Authors: Xavier Haro-Carrión*, Macalester College, Peter Waylen , University of Florida , Jane Southworth , University of Florida
Topics: Remote Sensing, Landscape, Latin America
Keywords: GIMMS NDVI, greening and browning, time series analysis, tropical Andes, tropical Pacific, Amazon
Session Type: Paper
Presentation File: No File Uploaded
Time series of vegetation data derived from satellite images and field observations indicate that tropical vegetation is greening. Yet, details about greening patterns in the tropical Andes remains poorly understood. In this work, we analyze changes in vegetation greenness across the coastal, Andean, and Amazonian regions of continental Ecuador, from 1982-2010. Using standardized Normalized Difference Vegetation Index (NDVI) anomalies derived from the Advanced Very High-Resolution Radiometer (AVHRR) on monthly and annual bases and regression-based approaches, we identify: i) long-term changes in annual NDVI, ii) seasonal shifts in greenness patterns and iii) spatial patterns of change in vegetation greenness. Results indicate overall significant greening, or NDVI increase, after the mid ’90s, with distinct seasonal and regional variations. In the Amazon, significant greening occurs between September and February, resulting in a prolonged growing season of four months during the later period. A similar, but not significant, trend is observed in the east part of the Andes. Significant increases are witnessed in coastal Ecuador between February and May and during January, February and September in the western part of the Andes but with no change in the growing season. Some scattered areas in the Amazon and in the inter-Andean valleys exhibit vegetation browning during May and June. Different greening patterns across continental Ecuador likely reflect a differential response of vegetation to changes in climate. This research contributes to the understanding of tropical vegetation change in a rapidly changing environment.
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