Phenological shifts and variations in vegetation along Amazon eco-climatic transect using MODIS VI time series
Piyachat
Ratana, Soil, Water, and Environmental Science Dept., University of Arizona, piyachat@ag.arizona.edu
(Presenting)
Alfredo
Ramon
Huete, Soil, Water, and Environmental Science Dept., University of Arizona, ahuete@ag.arizona.edu
Kamel
Didan, Soil, Water, and Environmental Science Dept., University of Arizona, kamel@ag.arizona.edu
The major land cover types along a north-south Amazon eco-climatic transect are tropical forest, forest-savanna transition zone, and cerrado or savanna. The Amazon contains the largest extent of tropical forest on Earth, and is undergoing rapid land cover changes. Similarly, the cerrado biome has been experiencing unprecedented rates of clearing and conversion. These have important environmental consequences to biological diversity, the hydrological cycle, energy balance, climate, and carbon dynamics at local, regional and global scales. To better understand these consequences, better knowledge of vegetation dynamics in the Amazon is needed. The Terra - Moderate Resolution Imaging Spectroradiometer (MODIS) was designed to monitor the spatial and temporal dynamics over large-scale areas. In this study, we investigated the seasonality and spatiotemporal behavior of an eco-climatic transect, from the cerrado biome near Brasilia to the cerrado-forest transition zone near Palmas-Xingu, and seasonal tropical forest at Tapajos National Forest near Santarem, using MODIS vegetation index (VI) time series data. MODIS VI 16-day composite data was employed to observe wet-dry seasonal patterns and phenologic shifts and responses in vegetation activity along the eco-climatic transect. Results showed the cerrado region exhibited the highest dry-wet seasonal contrast with a pronounced dry season from June through August and wet season from November to March. We found the transition from cerrado to forest was quite abrupt, but with variable and distinct profiles. Conversely, the tropical forest had the lowest seasonal contrast and during the dry winter months (August to November) had the highest response in their temporal profiles.
Submetido por Piyachat Ratana em 17-MAR-2004
Tema Científico do LBA: LC (Mudanças dos Usos da Terra e da Vegetação)