AMAZALERT examined how global and regional climate and land-use changes will impact Amazonian forests, agriculture, waters, and people; and how these impacts feed back onto climate. 

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“The AMAZALERT project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 282664, and was co-funded by many national agencies an institutes.”


Modeling forest dynamics along climate gradients in Bolivia

As reported in the Journal of Geophysical Research: Biogeosciences by authors C. Seiler, R. W. A. Hutjes, B. Kruijt, J. Quispe, S. Añez, V. K. Arora, J. R. Melton, T. Hickler and P. Kabat, a dynamic vegetation model (LPJ-GUESS) was adapted to simulate present day potential vegetation as a baseline for climate change impact assessments in the evergreen and deciduous forests of Bolivia.

Results were compared to biomass measurements (819 plots), and remote sensing data. Using regional parameter values for allometric relations, specific leaf area, wood density and disturbance interval, a realistic transition from the evergreen Amazon to the deciduous dry forest was simulated.

This transition coincided with threshold values for precipitation (1400 mm yr−1) and water deficit (−830 mm yr−1), beyond which leaf abscission became a competitive advantage. Significant correlations were found between modeled and observed values of seasonal leaf abscission (R2 = 0.6, p <0.001) and vegetation carbon (R2 = 0.31, p <0.01).

Modeled Gross Primary Productivity (GPP) and remotely sensed Normalized Difference Vegetation Index (NDVI) showed that dry forests were more sensitive to rainfall anomalies than wet forests. GPP was positively correlated to the El Niño Southern Oscillation index in the Amazon, and negatively correlated to consecutive dry days. Decreasing rainfall trends were simulated to reduce GPP in the Amazon.

The current model set-up provides a baseline for assessing the potential impacts of climate change in the transition zone from wet to dry tropical forests in Bolivia.

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Christian Seiler, Tuesday 6 May 2014