To determine factors controlling the carbon dynamics of an intensively managed landscape, we measured net CO2 exchange with the atmosphere using eddy covariance and soil CO2 fluxes using static chambers along a chronosequence of slash pine (Pinus elliottii var. elliottii) plantations consisting of a recent clearcut, a mid-rotation (10-yr-old) stand, and a rotation-aged (24-yr-old) stand…. More

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We measured net atmospheric exchanges of energy and water vapor using eddy covariance along a chronosequence of Pinus elliottii plantations in north Florida: a recent clear-cut, a mid-rotation stand, and a 24-year-old, rotation-aged stand. Reflected energy averaged 0.26 of incoming solar radiation at the clear-cut and 0.18 at the closed-canopy stands. The sum of sensible… More

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In this paper, we describe the process of assessing tower footprint climatology, spatial variability of site vegetation density based on satellite image analysis, and sensor location bias in scaling up to 1 km × 1 km patch. Three flat sites with different vegetation cover and surface heterogeneity were selected from AmeriFlux tower sites: the oak/grass site and the annual… More

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Inhibition of respiration has been reported as a short-term response of tree roots to elevated measurement CO2 concentration ([CO2]), calling into question the validity of root respiration rates determined at CO2 concentrations that differ from the soil [CO2] in the rooting zone. Our objectives were to validate previous observations of a direct CO2 effect on… More

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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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