Plant and Soil 77,391-394 (1984).
Ms. 5461
© U.S. Government.
Foliar chemical concentrations in red alder stands of various ages
D. S. DeBELL and M. A. RADWAN,
Forestry Sciences Laboratory, Pacific Northwest Forest and Range Experiment Station,
USDA, Forest Service, Olympia, Washington, USA
Received 26 April 1983. Revised August 1983.
Key words
Alder
Alnus rubra
Essential elements
N2"fixation
Nutrition
Stand deterior"
ation
Summary
Six stands of red alder (Alnus rubra Bong.) were sampled to assess the relation"
ship between stand age and foliar chemical concentrations. The stands ranged in age from 9
to 45 years, and were located near Olympia, Washington, on sites of similar soil, aspect, and
slope. Foliage was collected in July, and concentrations of most essential nutrients and alu"
minum were determined. Foliar concentrations of these elements varied among the different
stands. Highest concentrations of N, P, Ca, S, Fe, and Al were found in trees of the youngest
stand. Concentrations of N, P, S, and Fe were negatively correlated with stand age. The strong"
est correlation was obtained with P (r
=
-
0.96, P < 0.01), followed by N (r
=
-
0.85, P
=
0.03.). Results suggest that declining growth and deterioration of red alder stands with age
may be related, at least in part, to limiting supplies of essential nutrients, especially P, N,
and S.
Introduction
Red alder (Alnus rubra Bong.) is the most widely distributed hardwood tree species in the
Pacific Northwest. Because of its rapid juvenile growth and ability to fix atmospheric nitrogen,
it is often considered for use: (i) in forest plantations for fiber or energy production, and
(ii) as a site"improving species to manage in mixture or in rotation with northwestern conifer
species.
Red alder grows rapidly for the first quarter century of its life; growth slows substantially
thereafter. Some stands begin to show dieback and other symptoms of aging as early as 40
yearsl3• Reasons for the growth decline and deterioration are unknown, but such problems
are observed at earlier ages on sites of low quality than on sites of high qualityl3.
Data concerning foliar nutrient contents of field"grown red alder are very limited 1
2,14,15.
The available information has generally been obtained from trees of the same age in one stand,
and only a few of the essential nutrients have been examined. Our study was designed to
estimate the correlation between foliar concentrations of most essential elements and alu"
minum and age of red alder stands. Sampled stands were growing under similar site and soil
conditions. We felt that significant changes (especially decreases) in levels of certain nutrients
with time might provide clues to:
(i)
nutritional factors associated with growth decline and
premature aging in red alder stands, and (ii) opportunities for enhancing production by fer"
tilization. Foliar aluminum was included to assess possible phytotoxic effects.
Materials and methods
Study area and stand selection
The study area is in the Capitol Forest, southwest of Olympia, on land administered by State
of Washington Department of Natural Resources. Soils are of the Boistfort series, and are very
391
SHORT COMMUNICATION
392
Table 1. Concentrations of macro- and microelements in red alder foliage
Stand
N
P
K
Ca
Mg
S
Fe
Mn
Cu
Zn
Al
age
(year
per cent
ppm
------- ------
-------
45
9
2.45
0.17
0.96
0.44
0.15
0.18
58
173
9
33
18
1.96
0.16
0.97
0.4 2
0.17
0.15
47
96
12
38
26
28
1.79
0.15
0.99
0.38
0.13
0.14
46
109
7
30
35
38
1.8 2
0.14
0.94
0.35
0.15
0.15
46
103
12
35
31
42
1.87
0.13
0.89
0.39
0.15
0.14
47
111
10
31
38
45
1.65
0.14
0.97
0.40
0.16
0.14
46
186
11
42
27
Average
1.9 2
0.15
0.95
0.40
0.15
0.15
48
130
10
35
34
deep, well-drained clay loams formed on Eocene basalt in a mild, wet coastal climate. Site
index on these soils averages about 40
ill
and 30 m, respectively, at 50 years for Douglas-fir
and red alder". Overstory vegetation consists primarily of pure and mixed stands of Douglas­
fir (Pseudotsuga menziesii [Mirb.] Franco) and red alder. Understory species include swordfern
(Polystichum munitum (Kaulf.) Presl), sahnonberry (Rubus spectabilis Pursh), salal (Gaultheria
shallon Pursh), vine maple (Acer circinatum Pursh), elderberry (Sambucus spp.), and Oregon
grape (Berben's aquifolium Pursh).
Six stands of natural origin, ranging in age from 9 to 45 years, were selected. The stands
were located on sites of similar soil, aspect, and slope, and were of sufficient size (> 1 ha)
to minimize edge effects. Stand age was determined by averaging the number of rings counted
on cross-sections cut at ground level from trees in each stand.
