Three to five dominant trees from each of 445 ten-factor variable radius inventory points were utilized to evaluate the height- diameter relationships of 13 species or genera found on bottomland hardwood sites throughout east Texas. Regression analysis was performed using the linear model such that height = (30 + (31 x (d.b.h.). The species were placed into six groups: (1) pines (Pinus taeda and P. enchinata) ; (2) water oak/willow oak/white oak/swamp chestnut oak (Quercus nigra)/(Q. phe//os)/(Q. alba)/(Q. michauxi1) ; (3) blackgum/laurel oak/overcup oak (Nyssa sylvatica)/(Q. laurifolia)/(Q. lyrata); (4) ash/maple (Fraxinus spp.)/(Acerspp.); (5) hickories (Carya spp.), and (6) elms (Ulmus spp.), or were analyzed as individual species: (7) cherrybark oak (Q. pagoda) and (8) sweetgum (Liquidambar styraciflua) based on similar intercepts and slopes of the regression lines. The coefficients of the model were estimated and residual analysis conducted for each species group

Dale, Leslie A.

Holley, A. Gordon

Kronrad, Gary D.

Oswald, Brian P.

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Stephen F. Austin State UniversitySFA ScholarWorksFaculty Publications Forestry1998Initial Investigation of Height-DiameterRelationships of Dominant Trees in the mixedHardwood Bottomland Forests of East TexasBrian P. OswaldArthur Temple College of Forestry and Agriculture, Stephen F. Austin State University, boswald@sfasu.eduA. Gordon HolleyArthur Temple College of Forestry and Agriculture, Stephen F. Austin State UniversityLeslie A. DaleArthur Temple College of Forestry and Agriculture, Stephen F. Austin State UniversityGary D. KronradArthur Temple College of Forestry and Agriculture, Stephen F. Austin State UniversityFollow this and additional works at: http://scholarworks.sfasu.edu/forestryPart of the Forest Sciences CommonsTell us how this article helped you.This Conference Proceeding is brought to you for free and open access by the Forestry at SFA ScholarWorks. It has been accepted for inclusion inFaculty Publications by an authorized administrator of SFA ScholarWorks. For more information, please contact cdsscholarworks@sfasu.edu.Recommended CitationOswald, Brian P.; Holley, A. Gordon; Dale, Leslie A.; and Kronrad, Gary D., "Initial Investigation of Height-Diameter Relationships ofDominant Trees in the mixed Hardwood Bottomland Forests of East Texas" (1998). Faculty Publications. Paper 241.http://scholarworks.sfasu.edu/forestry/241INITIAL INVESTIGATION OF HEIGHT-DIAMETER RELATIONSHIPS OF DOMINANT TREES IN THE MIXED HARDWOOD BOTTOMLAND FORESTS OF EAST TEXAS Brian P. Oswald, Gordon Holley, Leslie Dale, and Gary D. Kronrad1 Abstract-Three to five dominant trees from each of 445 ten-factor variable radius inventory points were utilized to evaluate the height- diameter relationships of 13 species or genera found on bottomland hardwood sites throughout east Texas. Regression analysis was performed using the linear model such that height = (30 + (3 1 x (d.b.h.). The species were placed into six groups: (1) pines (Pinus taeda and P. enchinata) ; (2) water oak/willow oak/white oak/swamp chestnut oak (Quercus nigra)/(Q. phe//os)/(Q. alba)/(Q. michauxi1) ; (3) blackgum/laurel oak/overcup oak (Nyssa sylvatica)/(Q. laurifolia)/(Q. lyrata); (4) ash/maple (Fraxinus spp.)/(Acerspp.); (5) hickories (Carya spp.), and (6) elms (Ulmus spp.) , or were analyzed as individual species: (7) cherrybark oak (Q. pagoda) and (8) sweetgum (Liquidambar styraciflua) based on similar intercepts and slopes of the regression lines. The coefficients of the model were estimated and residual analysis conducted for each species group. INTRODUCTION There are about 180 million acres of commercial forest land in the Southern United States, 50 percent of which can be classified as being composed of hardwoods. Bottomland hardwood forests, growing on the flood plains of rivers and streams, comprise 14 percent (1.6 million acres) of the total commercial forest land in east Texas. These forests provide quality timber along with wildlife habitat. In east Texas, the