A comparison of five tree species for intesive fiber production

A comparison of five tree species for intesive fiber production

Forest Ecology and Management, 1(1977, published 1978) 249--254 249 © Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherland...

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Forest Ecology and Management, 1(1977, published 1978) 249--254

249

© Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands

A COMPARISON OF FIVE T R E E SPECIES F O R I N T E N S I V E F I B E R PRODUCTION*

R.F. WITTWER and M.J. IMMEL

Department of Forestry, University of Kentucky, Lexington, Ky. (U.S.A.) (Received 16 September 1977)

ABSTRACT Wittwer, R.F. and Immel, M.J., 1978. A comparison of five tree species for intensive fiber production. Forest Ecol. Manage., 1: 249--254. Total height, diameter growth, survival, and above-ground biomass production were evaluated for five deciduous tree species grown in closely space d (0.9 m x 0.6 m) plantations in the Ohio Valley Region of western Kentucky (U.S.A.). The five species tested were: American sycamore (Platanus oecidentalis L.), European alder (Alnus glutinosa L.), river birch (Betula nigra L.), green ash (Fraxinus pennsylvanica Marsh.) and a hybrid poplar (Populus sp.). Total biomass production for the various species ranged from 28 rot/ha for green ash to 92 mt/ha for the hybrid poplar. The relative ranking for biomass production was as follows: green ash < river birch < European alder < American sycamore < hybrid poplar. The ranking for height and diameter growth showed a similar trend. The hybrid poplar contained the highest proportion of bolewood in the total biomass, and the ranking by species for this factor followed the same trend as for total biomass production.

INTRODUCTION As the d e m a n d f o r f o r e s t p r o d u c t s increases a n d f o r e s t land is lost to agriculture, u r b a n and industrial use, n e w silviculture practices m u s t be f o u n d t o m e e t these d e m a n d s . Intensive cultural practices resulting in m o r e useable fiber per h e c t a r e will b e c o m e i m p o r t a n t , and p l a n t a t i o n s o f rapidly g r o w i n g tree species will be established and g r o w n using m e t h o d s similar to agriculture. R o t a t i o n age, species-site relationships, spacing, weed c o n t r o l and fertilization are i m p o r t a n t c o n s i d e r a t i o n s (Belanger and Saucier, 1 9 7 5 ) . This s t u d y c o m p a r e s t h e g r o w t h a n d yield o f five d e c i d u o u s species g r o w n u n d e r similar site c o n d i t i o n s p l a n t e d at a close spacing and h a r v e s t e d after a s h o r t r o t a t i o n period. * The investigation reported in this paper (77-8-143) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with approval of the Director.

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STUDY A R E A

The plm~tatio~~s reported on in this study were established with 1--0 seedling stock during the spring of 1973 in the Ohio River Valley Region of western Kentucky near Hawesville, Hancock county. The soil was formed in alluvium and is deep and moderately well-drained with silt loam surface horizons. The five species tested were: American sycamore (Platanus occidentalis L.), European alder (Alnus glutinosa L.), river birch (Betula nigra L.), green ash (Fraxinus pennsylvanica Marsh.) and a hybrid poplar (Populus sp.) of unknown origin. These species were selected because of fast juvenile growth rates, good sprouting ability for coppice regeneration, and availability from local nurseries. Three replicate plots, 5.4 m by 6.0 m, were established for each species. Each plot contained six rows, 0.9 m apart, with ten seedlings in each row spaced 0.6 m apart. At the end of the fourth growing season, the fall of 1976, the sample trees were harvested. Four sample trees representing the range of diameters were taken from each plot. Each sample tree was then separated into leaves, branches and bole and weighed separately to obtain green weight of each component. Sample tree component parts were dried at 65°C for determination of moisture contents and yields on a dry weight basis. One entire plot of each species in one replicate was also clearcut and weighed. Total height and diameter at the groundline of all trees on all plots were measured. Regression equations were derived for each species, utilizing height and diameter of sample trees as independent variables. Green weights were then predicted for the remaining plots. Individual tree weights were first obtained, added together and then expanded to an area basis. Six regression equations were used for each species to predict green weight. Variables used were: diameter, diameter squared, height, height squared, diameter and height, diameter squared and height. RESULTS AND DISCUSSION

