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Titolo:
Biogenic hydrocarbon emissions and landcover/climate change in a subtropical savanna
Autore:
Guenther, A; Archer, S; Greenberg, J; Harley, P; Helmig, D; Klinger, L; Vierling, L; Wildermuth, M; Zimmerman, P; Zitzer, S;
Indirizzi:
Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80303 USA Natl CtrAtmospher Res Boulder CO USA 80303 r Chem, Boulder, CO 80303 USA Texas A&M Univ, Dept Rangeland Ecol & Management, College Stn, TX 77843 USA Texas A&M Univ College Stn TX USA 77843 gement, College Stn, TX 77843 USA
Titolo Testata:
PHYSICS AND CHEMISTRY OF THE EARTH PART B-HYDROLOGY OCEANS AND ATMOSPHERE
fascicolo: 6, volume: 24, anno: 1999,
pagine: 659 - 667
SICI:
1464-1909(1999)24:6<659:BHEALC>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
ORGANIC-COMPOUND EMISSIONS; ISOPRENE EMISSION; UNITED-STATES; LAND-USE; ECOSYSTEM; MODEL; PHOTOSYNTHESIS; VARIABILITY; WOODLANDS; CLIMATE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Guenther, A Natl Ctr Atmospher Res, Div Atmospher Chem, 1850 Table Mesa Dr, Boulder, CO 80303 USA Natl Ctr Atmospher Res 1850 Table Mesa Dr Boulder CO USA 80303
Citazione:
A. Guenther et al., "Biogenic hydrocarbon emissions and landcover/climate change in a subtropical savanna", PHYS CH P B, 24(6), 1999, pp. 659-667

Abstract

Biogenic non-methane hydrocarbon (NMHC) emissions strongly influence the chemical composition of the troposphere. Thus, variations in emissions of these compounds are expected to cause changes in concentrations of important atmospheric trace gases. Here, we assess the relative magnitude of potential changes in NMHC (e.g., isoprene and monoterpene) emissions using field flux measurements from a subtropical savanna parkland/thorn woodland site in conjunction with model predictions of climate and landcover change. NMHC emissions of about 40 plant species were characterized. Grasses, as a group, had low emission rates. Several common woody species had high emission rates. However, there was little evidence of emissions being consistently related to woody plant taxonomy, growthform or functional groups. Above-canopy measurements were used to validate modeled isoprene flux predictions of about 2 mg C m(-2) h(-1) for savanna parkland/thorn woodland and ca. 0.7 mg C m(-2) h(-1) for the regional landscape, which is a mixture of savanna parkland/thorn woodland and cropland. Linkage of the biogenic emissions model with a plant succession model indicated that landcover change since the early 1800s has elicited a 3-fold increase in total NMHC emissions. This increasereflected changes in vegetation species composition (from domination by grasses which were typically 'low emitters', to shrubs and trees, many of which were 'high emitters') and increases in foliar density. Field measurements on two common shrub species indicated that isoprene emission increased exponentially with increases in leaf temperature from 20 to 40 degrees C and were not suppressed by drought stress. Accordingly, our model predicted that projected increases in ambient temperature (3 to 6 degrees C) emissions could produce a 2-fold increase in biogenic NMHC emissions. Cloud cover, precipitation, relative humidity, and winds also exerted some control over NMHC emissions, but their influence was highly variable and difficult to estimate. Although our results are specific to southern Texas USA, they indicatethe magnitude of change in NMHC emissions that could occur at other locations when climate and vegetation composition are altered. (C) 1999 Elsevier Science Ltd. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/07/20 alle ore 16:55:51