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2 resultados encontrados para: AUTOR: French, Nancy H. F
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Model comparisons for estimating carbon emissions from North American wildland fire
French, Nancy H. F. ; De Groot, William J. (coaut.) ; Jenkins, Liza K. (coaut.) ; Rogers, Brendan M. (coaut.) ; Alvarado, Ernesto (coaut.) ; Amiro, Brian (coaut.) ; De Jong, Bernardus Hendricus Jozeph (coaut.) ;
Contenido en: Journal of Geophysical Research-Biogeosciences Vol. 116 (May 2011), p. 1-21 ISSN: 0148-0227
Resumen en: Inglés |
Resumen en inglés

Research activities focused on estimating the direct emissions of carbon from wildland fires across North America are reviewed as part of the North American Carbon Program disturbance synthesis. A comparison of methods to estimate the loss of carbon from the terrestrial biosphere to the atmosphere from wildland fires is presented. Published studies on emissions from recent and historic time periods and five specific cases are summarized, and new emissions estimates are made using contemporary methods for a set of specific fire events. Results from as many as six terrestrial models are compared. We find that methods generally produce similar results within each case, but estimates vary based on site location, vegetation (fuel) type, and fire weather. Area normalized emissions range from 0.23 kg C m−2 for shrubland sites in southern California/NW Mexico to as high as 6.0 kg C m−2 in northern conifer forests. Total emissions range from 0.23 to 1.6 Tg C for a set of 2003 fires in chaparral-dominated landscapes of California to 3.9 to 6.2 Tg C in the dense conifer forests of western Oregon. While the results from models do not always agree, variations can be attributed to differences in model assumptions and methods, including the treatment of canopy consumption and methods to account for changes in fuel moisture, one of the main drivers of variability in fire emissions. From our review and synthesis, we identify key uncertainties and areas of improvement for understanding the magnitude and spatial-temporal patterns of pyrogenic carbon emissions across North America.

Quantifying burned area for North American forests: implications for direct reduction of carbon stocks
Kasischke, Eric S. ; Loboda, Tatiana (coaut.) ; Giglio, Louis (coaut.) ; French, Nancy H. F. (coaut.) ; Hoy, E. E. (coaut.) ; De Jong, Bernardus Hendricus Jozeph (coaut.) ;
Contenido en: Journal of Geophysical Research Vol. 116, G04003 (2011), p. 1-17 ISSN: 0148–0227
Resumen en: Inglés |
Resumen en inglés

A synthesis was carried out to analyze information available to quantify fire activity and burned area across North America, including a comparison of different data sources and an assessment of how variations in burned area estimate impact carbon emissions from fires. Data sets maintained by fire management agencies provide the longest record of burned area information. Canada and Alaska have the most well developed data sets consisting of the perimeters of large fires (>200 ha) going back to 1959 and 1950, respectively. A similar data set back to 1980 exists for the Conterminous U.S., but contains data only from federal land management agencies. During the early half of the 20th century, average burned area across North America ranged between 10 and 20 × 106 ha yr−1, largely because of frequent surface fires in the southeastern U.S. Over the past two decades, an average of 5 × 106 ha yr−1 has burned. Moderate-resolution (500–1000 m) satellite burned area products information products appear to either underestimate burned area (GFED3 and MCD45A1) or significantly overestimate burned area (L3JRC and GLOBCARBON). Of all the satellite data products, the GFED3 data set provides the most consistent source of burned area when compared to fire management data. Because they do not suitably reflect actual fire activity, the L3JRC and GLOBCARBON burned area data sets are not suitable for use in carbon cycle studies in North America. The MCD45A1 data set appears to map a higher fraction of burned area in low biomass areas compared to the GFED3 data set.