Number
162
Portland, Oregon November 1958
SITE CURVES FOR RED ALDER by
Daniel
M.
Bishop and Floyd A. Johnson
Pacific Northwe.st Forest and Range Experiment Station
I
I and
George R. Staebler
Forestry Research Center, Weyerhaeuser Timber Co.
The increasing commercial importance of red alder (Alnus rubra) in the Pacific Northwest has created a demand for research on this species. Noting the lack of information on growth of alder, the Puget Sound Research Center Advisory Committee established a subcommittee.!:/ in January
1956 to undertake coristruction of alder yield tables. Through the 'Jcooperative efforts of private and public forest agencies,3../
437 sample plots of varied sizes were measured in northwestern Oregon, western Washington, and British Columbia.
This preliminary report presents site curves developed in the process of yield table construction. The curves are based on stem analysis data from 43 felled and sectioned trees, geographically distributed throughout western Washington (table 1).
An attempt was made to distribute the sampling of alder tands over varied ecological conditions, at the same time allowing coverage of the entire band of site values.
J:../ William J. Lloyd, chairman; Laurence O. Barrett;
Royce Cornelius; Gilbert E. Liming; and L. T. Webster.
2/ Cooperating agencies are listed on the last page.

of red alder sample tr.ees
County
Clallam
Grays Harbor
Island
Kitsap
L e w i s
M a s o n
Pacific
Skagit
Whatcom
I
/
Sample trees
Number
10
3
3
3
3
4
8
6
- 3
Stands represented t Number
3
2
1
1
1
1
4
1
2
Site indices represented
'
78, 6 7, 80, 78
98
62,
100
88
88
94
104, 111
68, 92
104
The index stand age for these curves ds 50 years. Stand age was arbitrarily defined for all sites as breast - high age plus 2 years.
The stem analysis data led to the following equation:
S,L
=
Height (0. 60924 + 19. 538/Age) t,
Solution of the equation is shown graphically in figures 1 and 2, and numerically in table 2.
For most uses, interpolated site indices from figures 1 and
2 should be adequate. However, the formula can be used almost as quickly if a desk calculator is available.
I .
The general approach to the development of site indexing systems through stem analysis has been described by BuIL J and
Spurr.
4/
A detailed description of the procedure used for this j
Bull, Henry. The use of polymorphic curves in deter­ mmmg site quality in young red pine plantations. Jour. Agr. Res.
43: 1-28, illus. 1931.
4/ Spurr, Stephen H.· Soils in relation to site index curves.
Soc. Amer. Foresters Proc. 1955: 80 -85, illus. 1956.
- 2­

TOTAL HEIGHT (feet)
120
110
70
60
50
90
80
120
110
100
+
I , ,
I
+
I ,
, !
I I
I'
.' ,
I '
, '
•
<I·
.,
100
, L·
90
BO
70
-' 60
40
I'
•
30
II
20 o 10
I I I
20 30 40 50 60
I I
70 80
S T A 0 AGE (years)
Figure 1. --Average total height of dominant and codominant red alder trees, by stand age and .site index.
-
3
.-

I ff:>..
I
SITE
INDEX
10 12 18 20 22 24 26 28 30 35 40 45 50 14
I,
16
55
P.--H rTTTI
'--I
I I
12 0
I
I
1-'
'Ii
, I
-v iTI i
1./1 t j
L
!if±j
110
, I
11
�-i-t
'+-1
100
, j
I!
I
I,
90
Ii t-!
I ' j I
'+=1 i
I
-1
+++-,
, I i-
8 0
"I
70
1=+'
F+++1+'
, '
6 0
20 30 40
:I'
50
1-1
60 70 80
TOTAL HE I·G H T
90
( feet)
100 1 10
-r+J i
, ,
120
-;-1-'
•
1 30
Figure 2.' --Site index for red' alder,: by stand age and average total height of dominant and codominant trees.
:
70
75
80

