OF THINNING SCARLET OAK STANDS SOUTHERN MISSOURI. Richard A. Williams Forester International Paper Company Camden, Arkansas 71701

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1 425 SILVICULTURAL AND ECONOMIC IMPLICATIONS OF THINNING SCARLET OAK STANDS IN SOUTHERN MISSOURI Richard A. Williams Forester International Paper Company Camden, Arkansas William B. Kurtz AssociateProfessor University of Missouri Columbia, Missouri and Harold E. Garrett AssociateProfessor University of Missouri Columbia, Missouri ABSTRACT A silviculturaland economicanalysiswas conductedon thinnedand unthinned30-year-oldstandsof scarletoak. Diametergrowth was significantlygreater for released stands. Growthresponsewas relatedto bothdiameterof the residual trees and residual stocking level. The managementregime which included thinning yielded the higher return.

2 426 INTRODUCTION The scarlet-black oak species mix is a very important part of Missouri's forest resource. Twenty-three percent of Missouri's commercial timberland, predominantly located in the Ozarks, is comprised of immature stands of scarlet oak (Quercus coccinea Muenchh.) and black oak (Quercus velutina Lam. l _he scarlet oak component is typically found growing in dense overstocked conditions, although it has been reported that scarlet oak does not grow well under such conditions of high density stocking (Core, 1971). Both silvicultural and economic factors determine the management scheme and length of rotation to derive maximum benefits from a stand. As part of a comprehensive examination of the silvicultural and economic implications of thinning young, overstocked scarlet oak, this paper reports the growth responses and the financial feasibility of thinned and unthinned scarlet oak stands. STUDY AREA The study_site is located in Texas County, Missouri (370 20' N Lat., 91V 51' W Long.) on moderately dissected topography. The study stands comprise a portion of an even-age, second growth forest consisting of near pure stands of 30-year-old scarlet oak interspersed with black, white (Quercus alba L.) and northern red oak (Quercus borealis michx_ f.) dissected by pockets of young shortleaf pine (Pinus echinata Mill.) The forest originated from clearcuts conducted in the 1940's and has hadno previoustreatments. The soils of the area are highly variable ranging from clayey, mixed Typic Paleudults which are deep, well-drained and moderately permeable to fine-loamy, siliceous mesic Typic Fragiudalfs which are moderately well-drained with a dense fragipan 20 to 27 inches belo_ the surface. The mean annual temperature of the area is 56 F. The mean annual precipitation is 38inches.

3 427 MATERIALS ANDPROCEDURES _i_nnin_ Stands and Growth Measurements Individual mixed oak stands were thinned in 1975 leaving ure stands of scarlet oak Trees were felled with chain saws nd a four-pound per acre acid-equivalent of a low volatile,4,5,t herbicide mixed with #2 rue! oil was applied to all tumps. Approximately one-third of the existing basal area was emoved leaving residual stockings ranging from 50 to 70 square et per acre Downed trees were left on the site as no ntermediate market for small diameter material was available. n the fall of 1977, at the completion of the second growing eason after thinning, 24 one-tenth-acre square plots--four each residual basal area classes of 50, 55, 60, 65 and 70 square et per acre and four in non-thinned control stands--were stablished. Twelve trees, three from each of four one-inch iameter classes (4,5,6, and 7) were selected on each plot and ored to determine two-year growth increments. Growth data were nalyzed using analysis of variance and least significant ifference (LSD) at the 95% confidence level. conomic Procedures In order to evaluate the relative economic feasibility of inning scarlet oak stands a comparison was made between the two anagement alternatives considered- no thinning and thinning nce at 30 years, each carried to a 60-year rotation. Future tand volume for the no thinning alternative was estimated from ield tables developed by Gingrich (1971). For the thinning lternative, results from the thinned stands in combination with npublished yield estimates from a comparable stand thinned some 0 years previously at age 30 were utilized (Sander, I.L. 1978, ersonal communication. USDA Forest Service, North Central orest Experiment Station, Columbia, MO). The 20 years of rowth recorded in this unpublished material provided a basis for stimating anticipated growth of the study stands to age 50. To roject diameter growth an additional 10 years to age 60, the verage annual diameter increase recorded from age 30 to 50 was duced by 50 percent. The anticipated number of trees per acre r each of the stands under the respective management lternatives was based on actual tree counts recorded on the tudy plots. Final harvest volumes at the end of the rotation 60 years) were estimated to be 5,160 bd. ft. per acre for the o thinning alternative and 9,150 bd ft. per acre with one inning at a stand age of 30 years.

