PARENT SESSION
Oral Session 7: GIS / Remote Sensing I.
Presiding: E Ellis and P Valko
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room B 116.

Landscape patterns and environmental determinants of deciduousness in tropical forests in Panama.

Bohlman, Stephanie¹, ¹ Smithsonian Tropical Research Institute, Balboa, Panama

ABSTRACT- Spectral mixture analysis applied to a Landsat 7 satellite image was used to determine the level of dry season deciduousness in overstory trees in the tropical forests of the Panama Canal Zone. Deciduousness estimated from remote sensing showed a strong, unbiased correlation with deciduousness measured from the ground and aerial photographs. Across the canal, deciduousness increased as total annual rainfall declined, but deciduousness also depended on underlying geology and topography. Geologic formations with calcareous soils had much higher deciduousness than surrounding landforms. Pre-tertiary basalt-derived material had slightly lower deciduousness than surrounding geologic formations and showed no variation in deciduousness with rainfall. Across the canal and even in the wettest forests, there were patches of highly deciduous forests 3 to 250 ha in size which were related to soil and topographic characteristics. Deciduousness was also elevated on old river terraces and dredge deposits along the canal. There was high variability in deciduousness among adjacent 30 by 30 m pixels both in highly deciduous patches and surrounding green forest due to the high species and phenological diversity of these semi-deciduous tropical forests. These relationships between deciduousness and environmental variables may be important in modeling and monitoring how tropical forests respond to climate changes.

Key words: remote sensing, phenology, tropical forests, landscape patterns