area classified as bottomland hardwood has decreased by about 12 percent in the last 15 years, due primarily to the logging of accessible mature stands, shifts to croplands, and the development of man-made lakes (McWilliams and Lord 1988). The demand for hardwood products, both within the United States and for export, is increasing (McWilliams 1988, Hair 1980). The pulp and paper industry is utilizing more hardwoods in an effort to increase the quality of their product. In addition, the demand for high-quality logs for lumber, plywood, and veneer is increasing. Since 1975, the world demand for U.S. hardwood logs, veneer, and lumber has quadrupled (Araman 1989). Hardwood harvesting rates are increasing while the supply is decreasing {Tansey 1988, Birdsey 1983). Adequate information on bottomland hardwood growth and management has not kept pace with the knowledge we have on southern pines. (Porterfied 1972). Most of the research performed on bottomland hardwoods in the South to determine growth and yield information and management strategies of these species (Barrett 1995, Burns and Honkala 1990, Baker and Broadfoot 1979) often did not involve stands located in east Texas. The best management practices for the species found in these ecosystems in east Texas have not been determined, and growth equations, volume and yield tables, and site index curves for many southern hardwood species are lacking. This information gap is of such high priority to the National Hardwood Lumber Association, that resolution of this gap is one of their priorities for 1996. Since many of these questions can not be resolved in a single year, there will be a priority over the next decade to obtain the necessary information from which proper management decisions can be made. There is a need to obtain information on what species are found in the bottomlands of east Texas as well as the stand structure of these bottomlands. Basic height and diameter relationship information on the dominant trees in these stands will provide some of this information. The objective of this study was to evaluate the dominant tree height-diameter relationships of the major species in the mixed bottomland hardwood forests of east Texas. METHODS The study areas were chosen to represent bottomland hardwood stands common to the region and data was collected from numerous sites within Angelina, Nacogdoches, Newton, Sabine, San Augustine, and Shelby Counties in the summers of 1993, 1994, and 1995. Sample points were systematically located within the study areas. Distance between points was three chains, and distance between transect lines was five chains. Initially the tallest five trees sampled with a 10-factor prism were utilized in this study, and the species, total height (to nearest foot) breast height (d.b.h. to nearest tenth of a foot) were recorded for each of these sampled trees. Species included cherrybark oak (Quercus pagoda) , willow oak (Q. phellos), water oak (Q. nigra), laurel oak (Q. laurifolia), white oak (Q. alba), overcup oak (Q. lyrata), swamp chestnut oak (Q. michauxi1) , sweetgum (Liquidambar styraciflua) , blackgum (Nyssa sylvatica), and pines (Pinus taeda and P. enchinata). A variety of hickories (Carya spp.), elms (Ulmus spp.), ash (Fraxinus spp.) , and maples (Acer spp.) were also recorded. Additional species were initially included in the sample, but since they each totaled less than 10 individuals across all of the sample points, they were excluded from the analysis. 1 Assistant Professor, Research Associates, and Associate Professor, respectively, Arthur Temple College of Forestry, Stephen F. Austin State University, Nacogdoches, TX 75962. 608 Statistical analysis followed Oswald and others (1994). Preliminary analysis indicated that the relationship between tree height and d.b.h. of the dominant trees was linear. Therefore, the following equation was used for each of the above species: Height= 130 + 131 x (d.b.h.). (1) Based on the similarity of the intercepts and slopes of the regression lines for each species, some of the species were placed into species groups. The equation (1) was then fitted to each species group. Otherwise, the species were evaluated individually. Residual analysis was also conducted for each model. RESULTS AND DISCUSSION Among the 2, 165 dominant trees sampled, 73. 