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'
WESTERN RED CEDAR --DOES IT HAVE
A FUTURE?
Conference Proce dings.
University of British Columbia, Vancouver, B.C. July 13-14th 1987.
Sponsored by UBC Faculty of Forestry.
(article citation given at start of each abstract)
Organizing Committee:
J.P. Demaerschalk, R.W. Kennedy, K. Klinka, J.H.G. Smith, N.J. Smith, G.F. Weetman.
Session Chairpersons:
K. Iles, R.W. Kennedy,D. Lavender, G.F. Weetman.
Conference day volunteers:
Lynn Husted, Val Le May, Margaret Penner, Elizabeth Schnorbus, Rick Fournier, Albert Nussbaum, Guillaume Therien, Jim Thrower. Conference editor and compiler:
N.J. Smith.
Editor's note: The common name of either western red cedar or western redcedar Gust 2 words) is left to the dis­
cretion of the authors. The full scientific citation is:
Thuja piicata (Donn ex D. Don in Lamb.), with the "in Lamb."
part as optional, as cited by E.L. Little 1979. Checklist of U.S. Trees. Agric. Handbook #541, U.S.D.A. For. Serv.,
Washington D.C. 375pp. (Thanks to Karl Klinka for this reference). Most of the papers were submitted as camera
ready copies. However, these were all scanned or converted (as were many figures) to facilitate desktop publish­
ing. I apologize for any errors that occured during this process. I would like to thank the organizing committee,
chairpersons and volunteers, as well as all speakers and authors, Hilary Stewart for the splendid dinner speach,
and to the UBC Conference Centre (thank you Lauren Boni, coordinator).
/
.1
NUTRITION AND FER·TILIZATION OF WESTERN RED CEDAR existing second growth cedar could result in increased
growth and rapid establishment of stands. Nutrition
and fertilization information is important in prescrib­
ing effective management practices.
Information on nutrition and fertilization of western
red cedar is available from three types of studies:
G.F. WEETMAN, M.A. RADWAN, JANNA KUMI, AND ELIZABETH SCHNORBUS. Department of Forest Sciences, University of British
Columbia, Vancouver, B.C. V6T 1W5, USDA Forest
Service, 362S--93rd Av., Olympia, WA 98502, Mac­
Millan Bloedel Ltd., 65 Front St., Nanaimo, B.C. V9R
SH9 and University of British Columbia, Vancouver,
B.C. V6T 1W5, respectively.
ABSTRACT
Weetman, G.F., MA. Radwan, J. Kumi and E.
Schnorbus. 1988. Nutrition and fertilization of western
red cedar. In: Western red cedar--does it have a future?
Smith, NJ. (Ed.). Conference Proceedings, University
of British Columbia, Faculty of Forestry
Westem red cedar is considered to be a nutritionally
demanding species although there is little specific
infonnation about its nutritional requirements. A review
is presented of the nutritional factors which appear to
influence productivity. Foliar nutrient concentrations are
presented for natural stands, fertilized stands, and
seedlings grown in mineral nutrition studies. There has
been little operational forest fertilization
some preliminary data are presented.
of tlae
species;
Introduction
Western red cedar (Thuja plicata Donn ex D. Don)
is an important commercial species, particularly in
coastal areas where the majority of mature western red
cedar occurs. Because of its exce.}lent properties such
as high natural durability, weathering and decay resis­
tance and attractive appearance, and its many uses par­
ticularly its specialty uses, western red cedar is in
constant demand and commands a high price. Its uni­
queness in the world market implies a continued impor.­
tance and perhaps increased emphasis on this species
in the future. However, the western red cedar resource
. in British Columbia and the United States is being
depleted as a result of continual harvesting and little
renewal. In response to this problem, management of
1. The nutritional characteristics of the sites where
it grows naturally and where it has been planted outside
its natural range.
2. Fertilization and mineral nutrition of planting
stock in the nursery.
3. Fertilization of plantations and natural stands.
In comparison to Douglas-ru, (pseudotsuga men­
zies;; (Mirb.) Franco), Sitka spruce (Picea sitchensis
(Bo n g .) C a r r . ) and w e s t e r n h e m l o c k , (Tsuga
heterophylla (Raf.) Sarg.), its companion species in
natural forests, little is known about cedar. Most of the
information available is by repute, based on observation
or inference. There are relatively few published studies
on cedar nutrition and fertilization.
Western red cedar has a wide ecological amplitude
and a good competitive ability. It is not regarded to be
as nutritionally demanding as its companion species,
notably Sitka spruce. It is considered to be a 'calcium
pump' and is associated with ground vegetation indicat­
ing high nitrate availability. Cedar grows best on sites
which also are suitable for Douglas-fir. It is recom­
mended by some f or planting on nutrient rich and wet
sites with no seasonal moisture deficit (K. Klinka, 1987
pers comm.). Others (Nystrom et al. 1984) suggest that
planting of the species need not be limited to speciality
uses as on wet areas or sites infected with root rot fungi,
but can be established on mesic, well-drained upland
sites. On such sites in even aged stands, it produces
small limbed, untapered, unfluted stems with yields
equivalent to those of Douglas-fir.
