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Variation in specific gravity of red alder (Alnus rubra Bong.)1
CoNSTANCE A. HARRINGTON AND
DEAN S. DEBELL United States Department of Agriculture Forest Service, Pacific Northwest Forest and Range Experiment Station, Olympia, WA Received October 10, 19792 Accepted March 5, 1980
HARRINGTON, C. A., and D. S. DEBELL. 1980. Variation in spe..;ific gravityof red alder (;tlnus rubra Bong.). Can. J. For. Res. 10: 293-299. Specific gravity of breast-high wood did not vary significantly among ten 9-year-old sources used in an Alnus rubra (Bong.) provenance trial. Correlations between specific gravity and diameter were also nonsignificant. In a study of seven natural stands selected to cover a range of site conditions, specific gravity did not differ among stands and was not correlated with 25-year radius in six ofthe seven stands. Analyses of three- to five-ring samples from trees selected from the natural stands revealed no consistent relationships between specific gravity and age or distance from the pith. The correlations between specific gravity and ring width or ring area (measured on the three- to five-ring samples) were negative and highly significant; however, the actual values of the correlation coefficientswere quite low (r = -0.21, r = -0.20). The authors conclude that individual tree selection for growth rate or silvicultural treatments to increase growth will probably have little influence on specific gravity. The uniform specific gravity of wood from stands of varying ages and different locations is a desirable feature in the wood and fiber industries.
HARRINGTON, C. A., et D. S. DEBELL. 1980. Variation in specific gravity of red alder (;tlnus rubra Bong.). Can. J. For. Res. 10: 293-299. La masse volumique determine a partir d'eprouvettes prelevees a hauteur de poitrine sur des individus ages de 9 ans de 10 sources differentes dans un test de provenance Alnus rubra (Bong.) n'a pas varie de fa on significative.Les correlations entre Ia masse volumique et le diametre ne sont pas averees significatives.Dans une etude effectuee dans sept peuplements naturels choisis de fa on a couvrir une gramme de sites differents, Ia masse volumique ne s'est pas revelee differente selon les divers peuplements et n 'a pas pu etre correlee avec le rayon de l'arbre,a 25 ans pour six des sept peuplements. L'analyse d'eprouvettes contenant de trois a cinq cernes prelevees d'arbres choisis dans des peuplements naturels n'a demontre aucune relation consistante entre Ia masse volumique et !'age ou Ia distance mesuree depuis Ia moelle. Les correlations entre Ia masse volumique et Ia largeur des cernes ou Ia superficie des cernes (mesurees sur le eprouvettes de trois a cinq cernes) se sont montrees negatives et hautement significatives; toutefois, les valeurs obtenues se sont averees en realite tres basses (r = -0.21, r= -0.20). Les auteurs en concluent que Ia selection des arbres individuels sur Ia base du taux de croissance ou de traitements sylviculturaux dans le but d'augmenter Ia croissance n 'influeront probablement que tres peu sur Ia masse volumique. L'uniformite de Ia masse volumique du bois provenant de peuplements d'ages differents et de sites differents s'avere etre une caracterique desirable par les industries du bois et de Ia fibre. [fraduit par le journal]
Introduction (Leney et al. 1978). Even specific gravity, which is Red alder (Alnus rubra Bong.) is the most im considered the best single indicator of wood qual portant hardwood in the Pacific Northwest. The ity, has received only limited attention. Specific species is widely distributed and has wood suitable gravity is considered to be a good indicator of wood for a variety of end products. In the past, forest quality because it affects lumber strength and is management and research activities in the region directly related to both pulp yield and caloric con have focused on coniferous species. Recently, tent of wood. Available information indicates that however, interest in utilization and management of average specific gravity for the species probably red alder has increased (Briggs et al. 1978). Its rapid falls between 0.37 (Markwardt and Wilson 1935) juvenile growth rate and apparent adaptability to and 0.39 and appears to be little influenced by a range of site conditions