Skip to main content
Advanced Search

Filters: Tags: Carbon flux (X)

31 results (320ms)   

Filters
Date Range
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
Terrestrial carbon sequestration potential is widely considered as a realistic option for mitigating greenhouse gas emissions. However, this potential may be threatened by global changes including climate, land use, and management changes such as increased corn stover harvesting for rising production of cellulosic biofuel. Therefore, it is critical to investigate the dynamics of soil organic carbon (SOC) at regional or global scale. This study simulated the corn production and spatiotemporal changes of SOC in the U.S. Temperate Prairies, which covers over one-third of the U.S. corn acreage, using a biogeochemical model with multiple climate and land-use change projections. The corn production (either grain yield...
Riverine exports of organic and inorganic carbon (OC, IC) to oceans are intricately linked to processes occurring on land. Across high latitudes, thawing permafrost, alteration of hydrologic flow paths, and changes in vegetation may all affect this flux, with subsequent implications for regional and global carbon (C) budgets. Using a unique, multi-decadal dataset of continuous discharge coupled with water chemistry measurements for the Mackenzie River, we show major increases in dissolved OC (DOC) and IC (as alkalinity) fluxes since the early 1970s, for a watershed that covers 1.8 M km2 of northwestern Canada, and provides substantial inputs of freshwater and biogeochemical constituents to the Arctic Ocean. Over...
In forests, total belowground carbon (C) flux (TBCF) is a large component of the C budget and represents a critical pathway for delivery of plant C to soil. Reducing uncertainty around regional estimates of forest C cycling may be aided by incorporating knowledge of controls over soil respiration and TBCF. Photosynthesis, and presumably TBCF, declines with advancing tree size and age, and photosynthesis increases yet C partitioning to TBCF decreases in response to high soil fertility. We hypothesized that these causal relationships would result in predictable patterns of TBCF, and partitioning of C to TBCF, with natural variability in leaf area index (LAI), soil nitrogen (N), and tree height in subalpine forests...
Dynamic tidal export of dissolved inorganic carbon (DIC) to the coastal ocean from highly productive intertidal marshes and its effects on seawater carbonate chemistry are thoroughly evaluated. The study uses a comprehensive approach by combining tidal water sampling of CO2parameters across seasons, continuous in situ measurements of biogeochemically-relevant parameters and water fluxes, with high-resolution modeling in an intertidal salt marsh of the U.S. northeast region. Salt marshes can acidify and alkalize tidal water by injecting CO2 (DIC) and total alkalinity (TA). DIC and TA generation may also be decoupled due to differential effects of marsh aerobic and anaerobic respiration on DIC and TA. As marsh DIC...
We develop a new framework, based on Landsat time series data and forest inventories, to estimate the carbon in roundwood harvested from forest management activities, which will enter the HWP pool and remain stored in end uses and landfills. The approach keeps the distinction between the carbon from different types of roundwood sources, which allows for better integration with the regional HWP carbon lifetime information. We show that existing methods that are based on large scale regional/national values and linear interpolation of data gaps, can provide only very approximate carbon estimates. The model was applied to a US state using county level data, but can also suit different areas as long as sufficient harvest...
thumbnail
The Great Dismal Swamp (GDS) project is an application of USGS LandCarbon, at the US Fish and Wildlife Service's (FWS) Great Dismal Swamp National Wildlife Refuge (NWR), and is designed to produce local-scale carbon estimates (including fluxes, ecosystem balance, and long-term sequestration rate) to include in an ecosystem service assessment in support of Department of Interior (DOI) land management activities. The project will improve the understanding of the effects of past drainage, logging, farming, and management on carbon sequestration and fire risk in peatlands. Broad Science Questions: How are ecosystem services (including carbon sequestration, wildlife viewing, water quality, and others) impacted by management...
The Biologic Carbon Sequestration Assessment Program (LandCarbon) is designed to support the following goals: Assess the current and potential carbon balance (stocks and fluxes) in major terrestrial and aquatic ecosystems Evaluate the effects of both natural and anthropogenic driving forces on ecosystem carbon balance and greenhouse gas fluxes Develop carbon monitoring methods and capabilities Conduct research and provide science support for increasing carbon sequestration in land management policies and practices The LandCarbon Community serves as a content management system for the LandCarbon Data Portal. This Data Portal is an effort to catalog and provide access to data and information from a range of LandCarbon...