In the Interior CedarIHemlock zone of British
Columbia, natural stands on cutover land are often
characterized by residual trees and advanced regenera­
tion with much butt rot. This has given rise to uncer­
tainty as to whether rot-free plantations can be
produced (Corrin. and Peterson 1986). On the north­
ern coast of British Columbia in the Coastal Western
Hemlock zone, natural and planted cedar on oldgrowth
cedarlhemlock cutover land usually is chlorotic, slow
growing, and has an understory of dense ,alai (Gaul­
theria shallon Pursh.). In this region foresters are skep­
tical about the future of cedar plantations.
·t
48
Contemporary concerns about western red cedar
nutrition and fertilization include:
1. The nutritional requirements of the species;
2. The relationship between nutrition and certain
stand conditions, such as the stag-headed dead tops
characteristic of oldgrowth cedar and the interior
stands, with high incidence of rot;
3. The influence of slash burning oldgrowth
cedar/hemlock forests on productivity of secondgrowth
plantations and natural stands;
4. Effective fertilization prescriptions for container
seedlings, established cedar/hemlock secondgrowth
stands, and chlorotic cedar regeneration in dense salaI.
The purpose of this paper is to assemble and review
literature relevant to nutrition of red cedar, and to sum­
marize results of the fertilization trials carried out both
in the field and in the nursery.
Site nutrient conditions associated with cedat·
Krajina (1969) reporting on the ecology and silvics
of B.C. forest trees applied an edaphic grid technique
as an aid to express productivity in different ecosystems
for each biogeoclimatic subzone. The edaphic grid
consists of a nutrient gradient of five trophotopes (AE)
along the horizontal axis and a moisture gradient of
nine hygrotopes (08) along the vertical axis (Figure 1).
Each hygr otope/ trophotope combination is an
edatope. The productivity in each edatope is expressed
by site index (S1). Krajina (1969) reported that maxi­
mum growth of western red cedar in B.C.(S1 45-51
m) occurs on the edatope 6/E (hygric/subeutrophic) in
the following three biogeoclimatic subzones: the Wet­
ter Maritime Coastal Douglas-fir Subzone (CDFb), the
Drier Maritime Coastal Western Hemlock subzone
(CWHa), and the Wetter Maritime Coastal Hemlock
Subzone (CWHb) (Figure 1). As Krajina (1969) points
out, the growth class curves of the edaphic grids are
idealized and smoothened and productivity levels must,
therefore, be viewed as somewhat hypothetical. On the
edatope 6/E, productivity of western red cedar will vary
even further with the different biogeocoenoses, or plant
communities, in each biogeoclimatic unit. To sum up
the site nutrient conditions for optimum growth,
Krajina et al. (1982) stated that western red cedar is
edaphically very demanding, requiring nutrient rich soil
with a well balanced supply of both Ca and Mg, and with
N in the form of nitrate. Western red cedar has been
reputed to be a calciphile (Krajina 1969), growing best
on neutral to slightly acidic soils (Watts 1983).
=
Zit Uka JX"
The special nutrient conditions associated with
western red cedar that arc of particular interest include
the higher pH and higher calcium content of soils under
this species as compared with soils under other species.
Alban (1967, 1969) compared soils under western red
cedar and under western hemlock in eastern
Washington and northern Idaho. The foliage of
western red cedar contained 235 to 300 percent of the
Ca content of western hemlock foliage and 50 to 75 per­
cent of the Mg content. In the organic horizons of the
soil, Ca content was still higher under the western red
cedar. The pH, cation exchange capacity, base satura­
tion, and total weight of the organic horizons were also
greater under the western red cedar. These results in­
dicate that western red cedar may be an accumulator
of Ca, rather than simply requiring or prefering Ca rich
sites. However, Imper and Zobel (1983) found that m
southwestern Oregon, western red cedar distribution
was related to soil Ca:Mg ratios. Their findings suggest
that western red cedar grows on soils with large
amounts of Ca and N and high Ca:Mg ratios.
Another special nutrient condition associated with
western red cedar is the relatively high rate of nitrifica­
tion of the litter from this species. Harmer and
Alexander (1986) compared incubations with or
without starch amendments of LFH core samples col­
lected from beneath 16 conifer species growing on the
same site. They found nitrification to be negligible ex­
cept in western red cedar where nitrate constituted 68
or 83 percent of the mineral N present after incubation
with or without starch respectively. Harmer and
Alexander (1986) suggested low internal Ca + 2 con­
tents may limit nitrification in litter from other species,
although they acknowledge that other workers have
found that addition of Ca + 2 by liming has generally
depressed net mineralization, but not consistently in­
creased nitrification. They also suggested that nitrifica­
tion may occur in western red cedar as allelopathic
inhibitors present in the material of other species are
absent. This feature of Ca rieh litter that undergoes
nitrification may give western red cedar a competitive
advantage in the struggle for a limited supply of soil N.