make red alder an excel growth rate (Leney et al. 1978; DeBell and Wilson lent candidate for short rotations designed to pro 1978). Data used in the above studies have been duce sawlogs, pulplogs, and biomass for conver rather limited, and nothing has been reported as to sion to pulp or energy. how specific gravity of this diffusely porous wood Little information, however, is available regard varies with age or distance from the pith, two fac ing the variation in wood properties for red alder tors of potential importance in short-rotation man 'This article was written and prepared by U.S. Government agement systems. employees on official time, and it is therefore in the public do main. In this report we examine the influence of prove 2Revised manuscript received February 20, 1980. nance and site on variation in specific gravity and 294 CAN. J. FOR. RES. VOL. 10, 1980 look at the relationships between specific gravity bark (dib) were taken at right angles to each other (Fig. lA) and and age, distance from the pith, and radial growth then averaged. We used dib as a measure of growth rate. In this and the following study, the wood samples were refrigerated in rate. Our analyses are based on breast-high sam sealed plastic bags until green-volume determinations were ples taken from trees in two studies: (1) a prove made. The samples were then ovendried (105"C) and specific nance trial in north coastal Oregon involving seed gravity was calculated on a green-volume, ovendry weight ling sources from the range of red alder, and (2) a basis. The data collected were used in two analyses. First, an anal study of natural variation in western Washington. ysis of variance (randomized block design) was used to analyze The genetic variability in these two studies was the effects of provenance on variation in specific gravity. Sec assessed and reported on by DeBell and Wilson ond, the relationship between dib and specific gravity was de (1978). This paper presents an expanded analysis termined by calculating the simple correlation coefficient (r) for the combined data, and individually for each provenance. The and discussion of the specific gravity data they re correlation analyses we performed in this and the following ported and includes new data on the relationships study assume that the trees are independent rather than grouped over time in individual trees. or clumped as they occurred on the ground. We felt, however, that using simple correlation analysis was the best method avail Materials and methods able for looking at the relationships of interest and that any bias Provenance variation in the tests would be minimal. The provenance trial, located in the Cascade Head Experi Local variation mental Forest near Otis, OR, was planted in the spring of 1969 Stand diversity with wildlings collected from 10 locations ranging from Juneau, The second study used seven3 naturally regenerated stands AK, to Port Orford, OR. The trees were planted at a 1.5-m x near Olympia, WA. These stands were selected to represent a 3-m spacing in a randomized complete block design. Each block range in stand and site characteristics. Average site index (50 contained ten 10-tree rows. The trees were thinned to 3-m x 3 year base) ranged from 20 to 31 m with mean stand ages (in 1976) m spacing in December 1976; thus four or five trees (depending ranging from 35 to 73 years. In November and December 1976, on mortality) were cut in each row. Breast-high (bh) disks were eight randomly selected trees in each stand were felled and bh collected from 16 trees of each provenance, 4 trees from each sections were collected. A thin disk (3 to 5 em) was cut from of 4 blocks. The disks were about 3 em thick and ranged from each bh section; then a 2-cm-wide strip was cut from the disk to 13 em in diameter. Two measurements of diameter inside I so that the length of the piece was equal to the average diameter of the disk and was located as close as possible to the longest SHORT LONG RADIUS RADIUS radius of the disk (Fig. lB). The two radii were separated, and any wood beyond 25 growth rings from the pith was cut off. Specific gravity and the radius (pith to 25 years) were deter mined for each piece. As before, the data obtained were used in two analyses. We used a nested analysis of variance to assess the variation in spe cific gravity within trees, between trees, and between stands. In addition, we were again interested in examining the relation A B ship between specific gravity and average growth rate. In this study we used the radius from the pith to the end of the 25th