4 428 Cost and revenue transactions for each of the alternative management regimes were constructed to calculate investment profitability. Economic feasibility was evaluated through the use of a financial analysis computer program developed by Goforth and Mills (1975). Two measures of investment analysis, present net worth (PNW) and internal rate of return (IRR) were utilized to gauge each of the alternatives Costs incurred before age 30 were not included in the analysis since they may be considered as sunk costs. The magnitude and timing of such costs theoretically do not affect the choice of future management investment. alternatives Land costs of a landowner were likewise who retains his excluded, based on the assumption that the owner will the land not sell has no other his land after alternative harvesting use the and that timber. The period of analysis therefore starts at year 30 and ends at year 60. Annual costs are incurred every year from year 30 through final harvest at year 60; the cost of precommerical thinning is incurred at age 30. Both of these costs are carried at compound interest until the final harvest is made. The revenuefrom stumpage sale is obtained at 60 years, rotation's end. A stumpage price of $20.00 per MBF, the current market price for scarlet oak, was utilized in the anaylsis. Furthermore, an annual average increase in real stumpage price was incorporated to account for anticipated price increases in the hardwood stumpage market over and above all other costs and returns. Annual costs (property taxes and maintenance) were estimated to be $2.50 per acre and precommercial thinning costs at $16.00 per acre. No formal market exists at present for products of the thinning so it was presumed that this material would be left on the site whi.ch is the current practice. GrowthResponses RESULTS ANDDISCUSSION The biological importance of thinning overstocked scarlet oak stands in the Missouri Ozarks is clearly demonstrated by this study. Two-year diameter growth responses by thinned stands were consistently greater than unthinned stands. Diameter growth increment varied within diameter of the residual trees and residual stocking level.

5 429 Residual Stem Diameter and Growth Response: Independent of he residual basal area, annual increment of thinned and nthinned trees was directly related to diameter class (table 1). ean increases by diameter classes for all thinned piqts were o42_ 0o48_ 0 59 and 0.65 inches for classes 4 through 7 inches, espectively. Thinned trees within the 4- and 5-inch classes howed an average growth of only 0 06 inches more than the nthinned controls. In contrast, 6- and 7-inch trees had verage diameter increases of 0.16 and 0.15 inches more, espectively, than their unthinned counterparts during the same ime period. A comparison of diameter increase within diameter classes etween residual stocking levels indicates that 6- and 7-inch rees generally produced significantly greater growth when inned regardless of the residual stocking. However ignificant differences in the diameter growth of 4- and 5-inch ees between thinned and unthinned stands was observed only in o instances (table I). Due to the low market value of scarlet oak and an average ost of $16.00 per acre associated with a precommercial inning, the retention of stems 6 inches or larger takes on reat importance in the economic justification of a thinning eatment. Residual Stand Density and Growth Response" Scarlet oak tands, regardless of the residual stocking, produced ignificantly greater diameter growth (P<O.05) when thinned. ignificant differences observed in growth increments between e plots of various basal areas are attributed to a combination f species sensitivity to various stocking densities and to ifferences in site quality between plots. Though individual ites were selected on the basis of uniformity in appearance, oil classification following the collection of diameter growth ata revealed the presence of four soil series, Doniphan_ oulstone, Hobson and Gatewood. Doniphan and Coulstone are eep, well-drained soils. Hobson typically has a fragipan ositioned at a depth of 20 to 27 inches. Gatewood is likewise hallow with bedrock commonlylocated at less than 40 inches. A comparison of the two-year diameter growth of scarlet oak this study clearly illustrates the effects of the soils as monstrated in the following tabulation.

6 Table 1. TWO YEAR DIAMETER GROWTHOF THINNED AND UNTHINNED SCARLET OAK STANDS. Diameter Class Unthinned Plots Thinned Plots ---(inches) ResidualStocking(,sq.ft.of BA) _ Two-yeardiameter-growthininches 4 O.37a O.42ab O.39ab O.38ab O.46c 0.44bc 5 O.42a O.49a 0.48a O.42a O.50a O.50a a 0.61d 0.54bc 0.53b 0.64d 0.61cd a 0 63bc 0 59ab 0 60bc 0 74d 0 68cd 0.43a 0.54c 0.50b 0.48b 0.59d 0.56-c-6 Note" No significant difference (P>O.05) was found between those numbers having the same letter within a row.