Nutrients and Nutrition
Based on a review of several mineral nutrition
studies of western rcd cedar and other North American
coniferous tree species, Minore (1983) reported that,
though nutrient contents of western red cedar foliage
vary with season and site, generally, foliar Ca con­
centrations are relatively higher in western red cedar
than in other species, while N and S concentrations are
usually lower, as are P concentrations, with an excep­
tion (Smith et al. 1968). In a more recent study, Rad­
Jl&MJ&Z£nu:;;:;;
49
W,",r Mltilima CoUl,1
01111 MeI,lImo CO .... ,
Wilt"" Hemlock SublOn.
I
,I
4
,. / t
/.
,
t
..
..
to I
r it
I
I
''
,,/
-
'
I
Wltl"n Hemlock Subzont
I
I
t
,
I
I
/1'!. <1 f
-1/./ '
I
,'
I
t
,
'"
'I
Watt" MI"lImt cou,,1
Dougl
.. ·ftf Subzone
I
i
•
.•
_
\
"
,
,
l.,\ \t, \
\
"
"
1
1 ".
,I.
1'" -
:
-;'-I
I
hpllnllOty nolu
,
t
, , ,
,
HYQ'01op.1 Iv,.lttt'
o
I
1
l
..
mUle
"C
e
1
..
..
'"'YQ"C
lubhydr,(
lIQPhOl0P" fhOluonul
A
.. ot.g01l0P
•..
C
o
Sile index (SllC.,) lor Thuja pllCala i, a, loUow,'
growth cia,s
(, .. lubhygft(:
.. tubUIIC
.. IvbmUIC
"
" ,.1
•
v"y .tftt
la
b
Ua
b
" '"
HC lubmuOlloph,t .. muollopl'lIC .. p"mUOHOph,( ( .. lub'vllOph,c to tul/cohlc
IlIa b
J\'a
b
\'n
b
melers
45·51
42
39
36
33
30
27
24
21
18
<15
leet
150· 170
140
130
120
110
100
90
80
70
60
< 50
Fig. 1. Edaphic grids showing isolines of site indices for western red cedar in three biogeoclimatic subzones
(reproduced from Krajina 1969)
wan and Harrington (1986) found that foliar concentra­
tions of western red cedar were low in Mn and Al and
high in Ca and Mo, compared with known values for as­
sociated conifers. These values were based upon
samples collected from the upper crown; they consisted
of secondary lateral branchlets with their scale-like
leaves. Minore (1983) cautioned the use of foliage
nutrient concentrations when comparing species since
the relative nutrient concentrations do not necessarily
reflect the relative nutrient requirements for each
species. Krajina (1969) suggested western red cedar
may require very high nutrient levels for optimum nutri­
tion. Nevertheless, western red cedar does survive on
poor sites (Gregory 1957) and is observed to be abun­
dant on such sites.
While there is little specific information about the
mineral nutrient requirements of western red cedar,
some foliage nutrient levels reported for western red
cedar are presented in Table 1. These foliar nutrient
levels have been obtained from various field locations
in British Columbia, northwestern United States and
the United Kingdom. They represent levels in un­
treated trees and in trees following fertilization alone,
or fertilization in combination with another cultural
treatment. Also presented are the foliar nutrient levels
obtained from greenhouse studies, with variable
nutrient additions. Seedling macro-nutrient levels as
determined in greenhouse studies with nutrients added
are generally higher than field levels with or without fer­
tilization, with the exception of Ca which is lower than
the field levels without fertilization, but very similar to
the levels obtained in the field after fertilization.
Micronutrient levels are variable and difficult to com­
pare. Generally, N concentrations determined from
field studies are within the 1.5% deficiency level for see­
dlings (Walker ct al. 1955). While field fertilization
will increase levels of N, P, and K, depending upon
treatment, theN levels in the foliage are still within the
deficiency level for some low N treatments on northern
Vancouver Island, even for N applied at rates as high
as 300 kg N(ha in combination with thinning in coastal
Washington. Various nlltrient deficiency symptoms
observed in western red cedar seedlings were described
by Walker et al. (1955) and may be considered general­
ly applicable (see Table 2).
--------- --
!'OLIACK
Table 1.
MUTll.IKNT LEVELS i.UOlI.TIrn FOil. WESn:u 'ilID-CKIlAll (nlUJA
----- %
LOCATION AGE
N
(OD WT)
P
K
Ca
0.06
0.52
1.78
-- --Mg
S
!,LICATA
--Cu
Zn
DO\l]i KX. E. DON)
PPM ---- -
Mn
Fe
B
SOURCE
Field Locations
11
1.27
Western Washington
Adapted 1
0.7 1
Coast:BC, Washington, Oregon
1.06
0. 16
0.48
0.66
0. 13
0.09
6
20
160
54
18
Interior:BC, Washington, Oregon
1.29
0.28
0.83
0.76
0. 15
0. 1 1
8
29
170
54
21
2 1
United K ingdom 1.22
0. 10
0.38
1.05
0. 16
58
Terrace, B
. .
