New measure of tropical forest vulnerability to help avoid 'tipping
point'

Date:
July 23, 2021
Source:
Cell Press
Summary:
Humid tropical forests, vital in global efforts to limit rising
temperatures, are under threat as a result of changes in land
use and climate. Now, researchers have developed a new way to
keep tabs on the vulnerability of these forests on a global scale
using satellite data called the tropical forest vulnerability index
(TFVI).



FULL STORY ========================================================================== Humid tropical forests, vital in global efforts to limit rising
temperatures, are under threat as a result of changes in land use and
climate. Now, researchers reporting in the journal One Earth on July
23 have developed a new way to keep tabs on the vulnerability of these
forests on a global scale using satellite data. Called the tropical
forest vulnerability index (TFVI), the hope is that this method will
serve as an early warning for areas that are under the greatest threat
to enable actions aimed at protecting these forests before it's too late.


========================================================================== "Frequent droughts, higher temperature, and longer dry seasons, along with increasing pressures from deforestation and degradation in the last two decades, have pushed the tropical rainforests to the verge of a tipping
point," said Sassan Saatchi of NASA's Jet Propulsion Laboratory. "What
we predicted using climate models a decade ago, we are observing on the
ground. Now is the time to do something and not later. This work takes advantage of a suite of satellite observations made for the past few
decades to show how and where the tipping points may be reached and
to help policy makers plan for conservation and restoration of these
forests." There have been other ways to measure the vulnerability
of rainforests.

However, most of them relied on local studies and couldn't easily
be extended to larger regions or the globe. This lack of consistency
and ability to make comparisons from one region to another has led to
confusion and inaction. To get around these stumbling blocks, Saatchi and colleagues set out to develop a unique tropical rainforest vulnerability
index that could work across all rainforests based on observations of
climate and vegetation from satellites.

The new index combines numerous measurements and indicators of forest ecological functions and services, including carbon and water fluxes and biodiversity. It also provides spatial information with monthly updates
and allows researchers to identify and monitor areas with increasing vulnerability or potential threats before it's too late.

Their studies have shown that different regions of the tropics are
responding differently to climate threats, with some regions showing
more apparent resilience than others. For instance, forests in the
Americas appear to be more vulnerable to stresses than those in Africa,
where they are showing relative resilience to changing climate. In Asia, tropical forests appear more vulnerable to land use and fragmentation.

Individual rain forests also show important differences in their response
to climate and land use pressures. For instance, the Amazon Basin shows
large- scale vulnerability to drying condition in the atmosphere, with
frequent droughts and large-scale land use changes. The Congo Basin,
on the other hand, appears more resilient because of the historical
impacts of droughts, the overall dryer condition, and smaller-scale land
use change and fragmentation.

The researchers also uncovered strong interactions between climate,
land use, and biodiversity that define the vulnerability and resilience
of forests. The new index allowed them to identify the nature of these interactions over all global rainforests.

"The findings show 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," Saatchi
said. "In addition, the results of our study suggest that rainforests
are losing their capacity to cycle carbon and water as before. This is occurring gradually at the continental scale and more rapidly at the
regional scale, with significant implications for the global carbon
sink and climate." The TFVI was developed by many scientists and conservationists assembled by the National Geographic Society and Rolex
and therefore represents a consensus approach from the broader community, Saatchi notes. The hope is that the larger global community of scientists
and policy makers, particularly in tropical countries, will now make use
of the index to systematically assess the vulnerability of rainforest
resources and to develop nature-based solutions to meet their commitments
to the Paris Agreement. To keep tabs on future changes and threats to
the world's tropical forests, the researchers say that the new index
will continue to be renewed automatically as time goes on.

========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Sassan Saatchi, Marcos Longo, Liang Xu, Yan Yang, Hitofumi Abe,
Michel
Andre', Juliann E. Aukema, Nuno Carvalhais, Hinsby Cadillo-Quiroz,
Gillian Ann Cerbu, Janet M. Chernela, Kristofer Covey, Lina Mari'a
Sa'nchez-Clavijo, Isai V. Cubillos, Stuart J. Davies, Veronique De
Sy, Francois De Vleeschouwer, Alvaro Duque, Alice Marie Sybille
Durieux, Ka'tia De Avila Fernandes, Luis E. Fernandez, Victoria
Gammino, Dennis P.

Garrity, David A. Gibbs, Lucy Gibbon, Gae Yansom Gowae, Matthew
Hansen, Nancy Lee Harris, Sean P. Healey, Robert G. Hilton,
Christine May Johnson, Richard Sufo Kankeu, Nadine Therese
Laporte-Goetz, Hyongki Lee, Thomas Lovejoy, Margaret Lowman,
Raymond Lumbuenamo, Yadvinder Malhi, Jean-Michel M. Albert Martinez,
Carlos Nobre, Adam Pellegrini, Jeremy Radachowsky, Francisco Roma'n,
Diane Russell, Douglas Sheil, Thomas B.

Smith, Robert G.M. Spencer, Fred Stolle, Hesti Lestari Tata, Dennis
del Castillo Torres, Raphael Muamba Tshimanga, Rodrigo Vargas,
Michelle Venter, Joshua West, Atiek Widayati, Sylvia N. Wilson,
Steven Brumby, Aurora C. Elmore. Detecting vulnerability of humid
tropical forests to multiple stressors. One Earth, 2021; 4 (7):
988 DOI: 10.1016/ j.oneear.2021.06.002 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210723121508.htm

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