Potential and constraints of reforestation for climate mitigation

Date:
August 18, 2020
Source:
National University of Singapore
Summary:
A recent study showed that practical considerations, beyond where
trees could be planted, may limit the climate change mitigation
potential of reforestation. Hence, there is a need to understand
how these constraints operate to inform climate policies.



FULL STORY ========================================================================== Reforestation is a promising nature-based climate solution. However, there
are practical considerations beyond the suitability of land for planting
trees, such as financial, land-use and operational constraints, which
can limit its outcomes and thus need to be taken into account. A recent
study led by researchers from the National University of Singapore (NUS)
found that these constraints could limit the climate mitigation potential
of reforestation in the Southeast Asian context. Understanding how these constraints operate helps inform the prioritisation of cost-effective reforestation and investment opportunities.


========================================================================== Their findings were published in the journal Nature Climate Change on
17 August 2020.

Reforestation and climate change mitigation During the annual meeting
in Davos in January this year, the World Economic Forum launched an
ambitious initiative to plant one trillion trees worldwide to restore biodiversity and fight climate change.

Tree planting, and reforestation in general, have often been touted as
a cost- effective nature-based solution to address climate change. This
is due to the ability of trees and other natural vegetation to convert atmospheric carbon dioxide (CO2) to biomass through the process of photosynthesis, which is nature's way of capturing and locking up
carbon. However, broader considerations beyond where trees could be
planted may have impacts on the effectiveness of reforestation as a
climate solution.

Barriers to reforestation In the study, the research team led by Professor
Koh Lian Pin, who is from the NUS Department of Biological Sciences,
estimated the climate mitigation potential of reforestation across
Southeast Asia, and assessed the effects of biophysical, financial,
land-use, and operational considerations on different constraint
scenarios.



==========================================================================
The researchers found that 121 million hectares of land across Southeast
Asia are suitable for reforestation, and could potentially contribute
to climate mitigation at a rate of 3.4 gigatonnes of CO2 per year.

"However, only a fraction of that mitigation potential may be achievable
if practical constraints are taken into account," noted Prof Koh, who
is also Director of the NUS Centre for Nature-based Climate Solutions.

One example is the many pockets of "barren land" in Southeast Asia that
may actually be in use by farmers to grow crops for subsistence, or for
sale in local markets. NUS postdoctoral research fellow Dr Zeng Yiwen,
who is the first author of the paper, explained, "If we exclude these
small farmlands, the available land for reforestation in Southeast Asia
would be reduced to about 76 million hectares, and its climate mitigation potential would drop to 2.2 gigatonnes of CO2 per year." The team noted
that there may also be a need for reforestation sites to be near mature
forests which could act as sources of seeds or seedlings that are critical
for the reforestation process. Other considerations that the team took
into account included the cost of reforestation and protection status.

"If we want to maximise the success of reforestation projects and restrict
them to within two kilometres of existing intact forests, we would only
be looking at about 33 million hectares of available land in the region,
which would provide only 0.9 gigatonnes of CO2 sequestration potential
per year," said Ms Tasya Sarira, the second author of the study who is
from the University of Adelaide.



========================================================================== Reforestation: Balancing trade-offs Prof Koh explained, "The barriers to reforestation we have identified are not insurmountable. For example,
by involving smallholder farmers in the reforestation process, such as
through agroforestry or tree planting on their farms, climate mitigation potential can be realised while balancing trade-offs with food security
and local livelihoods." Reforestation is an important nature-based
solution, not only for climate mitigation, but also for the multiple co-benefits it provides, including biodiversity conservation, clean air
and water, and poverty alleviation.

"A more complete and nuanced consideration of both the potential and
limits of nature-based climate solutions is needed to inform climate
policies and decisions that are scientifically sound, economically
feasible and socially acceptable," he elaborated.


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


========================================================================== Journal Reference:
1. Yiwen Zeng, Tasya Vadya Sarira, L. Roman Carrasco, Kwek Yan Chong,
Daniel
A. Friess, Janice Ser Huay Lee, Pierre Taillardat, Thomas
A. Worthington, Yuchen Zhang, Lian Pin Koh. Economic and social
constraints on reforestation for climate mitigation in Southeast
Asia. Nature Climate Change, 2020; DOI: 10.1038/s41558-020-0856-3 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200818094046.htm

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