C
0.73
0. 13
0.52
1. 16
0. 10
Western Washington
1. 13
0.08
0.53
1.33
0.93
Western Oregon
1. 17
0. 15
0.67
1.54
0. 15
19-30
19-34
100
0- 130
Radwan
from:
and Harrington,
aL,
1950
1986
(mean values)
Ovington,
0.07 !£
Gessel,
Beaton,
1956
!£
.,
Adaptedl from:
Adapted from:
1965
Gessel,
!£
.,
Imper and Zobel,
1950
1983
(mean values)
36-169 Idaho, Montana, Eastern Washington
Pacific Northwest (Litter)
0.90
0. 13
0.59
1.27
0. 10
0.62
0.09
0.36
2.24
0.04
0.04
5
16
13 1
159
14
Graham,
Adapted2
1982
from: Tarrant,
!£
. •
1951
Greenhouse Studies
1+ 0
Tank culture, complete nutrients
2.70
0.34
2.30
0.89
0.23
0.3 1
Seedlings
Sand culture, complete nutrients
2 94
0.36
1.86
0.90
0.28
0.26
Soil culture, 224
N
0.90
0. 17
1.20
1.22
0.23
Seedlings
P 196
K93
kg/ ha
66
163
1+0
seedlings, tank culture
2.74
0.33
2.72
0.80
0. 14
13
23
164
59
2+0
seedlings, tank culture
2.88
0.40
2.39
0.56
0. 19
14
26
102
139
3.29
0.44
2.92
0.74
0.2 1
10
63
2 16 120
1 2+0
/
seedlings, sand culture
(N,P,K
,Ca,Mg+
l
Adapted
from: Walker,
al., 1955
33
Ry a n, 1983
(mean values)
micro nutrients)
To be cont 'd.
�------
j
(Cont'd)
FOLIAGE ImllUmrr ILVKLS IP;POnED FOIl.
----- %
AGE
Field Studies:
4-6
N
LOCATION
1.56
UBC Research Forest
Fertilized N296-900, P18S-563,
2+0
K228-1339, S13-161 kg/ha
5-8
Northern Vancouver Island, B.C.
(OD WT) --'----
K
Ca
Hg
0.58
0.12
S
0.13
0.62
(Na turaI)
Cu
Zn
Hn
Fe
B
SOtfRCF.
Smith, et al., 1968 (m an valuc
2nd and
t
Control
1 .12
0.16
0.57
0.62
0.15
W p et ma n
1.41
0.16
0.60
0.67
0.14
for 1st grow!np, s
Nl50
1.66
0.15
0.64
0.59
0.14
ferUl17:atlon)
N225
1.98
0.15
0.59
0.65
0.13
N75-225 P75
1.62
0.25
0.54
0.75
0.14
N75-225 K75
1.46
0.16
0.70
0.63
0.14 N75-225 P75 K75
1.53
0.26
0.71
0.69
0.14 Control
1.21
0.18
0.74
0.64
0.16
NI00 P50 kg/ha
1.68
0.23
0.70
0.74
0.16
N200 P50
1.76
0.23
0.69
0.76
0.14
N300 P50
2.08
0.24
0.65
0.72
0.15
2.14
0.28
0.75
0.75
0.14
1.93
0.25
0.97
0.97
0.15
N300 PIOO
+ B,Cu,Zn,Hn
&
Fe
85
66
46
116
76
105
14
210
32
19
13
190
33
21
14
220
35
19
13
240
29
18 14
160
30
23 20
259
38
26 ( u npuh 1.) ( value s
son following
Weetman (unpubl.) (N, P, K,
mean values of 1st,
Ca
and Mg -
2nd and 3rd gro win g
seasons fol 1ow l n p, fertilization)
Northern Vancouver Island, B.C.
(unpubl.) (mean
1.09
0.18
0.75
0.59
0.15
Weetman
Sala1 r emoved 3
1.36
0.20
0.81
0.64
0.15
and 2nd grow!ng se sons
NO
1.24
0.22
0.78
0.63
0.16
1.70
0.21
0.74
0.66
0.15
PO
1.55
0.18
0.76
0.63
0.15 PI00
1.55
0.24
0.75
0.67
0.15 W i th salal
of
growing seasons)
N75 kg/ha
N300 Pl50
12-16
D<Mi EX. It. DOH)
PPH ---
0.13
Northern Vancouver Island, B.C. 9
(THUJA PLICATA
Fertilization
(Plantat i o n)
( Pla nta tion)
P
R1I IIID....omAR.
values of 1st
following
f ert iIi zaUon)
N200 kg/ha4
20-22
Coastal Washington
1985 ( me an
(Natural)
Unthinned, unfertilized
1.02
0.14
0.57
0.79
0.12
0.11
Harrington and Wierman,
(5900 sph)
Thinned (1100 sph),
1.13
0.15
0.64
0.83
0.12
0.11
values of 1st, 2nd and Jrd growlnp,
unfertilized
1.45
0.14
0.58
0.85
0.12
0.13
seaBons following fcrtilization nndl
Thinned + N300 PIOO
1.43
0.23
0.55
0.97
0.12
0.14
or thinning)
Thinned + N300 PIOO KI00
1.38
0.24
0.68
0.91
0.12
0.13
Thinned + N300 kg/ha
1.