7 percent were oaks (Q. spp.) with willow oak (26.1 percent), cherrybark oak (15.5 percent) , and water oak (14.0 percent) being the dominant species (table 1 ). Only sweetgum (15.2 percent) approached these oaks in frequency. The tallest species tended to be cherrybark, white, willow and water oaks, while those with the largest d.b.h . were swamp chestnut oak and cherrybark oak. As is usually found on these sites, the maples, ash, and blackgum had the smallest mean diameters, while maple was the shortest in mean height. The equation (1) was fitted to each species with more than 10 individuals over all of the plots. Based on similarity of the intercepts and slopes of the regression lines for each species, the species were placed into six species groups : Pines, water oak/willow oak/white oak/swamp chestnut , blackgum/laurel oak/overcup oak, ash/maple, hickories, and elms, or were analyzed as individual species: cherrybark oak and sweetgum. Then the equation (1) was refitted to the groups and the resulting models obtained: (1) Ash/maple : HT = 54.40 + 1.82(d.b.h.) with N = 42, R2 = 0.39, and C. V. = 18.1 percent (2) Blackgum/laurel oak/overcup oak: HT= 63.05 + 1.30(d.b.h.) with N = 327, R2 = 0.35, and C.V. = 13.7 percent (3) White oak/swamp chestnut oak/willow oak/water oak: HT= 76.27 + 1.1 O(d.b.h.) with N = 990, R2 = 0.26, and C.V. = 12.1 percent (4) Cherrybark oak: HT= 82.59 + 1.08(d.b.h.) with N = 334 , R2 = 0.26, and C. V. = 13. 7 percent (5) Pine spp: HT= 67.46 + 1.45(d.b.h.) with N = 81 , R2 = 0.39, and C.V. = 9.7 percent (6) Sweetgum: HT = 60.02 + 1.95(d.b.h.) with N = 328, R2 = 0.47, and C.V. = 12.6 percent (7) Hickory spp.: HT= 69.87 + 1.23(d.b.h.) with N = 43, R2 = 0.16, and C. V. = 16.5 percent (8) Elm: HT= 19.50 + 3.07(d.b.h.) with N = 12, R2 = 0.57, and C.V. = 18.9 percent Equation ( 1) was also fitted to the total number of trees (2, 165) to provide an overall equation for the relationship between height and diameter of all of the dominant trees: HT= 69.78 + 1.36(d.b.h.) with R2 = 0.33, and C.V. = 13.67 Table 1-Total number of trees, averages, and ranges of tree diameter and height of the dominant trees Species Fraxinus spp. Nyssa sy/vatica Ulmus spp. Carya spp. Pinus spp. Acer spp. Liquidambar styraciflua Quercus pagoda Q. /yrata Q. michauxii Q. nigra Q. alba Q. phel/os Q. /aurifolia Total No. Mean trees d.b.h. 33 18.9 59 18.1 13 20.7 44 21 .7 82 22.1 10 18.8 329 19.7 335 25.2 116 22 .9 70 25.9 303 22.4 52 22.4 566 22.9 153 19.8 2165 21 .6 Mean Range height Range Inches Feet 7.1-35.4 92.9 45-150 6.6-39.1 85.8 58-135 11 .8-28.3 83.2 45-125 9.3-38.8 95.7 53-127 9.6-34.4 99.5 76-133 12.4-26.7 75 55-92 4.0-40.2 98.6 16-141 2.5-70.5 109.9 20-163 10.4-38.9 93.5 60-124 12.5-55.3 98.3 67-128 7.7-43.4 101.4 46-153 10.9-37.3 101 70-130 7.5-60.0 102 51 -144 4.8-48.6 88.7 58-136 2.5-70.5 94.7 20-163 Although the R2's of the models appear low, the primary purpose of the study was to evaluate the relationship between height and diameter of the dominant trees, not for prediction . The simulations using the above models for the groups are illustrated in figure 1. The dominant oak species (cherrybark, willow, and water) all have good-to-excellent growth rates, are intolerant to shade, and are intermediate to very intolerant to periodic flooding . Cherrybark is the best of the red oaks in the region, while water and willow oaks can be favored through management on the flats (Barrett 1995). The other highly frequent species, sweetgum, needs release for best growth and form, but shows medium growth rates when compared to the above oaks. Some of the other species found in this study, specifically the hickories and ashes, can be managed for, as they can provide good-quality products for a variety of uses when found on better sites. The two pine species will