Yield estimation and measurement When predicted and actual weights of the plots composing replicate one were compared (Table I), diameter was the closest predictor for American sycamore and height was best for green ash. Height squared equations most nearly approximated yields for hybrid poplar and European alder. The diameter squared plus height equation worked best for river birch. This substantiates earlier assumptions that little advantage is obtained by multiple regressions if simple linear functions can be implemented (Crow, 1971).

Growth and yield Hybrid poplar not only showed the best height growth and weight pro-

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duction (Table II) but also had the largest percentage of weight in wood (Table III). Height and diameter growth of American sycamore were not significantly differer~t horn those of the poplar, but weight production was sig~lific~:~tly lower. Analysis of variance further showed green ash to rank lowest in growth and weight production. European alder and river birch were not significantly different from American sycamore in their growth and yield. Yie~.d st~Jdies by other scientists provide comparisons of the relative productivity for some of the species and spacing, rotation age, and site conditions of the study. Bowersox and Ward (1976) reported dry weight yields of stemwood, bark and branches in the 14--26 mt/ha range for 4-year-old Populus hybrids grown at a spacing slightly less (0.6 m × 0.76 m) than ours. Our yields for Populus excluding leaves on a dry weight basis (Table IV) were calculated to be about 40 rot/ha and exceeded the upper limit of this range by about 50% (26 mt/ha vs 40 mt/ha). A 3-year-old irrigated and fertilized plantation of a Populus hybrid in Wisconsin yielded 17.7 mt/ha of wood, branches and bark on a dry-weight basis for a 0.6 m × 0.6 m spacing (Dawson et al., 1976). TABLE II Mean diameter, height, survival and green weight production a by speciesb Species

Diameter c (cm)

Height (m)

Survival (%)

Weight (mt/ha)

Hybrid poplar American sycamore European alder River birch Green ash

5.8a 6.0a 5.3a 4.5ab 3.7b

6.1a 5.2ab 4.7b 4.1b 2.9c

71a 69a 75a 89a 82a

92.3a 73.0b 61.6b 61.2b 28.0c

aGreen weight production is the mean of all six prediction equations for each of the three replications. bWithin each column, values not designated with the same letter are significantly different at the 0.05 level of probability by the Student--Newman--Keuls test. CDiameter measured at ground level. TABLE III Component parts of total biomass by species based on green weights Species

Leaves (%)

Branches (%)

Bole (%)

Hybrid poplar American sycamore European alder River birch Green ash

6.1 9.3 12.3 7.6 14.7

15.9 14.8 20.3 26.5 27.4

78.0 75.9 67.4 65.9 57.9

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TABLE IV Ratio of dry weight to green weight by species Species

