. : ·<if:
basic density was lower (though not statistically
In the heartwood, there were no significant rel,atio'!.-- · .7 significant) in the sprayed trees than the unsprayed
trees {Table 4). To understand whether the changes in
ships between the treatments for moisture cont .,. er··
the volumetric wood, water, and gas contents were
or green density, .sapwood width, sapwood. e ;<or
....
volumetric percentages of wood, wat ; or "·gas
simply a function of latewood percentage; the per(P > 0.05, data not shown). However, there w<lS' a
centages of wood, water and gas were examined in 15
trend toward lower percentage of water,in1t e. s;f om
healthy trees in the McDonald-Dunn Forest. A simthe sprayed plots than the unsprayed fj>Iots, · oth in
pie t-test indicated that all three wood properties
differed between the earlywood and latewood
May (15.1 vs. 16.0%, respectively, P 0:0815)·and in
September (14.6 vs. 15.4%, P 0:0670)_.- Further
(P 0.001, Table 5). The latewood had higher perresults are only reported for sapw9od_ ::.-.:.:: :
centages of wood {35 vs. 18%) and gas (29 vs. 21%),
Table 3
Moisture content In sapwood and heartwood (means, standard
deviations and coefficients of variation) for all sample trees
Mean
S.D. Coefficient
moisture
(%) of variation
(%)
content(%)
21
Sapwood(May, n 120)
99
19.9
36
6
Heartwood(May)
2.3
23
Sapwood(September, 94
21.6
=
/
=
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
·
- - ··
=
=
=
"(:;_;�::...)
..,{\'
j)
-....::Z.2,.§
.c:
...
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374
375
376
377
378
379
380
381
382
383
384
G.R. Johnson et al.I Forest Ecology and Management xxx (2003) xxx-xxx
7
Table 4 Moisture content, wood density and volumetric percentage of wood, water and ga5 In the sapwood of trees that were not sprayed(control) vs. those that were sprayed with chloranthalonil(Bravo)" September sample (n 116)
May sample (n 120)
Wood property
P-value
Bravo
Bravo
P-value Control
Control
Mean
Mean
S.E.
S.E.
Mean
S.E.
S.E.
Mean
=
=
87.9
2.2
109.6
2.2
0.0020
84.6
4.8
104.6
4.8
0.0557
Moisture content(%)
Density(basic) (g/cm3)
0.480
0.007
0.458
0.007
0.0843
0.481
0.010
0.461
0.010
0.2459
Density(green) (g/cm3)
0.897
0.008
0.954
0.008
0.0089
0.882
0.008
/.l0.936 0.008 0.0197
I/ s.11 0.13 0.0301
Sapwood width(cm)
3.9
0.20
4.8
0.20
0.0552
4.1
0.13
Sapwood area(cm2)
175.5
18.6
238.7
18.6
0.1263
189.5
12.1
256.7..
. 12.1
0.0174
· ·
Percentage of wood
31.3
0.44
29.9
0.44
0.0843
31.4
0.65 /?' 30.1 _;
0.65
0.2459
47 5.
1.46
0.0391
Percentage of water
41.8
0.71
49.6
0.71
0.0014
40.4
1.46 / ('
20.4
0.70
0.97
0.0232
26.9
0.0029
0.97 '":;_._ - '?-}
0.71
Percentage of gas
28.2
•Reported are means, standard errors and P-values for two sample dates(May and September 200lf'Cci0iparisons In bold are statistically
I.{
.
significant at P 0.05.
0)
'< -..- . /.-'
.
,1;::;:i \ .Table 5 /·;'
Moisture content, basic density(dry mass/fresh volume), and volumetric content of wood, water, and gas·fo earlywood vs. latewood of healthy
Douglas-fir trees(means and standard deviations)"
- ": =.:-�j
.
. , \
"•
P-value
Latewoodl
Wood property
Earlywood I'
S.D.
S.D. Mean
=
·
.•
J
_.._
·1
227.6
38.8
Moisture content(%)
Basic density(g/cm3)
0.033
0.272
2.2
17.8
Percentage of wood
5.2 Percentage of water
60.8
4.8
21.4
Percentage of gas :
t-Test significance levels for comparing earlyw od and latewood are rep()rted:'- :-- ..:/
•
385
386
387
388
389
390
391
392 393
394
395
396
397
398
399
.
:·) ,')'.'·- ·=-:.. , ..
and a lower percentage of water (35 vs. 61%) than the
earlywood. <0.0001
<0.0001
<0.0001
<0.0001
0.0003
11.7
0.043
2.8
3.5
2.3
__
,greater growth advantage because they had consider."'.ably iri"ore foliage producing photosynthate than the
i':J "trec::s:eifl the unsprayed plots. After the new foliage
p ; a ured and became a net exporter of photosynthate,
4. Discussion
·<-. :;)h '.iadvantage decreased. This pattern is consistent
'.;.<: >., '·With our data on radial growth increments: the BravoThe 5 years of spraying did not achieve comple. e _'i:s;s:sprayed plots had 68% more earlywood than the
control of the disease; significant amounts of P. gaeu· .f . unsprayed plots, but only 44% more latewood.
