USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO 80526, USA.
Published: October 2009
AI Article Synopsis
Article Abstract
We measured CO(2) efflux from wood for Eucalyptus in Hawaii for 7 years and compared these measurements with those on three- and four-and-a-half-year-old Eucalyptus in Brazil. In Hawaii, CO(2) efflux from wood per unit biomass declined approximately 10x from age two to age five, twice as much as the decline in tree growth. The CO(2) efflux from wood in Brazil was 8-10x lower than that for comparable Hawaii trees with similar growth rates. Growth and maintenance respiration coefficients calculated from Hawaii wood CO(2) efflux declined with tree age and size (the growth coefficient declined from 0.4 mol C efflux mol C(-1) wood growth at age one to 0.1 mol C efflux mol C(-1) wood growth at age six; the maintenance coefficient from 0.006 to 0.001 micromol C (mol C biomass)(-1) s(-1) at 20 degrees C over the same time period). These results suggest interference with CO(2) efflux through bark that decouples CO(2) efflux from respiration. We also compared the biomass fractions and wood CO(2) efflux for the aboveground woody parts for 3- and 7-year-old trees in Hawaii to estimate how focusing measurements near the ground might bias the stand-level estimates of wood CO(2) efflux. Three-year-old Eucalyptus in Hawaii had a higher proportion of branches < 0.5 cm in diameter and a lower proportion of stem biomass than did 7-year-old trees. Biomass-specific CO(2) efflux measured at 1.4 m extrapolated to the tree could bias tree level estimates by approximately 50%, assuming no refixation from bark photosynthesis. However, the bias did not differ for the two tree sizes. Foliar respiration was identical per unit nitrogen for comparable treatments in Brazil and Hawaii (4.2 micromol C mol N(-1) s(-1) at 20 degrees C).
Sulfate-reducing microorganisms (SRMs) show promise for heavy metal removal from contaminated environments, but their scalability is limited by reliance on organic carbon, sludge formation, and CO emissions. This study investigates using photoelectrons from biogenic (Bio-ZnS) and abiogenic (Abio-ZnS) sphalerite nanoparticles to enhance the activity of G20 (G20) for sulfate reduction and lead removal without organic substrates. Both Abio-ZnS and Bio-ZnS NPs promote sulfate reduction and energy production in G20 cells under illumination without the addition of organic substrates, with Bio-ZnS achieving 1.
Drying and rewetting of soil stimulates soil carbon emission. The Birch effect, driven by these cycles, leads to CO efflux, which can be monitored using real-time mass spectrometry (RTMS). Although soil fungi retain water during droughts, their contribution to CO release during drying-rewetting cycles remains unclear.
Blue Carbon Lab, Deakin Marine Research and Innovation Centre, Deakin University, Burwood campus, 221 Burwood Hwy, VIC 3125, Australia; Centre for Nature Positive Solutions, Biosciences and Food Technology Discipline, School of Science, RMIT University, Melbourne, VIC 3000, Australia.
Blue carbon cycling in mangrove ecosystems is more intricate than initially believed, prompting the use of structural equation modeling (SEM) for a deeper analysis.
The study utilized data from the Indian Sundarban to illustrate how SEM effectively integrates different data types to understand CO fluxes in mangroves, including key interactions between the atmosphere, water, and soil.
Findings indicate that atmospheric, water, and soil temperatures significantly drive CO emissions from mangrove ecosystems, demonstrating the utility of SEM in capturing complex biogeochemical cycles in blue carbon environments.
Department of Natural Resources and the Environment, Center for Soil Biogeochemistry and Microbial Ecology, University of New Hampshire, Durham, New Hampshire, USA.
Roots contribute a large fraction of CO efflux from soils, yet the extent to which global change factors affect root-derived fluxes is poorly understood. We investigated how red maple (Acer rubrum) and red oak (Quercus rubra) root biomass and respiration respond to long-term (15 years) soil warming, nitrogen addition, or their combination in a temperate forest. We found that ecosystem root respiration was decreased by 40% under both single-factor treatments (nitrogen addition or warming) but not under their combination (heated × nitrogen).
