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Title: CORRELATIONS OF DAYTIME CARBON DIOXIDE FLUX WITH REMOTELY-SENSED VEGETATIONINDEX FOR FOUR DIFFERENT MOUNTAIN/PLAINS ECOSYSTEMS

Author
item KELLY, ROBERT - UNIVERSITY OF WYOMING
item Hunt Jr, Earle
item REINERS, WILLIAM - UNIVERSITY OF WYOMING
item SMITH, WILLIAM - WAKE FOREST UNIVERSITY
item WELKER, JEFFREY - UNIVERSITY OF WYOMING

Submitted to: Nature
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: With increasing evidence of global warming and potential for ecological changes, there is a need for large-scale monitoring of plant cover and corresponding surface fluxes of carbon dioxide. Satellite-borne sensors provide the only effective means for monitoring land cover conditions at regional and global scales. Such remote sensing measurements must in turn be related to surface processes as measured in the field. This paper presents empirical relationships between a remotely-sensed vegetation index and daytime carbon dioxide flux (difference between gross photosynthesis, autotrophic respiration, and heterotrophic respiration) as measured by aircraft, over flight-lines of 19-25 km over four different ecosystems characterizing large areas of North America. Over a year, our results show linear relationships between CO2 fluxes and normalized difference vegetation index (NDVI) over a mixed-grass prairie, sagebrush shrub land, and coniferous forest, in southeastern Wyoming, USA. However, for a nearby mixed irrigated/dryland agricultural area, fluxes were not correlated with NDVI, suggesting carbon sequestration by these agricultural systems can not be remotely sensed.

Technical Abstract: With increasing evidence of global warming and consequent prognoses for resulting ecological changes, there is a need for large-scale characterization and subsequent monitoring of plant cover and corresponding surface fluxes of carbon dioxide. Satellite-borne sensors provide the only effective means for monitoring land cover conditions at regional and global scales over long time periods. Such remote sensing measurements must in turn be related to surface processes as measured in the field. This paper presents empirical relationships between net, daytime carbon dioxide flux over an annual cycle as a function of normalized difference vegetation index (NDVI) for four different ecosystems characterizing large areas of North America. Our results show linear relationships between CO2 fluxes and NDVI for flight-lines of 19-25 km over a mixed-grass prairie, sagebrush shrub-land, and coniferous forest, in southeastern Wyoming, USA. However, for a nearby mixed irrigated/dryland agricultural area, fluxes were not correlated with NDVI, suggesting carbon sequestration by these ecosystems can not be remotely sensed.