In Alaska, an outbreak of spruce beetles (Dendroctonus rufipennis) recently infested over one million hectares of spruce (Picea spp.) forest. As a result, land management agencies have applied different treatments to infested forests to minimize fire hazard and economic loss and facilitate forest regeneration. In this study we investigated the […]
[1] Nitrous oxide (N2O) is an important greenhouse gas and participates in the destruction of stratospheric ozone. Soil bacteria produce N2O through denitrification and nitrification, but these processes differ radically in substrate requirements and responses to the environment. Understanding the controls over N2O efflux from soils, and how N2O emissions may […]
The labeled atoms of carbon and nitrogen are widely used in biology, biochemistry, and soil science. Both radioactive (14C) and stable (12C, 13C,15N) isotopes are used as such labels. Recently, an increase in mass spec-trometry sensitivity made it possible to study natural ratios of carbon (13C/12C) and nitrogen (15N/14N) stableisotopes […]
1. The effects of global change on below-ground processes of the nitrogen (N) cycle have repercussions for plant communities, productivity and trace gas effluxes. However, the interacting effects of different components of global change on nitrification or denitrification have rarely been studied in situ. 2. We measured responses of nitrifying enzyme activity […]
[1] Measuring the stable isotope composition of nitrous oxide (N2O) evolved from soil could improve our understanding of the relative contributions of the main microbial processes (nitrification and denitrification) responsible for N2O formation in soil. However, interpretation of the isotopic data in N2O is complicated by the lack of knowledge of […]
Free air carbon dioxide enrichment (FACE) and open top chamber (OTC) studies are valuable tools for evaluating the impact of elevated atmospheric CO2 on nutrient cycling in terrestrial ecosystems. Using meta-analytic techniques, we summarized the results of 117 studies on plant biomass production, soil organic matter dynamics and biological N2 […]
Amidst a network of tunnels and pores, soil organisms recycle carbon and nutrients. They mix plant litter and detritus, causing changes in soil structure that can ultimately influence the amount of water and oxygen available for plant roots. They are also eaten by aboveground predators, providing direct connections between below-and […]
Increased carbon storage in ecosystems due to elevated CO2 may help stabilize atmospheric CO2 concentrations and slow global warming. Many field studies have found that elevated CO2 leads to higher carbon assimilation by plants, and others suggest that this can lead to higher carbon storage in soils, the largest and […]
Hurricane disturbances have profound impacts on ecosystem structure and function, yet their effects on ecosystem CO2 exchange have not been reported. In September 2004, our research site on a fire-regenerated scrub-oak ecosystem in central Florida was struck by Hurricane Frances with sustained winds of 113 km h−1 and wind gusts as high […]
Forest management, climatic change, and atmospheric N deposition can affect soil biogeochemistry, but their combined effects are not well understood. We examined the effects of water and N amendments and forest thinning and burning on soil N pools and fluxes in ponderosa pine forests near Flagstaff, Arizona (USA). Using a […]