2.
Adapted from original data in meg/l00g converted to
% -
3.
from o ri g i na l data in lbs/acre.
Abov -p'rotJnd salal m;lnually eradi,ated from 20
4.
Nitrogl'n added as ammonium nitrate or IJrf'a:m .. an vnlues.
5.
n.
Adapted
x 20
(meg/IOOg) x
(atomic wt/valence)/1000.
m plots.
H"an v:Jlllf'S of I t ancl 3rd groIJing SE'<lSOn foll owin g f"rtili".,tion.
V"lnc of 3rd growing Sf'ason follolJing fe['tili7. rion.
Vl
f-'
52
Table
2.
Deficiency levels and nutrient deficiency symptoms in western red
ce dar seedlings (from Walker,
al. 1955).
Macronutrients
Symptoms
Foliar Concentrations
(%, dry mass basis)
Nitrogen
Phosphorus
< 1.5
Foliage yellowish: stems reddish in
young seedlings; dying of older
foliage conspicuous
but little
shattering; roots a b normally long
in solution cultures; foliage
sparse.
0.4
Stems and older foliage reddish or
purplish during the first year,
turning reddish brown and becoming
necrotic in older seedlings; old­
est foliage dies but does not shat­
ter: youngest foliage retains good
green color
•
Potassium
•
39 - .78
Sterns limber, foliage appears
drooping, sparse, fourth-order
branches apparently do not elon­
gate; branch tips a good green, but
older foliage necrotic or dying and
many lower-leaves and branches dead
and brown.
Calcium
.10 - .20
Browning and drying at the tips of
the leader and branch shoots' good
green maintained in lower fo i iage:
browning and dying of roots obvious
in solution cultures
•
Magnesium
Sulphur
Micronutrients
•
06 - .18
.08 - .16
Foliage yellowish; older foliage
paler than normal, althou h not so
yellowish as younger port10ns of
the plants.
Foliar Concentrations
(ppm, dry mass basis)
Youngest foliage quite yellow; old­
er foliage green; the difference
more striking as the plants
become
.
older. Iron
Boron
Good height growth; youngest foli­
age green, but older branchlets
turn yellow or white
then brown; a
)
marked tendency to Shatter result­
ing in plants with a green tuft at
the tip but bare branches below.
(Other deficiencies do not seem to
produce the white or yellow stage
in necrosis characteristic of
magnesium.)
15
Elongation in growing regions much
restricted, so that needles are
closely bunched, approaching the
"rosette" in angiosperms; stems
weak, upper parts of plant lop
over: older foliage near normal;
younger foliage "bronzed" in
advanced stages; roots short with
branches somewhat bulbous on the
ends.
53
Nitrogen, when present at low levels, was found to
be the nutrient that limited seedling yield the most in a
greenhouse culture trial (Walker et al. 1955). Western
red cedar seedlings were also shown to require more N
than Sitka spruce, western hemlock or Douglas-fir see­
dlings for optimum growth (Krajina 1959). In a study
of 19 coastal and interior sites in western Oregon,
Washington and Vancouver Island, British Columbia,
Radwan and Harrington (1986) found western red
cedar foliar N concentrations to be within the deficien­
cy level of less than 1.5% for seedlings (Walker et a1.
1955) on most sites. They suggested N fertilization
would likely result in improved growth of cedar on these
sites.
Nitrogen has been reported to be used more effi­
ciently by western red cedar in the form of nitrate than
as ammonium in sand and solution cultures (Krajina
1971, Krajina et al. 1973). Minore (1983) identified the
need for further work to dctermine the relationship be­
tween nitrogen form and growth of western red cedar
in nature. Mineral nutrition studies do not explain
whether the nitrate preference is real or, rather, in­
duced as a result of a relatively high proportion of avail­
able nitrate produced by nitrification of western red
cedar litter (Harmer and Alexander 1986).
Phosphorus, although it can b tolerated by western
red cedar at lowcr levels than Douglas-fir and Sitka
spruce (Krajina 1969), was reported by Walker et al.
(1955) to be the second element, after N, to limit see­
dling yields when present at low levels. Western red
cedar P nutrition problems have been observed in the
United Kingdom; on Irish sod-peat bog where P fer­
tilization increased root growth (Carey and Barry 1975)
and in upland British heaths where P and N deficien­
cies were believed to be the cause of plantation check
(Forestry Abstracts 1964).
In the Pacific Northwest, on a range of sites, Rad­
wan and Harrington (1986) found some levels of S, K,
and Mg, as well as N, of western red cedar to be within
the deficiency levels for seedlings (Walker et al. 1955).
They recommended fertilization to enhance levels of
essential elements such as N, S, P, B and Mo and to in­
crease western red cedar productivity. Minorc (1983)
suggested that only low levels of S seem to be required
by wCiitcrn red cedar. Sulfur fertilization in one study
(Smith et al. 19(8) actually resulted in reduced height
growth of young western red cedar, although this may
have been a response to fertilizer induced pH changes.