I
111
I
... .
>
Table 2.--Site index for red alder, by stand age and average
· tot l
1 height of dominant and codominant trees
\.
Stan agel
1
(years)
20 25 30 35 40 45
10
12
14
16
18
20
22
24
26
28
30
42
44
46
48
50
32
34
36
38
40
51 64
56
50
77
67
60
55
51
--
90
78
70
64
59
56
52
50
--
62
64
66
68
70
52
54
56
58
60
72
74
76
78
80
1/ Breast-high age
+
2 years.
-
"
103 115
89 101
80
73
68
63
90
82
76
71
60
57
54
52
50
67
64
61
59
57
55
53
52
49
50 55
54
53
52
51
50
61
59
58
56
55
128 141
112 123
100 110
92
85
79
101
93
87
75
71
68
65
63
82
78
75
72
69
54
53
53
52
51
51
50
59
58
57
56
55
67
65
63
62
60
60
Total height (feet)
65
53
52
52
52
51
55
55
54
54
53
59
58
57
57
56
64
63
62
61
60
73
71
69
67
66
134
120
1io
102
95
90
85
82
78
76
57
57
56
56
55
60
59
59
58
58
64
63
62
61
61
70
68
67
66
65
79
77
75
73
71
130
1I9
110
103
97
92
88
85
82
70 75
136
127 135
120 127
114 121
109 116
105
101,
III
107
104
101
98
95
93
91
90
88
86
85
79
78
77
76
75
75
74
74
73
73
84
83
81
80
79
70
70
69
69
68
74
73
72
72
71
79
78
77
76
75
86
84
83
81
80
98
95·
92
90
88
140
128
119
137
127
III 119
·105 116
100 .107
95 102
91
88
98
94
75
74
72
71
70
85
83
81
79
92
89
86
84
77 .;;.- 82
81
79
78
76
75
66
65
65
64
64
69
69
68
67
67
74
73
72
71
70
62
61
61
60
60
65
64
63
63
62
69
68
67
66
65
80 85 90 95 100
79
79
78
77
77
83
82
81
81
80
135
128
122
118
113
110
107
104
101
99
135
129
124
120
136
131
126
89
87
86
85
84
97 102
95 100
93
91
90
98
97
95
94
92
91
90
89
116 "'122
112
109
107
104
118
115
112
110
107
105
103
102
100
98
97
96
95
94
84
83
82
82
81
88
87
86
85
84
88
87
87
86
85
92
92
90
90
89
105 110
137
132
128
124
121
118
115
134
130
127
124
121
113 118
III 116
109 114
107 112
105 110
103
102
101
99
98
108
107
105
104
103
93
92
91
90
90
97 102
96 101
95 100
94
93
99
98
97
96
95
95
94
115
113
112
110
109
108
106
105
104
103
102
101
100
100
99
98
136
132
129
126
124
121
119
117
115
120
138
135
132
129
126
124
122
120
118
117
115
114
112
III
110
109
108
107
106
105
104
103
102

particular application of the stern analysis technique is beyond the scope of this paper and will be covered in a later report . . The pri­ mary purpose of this research note is to make the site curves avail­ able for use. For now, it may be enough to say that the analysis problem waS essentially one involving multiple regression. The de­ rived site system fitted the basic data well, greater accuracy near age 50. with a tendency toward
The data on accuracy of site determination plus experience gained in collecting the information suggest that site should be based on measurement of at least 3 trees. These should be from the dominant- codominant component of the stand and should show no evidence of serious top damage. Heights of the measured tree s should not range more than 5 feet above or below the average of the sample; ages should not range more than 2 years from the average, though in uneven-aged stands it may
1:> e necessary to extend the limit to 5 years.
(
I'
'
.
)
- 6­

,
I
COOPERATING AGENCIES
1. Bloedel Timberlands
2. British Columbia Forest Service
3. Bureau of Land Management
4. Crown Zellerbach Corp.
5. Fibreboard Products, Inc.
6. Gifford Pinchot National Forest
7. Kaiser Gypsum Co.
B. Longview Fibre Co.
9. Milwaukee Land Co.
10. Mt. Baker National Forest
11. Northern Pacific Railway Co.
12. Olympic National Forest
13. Pope & Talbot, Inc.
14. Puget Sound Pulp & Timber Co.
15. Rayonier, Inc.
16. St. Paul & Tacoma Lumber Co,
17. St. Regis Paper Co. lB. Seattle Water Dept.
19, Scott Paper Co.
20, Simpson Logging Co.
21. Snoqualmie National For st
22. Soil Conservation Service
23. Washington State Dept. of Natural Resources
24. Western Washington Indian Agency
25. West Tacoma Newsprint Co.
26. Weyerhaeuser Timber Co.
27. Willapa
V alley Water District
2B. Willamette Research Center
L
-7 ­
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