Foliar sampling and chemical analyses
Three composite samples were collected in each stand in July 1979. Each sample was
obtained from two trees, selected at random; and only fully expanded, m ature leaves from
the sunlit portion of the crown were collected. The samples were dried to constant weight
at 65°C, ground to 40 mesh in a Wiley mill, and stored in closed containers at -15°C until
analyzed.
All chemical analyses were carried out at least in duplicate on each of the three composite
samples for each stand. Total N (including nitrate) was determined by the standard micro­
Kjeldahl procedure'. Analyses of the minerals were performed on the dried foliage or on
solutions of ashed tissue as follows: P by the molybdenum blue technique4; total S and sulfate-S
(extracted with 0.6 N HCI) by the turbidimetric technique3; and Ca, Mg, K, Fe, Mn, AI, Cu,
and Zn by standard atomic absorption spectrophotometric methods'o.
Correlation coefficients (r) between concentrations of each element and stand age were
calculated from mean values for each stand. Correlations were considered significant at P .;;
0.10.
Results and discussion
Foliar concentrations of the elements shown in Table 1 varied among the different stands.
In general, average concentrations were within the ranges reported in leaves of conifers and
other hardwood species·,?,·,17. More specifically, average concentrations of N, K, Ca, Mg, and
Mn were lower, and those of P were higher than the levels reported for field-grown red alder 15.
Moreover, average concentrations of P, Ca, Mg, Fe, Mn, and Al were lower, and those of Cu
were higher than levels in the leaves of Alnus crispa·'? There are no data in the literature
for S, S04-S, Fe, Cu, Zn, or Al in foliage of field-grown red alder.
Sulfate was not detected in any of the foliage collected. Leaves of deciduous species and
foliage of conifers commonly found in mixtures with red alder normally contain measurable
393
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.20
P
.10
.15
CI)
u
c
0
u
r= -.96
.05
p=
.01
CQ
.10
r= -.79
.05 p=
.06
CQ
0
.00
u.
E
Q,
N
c
0
...
.e-
c
'" u
c
0
u
r= -.85
CQ
p = .03
5
10
60
c
0
...
CQ
•
0
0
.00
u.
3
u.
•
c
0
...
CQ
...
c
Q)
u
c
0
u
0
.20
If'.
c
0
.15
...
15
20
25
30
...
c '"
Q) u.
u
c
0
u
CQ
35 40
45
•
-
50
•
•
_.
•
40
30
r= -.74
20
p=
.09
10
0
u.
0
0
5
10 15
Stand age (year)
20
25 30
35 40
45
Stand age (year)
Fig. 1. Correlations of foliar concentrations of P, S, N, and Fe with age of red alder stands
sampled.
amounts of sulfateS,1l,!6. In this study, it is possible that foliar sulfate was used faster than
it was replenished from the soil because of high N levels and low rates of S mineralization.
For some conifers, our unpublished data indicate depletion of foliar sulfate following applic­
ation of N fertilizers.
Highest concentrations for N, P, Ca, S, Fe, and Al were found in trees of the youngest
age sampled (9 years), and concentrations of four of these elements showed significant nega­
tive correlations with stand age (Table 1 and Fig. 1). The strongest correlation was obtained
with P (r
==
-0.96, P < 0.01) followed by N (r
obtained with S (r
==
-0.79, P
==
==
-0.85, P
0.06) and Fe (r
==
==
0.03); weaker correlations were
-0.74, P
==
0.09). Previous work also
showed a significant decrease in foliar N concentration with age! .
Results also indicate that foliar concentrations of P, N, and S were usually lowest in the
42- or 45-year-old stands. Such findings, in addition to the aforementioned negative correl­
ations, suggest that supplies of one or more of these elements may become limiting in red
alder stands more than 40 years old. Nutrient deficiencies may, therefore, be involved to
some extent in the growth decline and deterioration of red alder stands with age. This view
is supported, first, by greenhouse studies now in progress which indicate that red alder is
very sensitive to low soil P. Secondly, as with agricultural legumes, decreasing status of im­
portant nutrients such as P and S in the soils and leaves may adversely affect root and nodule
development. This could depress N2-fixation and, in turn, lead to lower foliar N concentrations,
growth decline, and premature aging of alder.
This study was limited to six stands of red alder because we were unable to find more
stands of acceptable size and age on the same soil type. Similar studies with stands established
on other soil types are needed to strengthen our findings and speculations. We propose field
fertilization trials, especially with P fertilizers, and additional studies of the relationship of
nutrient status to inherent site productivity and aging for red alder.
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394
Acknowledgement
We thank Joseph M. Kraft USDA Forest Service for assistant in chemical
analyses and the U.S. Department of Energy, Biomass Energy Technology Division, Short
Rotation Woody Crops Programs for funds which helped support this research.
References
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