The requirement of western red cedar for Ca is un­
clear and complex. Western red cedar was reported to
be less tolerant than western hemlock, Sitka spruce or
Douglas-fir to low levels of Ca, Mg or both (Krajina
1959, 1969). It has been described as a calciphile
(Krajina 1969) requiring Ca rich sites to grow on. Yet
the high levels of Ca in western red cedar foliage and
litter (Gessel et al. 1950, Tarrant et aI. 1951, Dauben­
mire 1953, Beaton et al. 1965, Radwan and Harrington
1986) relative to other coniferous tree species may be
attributed to an ability of western red cedar to accumu­
late Ca in excess of its nutrient requirements, thereby,
acting as a Ca pump to the site. Indirect evidence that
western red cedar may act as a Ca accumulator was
presented by Radwan and Harrington (1986). In a
study of foliar concentrations and site productivityrela­
tions in western red cedar, they found that, with one
minor exception, Ca concentrations were not corre­
lated with other elements while all macronutrients ex­
cept Ca were positively related to terminal growth.
Similarly, Harrington and Wierman (1988) reported
that five years after fertilization and thinning in a young
western red cedar stand, the control, the treatment with
the poorest growth, had the highest Ca concentration
while the treatment with the best growth had the lowest
Ca concentration, implying luxury consumption of Ca.
According to Walker et aI. (1955), the ability of western
red cedar to accumulate Ca is related to the availability
of other nutrients as well as Ca in the soil. In sand cul­
tures, treatments with low Mg or low K resulted in the
highest foliar Ca, while in tank cultures, treatments with
low N or K resulted in higher foliar Ca.
Foliar nutrient concentrations have been shown to
vary significantly between western red cedar growing
on the coast and in the interior of western Washington
and Oregon and western Vancouver island, British
Columbia (Radwan and Harrington 1986). Concentra­
tions of P, K, Ca, Mg and S were significantly higher in
the interior than on the coast. This was attributed to
differences in the contents of extractable minerals in
the soils on the coast versus interior. Similarly, B, Zn,
Cu and particularly Mo concentrations were sig­
nificantly higher in the interior, this being attributed by
the authors to soil pH differences and effects on ele­
ment availability. To simplify the relationship between
foliar nutrient concentrations and site productivity,
Radwan and Harrington (1986) suggested that, based
on significant correlations between some foliar con­
stituents and site index and terminal growth, COll­
stituents such as N, chlorophyll, S and B may be useful
as indicators to assess site quality for red cedar produc­
tion. Thc intcraction of sitc conditions, foliar nutrient
concentrations and western red cedar growth is an im­
portant relationship to understand in order to identify
nutritional problems and prescribe appropriate cul­
tural treatments such as fertilization to improve growth.
It will also be important in managing western red cedar
to distinguish between adequate nutrition'and optimum
nutrition. While western red cedar has been observed
to outgrow other species without fertilizer, and, on the
other hand, seems able to survive and grow on nutrient­
54
poor sites, it is hoped that under optimum nutrient and
moisture conditions, western red cedar may grow as
well or better than other coniferous species.
Field Fel'tilization Trials
Table 3 summarizes the response data from four tri­
als. This very limited data suggest that cedar responds
in a conventional way to nitrogen additions; urea seems
to be equally or more effective than ammonium nitrate.
There is no evidence to date of variable response
problems to N additions as with western hemlock.
There is some evidence for response to added P. The
most longterm results are from an experiment con­
ducted by Harrington and Wierman (1988) with seven
treatment combinations of thinning and fertilization,
including a control, in a young cedar stand in coastal
Washington. The two nitrogen sources urea and am­
monium nitrate were used and both increased growth.
However, the urea treatment produced significantly
greater five-year height growth than the ammonium
nitrate treatment. Annual diameter growth was also
consistently slightly above that in the ammonium nitrate
treatment, but five-year diameter growth was not sig­
nificantly different. The larger and possibly longer
response to urea was said to be related to the higher N
concentrations present in the foliage of the urea treat­
ment. The addition of P in the form of dicalcium phos­
phate resulted in a further increase in growth above the
response to N, but the further addition of potassium sul­
fate did not. Since increases in foliar N and P as­
sociated with the fertilization were still evident after
five years, the response may be of long duration.
Height response is difficult to measure because of
indeterminate growth. However, Parker and Johnson
(1987) have deVeloped a simple nondestructive techni­
que for aging western red cedar terminals for the pre­
vious 3 to 6 years (Figure 2). In western red cedar, a
developing branch is often taller than the terminal. The
main stem can be distinguished as having a greater
number of leaf pairs between branches than does a
lateral. Also, to determine past year's height growth, it
is necessary to identify the overwintering point which is
normally 1 to 2 centimeters above a branch junction.
The distinction between one year's growth and the next
is made on the basis of differences in colour and texture
or presence of the stem leaves. This forms the basis of
the terminal aging teclmique.
The lack of determinate growth also makes it dif­
ficult to use end of first growing season foliar vector
analysis to diagnose stand nutrient status and probable
response to fertilization (Timmer and Morrow 1984).
