New Study: One Size Approach Does Not Fit All Rainforests

London, UK – A new study published today in the scientific journal, One Earth introduces a unique tropical rainforest vulnerability index (TFVI) to detect and evaluate the vulnerability of global tropical rainforests to increasing threats from changes in land-use and climate. Using satellite data from the past few decades, the TFVI is a simple and practical index that provides a baseline for scientists and the general public. It contains information about the intensity and direction of vulnerable ecosystems and tracks the response of tropical forests to multiple stressors by providing early-warning signals for regions undergoing these critical transitions.

“Rainforests are perhaps the most endangered habitat on earth threatened by large-scale land-use activities to clear land for farming or to harvest trees for timber. At some point in early 2000s threats from climate change started to rival land-use as the most important impact on habitat degradation and biodiversity,” said Sassan Saatchi, Principal Scientist Carbon Cycle and Ecosystems Jet Propulsion Laboratory California Institute of Technology and lead author of the study Detecting Vulnerability of Humid Tropical Forests to Multiple Stressors. “The average temperature has risen across rainforests by 1-1.5o C, in some parts, the dry season has expanded for almost a month over the past 4 decades, and severe droughts have hit different regions of rainforests 3-4 times since early 2000s.”

Rainforests are a powerful natural climate solution. Conserving and restoring rainforests not only improves water filtration, biodiversity habitats, and enhances climate resilience but can also contribute to stabilizing global warming to below 2 °C. The vulnerability of humid rainforests in the past was only measured through a large number of indicators that were mostly from local studies. These studies could not be easily extended to larger regions or globally. In the development of the TFVI, researchers looked at all tropics systematically using advanced satellite measurements including climate and vegetation observations that have not been used in previous indicators.

Key findings include:

• Different regions of tropics have different responses to climate threats and some regions appear to be more resilient than others.
• There are strong interactions between climate, land use, and biodiversity that define the vulnerability and resilience of forests and our new index was able to identify the nature of these interactions over the entire global rainforests.
• Rainforests at different continents had different responses to climate and land use pressures.
  • The Amazon Basin shows large-scale vulnerability to drying conditions of atmosphere, frequent droughts and large-scale land use changes.
  • The Congo Basin, on the other hand, seems to be more resilient because of historical impacts of droughts, the overall dryer condition, and smaller scale land use change and fragmentation.
  • Rainforests in Southeast Asia appear to be suffering more from land use and fragmentation than climate except for areas of peatlands that have become more vulnerable to fire during El Nino years.

Saatchi said, “TFVI will allow scientists and policy makers, particularly those in tropical countries, to better understand the vulnerability of their rainforest resources, and invest on conservation and restoration efforts. Understanding the specific vulnerabilities that their country’s rainforests are experiencing, will better equip these governments to meet their commitments to the Paris Climate Agreement.”

The data from the TFVI will provide scientists with an opportunity to perform more in-depth examinations on the ground of natural ecosystem processes within rainforests including carbon storage and productivity, energy, water exchanges and biodiversity in order to assess how rapidly these ecosystems may approach a tipping point. To provide accurate early-warning signals, TFVI is designed to be continually updated with new data. Once new satellite, climate and field study data become available, they will get integrated in an automated model to assess the stress and response of the ecosystem and to evaluate if ecosystem vulnerability has increased or reduced.

“Rainforests are many things at once: the greatest repository of biological diversity, a major aggregation of freshwater rivers, influential on climate and even a flywheel of continental climate in some cases…. important in many nutrient cycles. This index is a Godsend,” said Tom Lovejoy, Senior Advisor to the President, United Nations Foundation and University Professor, Department of Environmental Science and Policy, George Mason University.

The TFVI shows that the vulnerability of rainforests is much larger than predicted in the past and areas that are disturbed or fragmented have almost no resilience to climate warming and droughts. In addition, the study’s results suggest that rainforests are losing their capacity to cycle carbon and water. This is occurring gradually at the continental scales and more rapidly at regional scales with the implications of significant impacts on how the rainforests absorb carbon dioxide from fossil fuels emissions and regulate the climate in future.

“The tropical forest biome is home to most of the world's biological wealth and important for so many aspects of planet's healthy functioning, yet is under threat as never before. To deal with this threat appropriately we need to understand what is going on and where. This study makes a huge contribution to fulfilling this need by bringing together a vast array of data to build a unique indicator and health check on the threats to the tropical forests,” said Yadvinder Malhi, Professor of Ecosystem Science at Oxford University.

The National Geographic Society, with the support of Rolex, convened leading scientists and conservationists in 2019 to create this novel index to understand rainforest vulnerability over space and time. The science indicates that each rainforest reacts differently to different stressors and therefore, each region and subregion requires a diversity of solutions.

“The novelty of the index is that the solutions are not a one size fits all approach,” said Nicole Alexiev, Vice President, Science and Innovation at the National Geographic Society. “A diverse suite of solutions will be required to address rainforest vulnerability given each ecosystem’s unique response to different stressors. Through our partnership with Rolex, we’re excited to use the findings from this index to support scientific expeditions to some of the world’s most threatened rainforests to help identify new solutions to protect them.”

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ABOUT THE ROLEX PERPETUAL PLANET INITIATIVE

As the 21st century unfolds, Rolex has moved from championing exploration for the sake of discovery to protecting the planet and reinforced its commitment by launching the Perpetual Planet initiative in 2019. It supports individuals and organizations using science to understand the world’s environmental challenges and devise solutions that will restore balance to our ecosystems and safeguard the Earth for future generations.

The Rolex Perpetual Planet initiative for now focuses on three key areas: supporting individuals who contribute to a better world through the Rolex Awards for Enterprise; preserving the oceans, notably through the company’s association with Mission Blue; and understanding climate change through data as part of its enhanced association with National Geographic, a Rolex partner since 1954.

Under the name Perpetual Planet Expeditions, National Geographic and Rolex have partnered to support trailblazing scientific research expeditions to critical ecosystems harnessing world-renowned scientific expertise and cutting edge technology to reveal new insights into how environmental change is impacting these systems and identifying the solutions needed to protect them. Past expeditions have explored the water towers of the Himalaya and the Southern Andes and future expeditions will explore tropical rainforest ecosystems and ocean environments.