Inland water ecosystems dynamically process, transport, and sequester carbon. However, the transport of carbon through aquatic environments has not been quantitatively integrated in the context of terrestrial ecosystems. Here, we present the first integrated assessment, to our knowledge, of freshwater carbon fluxes for the conterminous United States, where 106 (range: 71–149) teragrams of carbon per year (TgC⋅y−1) is exported downstream or emitted to the atmosphere and sedimentation stores 21 (range: 9–65) TgC⋅y−1 in lakes and reservoirs. We show that there is significant regional variation in aquatic carbon flux, but verify that emission across stream and river surfaces represents the dominant flux at 69 (range:...
thumbnail
This assessment was conducted to fulfill the requirements of section 712 of the Energy Independence and Security Act of 2007 and to contribute to knowledge of the storage, fluxes, and balance of carbon and methane gas in ecosystems of Alaska. The carbon and methane variables were examined for major terrestrial ecosystems (uplands and wetlands) and inland aquatic ecosystems in Alaska in two time periods: baseline (from 1950 through 2009) and future (projections from 2010 through 2099). The assessment used measured and observed data and remote sensing, statistical methods, and simulation models. The national assessment, conducted using the methodology described in SIR 2010-5233, has been completed for the conterminous...
The Upper Mississippi River, engineered for river navigation in the 1930s, includes a series of low-head dams and navigation pools receiving elevated sediment and nutrient loads from the mostly agricultural basin. Using high-resolution, spatially resolved water quality sensor measurements along 1385 river kilometers, we show that primary productivity and organic matter accumulation affect river carbon dioxide and methane emissions to the atmosphere. Phytoplankton drive CO2to near or below atmospheric equilibrium during the growing season, while anaerobic carbon oxidation supports a large proportion of the CO2 and CH4 production. Reductions of suspended sediment load, absent of dramatic reductions in nutrients, will...
thumbnail
This project links climate, hydrological, and ecological changes over the next 30 years in a Great Basin watershed. In recent years, climate variability on annual and decadal time scales has been recognized as greater than commonly perceived with increasing impacts on ecosystems and available water resources. Changes in vegetation distribution, composition and productivity resulting from climate change affect plant water use, which in turn can alter stream flow, groundwater and eventually available water resources. To better understand these links, project researchers implemented two computer-based numeric models in the Cleve Creek watershed in the Schell Creek Range, east of Ely, Nevada. The application of the...
thumbnail
This research focuses on understanding the rates, causes, and consequences of land change across a range of geographic and temporal scales. Our emphasis is on developing alternative future projections and quantifying the impact on environmental systems, in particular, the role of land-use change on ecosystem carbon dynamics. This project supports the development of the Land-use and Carbon Scenario Simulator (LUCAS) model. LUCAS tracks changes in land use, land cover, land management, and disturbance, and their impacts on ecosystem carbon storage and flux by combining: A State-and-Transition Simulation Model (STSM) to simulate changes in land-use across a range of geographic scales. A Stock and Flow Model to track...
Inland waters are an important component of the global carbon cycle through transport, storage, and direct emissions of CO2 and CH4 to the atmosphere. Despite predictions of high physical gas exchange rates due to turbulent flows and ubiquitous supersaturation of CO2—and perhaps also CH4—patterns of gas emissions are essentially undocumented for high mountain ecosystems. Much like other headwater networks around the globe, we found that high-elevation streams in Rocky Mountain National Park, USA, were supersaturated with CO2 during the growing season and were net sources to the atmosphere. CO2 concentrations in lakes, on the other hand, tended to be less than atmospheric equilibrium during the open water season....
thumbnail
Our research focuses on assessing the components of the Net Ecoystem Carbon Balance using the eddy covariance approach to measure atmospheric fluxes of heat, energy, carbon dioxide and methane and testing equipment and techniques to measure the tidal exchange of dissolved organic (DOC) and inorganic carbon (DIC). The atmospheric flux tower is located south of Solano Land Trust's Rush Ranch, a working ranch encompassing 2,070 acres of marsh and rolling grasslands that provides both recreational and educational experiences for the public (http://www.solanolandtrust.org/RushRanch.aspx). Lateral fluxes are being collected at the San Francisco Bay National Estuarine Research Reserve First Mallard water quality station...
thumbnail
This assessment was conducted to fulfill the requirements of section 712 of the Energy Independence and Security Act (EISA) of 2007 and to improve understanding of carbon and greenhouse gas (GHG) fluxes in the Great Plains region in the central part of the United States. The assessment examined carbon storage, carbon fluxes, and other GHG fluxes (methane and nitrous oxide) in all major terrestrial ecosystems (forests, grasslands/shrublands, agricultural lands, and wetlands) and freshwater aquatic systems (rivers, streams, lakes, and impoundments) in two time periods: baseline (generally in the first half of the 2010s) and future (projections from baseline to 2050). The assessment was based on measured and observed...
