Site quality evaluation of loblolly pine on the South Carolina Lower Coastal Plain, USA

Abstract

Eleven soil types, which can be identified and delineated using conventional soil survey procedures, were characterized for loblolly pine (Pinus taeda L.) productivity. Four 4-hectare study sites, each containing four measurement plots, were established for every soil type studied. In a stepwise multiple regression, both soil parent material (i.e. a combination of subsoil texture and geology) (p<0.001), and drainage class (p=0.006) were significant predictors of site index (tree age 25), and the overall linear regression model had an R ² value of 0.55. The extremes of soil parent material differed by 3.9 m site index (loamy subsoil on the Wicomico-Penholoway surfaces versus clayey subsoil on the Pamlico-Princess Anne surfaces). Each increment of drainage class differed by 0.7 m site index. For example, a poorly drained soil had 0.7 m lower site index than a somewhat poorly drained soil. For seven of the eleven soil types studied, there is greater than 80% probability that estimated mean site index is within ±0.8 m of the actual soil type mean site index. The other four soil types (labeled G, I, C and K) need to be either redefined or sampled more intensively. Two of these need to be subdivided in order to adequately characterize site quality, one based on geology (Soil type G) and one based on soil drainage class (Soil type I). Variation in soil drainage class and varying amounts of topsoil displaced into windrows were both factors influencing site quality variation of a third soil type (Soil type C). The wide variation in site index data for a fourth soil type (Soil type K) appeared to be due, in part, to sampling study locations and individual measurement plots with less than optimum bedding and/or artificial drainage. Soil parent material (subsoil texture and geology) along with drainage class were found to be important factors influencing site quality on the South Carolina Lower Coastal Plain.

Keywords

site index / geology / soil parent material / soil texture / drainage class

References

[1] Allen H.L., Fox T.R., Campbell R.G. What is ahead for intensive pine plantation silviculture in the South? South J App. For, 2005, 29(2): 62-69.

[2] Campbell R.G. Balmer W.E. The Weyerhaeuser land classification system Proceedings soil moisture-site productivity symposium. USDA Forest Service, Southeast. Area State and Private Forest, 1978 Washington, D.C: U.S. Government Printing Office 74-82.

[3] Carmean W.H. Forest site quality evaluation in the United States Adv. Agron, 1975, 27(1): 209-269.

[4] Clutter J.L., Lenhart J.D. Site index curves for old-field loblolly pine plantations in the Georgia Piedmont Georgia For. Res. Council Rep. No. 22, 1968 Atlanta, GA: State of Georgia Printing Office 1-4.

[5] Colquhoun D.J. Geomorphology of the Lower Coastal Plain of South Carolina S.C. Div. Geol. Rep. No. MS-15, 1969 Columbia, SC: State of South Carolina Printing Services 1-36.

[6] Colquhoun D.J. Oaks R.Q. Jr., DuBar J.R. Cyclic surficial stratigraphic units of the Middle and Lower Coastal Plains, central South Carolina Post-Miocene stratigraphy central and southern Atlantic Coastal Plain, 1974 Logan, UT: Utah State Univ. Press 179-190.

[7] Colquhoun D.J., Woolen I.D., Nieuwenhuise D.S., Van G.G., Padgett R.W., Oldham D.C., Boylan J.W., Bishop, Howell P.D. Surface and subsurface stratigraphy, structure and aquifers of the South Carolina Coastal Plain S.C. Dept. Health Environ. Control, 1983 Columbia, SC: State of South Carolina Printing Services 1-78.

[8] Cooke C.W. Geology of the Coastal Plain of South Carolina U.S. Geol. Survey Bull. 867, 1936 Washington, D.C: U.S. Government Printing Office 1-196.

[9] Ellerbe C.M., Smith G.E. Jr. Apparent influence of phosphate marl on site index of loblolly pine in the Lower Coastal Plain of South Carolina J. For, 1963, 61(4): 284-286.

[10] Harrington C.A. PTSITE — a new method of site evaluation for loblolly pine: model development and user’s guide Gen. Tech. Rep. SO-81. USDA For. Service. So. For. Exp. Sta., 1991 Washington, D.C: U.S. Government Printing Office 1-28.

[11] Malde H.E. Geology of the Charleston phosphate area, South Carolina U.S. Geol. Survey Bull. 1079, 1959 Washington, D.C: U.S. Government Printing Office 1-105.

[12] McCartan B.L., Lemon E.M. Jr, Weems R.E. Geologic map of the area between Charleston and Orangeburg, South Carolina U.S. Geol. Survey Map I-1472, 1984 Washington, D.C: U.S. Government Printing Office 1-2.

[13] McKee W.H. Soil-site relationships for loblolly pine on selected soils Proc. Sixth South. For. Soils Workshop. USDA Forest Service, Southeast. Area State and Private Forest, 1977 Washington, D.C: U.S. Government Printing Office 115-120.

[14] Stone E.L. Balmer W.E. A critique of soil moisture-site productivity relationships Proceedings soil moisture — site productivity symposium. USDA Forest Service, Southeast. Area State and Private Forest, 1978 Washington, D.C: U.S. Government Printing Office 377-387.