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Esecaflor Project
WHAT EXPERIMENT SIMULATING DROUGHT IN AMAZON FOUND
Context: The Esecaflor project, the world’s longest-running rainforest drought experiment in the Amazon, has shown that prolonged drought causes significant biomass loss and turns the forest from a carbon sink into a carbon emitter. Scientists are now studying whether the forest can recover after 24 years of simulated drought.
Introduction to the Experiment
- A controlled drought simulation project called Esecaflor (short for Forest Drought Study Project in Portuguese) was launched in 2000 by Brazilian and British scientists.
- It is located in the Caxiuanã National Forest, within the Amazon rainforest.
- The goal was to mimic long-term drought conditions and observe the rainforest’s response to climate-induced rainfall decline.
- This is the longest-running drought simulation project of its kind globally.
Why Does It Matters?
- The Amazon stores carbon equivalent to two years of global carbon emissions.
- Tree death from drought releases stored carbon back into the atmosphere, intensifying global warming.
- Understanding forest responses helps predict climate feedback loops.
Drought Simulation Setup
- A 1-hectare plot (about the size of a football field) was covered with 6,000 transparent plastic panels.
- These panels diverted approximately 50% of rainfall from the forest floor.
- Panels were mounted 1 metre above the ground at the edges and up to 4 metres in the centre.
- Rainwater was channelled away through gutters and perimeter trenches.
- An adjacent plot was left untouched as a control.
Monitoring and Data Collection
- Scientific instruments were:
- Attached to trees, placed on the ground, and buried in soil.
- Used to monitor soil moisture, air temperature, tree growth, sap flow, and root development.
- NASA radars atop two metal towers measured water content in vegetation.
Key Findings Over 24 Years
- For the first 8 years, the forest showed resistance to drought.
- After 8 years, significant changes occurred:
- High mortality among the largest trees.
- Approximate 40% loss in total vegetation biomass and carbon storage in the plot.
- Published in May in Nature Ecology & Evolution.
- Forest transitioned from a carbon sink to a carbon emitter.
- Draws a parallel to real-life droughts in the past two years, intensified by El Niño and climate change. Both scenarios show forests losing their ability to absorb carbon and instead releasing it.
- Despite prolonged drought, the forest did not turn into savanna, contradicting earlier model-based predictions.
Current Focus: Recovery Phase
- In November, most of the 6,000 plastic panels were removed.
- Scientists are now observing how the forest responds post-drought.
- According to João de Athaydes, Esecaflor’s vice coordinator:
- The forest has shown adaptation.
- The current objective is to track if and how it can regenerate and return to baseline conditions.
About Amazon Rainforest
- The Amazon Rainforest, also known as Amazonia, is the world’s largest tropical rainforest.
- It spans 6.7 million square kilometres across nine South American countries: Brazil, Peru, Colombia, Venezuela, Ecuador, Bolivia, Guyana, Suriname, and French Guiana.
- Global Significance: Often referred to as the “lungs of the Earth”, it produces approximately 20% of the world’s oxygen through photosynthesis. It serves as a massive carbon sink, playing a critical role in regulating the global climate.
- Amazon River System: The Amazon River is the largest river in the world by discharge volume. It has over 1,100 tributaries and carries more water than the next seven largest rivers combined.
- Iconic wildlife includes: Jaguars, sloths, anacondas, piranhas, and the Amazon river dolphin etc.