T growth ring as our measure of growth rate. The correlations be AVERAGE DIAMETER tween specific gravity and 25-year radius were calculated for the combined data and individually for each stand. Growth ring analysis c A further analysis was then conducted using 18 of the trees Discord 25 Growth Rings 25 Growlh Rings Discord from the stand diversity study. The trees were selected to evenly cover the range in observed radial growth rates. A second disk -(((��(((((((((((((((@�J»))ill))lli))J D))])])))»»)�)]] was cut from the previously collected bh sections and used in SHORT RADIUS LONG RADIUS this phase of the analysis. As before, a 2-cm-wide strip was cut from the disk so the length of the strip was equal to the average D GROWTH RINGS FROM THE PITH diameter of the disk and came as close as possible to including 26·30 21·25 16·20 13-15 4-£ 1-3 1·3 4-6 13·15 16·20 21·25 26·30 the longest radius. The two radii were separated at the pith, then each piece was subdivided into segments, with each segment 1-111illi-(ill m rn Im ))))))JJ-1 containing three or five annual rings (Fig. 1C). Each of the first SHORT RADIUS LONG RADIUS five segments going out from the pith included three growth rings; further out, as the rings became narrower, each segment FIG. I. Measurement of wood disks. (A) For the samples taken from the provenance trial, diameter inside bark was de included five growth rings. termined by taking two measurements at right angles and av The segments were marked so the identity of the rings (in re eraging them. (B) In the natural variation study a strip was cut lation to the pith) was maintained. Specific gravity and segment through each disk to be as long as the average diameter and to width (along the radius) were determined separately for each come as close as possible to the line containing the longest and segment; then the values for the two corresponding segments shortest radii. (C) The strip was then separated at the pith and wood beyond the 25th growth ring was discardd. (D) For the :fJ'heoriginal study reported by DeBell and Wilson (1978) used growth ring analyses, strips were cut from disks as in (B) and eight stands. We excluded the youngest stand as we did not have then divided into segments of three or five annual rings. a measure of 25-year radius. HARRINGTON AND DEBELL 295
(i.e., the same ring numbers for a tree) were averaged. We felt A averaging the segment widths would give the best estimate of radial growth rate (Reukema 1971). We then calculated, based 0.45 I I I on the average segment width, distance from the pith to the seg ment midpoint, average ring width, and average ring area. Av erage ring width and average ring area were calculated by di or - viding segment width area by the number of years in the > 040 . segment.
TABLE 1. Specific gravity values and correlations between specific gravity and diameter inside bark by provenance
Correlation between Specific gravity specific gravity and diameter
Provenance Mean Range Correlation (r) Probability (p)
Juneau, AK 0.41 0.35-0.47 -0.17 0.54 Jordan River, B.C. 0.41 0.36-0.47 -0.07 0.80 Concrete, WA 0.40 0.35-0.50 -0.10 0.71 Olympia, WA 0.40 0.37-0.46 0.45 0.08 Amboy, WA 0.40 0.35-0.46 0.13 0.64 Lincoln City, OR 0.39 0.36-0.42 0.26 0.34 Cottage Grove, OR 0.40 0.34-0.45 0.02 0.93 Port Orford, OR 0.40 0.33-0.44 0.27 0.30 Sequim, WA 0.39 0.34-0.44 0.25 0.35 Sand Point, ID 0.40 0.35-0.46 0.10 0.70 All provenances pooled 0.40 0.33-0.50 -0.03 0.72
- TABLE 2. Specific gravity values and correlations between specific gravity and 25-year radius by stand
Correlation between Specific gravity specific gravity and 25-year radius
Stand Mean Range Correlation (r) Probability (p)
McKenny 0.38 0.35-0.41 -0.52 0.04 Schafer 0.40 0.35-0.42 -0.19 0.46 Rock Candy 0.39 0.38-0.42 0.22 0.42 Taylor Towne 0.38 0.30-0.46 -0.15 0.58 McCleary 0.38 0.35-0.41 0.27 0.31 Porter 0.39 0.38-0.41 -0.32 0.22 Stillwater 0.39 0.34-0.42 -0.37 0.15
All stands pooled 0.39 0.30-0.46 -0.11 0.24
