Releases of the greenhouse gases carbon dioxide (CO2) and methane (CH4) from thawing permafrost are expected to be among the largest feedbacks to climate from arctic ecosystems. However, the current net carbon (C) balance of terrestrial arctic ecosystems is unknown. Recent studies suggest that these ecosystems are sources, sinks, or approximately in balance at present…. More

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Aerodynamic canopy height (ha) is the effective height of vegetation canopy for its influence on atmospheric fluxes and is a key parameter of surface‐atmosphere coupling. However, methods to estimate ha from data are limited. This synthesis evaluates the applicability and robustness of the calculation of ha from eddy covariance momentum‐flux data. At 69 forest sites,… More

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Soils contain about twice as much carbon as Earth’s atmosphere, so their response to warming is crucial to understanding carbon fluxes in a changing climate. Past studies have heated soil to a depth of 5 to 20 cm to examine such fluxes. Hicks Pries et al. heated the ground to a depth of 100 cm…. More

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During the summer of 2001, NO2, total peroxy nitrates (ΣPNs), total alkyl nitrates (ΣANs), HNO3, volatile organic compounds (VOC), CO2, O3, and meteorological variables were measured at Granite Bay, CA. The diurnal variation in ΣPNs, ΣANs and HNO3 were all strongly correlated with sunlight, indicating both that they are photochemically produced and that they have… More

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Ponderosa pine is one of the most sensitive species to ozone and a dominant species in the Sierra Nevada Mountains. To assess the factors controlling ozone deposition to the forest and to study the forest response, we established a research site in a ponderosa pine plantation ∼75 km northeast of Sacramento. Ozone concentration and ozone… More

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The largest biological fractionations of stable carbon isotopes observed in nature occur during production of methane by methanogenic archaea. These fractionations result in substantial (as much as ≈70‰) shifts in δ13C relative to the initial substrate. We now report that a stable carbon isotopic fractionation of comparable magnitude (up to 70‰) occurs during oxidation of… More

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