Temperate freshwater wetlands are among the most productive terrestrial ecosystems, stimulating interest in using restored wetlands as biological carbon sequestration projects for greenhouse gas reduction programs. In this study, we used the eddy covariance technique to measure surface energy carbon fluxes from a constructed, impounded freshwater wetland during two annual periods that were 8 years apart: 2002–2003 and 2010–2011. During 2010–2011, we measured methane (CH4) fluxes to quantify the annual atmospheric carbon mass balance and its concomitant influence on global warming potential (GWP). Peak growing season fluxes of latent heat and carbon dioxide (CO2) were greater in 2002–2003 compared to 2010–2011. In...
Organic carbon (OC) burial in lacustrine sediments represents an important sink in the global carbon cycle; however, large-scale OC burial rates are poorly constrained, primarily because of the sparseness of available data sets. Here we present an analysis of OC burial rates in water bodies of the conterminous U.S. (CONUS) that takes advantage of recently developed national-scale data sets on reservoir sedimentation rates, sediment OC concentrations, lake OC burial rates, and water body distributions. We relate these data to basin characteristics and land use in a geostatistical analysis to develop an empirical model of OC burial in water bodies of the CONUS. Our results indicate that CONUS water bodies sequester...
thumbnail
The disturbance team contributes to the goals of the LandCarbon project and conducts research focusing on 3 main components: (1) monitoring disturbance patterns and their impacts on carbon cycling, (2) understanding drivers creating the patterns and impacts, and (3) using scenarios of change to project future potential disturbance patterns, their interactions with other disturbances, and subsequent impacts on carbon cycling. Key research questions driving our work include: (1) Monitoring: How can remotely sensed, field-based, and other data best be used individually and synergistically to track changes in fire occurrence in ecosystem types with long fire-return intervals and the impacts on carbon? How do disturbances...
Changes in vegetation and snow cover may lead to feedbacks to climate through changes in surface albedo and energy fluxes between the land and atmosphere. In addition to these biogeophysical feedbacks, biogeochemical feedbacks associated with changes in carbon (C)storage in the vegetation and soils may also influence climate. Here, using a transient biogeographic model (ALFRESCO) and an ecosystem model (DOS-TEM), we quantified the biogeophysical feedbacks due to changes in vegetation and snow cover across continuous permafrost to non-permafrost ecosystems in Alaska and northwest Canada. We also computed the changes in carbon storage in this region to provide a general assessment of the direction of the biogeochemical...
* 1 Soils are one of the last great frontiers for biodiversity research and are home to an extraordinary range of microbial and animal groups. Biological activities in soils drive many of the key ecosystem processes that govern the global system, especially in the cycling of elements such as carbon, nitrogen and phosphorus. * 2 We cannot currently make firm statements about the scale of biodiversity in soils, or about the roles played by soil organisms in the transformations of organic materials that underlie those cycles. The recent UK Soil Biodiversity Programme (SBP) has brought a unique concentration of researchers to bear on a single soil in Scotland, and has generated a large amount of data concerning biodiversity,...


map background search result map search result map Understanding and Projecting Changes in Climate, Hydrology, and Ecology in the Great Basin for the Next 30 Years LandCarbon Ecosystem disturbances monitoring an modeling Great Dismal Swamp Project LUCAS modeling Suisun Marsh, CA:  Net Ecosystem Carbon Balance Baseline and projected future carbon storage and greenhouse-gas fluxes in ecosystems of Alaska Understanding and Projecting Changes in Climate, Hydrology, and Ecology in the Great Basin for the Next 30 Years Suisun Marsh, CA:  Net Ecosystem Carbon Balance Great Dismal Swamp Project Baseline and projected future carbon storage and greenhouse-gas fluxes in ecosystems of Alaska Ecosystem disturbances monitoring an modeling LUCAS modeling