some r values for individual trees were highly sig greater than zero and will approach 1. 00 over time. nificant with correlations ranging from 0. 91 to It is of interest, however, to examine the curve to -0.83. The relationships between specific gravity see how the r values change over time. By age 9, and the two measures of growth rate, average ring the correlation coefficient was statistically signifi width (Fig. 3B) and average ring area (Fig. 3C), cant (r = 0. 51); by age 12, the correlation coeffi were similar. The combined tree correlation coef cient was highly significant (r = 0.63). The largest ficients of -0.21 for ring width and -0.20 for ring average increase in r, that is, the change in r di area, however, were highly significant. Individual vided by the change in number of years, took place tree r values ranged from 0. 80 to -0. 95 for ring between 12 and 15 years. width and from 0.81 to -0.84 for ring area. Step wise multiple regression analysis including the four Discussion independent variables, distance from the pith, age, The mean values obtained for specific gravity of average ring width, and average ring area, resulted 0. 40 in the provenance trial and 0.39 in the local 2 in a nonsignificant r value of 0.07. diversity study are both higher than the value of Plotting the correlations between specific gravity 0.37 reported by Markwardt and Wilson (1935) and of the disk at age 30 and specific gravity of the disk repeated in Wood Handbook: Wood as an Engi at earlier ages resulted in an S-shaped curve (Fig. neering Material (Forest Products Laboratory 4). Since these correlations were based on weighted 1974). The original determination by Markwardt values, that is, the value at age 30 includes all pre and Wilson (1935) was based on six trees. Whether vious values, the correlations will always be the difference in mean values may be due to sample HARRINGTON AND DEBELL 297
TABLE 3. Specific gravity values and correlations between specific gravity and distance from the pith, age, average ring width, and average ring area for individual trees
Correlation between specific gravity and
Distance Average ring Average ring Specific gravity from the pith Age width area
* Tree Mean Range r pt r p r p r p 49 0.40 0.38-0.43 0.74 0.02 0.66 0.04 -0.69 0.03 0.81 0.00 58 0.36 0.34-0.38 0.29 0.42 0.26 0.47 -0.30 0.40 0.30 0.40 59 0.38 0.37-0.41 -0.66 0.04 -0.56 0.09 0.80 0.01 -0.17 0.64 64 0.37 0.36-0.40 0.62 0.06 0.68 0,03 -0.19 0.59 0.81 0.00 72 0.38 0.36-0.38 -0.38 0.28 -0.14 0.71 0.43 0.21 -0.67 0.04 73 0.39 0.38-0.42 0.47 0.17 0.56 0.09 -0.42 0.01 -0.23 0.52 74 0.37 0.36-0.38 -0.37 0.37 -0.37 0.36 -0.52 0.19 -0.57 0.14 75 0.38 0.37-0.40 -0.53 0.14 -0.58 0.10 0.73 0.03 -0.04 0.92 76 0.37 0.34-0.40 0.87 0.00 0.88 0.00 -0.95 0.00 -0.04 0.92 78 0.40 0.39-0.44 0.63 0.10 0.83 0.01 -0.66 0,07 -0.48 0.24 79 0.39 0.36-0.44 -0.02 0.96 0.16 0.70 -0.50 0.21 -0.84 0.01 80 0.38 0.36-0.40 -0.40 0.26 -0.26 0.47 -0.12 0.75 -0.81 0.00 81 0.39 0.38-0.40 -0.19 0.62 -0.11 0.78 -0.07 0.86 -0.64 0.06 82 0.35 0.34-0.44 -0.03 0.94 0.16 0.67 -0.82 0.01 -0.73 0.02 83 0.40 0.36-0.44 0.91 0.00 0.91 0.00 -0.46 0.30 0.74 0.06 84 0.36 0.34-0.39 0.83 0.02 0.83 0.02 -0.37 0.41 0.72 0.07 86 0.40 0.35-0.43 0.69 0.03 0.67 0.03 -0.75 0.01 0.53 0.12 94 0.38 0.37-0.43 -0.83 0.00 -0.84 0.00 0.45 0.19 -0.61 0.06
All trees pooled 0.38 0.34-0.44 0.00 0.95 0.13 0.11 -0.21 0.01 -0.20 0.01 *Correlation coefficient. tProbability. size, natural variation, or to differences in collec ual-tree approach to selection. The correlations tion and sensitivity in processing of samples is un between the weighted tree specific gravity at age known. The specific gravity values obtained in this 30 and at earlier ages became significant at age 9 study agree well with the more recent value of 0. 39 and highly significant by age 12. Based on the in reported by Leney et al. (1 978) based on 55 sam crease in the correlation coefficient over the incre ples. Neither Leney et al. (1 978) nor Markwardt ment in years, it appears that an appropriate time and Wilson (1 935) were using samples specifically for second-generation selection or progeny test collected at breast height. evaluation (based on specific gravity) would be With the exception of growth rate, the relation around age 15. At this point, halfway through the ships between specific gravity and the other vari specified rotation, the juvenile-mature correlation ables were not statistically