Plant Community Response to Compaction and Harvest Removal in a Coastal Plain Loblolly Pine (Pinus taeda) Plantation
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Date
2008-03-13
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Abstract
In 1992 the Southern Research Station, United States Department of Agriculture Forest Service, constructed three Long-Term Soil Productivity (LTSP) installations in a loblolly pine (Pinus taeda) plantation on the Croatan National Forest in Craven County, NC. The LTSP study consists of a nationwide network of experiment sites designed to examine the long-term effects of soil disturbance (compaction and organic matter removal) on forest productivity, one aspect of which is the development of forest plant communities. A vegetation survey, focusing on the extremes of the soil compaction (no compaction, severe compaction) and organic matter removal treatments (bole only, whole tree + forest floor), was performed in the summer of 2006 to address the following objectives: (1) to characterize the plant communities on the site, (2) to determine the interaction of organic matter removal and compaction treatments 14 years post-treatment, and (3) to compare current vegetation patterns with the pre-treatment and two years post-treatment vegetation described by earlier vegetation surveys. Analyses focused on changes (pre-harvest to 2006) in vascular plant richness, 2006 density of stems, multivariate between-plot differences in 2006, changes in species composition over time, and ordination of plot successional trajectories over time.
Both treatment factors influenced early-successional changes in species composition, but by 2006 post-treatment organic matter removal effects were limited. Severe compaction still negatively influenced vascular plant richness. Successional changes in species composition and richness appear to have proceeded at a delayed pace on severely compacted plots. Analyses by vascular plant growth form identify vines as particularly sensitive to both compaction and organic matter removal. Study results also suggest that the impacts of such experimental treatments, even when statistically significant, on the development of plant communities in loblolly plantations are not as strong as the general influences of timber harvest and site soil conditions. If conservation of species richness is a value, forest land managers are cautioned to avoid extremes of soil compaction.
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Croatan National Forest, CVS Protocol, vegetation survey, harvest disturbance, organic matter removal, soil compaction
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MS
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Natural Resources