7 431 Soil t e Diameter _rowth (inches) Doniphan 0o55 Coulstone 0.54 Hobson 0.52 Gatewood O.48 Significantly less diameter growth was observed on the Gatewood soils. The least diameter growth response at a residual stocking level of 60 square feet (table 1) is attributed to the placement of two of four plots on this soil type. By considering only plots containing either Doniphan or Coulstone soils, the effects of residual stocking on diameter growth may be more clearly defined. An average annual diameter increase of 0.28 inches was found over the two-year period for residual stockings_of 60 and 65 square feet per acre while plots with basal areas of 70 yielded an increase of 0.27 inches. The least growth was observed on plots containing 50 and 55 square feet with each having average annual diameter increases of 0.25 inches. Gingrich (1971) suggested that approximately 70 percent residual stocking should remain following the first thinning of upland hardwoods at age 30. This corresponds to a residual basal area of approximately 60 in our study. Growth responses observed over the first two years following thinning in scarlet oak appear to support Gingrich's recommendation. Economic Implications As indicated in the preceding, a significantly higher increment of diameter growth can be expected as the result of thinning scarlet oak. The question still remains however as to the economic feasibility of applying such a management practice. The anticipated financial yields of the two management alternatives in terms of IRR and PNW(5% interest rate) are presented below. Management Alternative IRR PNW(5%) T $/ac. '... Nothin Thin years

8 432 Under the conditions outlined in this study a management alternative in which scarlet oak stands are thinned once at age 30 yields higher financial returns than a management alternative which does not include thinning. This relationship indicates that the increase in volume as a result of thinning more than offsets the corresponding increase in costs, even when carried for 30 years at compound interest. It should be emphasized however that the financial return from the thinning practice investment is relatively low. Thus, a prudent timberland owner with an alternate possibility for his capital yielding greater than 5.3 percent would invest in this alternative use. In a similar vein, for stands such as included in this study, Farrell (1964) found the practice of letting Ozark timberland develop without any silvicultural treatment to be low profit yielding. Conversely, moderate profits were obtained for intensively managed stands with available markets for the products of intermediate thinnings. As previously indicated though, no such market exists in the area for intermediate thinning products from scarlet oak so financial yields were somewhat lower for this analysis. CONCLUSI ONS Significant increases in diameter growth of scarlet oak occurred as a result of thinning. This increase was evident even though only two years of growth measurements were recorded. Diameter growth response was found to be significantly related to both the diameter of the residual trees and the residual stocking level. Trees within the 6- and 7-inch diameter classes grew at significantly greater rates than 4- and 5-inch trees and should be emphasized in early thinnings of this species. Residual stocking levels,within the range from 60 to 70 square feet of basal area, did not appear to be as important as the diameter of the residual trees in influencing diameter increases. However, a residual stocking level of from 60 to 65 square feet provides the greatest diameter increase and allows for full utilization of the site under the conditions of this study. Financial returns from thinned stands were greater than from unthinned stands of scarlet oak. A 5.31 percent IRR for the thinning alternative resulted from a volume increase which more than offset the additional costs of thinning. Increased growth and corresponding financial gains emphasize the importance of thinning young, overstocked scarlet oak stands in the Missouri Ozarks.

9 433 LITERATURE CITED Core, Eo SILVlCAL CHARACTERISTICSOF THE FIVE UPLAND OAKS Oak Symposium Proceedings. USDA Forest Service, Northeast. For. Exp. Sta., Upper Darby, Pa. 161 p. Farrell, J. Ho TIMBER INCOMEPOTENTIAL FROMSMALL FORESTS IN THE MISSOURI OZARKS. USDA For. Serv. Res. Pap. CS-11, Cent. St. For. Exp. Sta., Columbus, OH 74 p. Gingrich, S MANAGEMENTOF YOUNGAND INTERMEDIATE STANDS OF UPLAND HARDWOODS. USDA For. Serv. Res. Pap. NE-195, Northeast. For. Exp. Sta., Upper Darby, PA 26 po Goforth, M.H. and T.J. Mills A FINANCIAL RETURNPROGRAM FOR FORESTRY INVESTMENTS. USDA For. Serv. Agric. Hdbk. 488, Wash. D.C. 18 p.