significant. Generally, is r = 0.86. when the larger data sets were broken down into The fact that specific gravity did not vary much smaller units, based on provenance, stand, or in by provenance, stand, or age may indicate that dividual tree, some significant correlation coeffi there is not much variation in specific gravity be cients were obtained; however, these were both tween different loads of alder delivered to the mill. positive and negative indicating the lack of a con This kind of uniformity is of particular interest to sistent relationship. the wood fiber based industries. A mill utilizing red Neither differences between wide-ranging alder of different ages coming from a number of lo provenances grown at a common location nor be cations would not expect to experience major dif tween stands in a local area were significant. Var ferences in pulp yields. iation between trees in a stand, however, was Red alder apparently does not have a juvenile highly significant. Thus, tree improvement pro core of low density wood as is present in some spe grams in red alder should probably take an individ cies. This conclusion is supported by the low cor 298 CAN. J. FOR. RES. VOL. 10, 1980
A 0. 1.00 45 1- z
>- 0.80 1- lLi:L: 040 0::: u 0.60 (!) z ...... 0.40 LJ... <( _j <...> 0.35 w w 0.20 a.. 0 (f) u 000 0.30 --'-- ...1.---'---'--...l.....-.L.. 1_.L_1--L _...L____J 0 3 6 9 12 15 18 21 2.4 27 30 0 4 8 2 G I I 20 AGE (YEARS FROM THE PITH) DISTANCE FROM PITH ( CM) FIG. 4. Correlation between specific gravity at age 30 and spe cific gravity at earlier ages. 8 r:---r-.---.--.---.--.-----,--..,-----,---, 0.45 r--,---,lr--..,.,,--,--1 ---,-----,r----, The relationship between specific gravity and growth rate is not clear cut. The correlations be tween specific gravity and diameter in the prove nance trial, and between specific gravity and 25 0.40 year radius in the stand diversity study, were not 0::: (!) ...... significant. Much stronger correlations, both pos ...... u itive and negative, were obtained when these re LL: 0.35 - lationships were examined for trees within a single provenance or stand. In the growth ring analysis, a.. (/) when the measures of growth rate were based on
I a smaller number of years, the correlations be 0. 3 Q -- -- -- ---- -- -- I I I I 0 0.2 0.4 0.6 0.8 1.0 1.2 tween specific gravity and average ring width and AVERAGE RING WIDTH (CM) average ring area were highly significant.The anal ysis of the relationships in individual trees, how c ever, revealed both positive and negative correla 0.45 tions that were highly significant. Thus, the relationships between specific gravity and measure 1- of growth rate were not consistent in any of the . . analyses. 0::: 040 ...... 0 . .. (!) ...... Other researchers have reported finding both . . positive and negative relationships between growth u • 0 0 •• - . . iL rate and specific gravity. Brown and Valentine w(} 0.35 (1963) found both positive and negative correla a.. (/) tions between specific gravity and growth rate for different trembling aspen clones. Taylor (1977), in I his analysis of eight southern hardwoods, found 0.30 I I l_ I I I _l I 0 10 20 30 50 that the strength and the sign of the correlation be AVERAGE RING AREA tween specific gravity and growth rate varied FIG. 3. Relationships between specific gravity and other var among locations. He concluded there were no con iables analyzed in the growth ring phase of the analysis. (A) Spe sistent relationships for any of the species studied. cific gravity versus distance from the pith to the midpoint of the Leney et al. (1978) in their work on red alder found section. (B) Specific gravity versus average ring width. (C) Spe essentially no relationship between specific gravity cific gravity versus average ring area. and ring width (r = -0. 01). In our analyses, more of the significant correla relations between specific gravity and age, and vis tions between specific gravity and growth rate were ual examination of the plotted data (specific gravity negative than were positive. As Kennedy (1968) versus age). The fact that there were no consistent suggested for poplar, this may indicate that there relationships betwzen specific gravity and age or is a slight negative relationship between growth distance from the pith is in agreement with recent rate and wood density. With such low r2 values work by Parker et a!. (1978). (0.04 and 0.04 between specific gravity and ring HARRINGTON AND DEBELL 299 area and ring width), however, silviculturists can BRIGGS, D. G., D. S. DEBELL, and W. A. ATKINSON (Compi probably accelerate growth in red alder stands lers.) 1978. Utilization and management of alder. USDA For. without major reductions in wood density. Addi Serv. Gen. Tech. Rep. PNW-70. BROWN, I. R., and F. A. VALENTINE. 