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LTSP Root Growth and Methodology

FS-SRS- 4160-201 - Measuring Growth of Pine and Competitor Roots under Ten Silvicultural Treatments

This study is in addition to the standard LTSP measurements, and will test to what degree harvesting and silvicultural treatments, such as soil compaction and removal of organic matter before planting, and herbicide control of regrowth, affect the root elongation rates and distribution of competing plant species. The results of this study will be related to other concurrent studies of aboveground growth, decomposition rates and nutrient cycling.

The absorbing surface of a root system is the principle component to water and nutrient uptake. A remarkably constant relationship has been shown between root system biomass and stem diameter for coniferous and deciduous tree species. A relationship between root length and pine seedling height has also been shown for loblolly pine (Ludovici 1995). Aboveground physiological responses of trees to environmental factors will subsequently impact belowground growth processes including root extension, longevity and turnover and decomposition. Each of these root processes is independently impacted by water and nutrient availability.

Objectives

Four objectives were targeted with this research. The first is to compare root morphological and biomass distributions by depth for pines grown under different compaction and organic matter removal treatments. The second is to compare root morphological and biomass distributions for split-plot treatments of competition control. The third objective is to quantify the increased root growth and changes in distribution on the ameliorated plots compared to the other treatments, and the fourth objective is to relate root density and growth rate to shoot volume or elongation rate.

Methods

The study site was established in 1991 at the Croatan National Forest in Craven County, North Carolina. Soils in the area are Aquic Paleudults and Aeric Paleaquults. An approximately 60-year-old mixed pine hardwood stand occupied the site prior to harvest. A factorial design, with three levels of soil compaction and three levels of organic matter removal, and split plot treatments for competition control, was randomly imposed on 0.4 ha plots and replicated in each of three blocks. Root windows were first installed in October 1996. Subsequent efforts included development of an improved root window design, and mechanization of data collection and measurements.

Products

Ludovici, K.H., F.G. Sanchez and M.A. Buford. 1999. The Croatan LTSP: A Case Study in The Role of Plantation Forestry in Carbon Sequestration. SSSA. Oct. 31-Nov. 4, Salt Lake City, Utah (Abstract)

Ludovici, K.H., M.A. Buford, R.J Eaton and F.G. Sanchez. 1999. Five year Nutrient Use on the Croatan NF Long Term Soil Productivity Study. SSSA. Oct. 31-Nov. 4, Salt Lake City, Utah (Poster)