Document: JOH-3-40-31

Fossil pollen records and AVHRR: Complementary sensors of the vegetation.

WILLIAMS, J.W* ¹ and S.TJACKSON ²

University of California Santa Barbara, Santa Barbara, CA USA ¹
University of Wyoming, Laramie, WY, USA ²

Abstract:
Satellite-based instruments and fossil pollen records each are synoptic sensors of the vegetation that together potentially permit vegetation dynamics to be studied across a wide range of spatial and temporal scales. However, the information provided by the two sensors has never been compared explicitly. One difficulty is that fossil pollen records and satellites reflect different aspects of the vegetation: satellite-based sensors such as the Advanced Very High Resolution Radiometer (AVHRR) provide information about seasonal and interannual variations in biogeophysical variables such as leaf onset, leaf area, and vegetation productivity, whereas fossil pollen records indicate millennial-scale changes in the abundances of individual plant taxa. The concept of plant functional types provides the theoretical grounding to bridge the gap between the two sensors. Using a dataset of modern pollen samples from North America, we reclassify pollen taxa into functional categories and compare the pollen abundances of the plant functional types to AVHRR-derived estimates of percent coverage. A search window of varying size was centered on each pollen site, and all pixels within the window were averaged. There is a good correlation between the pollen abundances of the various plant functional types and the AVHRR-derived estimates, with the best matches occurring at search window radii of 25 km or greater. With the correlation between the pollen and satellite data established, future research will include the development of transfer functions between pollen abundances and AVHRR-based estimates of biogeophysical variables so that these properties may be estimated for past ecosystems.

Keywords: AVHRR, pollen, North America, vegetation, plant functional types, leaf area index

This abstract is being presented at: 4:30 PM in session:
Oral Session #64: Remote Sensing.