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
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
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
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
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
We examined the effects of forest harvesting on the net exchange of methane (CH4) between the atmosphere and sandy soils in two mature slash pine (Pinus elliottii Engelm. var. elliottii) plantations in northern Florida. Before each of the stem-only harvests, soils in these plantations were net sinks for CH4 (-0.03 to -2.6 mg CH4·m-2·d-1) on… More
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
The AmeriFlux QA/QC Tech Team is currently concluding the 2014 site visit season. 8 site visits have been completed and 1 more is scheduled. This season, the team visited 4 sites for the first time (US-Dia, US-Cpk, US-Ha2, US-Myb).