1963. Natural variation tionally, genetic selection for increases in either in specific gravity and fiber length in Populus tremuloides specific gravity or growth rate can probably be clones. In Proceedings of the lOth Northern Forest Tree Im made without associated losses in the other factor. provement Conference. Edited by Ernst J. Schreiner. North In summary, our results indicate that specific eastern Forest Experimental Station,Upper Darby, PA. pp. 25-39. gravity in red alder varies substantially among and DEBELL, D. S., and B. C. WILSON. 1978. Natural variation in within individual trees and is only minimally cor red alder. In Utilization and management of alder. Compiled related with growth rate. Opportunities appear ex by D. G. Briggs, D. S. DeBell, and W. A. Atkinson. USDA cellent for yield improvement through individual For. Serv. Gen. Tech. Rep. PNW-70. tree selection for specific gravity. In addition, alder FOREST PRODUCTS LABORATORY. 1974. Wood Handbook: wood as an engineering material. U.S., Dep. Agric., Agric. does not have a low density, juvenile core. These Handb. No. 72. findings provide additional support for earlier sug FREESE, F. 1967. Elementary statistical methods for foresters. gestions of red alder as a promising candidate for U.S.,Dep. Agric., Agric. Handb. No. 317. U.S. Department intensive, short-rotation management (Smith 1968). of Agriculture Forest Service, Washington, DC. KENNEDY, In addition, our data indicate that purchasers of R. W. 1968. Anatomy and fundamental wood prop erties of poplar. In Growth and utilization of poplars in Can alder fiber may expect reasonable uniformity in ada. Edited by J. S. Maine and J. H. Cayford. Dept. For. specific gravity among supplies of alder, even Rural Dev. Pub!. No. 1205. Minister of Forest and Rural De though the supplies may come from stands that velopment, Ottawa, Canada. pp. 149-168. vary in age, geographic location, and site condi LENEY, L.,A. JACKSON, and H. D. ERICKSON. 1978. Properties of red alder Bong.) and its comparison to other tions. (Alnus rubra hardwoods. In Utilization and management of alder. Com Acknowledgments piled by D. G. Briggs, D. S. DeBell, and W. A. Atkinson. We are grateful for the foresight of B. S. Douglas USDA For. Serv. Gen. Tech. Rep. PNW-70. MARKWARDT, L. C., and R. C. WILSON. 1935. Strength and re and R. K. Peter in establishing the provenance trial lated properties of woods grown in the United States. U.S. and wish to acknowledge our use of the unpub Dep. Agric. Tech. Bull. No. 479. U.S. Government Printing lished plans, field data, and reports on the prove Office, Washington, DC. nance trial, prepared from 1968 to 1976 by B. S. PARKER, M. L.,J. H.G. SMITH, and S. JoHNSON. 1978. Annual ring width and density patterns in red alder. Wood Fiber Douglas, R. K. Peter, and V. W. Clapp, U.S. De 10(2): 120-130. partment of Agriculture Forest Service, State and REUKEMA, D. L. 1971. Considerations and problems in deter Private Forestry, Portland, OR. mining volume growth of individual trees. In Contributions We would also like to thank Crown Zellerbach to increment research. IUFRO Mitt. Forst!. Bundes-Versuchsanst. Wein. 91: 11-32. and the Washington State Department of Natural SMITH, J. H. G. 1968. Growth and yield of red alder in British Resources for their assistance in data collection, Columbia. In Biology of alder. Edited by J. M. Trappe, J. F. and, from the U. S. Department of Agriculture For Franklin, R. F. Tarrant, and G. M. Hansen. Pacific North est Service, Jack A. Booth for his assistance in west Forest and Range Experimental Station, Portland,OR. pp. 273-286. sample collection, John F. Leverington for his as TAYLOR, F. W. 1977. Variation in specific gravity and fiber sistance in sample processing, and James E. Wil length of selected hardwoods throughout the mid-South. For. cox for his assistance in data analysis. Sci. 23(2): 190-194.