most likely become even less of a component of these stands with harvesting and succession. Even-aged management in the form of clearcuts or modified shelterwood (Loftis 1990), or with uneven management through group-selection, are common management tools used in other bottomland hardwoods in the South (Barrett 1995), and should be effective in producing a high-quality product while maintaining the stand structure found on these sites. CONCLUSIONS Stands similar to those utilized in this study are found throughout east Texas. Many of these stands have been mis-managed, poorly managed, or not managed for a number of years. These same stands had been high-graded in the past, and are now made up of a variety of species, 609 .w ..i:: .....---- Ash/maple -e- BLO _...,._ wws -+- cherry bark -0- pine 0 sweetgum -tr- hickory --<>- elm 175--+-~-+-~~+-~-+-~__,,,,,___,..>-___ ~ -~ 15 0 -+----+---+---t-.<~--.1.::,...c..7"' .... ~~ .... Q) :r: 125-t-~--r~----;1,~:,ti,.p~""f-~--r~---i 50<> ........ ~-+-,~.,....,..-1--.~~+---~~"--........ ....-..~~.-1 10 20 30 40 50 60 70 Diameter Figure 1-Simulation models of eight species groups. many of which do not have traditional market value. With the increase in demand for hardwood by the pulp and paper industry, these species-traditionally an impediment to harvesting, regeneration, and management-make these stands more attractive for management. As can be seen from this study, these stands can and do produce good individual stems of high-quality species such as cherrybark and some of the other oaks, as well as sweetgum and occasionally loblolly pine. More information is needed on stand structure, age/height/diameter relationships and site productivity before the necessary management guidelines can be developed. 610 LITERATURE CITED Araman, P.A. 1989. The changing hardwood export market and research to keep the U.S. competitive. Proceedings of 16th annual hardwood symposium of the Hardwood Research Council: 168-183. Baker, J.B.; Broadfoot, W.M. 1979. A practical field method of site evaluation for commercially important southern hardwoods. Gen. Tech. Rep. S0-26. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 51 p. Barrett, J.W. 1995. Regional silviculture of the United States. New York: John Wiley and Sons. 643 p. Birdsey, R.A. 1983. Tennessee forest resources. Resour. Bull. S0-90. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 35 p. Burns, R.M.; Honkala, B.H. 1990. Silvics of North America. Vol. 2. Hardwoods. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service. 887 p. Hair, D. 1980. Timber situation in the U.S.-1952-2030 . Journal of Forestry. 78(11 ): 683-686. Loftis, D.L. 1990. A shelterwood system for regenerating red oak in the Southern Appalachians. Forest Science. 36(4): 917-929. McWilliams, W.H. 1988. Hardwood supply and availability in the Midsouth Highlands. Hardwood Research Cooperative. Series 7. Availability of hardwoods in the upland South. p. 47-95. McWilliams, W.H.; Lord, R.G. 1988. Forest resources of east Texas. Resour. Bull. S0-136. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. Oswald, B.P.; Zhang, L.; Green, T.H. 1996. Height-diameter relationships of dominant trees in the mixed upland hardwood forests of North Alabama. Proceedings of eighth biennial southern silvicultural research conference; Auburn, AL. Gen. Tech. Rep. SRS-1. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 596-599. Porterfield, R.L. 172. Financial returns from managing southern hardwood stands for pulpwood. Journal of Forestry. 70(10): 624-627. Tansley, J.B. 1988. The hardwood resource in the Southern Uplands. Hardwood Research Cooperative. Series 7. Availability of hardwoods in the upland South. p. 4-45. 

Initial Investigation of Height-Diameter Relationships of Dominant Trees in the mixed Hardwood Bottomland Forests of East Texas

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Initial Investigation of Height-Diameter Relationships of Dominant Trees in the mixed Hardwood Bottomland Forests of East Texas

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