We describe a simple method for sampling soil gas at different profile depths and analyzing CO2 concentration in the gas sample. Soil gas samples were taken on the soil surface from each chosen depth through a gas circulation system and analyzed in situ with an infrared gas analyzer. The method is suitable for quickly handling… More

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In this paper, the one-dimensional, process-based soil CO2 model (PATCIS) described in Part 1 is parameterized and validated with field data collected in a mature slash pine plantation in Florida. The results of a model sensitivity analysis show that CO2 efflux in the plantation is most sensitive to soil temperature and associated parameters and that… More

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Phenological observations were used in conjunction with destructive sampling and measurements of plant cover to determine the aboveground seasonal dynamics, annual aboveground net primary production (ANPP), and responses to fertilizer applications of the rhizomatous, perennial, understory species, saw palmetto (Serenoa repens (Bartr.) Small), in a north-central Florida pine ecosystem. Phenology was not significantly affected by… More

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Eddy covariance was used to measure energy fluxes from July 2000 – June 2002 above the tree canopy and above the understory in a mature, naturally regenerated slash pine (Pinus elliottii Engelm. var. elliottii) – longleaf pine (Pinus palustris Mill.) flatwoods forest. Understory latent energy (λE) and sensible heat (H) fluxes accounted for 45% and… More

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Net photosynthesis was measured under field conditions in 23-year-old slash pine (Pinus elliottii Engelm. var. elliottii) trees to determine how it was affected by fertilization and climate. There was only a small decrease in rates of net photosynthesis from late summer through winter demonstrating that appreciable carbon gain occurs throughout the year in slash pine…. More

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In order to develop a model of the carbon cycle for mature slash pine (Pinus elliottii) stands in north Florida, we studied seasonal variation in leaf area index (LAI, allsided), aboveground biomass increment and litterfall, and light penetration through the forest canopy, over a 3—yr period. The primary approach to establishing monthly LAI included annual… More

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