A test of seven shoot parameters (MacGregor 1987) to
measure growth response in cedar single tree screen­
ing fertilizer trials, involving branchlet area, length and
weight, showed branchlet weight to be most highly cor­
related with height growth. Figures 3a and b show the
vector diagrams for nitrogen and phosphorus and
Figure 3c shows the corresponding first-year height
growth response surface. On the same sites, planted
Sitka spruce showed first-year vector shifts and sub­
sequent 3 year matching basal response with a clear im­
provement due to P additions. This result suggests that
cedar is less demanding of P than Sitka spruce.
*
."
...",. .., ' - ·l ·
Fig. 2. Branching pattern in western red cedar (from
Parker and Johnson 1987).
The deficiency levels and symptoms listed in Table
2 can assist in the diagnosis of nutrient deficiencies in
cedar based on foliar analysis. As with its companion
species, there is still no reliable technique to accurate­
ly predict cedar response to fertilization. Early reliable
measurements of fertilizer trials to detect foliage
response to fertilization are difficult with indeterminate
growth. Radwan and Harrington (1986) have shown
that chlorophyll may be used to estimate N status of
cedar. Their finding that interior and coastal cedar
stands have differing foliar nutrient concentrations sug­
gests different fertilization strategies for these areas.
To date, because very few cedar stands have been fer­
tilized, it is not possible to develop any guidelines.
On the northern coast of British Columbia, the
ability of cedar to grow in dense salal dominated sites
led to the first aerial fertilization of cedar at Port Mc­
Neill in December 1986. The fertilization prescription
,-.-- --- --
-- -
------
---- ----
FKlitTILIZK1t RESPONSE JB WKSTElUi 21m CKIlAJt
Table 3.
Stand and Site Age
Location
Treatments Characteristics
Response
Reference
2-year height growth
1) Northern Vancouver
Island,
5-8 years
B.C.
Planted 1000 sph;
30-35 m;
SI (100)
height: 1-2 m;
thick humus, well drained
NO
44 cm (100)a
N75 kg/ha
57 cm (130)b
NlS0
61 cm (139)c
N225
63 cm (143)c
Weetman (unpubl.)
2-year height growth
2) Northern Vancouver
Isl an d ,
12-16 yrs
B.C.
Natural,
5000 sph; SI (100)
No salal removal
83 cm (100)a
30-35 m;
height:
Salal removal
108 em (130)b
2-4 m;
Weetman (unpubl.)
thick humus; well drained
NO
82 em (100)a
N200 kg/ha
99 em (121)b
(ammonium nitrate)
105 em (128)b
N200 (urea)
J)
3-year height growth
Northern Vancouver
Island,
9-years
Control
79 em (100)a
NI00 PSO kg/ha
112 em (143)b
1-3 m; thick humus; well
N200 PSO
122 em (1S4)b
drained
N300 P50
130 em (16S)b
N300 P150
112 em (142)b
Natural,
SI
B.C.
5000 sph;
(100) 30-35 m; height
N300 PlS0 K91 +
B,
Cu, Zn, Mn, Fe
4)
Weetman (unpubl.)
124 cm (157)b
5-year height and diameter growth
Coastal Washington
20-25 yrs
Natural, 5900 sp ,
51
(50) 18-22 m; thin
humua;
poorly drained
170 cm (100)a
3.2 em (100)a
Harrington "
280 cm (165)d
5.8 cm (181)e
(submitted for
210 cm (124)b
4.3 cm (134)b
thinned + N300 (u)
270 em (l59)d
6.3 cm (197)d
tryinned + N300 (an)
thinned + N300 (an)
250 em (l47)e
5.9 em (184)cd
unthinned,
Wi erman, 1987
unfertilized
unthinned +
N300
(an), PIOO, KIOO
thinned (1100 sph),
publication)
unfertilized
PlOO
thinned + N300 (an)
280 em (l65)d
6.8 em (212)e
280 cm (165)d
7.0 em (219)e
PI00 KI00
lJ1
lJ1
'/ 1
1
1
"
j
56
I
a)
I
RELATIVE SHOOT WEIGHT
220
Z
0
a::
IZ
UJ
0
Z
0
()
UJ
>
-'
UJ
a:
150
100
350
300
250
200
l.!eatment
200
2
3
4
5
6
180
160
7
8
140 CIt
120
Legend
NO
o Nl
9
10
11
12
13
14
15
16
Codes
NO
NOP
NOK
NOPK
Nl
NIP
NIK
NIPK
N2
N2P
N2K
,:1N2PK
NJ
N3P
NJK
NJPK
6. N2
100
o
100
·200
300
400
500
RELATIVE CONTENT
N3
700
600
Fig. 3a. Cedar regeneration fertilization screening trials at Port McNeill, B.C. Relationships between concentration,
shoot weight and shoot-nutrient content at end of first growing season following fertilization for nitrogen
RELATIVE SHOOT WEIGHT
b)
240
Z
0
a:
lZ
UJ
0
Z
0
()
150
100
220
300
200
350
180 160 -
Treatment
I
2
3
4
5
6
7
8
UJ
140 -
t:(
-'
120
9
>
UJ
a:
250
200
0
NO
0 Nl
100 -
10
11
12
13
14
15
16
Codes
NO
NOr
NOK
NOPK
Nl
NIP
NIK
NIPK
N2
N2P
N2K
11N2PK
NJ
NJP
N3K
NJPK
6. N2
80
0 N3
100
200
300
400
500
600
RELATIVE CONTENT
Fig.3b. Cedar regeneration fertilization screening trials at Port McNeill, B.C. Relationships between concentration,
shoot weight and shoot-nutrient content at end of first growing season following fertilization for phosphorus.