Hybrid poplar American sycamore European alder River birch Green ash

Dry weight to green weight ratio a Mean b

Range

0.49 0.47 0.47 0.57 0.61

0.49--0.50 0.46--0.48 0.46--0.49 0.56--0.57 0.58--0.63

a Dry weight to green weight ratio = total dry weight of four sample trees per plot total green weight of four sample trees per plot b Mean of ratio from three replicate plots for each species. Weight yields of intensively cultured American sycamore have been reported for plantations in Georgia (Steinbeck and May, 1971; Saucier, et al., 1972), Mississippi (Kennedy, 1975) and Kentucky (Wood et al., 1976). Total green weight yields for 4-year old sycamore seedlings on a bottomland site in the Piedmont region of Georgia (Saucier et al., 1972) were very similar to our results. Dry weight yields were also comparable since the dry weight to green weight ratios were very similar for both studies. Kennedy (1975) reported yields very similar to ours for a 4-year-old plantation established at a 0.6 m × 1.5 m spacing on a Mississippi River Valley bottomland silt loam soil near Greenville, Mississippi. The yields by Wood et al. (1976) for adjacent study plots harvested after 3 years were less than one-half of those determined in this study. These large differences can probably be attributed to the very favorable soil moisture supply during the 1974 growing season as well as the difference in rotation age. European alder ranked third in the total weight yield in this study. Other studies of biomass production for species of this genus have involved red alder (Alnus rubra Bong.) in the Pacific Northwest region of North America (DeBell, 1972; Smith, 1973). DeBell found 3- and 4-year-old natural stands of red alder to yield about 3.6 m t / h a / y e a r of bark and wood, or 14.4 m t / h a for a 4-year-old stand, while yield of these components in our study was about 19.5 mt/ha. It is emphasized that the preceding discussion has dealt exclusively with yields from seedlings and that yields of coppice stands from established root stocks may be greater. CONCLUSIONS (1) There was a m a x i m u m difference of more than three-fold in total weight yields (28.0 vs 92.3 mt/ha) for five deciduous tree species planted at a close spacing (0.9 m × 0.6 m) and harvested after four growing seasons. (2) Yield data for hybrid poplar, American sycamore and European alder

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compared favorably with published yields for similar species and growing conditions. ACKNOWLEDGEMENTS

Fin~mcial support of Western Kraft Corporation, Hawesville, Kentucky, and the McIntire-S~ennis Cooperative Research Program is gratefully acknowledged. The authors are indebted to Mr. Robert King and Mr. James Clayton of Western Kraft Corporation; and to Dr. E.H. White, University of Minnesota and Dr. D. Hook, Clemson University for their efforts in the conduct of this research project. REFERENCES Belanger, R.P. and Saucier, J.R., 1975. Intensive culture of hardwoods in the south. Iowa State J. Sci., 49: 339--344. Bowersox, T.W. and Ward, W.W., 1976. Growth and yield of close-spaced, young hybrid poplars. For. Sci., 22: 449--454. Crow, T.R., 1971. Estimation of biomass in an even-aged stand --regression and "mean tree" techniques. In: H.E. Young (Editor), Forest Biomass Studies. Univ. Maine Press, Orono, Maine, pp. 35- 48. Dawson, D.H., Isebrands, J.G. and Gordon, J.C., 1976. Growth, dry weight yields, and specific gravity of 3-year-old Populus grown under intensive culture. USDA For. Serv. Res. Pap. NC-122, North Cent. For. Exp. Stn., St. Paul, Minn., 7 pp. DeBell, D.S., 1972. Potential productivity of dense young thickets of alder. Crown Zellerbach, Central Research, Camas, Wash. For. Res. Note No. 2, 7 pp. Kennedy, Jr., H.E., 1975. Influence of cutting cycle and spacing on coppice sycamore yield. USDA For. Serv. Res. Note SO-193. S. For. Exp. Stn., New Orleans, La., 3 pp. Saucier, J.R., Clark, A. and McAlpine, R.G., 1972. Above ground biomass yields of short-rotation sycamore. Wood Sci., 5: 1--6. Smith, J.H.G., 1973. Biomass of some young red alder stands. In: H.E. Young (Editor), IUFRO Biomass Studies. Univ. of Maine Press, Orono, Maine, pp. 401--409. Steinbeck, K. and May, J.T., 1971. Productivity of very young Platanus occidentalis L. plantings grown at various spacings. In: H.E. Young (Editor), Forest Biomass Studies. Univ. of Maine Press Orono, Maine, pp. 153--162. Wood, B.W., Carpenter, S.B. and Wittwer, R.F., 1976. Intensive culture of American sycamore in the Ohio River Valley. For. Sci., 22: 338--342.