Site preparation is fundamental for establishing loblolly pine (Pinus taeda L.) plantations, but long-term sustainability of plantations established using mechanical treatments is in question because of concerns regarding soil tillage and the removal of harvest residue and soil organic matter. A study was installed in 1981 on 12 locations in northeastern Georgia and west-central South Carolina to evaluate pine plantation response to mechanical site preparation. Site preparation treatments induced gradients of organic matter manipulation and soil tillage. The treatments included: Control, Chop/Burn, Shear/Disc, Shear/V-Blade, Shear/Rake, and Shear/Rake/Pile. Research was conducted to address the following objectives: (i) compare rotation-age forest response to several intensive site preparation treatments used to establish pine plantations in the Piedmont of the southeastern United States; (ii) correlate growth response with the gradients of soil organic matter removal, soil tillage, and hardwood control; (iii) determine the influence of intensive management on the amount of carbon contained in pine plantations.
All site preparation treatments increased year-18 volume accumulation compared to the control treatment. Chop/Burn and Shear/Disc treatments, with pine volumes of 214 m3 ha-1 and 232 m3 ha-1, respectively, conserved harvest residue and out-performed the Shear/Rake treatment (191 m3 ha-1), which completely removed harvest residue. Treatments that included tillage provided growth benefits that lasted throughout the rotation even when tillage was accompanied by complete organic matter removal. Hardwood competition had the greatest influence on pine volume accumulation, explaining over 54% of the variation in pine growth at age 18. Treatments that included tillage most effectively controlled hardwood competition.
At year 18, site preparation treatments significantly affected soil organic matter (SOM) content; however, soil nitrogen, foliar nitrogen, bulk density, and macroporosity were not affected by site preparation. All treatments were equally deficient in foliar nitrogen. The Shear/Disc and Shear/Rake/Disc treatments had a significantly positive relationship between foliar nitrogen and pine volume. These treatments had lower hardwood basal areas (below 15%), indicating that once hardwoods were controlled, nitrogen became limiting to pine growth.
Using pre-harvest characterization data, carbon accumulation during old-field succession increased fourfold compared to agricultural sites on the nearby Calhoun Experimental Forest. Carbon accumulation on these old-field loblolly pine sites reached quasi-equilibrium after 40 years as shown by uncut reference stands. Site preparation significantly affected the amount of soil C in the upper 20 cm of the soil. Those site preparation treatments that removed harvest residue and accelerated SOM decomposition through tillage had the lowest soil carbon levels. The Shear/Rake/Disc treatment had 10% lower soil carbon content than the Control and Shear/V-Blade treatments. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/31435 |
| Date | 16 March 2004 |
| Creators | Cerchiaro, Michael Paul |
| Contributors | Forestry, Burger, James A., Zedaker, Shepard M., Aust, W. Michael, Torbert, John L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | Cerchiaro.pdf |
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