57
Ix AX IS
11 - NO
N1
i2
13 - N2
!
N3
: 4
Y AXIS
1 - POKO
2 - PIKO
3 - POKI
PIKI
4
-
Fig. 3 c. First year height growth response to fertiliser treatments where N l, N2 and N3 are 7 5, 150 and 22 5 kg N per
ha, respectively, P is 7 5 kg P per ha and K is 7 5 kg K per ha.
of 300 kg N/ha and 50 kg P/ha was based on results from
singletree fertilizer screening trials and foliar vector
analysis. The objective of this fertilization is to ac­
celerate crown closure of the plantation in order to
smother the salal. This study is part of a larger project
the SalallCedarlHemlock Integrated Research Project
(SCHIRP 1986) concerned with maintaining the
productivity of cut-over old-growth cedar/ hemlock
forests. Fertilizer may be an essential cultural treat­
ment to overcome N and P deficiencies of plantations
established on such cutovers.
emphasis is being placed on micronutrients such as
boron and zinc. Cedar is being grown experimentally
under lngestad's concepts of steady state nutrition, and
the interactions between nutrient levels and botrytis are
just some of the areas where work is progressing.
Nub'ient Cycling and the Decline of Old Growth
There is a paradox between the apparently nutrient
demanding features of western red cedar, its role as a
"calcium pump" and its natural occurrence on coastal
salal dominated sites on folisols which are deficient in
N and P. While nutrient demanding, it also appears to
have a wide nutritional ecological amplitude with an
ability to take up nutrients on mor humus soils. So lit­
tle work has been done with soil/site relationships,
nutritional studies and fertilization that it is difficult to
draw any firm conclusions about cedar nutrition.
Cedar Stands
Ancient cedar forests in the wet maritime climate on
the northern coast of British Columbia are commercial­
ly very valuable. They are characterized by living trees
of up to 1000 years old wit h dead tops, growing wit h
hemlock and Sitka spruce in dense salal in deep lUor
humus layers. Interestingly, these stands are inter­
spersed by younger fast-growing stands of hemlock and
silver fir with a history of repeated blowdown. There is
a side by side contrast of vigorous blowdown stands
with active and relatively rapid nutrient cycling, with
decadent slow-growing cedar dominated stands with
slow nutrient cycling in ericaceous dominated mar
humus layers in regulating seedling morphology. More
Discussion
The apparent breadth of its ecological amplitude
and its apparent responsiveness to fertilizers and its
ability to outproduce Douglas-fir on sites are all very
positive features of the species that require further ex­
ploration. Since the mineral soils are the same, it is sug­
58
gested that periodic windthrow may be an essential re­
quirement to rejuvenate and maintain vigorous nutrient
cycling in oldgrowth stands. Bormann (1987) has also
made similar observations and recommendations for
oldgrowth forests in the Tongass National Forest in
Alaska. Whether or not the decline in individual tree
vigour and the dead tops of old cedar is related to a
progressive decline in nutrient availability is yet to be
determined. "Check" in cedar and other conifer plan­
tations on heathland-dominated soils is a well known
and much studied phenomenon in Britain (Zehetmayr
1960, Read 1984). "Environmental stress" of an un­
known nature has been suggested by Shaw et al.(1985),
as the cause of death of Alaska cedar (Chamaecyparis
Ilootkatellsis) over the last 15 years in southeastern
Alaska.
Nurselj' Nutrition
The number of red cedar seedlings produced in
British Columbia crown and private nurseries has
grown from 2.8 million in 1981 to a 1987 sowing request
of 6.5 million. Operationally, cedar has been grown
under similar fertilizer regimes as Douglas-fIr. Starters
and fmishers with higher phosphorus concentrations
(10-52-17) are interrupted with a more balanced NPK
fertilizer (20-20-20) during the period of rapid growth.
Cedar has acted like a nitrogen collector under this
regime. Whereas Douglas-fir may have a nitrogen con­
centration of 2.5% N, cedar will have concentrations
approaching 4 to 5% N. This phenomenon has led to
problems with cedar stock being tall, unbalanced in
root:shoot ratios and prone to disease.
This past year, new initiatives in research and opera­
tiona procedures have begun to look at the nutritional
regimes under which red cedar should be grown. Nur­
series are attempting to drastically reduce nitrogen
levels. Research is directed toward investigating the
role of sulfur and phosphorus
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