Foliage and litter chemistry, decomposition, and nutrient release in Pinus taeda

Abstract

Following fertilization of forest plantations, high accumulations of nutrients in the forest floor creates the need to assess rates of forest floor decomposition and nutrient release. The study site was a 25-year old experimental loblolly pine plantation in the North Carolina Sandhills Region. Soluble and insoluble N, P, carbohydrate and phenol-tannin fractions were determined in foliage and litter by extraction with trichloroacetic acid. The long-term forest floor decomposition rate and decomposition and nutrient release in an experiment simulating removal of the overstory canopy were also determined. In litter, insoluble protein-N comprised 80%-90% of total-N concentration while soluble inorganic- and organic-P comprised 50%-75% of total-P concentration explaining forest floor N accumulations. Fertilization did not increase soluble carbohydrates in litter and forest floor decomposition rates. Loblolly pine forest floor decomposing in environmental conditions simulating removal of the overstory canopy was greatly accelerated and indicated 75% mass loss and release of 80% of the N pool within one year. This could result in a loss of substantial quantities of N at harvest due to low N uptake by seedlings in the newly planted next rotation suggesting management of the forest floor at harvest is essential to conserve site N capital in these N limited systems. © 2013 by the authors.