Restoration helps forests recover faster

Date:
August 13, 2020
Source:
ETH Zurich
Summary:
Actively restored forests recover above ground biomass faster than
areas left to regenerate naturally after being logged, according
to a long-term study on Borneo lowland rainforest.



FULL STORY ==========================================================================
The rainforests of Southeast Asia are among the fastest declining
tropical ecosystems worldwide. Researchers from 13 institutions studied
an area of tropical forest in Sabah, Malaysian Borneo that had suffered
heavy logging in the 1980s but was subsequently protected from further deforestation or conversion to agricultural land.


==========================================================================
This long-term study paid special attention to the forest's capacity
to rebuild biomass. The researchers found that areas left to regenerate naturally recovered by as much as 2.9 tonnes of aboveground carbon per
hectare per year.

"This quantitatively confirms that if degraded forests get effective protection, they can recover well naturally," says Christopher Philipson, Senior Scientist at ETH Zurich's Chair of Ecosystem Management.

More importantly, the research team found that areas of forest that
underwent active restoration recovered 50% faster, from 2.9 to 4.4 tonnes
of aboveground carbon per hectare per year.

The research, published today in Science, has its origins in work that Professor Mark Cutler from University of Dundee carried out in Borneo
almost 25 years ago. Cutler led the project with Professor David Burslem
at the University of Aberdeen, and ETH Zurich's Christopher Philipson,
first author of the paper, who carried out the research at ETH Zurich
and Dundee.

Fostering damaged forest Commercial, selective logging in Sabah has
been going on for decades, and has severely degraded large areas of the
forest estate. While Sabah retains over 50% natural forest cover (with
almost half of this area being fully protected), relatively little of
this forest is in pristine condition. Restoration - - particularly in
heavily logged lowland forests -- is considered essential to maintain biodiversity, carbon sequestration, and other ecosystem services.



========================================================================== "This active restoration encourages naturally diverse forest, and is
therefore much more beneficial for biodiversity than monocultures or
plantation forests," stresses Philipson. The approach involves cutting
lianas (climbing plants that thrive in degraded forests, competing with
trees and reducing seedling survival and growth) as well as weeding,
and 'enrichment planting' of seedlings. The latter seeks to increase
the valuable, native tree species in degraded forests that have been
reduced through commercial logging. "In this way, restoration helps
previously over-used forests not only to recover carbon, but also to
become ecologically sound and diverse again," Philipson says.

Carbon price doesn't cover the cost Now, for the first time, a long
time-series dataset has demonstrated that active restoration helps forests
to regenerate after disturbances. However, the current price of carbon
doesn't cover the cost of restoration, and this limits the impact that restoring forests could have as a means of mitigating climate change.

"The increase in forest regrowth from restoration coupled with average
global restoration costs suggests carbon prices need to be much higher. If
they were around US$40-80 per tonne CO2 in accordance with the 2016 Paris climate agreement, this would be an incentive to invest in restoration,"
argues Dundee's Professor Cutler. He sees protecting previously logged
tropical forests from further degradation or even clearance as vitally important for reducing carbon emissions and conserving biodiversity. "We
must find sustainable mechanisms for funding." Collaborative partnership
on the ground According to David Burslem, last author and Professor at
the University of Aberdeen, scientists have known for some while that
tropical forests can regenerate from logging if left undisturbed for
long enough. But the extent of the reduction in recovery time achieved
by simple low-tech restoration techniques certainly was a surprise. "We
gained this insight through a sustained investment in research by a multi-national team over more than 20 years," Burslem says.

For this study, Philipson ventured to remote areas of forest to measure
the growth and biomass accumulation of trees. His work and indeed
the entire study actively involved many local staff, scientists and organisations, while the Sabah government guaranteed effective protection
of the forest. "The people and community of Sabah made this project
successful; I'm looking forward to seeing more endeavours like this that promote the protection and restoration of tropical forests," he says.


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


========================================================================== Journal Reference:
1. Philipson CD, Cutler MEJ, Brodrich PG, et al. Active restoration
accelerates the carbon recovery of human-​modified tropical
forests. Science, 2020 DOI: 10.1126/science.aay4490 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200813142321.htm

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