HR: 13:55h
AN: B53D-02    [Abstracts]
TI: Dynamic Phenological Patterns in Tropical Ecotonal, Disturbed, and Regenerating Forests
AU: * Huete, A R
EM: ahuete@cals.arizona.edu
AF: Dept. Soil, Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, Tucson, AZ 85721, United States
AU: Didan, K
EM: kamel@ag.arizona.edu
AF: Dept. Soil, Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, Tucson, AZ 85721, United States
AU: Ratana, P
EM: piyrat@kku.ac.th
AF: Dept. of Geotechnology, Khon Kaen University, Muang District, Khon Kaen, 4002, Thailand
AU: Saleska, S
EM: saleska@email.arizona.edu
AF: Dept. Ecology and Evolutionary Biology, University of Arizona, BioSciences West room 310, 1041 E. Lowell St., Tucson, AZ 85721, United States
AU: Restrepo, N
EM: ncoupe@email.arizona.edu
AF: Dept. Ecology and Evolutionary Biology, University of Arizona, BioSciences West room 310, 1041 E. Lowell St., Tucson, AZ 85721, United States
AU: Miura, T
EM: tomoakim@hawaii.edu
AF: Dept. of Natural Resources and Environmental Management, University of Hawaii, 1910 East-West Road, Sherman Lab 101, Honolulu, HI 96822, United States
AU: Kim, Y
EM: ywkim@ag.arizona.edu
AF: Dept. Soil, Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, Tucson, AZ 85721, United States
AB: We examined patterns of optical- phenologic variability in intact, disturbed, and transitional evergreen broadleaf tropical forests in the Amazon, using space-borne hyperspectral (Hyperion) and moderate resolution satellite measurements from MODIS. Moderate resolution satellite data provide high frequency but poor spatial resolution data of limited spectral content, while hyperspectral data offer finer resolution and spectral detail but at infrequent time intervals. Our goal was to investigate landscape phenology patterns in complex tropical rainforests and assess the extent, magnitude, and synchrony of phenology patterns in response to disturbance and variations in climate. We found wide variability and large seasonality in spectral signatures in the tropical forests analyzed here, with much of the variation occurring in forest conversion and regenerating areas of varying age classes and type of secondary forest regrowth. Unique phenology responses to seasonal drought periods were observed across all vegetation types, both spectrally and temporally. Phenologic variability in moist tropical forests were largely driven by the availability of solar radiation, however, this enhanced dry season, greening signal became weaker with less developed regenerating forests, and was completely reversed in pasture and agriculture areas, where moisture limitations became the dominant control on phenology. Regenerating forests also appear to exhibit leaf flushing and green-up, prior to the start of the new rainy season. Thus, optical-phenology variations were observed in response to increases in physiologic activity as well as canopy structural changes. The more complex phenology patterns of the regenerating forests, with simultaneous browning and greening, were partly a result of the contribution of understory vegetation reflectances that mix with those of the forest canopy. This drying effect was more pronounced in the younger and more open forest canopies, relative to the older, closed, and more developed regenerating forests. The right combination of spectral, spatial, and temporal detail are needed for improved tropical forest phenology characterization for use in carbon and ecosystem production models.
DE: 0428 Carbon cycling (4806)
DE: 0429 Climate dynamics (1620)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0480 Remote sensing
SC: Biogeosciences [B]
MN: 2007 Fall Meeting