: Increased availability of photosynthates is assumed
manni were present in the needles of the spraye ·.tree
during the fifth year of spraying (Stone et al., :?002):to increase cell wall thickness (Larson, 1969; Savidge,
Nonetheless, needle retention increased for t e_.la t'.:3>
1996) and is a logical explanation for the increased
years of spraying; the unsprayed trees carried abil t
cell wall thickness found in the earlywood of the
1.9 years of foliage whereas the treated trees.had t:8
treated trees.
years of foliage (Mainwaring et al., 2002h
The'dlrCompared to the unsprayed trees, trees treated with
'' I
ference in foliage quantity was most Pt moun'ced in
fungicide showed increased radial growth rates, lower
spring before the new foliage emerged>Theiefore,
percentages of latewood, lower ring density and higher
during spring and early summer (when'tileQ'f!w.foliage
moisture contents. It appears that the sapwood of trees
was maturing)'. the trees in the spray c!:plotSwere at a
with severe SNC have a diminished capacity to trans-
)
400 401
402
..
403
404
405
.
407
408
.••
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·
4"
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438
439
440
441
442
443
444
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446
447
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G. R. Johnson et al.I Forest Ecology and Management
xu (2003) xu xu
-
port water relative to healthy trees. A decrease in
niecki, 1999). Experiments with phloem-girdled stems
sapwood water content is associated with a decrease
suggest that photosynthate is required to refill an
in specific conductivity (Puritch, 1971; Edwards and
embolism in order to recover specific conductivity
Jarvis, 1982) and sap flow (Granier et al., 2000).
(Salleo et al., 1996; Zwieniecki and Holbrook, 1998)
Whereas our methods did not distinguish between
and moisture content (Taylor and Cooper, 2002; Wil­
water being transported in the tracheids and extracel­
son and Gartner, 2002). This reduction in moisture
lular water (which is not being transported), the
content could, therefore, be a function of the tre·e's
reduction in moisture content cannot be accounted
poor vigor, preventing a phosynthate pool sufficient
for by extracellular water alone. Likewise, this differ­
for reversing many of the gas mbolisms that occur on
/: ··r
ence was not solely the result of increased latewood, a daily basis. j'!
/•
although de Kort (1993) demonstrated that latewood The reduction in sapwood:, .rea in the unsprayed
percentage impacts moisture content. de Kort (1993) trees was also expected. PY.'. '(farea is related to the
found that a 1% _increase in latewood percentage . amount of foliage (Gri t and Waring, 1974) and the
resulted in a 1.7% decrease in moisture content. Based unsprayed trees had less f9liage as measured by the
on average sapwood width and average ring widths, number of years tha.t;iieedf swere retained.
the sapwood-heartwood boundary generally occurred The observed ch3'{ges in ''.wood properties have eco­
at the 1992 growth ring for both the sprayed and nomic ramificatioJis: EQ[. · given log size, log weights
control plots. The latewood percentage, weighted by from the spraye ;pio ''.VPl be greater than those from
ring width, for this time period (1992-2000) was the unsprayed plq (,The sprayed trees have more sap­
50.7% in the sprayed plots and 54.5% in.the control. wood, which is;of higher green density than heartwood.
Using de Kort's (1993) relationship, the reduction in Also, the mo tur ' content of the sapwood is greater in
moisture content due to the increased latewood in the. the sprayed· trees'. . The average green density of the
unsprayed plots would have been 6.5%; Similarly, the entire pith-to-bark'C:ore for the May sample averaged
data from healthy trees on McDonald-Dunn Forest 0.765 i";the sRraYed plots and 0.712 in the unsprayed
suggested a decrease of between 5 and 6% could be plots. .ali's.ed u n the breast-height disk, a load of logs
attributed to the higher latewood proportions. The from :.the· ·sp ed plots would weigh approximately
21% decrease in moisture content between the sprayed 7.4 ·m.pre . !han an equal load (same volume) of
and unsprayed plots is, therefore, considerably more unsprayedJ9gs. However, there would be no difference
than the amount accounted for by the increased pro­
een the dry masses of the loads because the basic
portion of latewood. denstties ,were identical (0.445 in the unsprayed plots
Similarly, the increase in percent gas between the .t· vs. Q.447 in the sprayed plots).
, .
. \
treatments cannot be explained by an increase in :.'
Th reduced amount of sapwood in the unsprayed
latewood. Healthy trees on McDonald-Dunn Forest rr '-'.::u:.e s·;could also have negative consequences if one is
exhibited a 7.4% absolute difference in the percentage .. {lsell.ing the timber for poles or pilings. A minimum
of gas between the earlywood and latewood (28.8o/o' t:'L pwood width (19 mm) is required to insure adequate
gas vs. 21.4% gas, Table 5). The difference betwe n'.;\ "(.;preservative penetration (AWPA, 1999). Sapwood
the sprayed and control treatments in the Bravo st i:ly.L.iJ:�::: width averaged 9 mm less in the untreated than the
was very similar (6.5% in May and 5.8% lit Sepferii:l\.,, treated trees. Even if a tree has sufficient sapwood,
her, Table 4). The difference in latewood perc; t g!'l ::::? CCA (copper chromium arsenate) retention could be
for the sprayed and unsprayed trees in the Brayo pfotS" poor given the larger proportion of latewood in
unsprayed t es and the fact that earlywood retains
was only 4%; not enough to account for the .differ:: more
CCA than latewood (Guo et al., 2002).
ences in the percent of gas.
:{'
"\·.
I,
'
We hypothesize that the decreased moistii_re co9(ent of diseased trees resulted from their -poor :::rarbon 5. Conclusions
economy resulting in insufficient e rgy '(photo­
synthate) to reverse sapwood embolj Dis , Nr
embo­
It is impossible to construct a study in coastal
lisms in the xylem can be refilled 6f:tree :· but the Oregon
that examines infected and uninfected trees
exact mechanism is unknown (HplbrooJCand
Zwie­
',•.·:-
:
pa
y
.•
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_
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479
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489
490
491
492
493
494
495
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497
498
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500
501 502 503
504
505
506
507
508
509
510
G.R. Johnson et al./ Forest Ecology and Management .o:x (2003)
539
without the use of fungicide because-suitable healthy
controls cannot be found. The healthy trees in this
study are not simply trees with less SNC, instead,
they have had repeated applications of Bravo fungi­
cide. Therefore, one cannot state unequivocally that
the observed changes in wood properties are the
result of SNC alone; but rather that fungicide had
an effect. However, if we. assume that the fungicide
simply reduced the amount of fungus, then several
conclusions regarding SNC can be drawn. First,
severe SNC reduced growth rate in a manner similar
to that found by Maguire et al. (2002) and Main­
waring et al. (2002). Second, the growth depression
was more severe in earlywood than in latewood,
resulting in higher latewood proportion and wood
density. In addition, the decline in tree vigor also
adversely impacted the hydraulic properties of the
stem by reducing the amount of sapwood and the
moisture within the sapwood. Tracheid wall thick­
ness was also reduced in the earlywood of severely
infected trees.
Future research will look more closely at possible
changes in the strength properties of wood coming
from severely infected stands. The increased wood
density resulting from increased proportions of late­
wood suggests potentially stronger wood. However,
the weakest portion of wood is the earlywood and the
reduced cell wall thickness found in this study sug­
gests that the "weakest link" has been weakened.
540
Acknowledgements
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
542
544
·
545
' ....;_,
424.
:·
Kellogg, R.M.,_Wangaard, F.F. . 1969. Variation In the cell-wall
density 9f wio(\;, Wood Fiber Sci. 1, 180-204.
Krause, c,; orln, H,;; 1995. Impact of spruce budworm defoliation
on the nuniber,;iif latewood tracheids In balsam fir and black
spn/c . Gan. J:For. Res. 25, 2029-2034.
Larsori/P.R?,' 1969. Wood Formation and the Concept of Wood
Qu ilty. B ietin No. 74. Yale University, School of Forestry.
Lluf."cJ .. Ols;;n, J.R.. Tian, Y.. Shen, Q.. 1988. Theoretical wood
IJd risttometry. I. Mass attenuation equations and wood density
mod ls.Wood Fl er Sci. 20, 22-34.
p
qMaguire.D.. Kanaskte, A., Voelker, B.. Johnson, R., Johnson, G. .
\\ 200,Z_; Growth of young Douglas-fir plantations across a
;} "·-'=gradient In Swiss needle cast severity. West. J. Appl. For. 17,
uf
•,
'. .'c, ...>::::. :t
<':/:::::, : ;:-:�
r:/
_ __
_,-.
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· , '
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de
The authors wish to thank the Oregon State Uni- // /? 86-95.
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by a special USDA grant to Oregon State Univers\fy /-,;...;:•.:: gaeumannii: .volume growth, branch elongation, and foliage
dynamics. In. Filip, G. (Ed.), Swiss Needle Cast Cooperative
· · '"
tior wood Utillzation research
'-- :<:;:,,
Annual Report 2002. Oregon State University, College of
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9
x.u-x.u
'
ASTM (American Society for Testing and Mater! ). 19. 9.
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'
AWP (American Wood-Preservers' Association), 1999,:;Siandard
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u Process.
AWPA Book of Standards, Granbury,
.-pp;'51:.64.
L.
'• ··.'": :
;,
..
_
);
.
': ·::::::-::;��:· ;
-.."-,,,,_
-...;."""·-
J.''.j
Forestry, Corv allis, OR, pp.82 8 .6
­
Manter, D. K.. Bond, B J ., Kavanagh, K.L.. Rosso, P.H.. Filip, G. M..
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C02 assimilation. New Phytol. 148, 481-491.
Onaka, F.. 1950. The effects of such treatments as defoliation,
debudding, girdling, and screening of light in growth and
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Univ. For. 18, 55-95.
Purltch, G.S.. 1971. Water permeability of the wood of grand fir
(Abies grandis ( Doug!.) Lindi.) In relation to Infestation by the
.
"
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-.w.
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