including mitigation and adaptation strategies to global climate change; (2) to
address biodiversity conservation at the landscape level; and (3) to provide
socioeconomic security to the people who are already making a livelihood on the
peatlands.
Keywords Carbon negative · Biodiversity conservation · Conservation planning ·
Drainage-based water management · Stock-based water management
3.1 Introduction
Tropical peatlands are widespread in the Amazon Basin, Congo Basin, Southeast
Asia, and New Guinea, covering areas of 54.5 Mha, 14.6 Mha, 24.8 Mha, and
10.1 Mha, respectively (Gumbricht et al. 2017; Dargie et al. 2017; Page et al. 2011).
Peat consists of dead, incompletely decomposed plant material that has accumulated
over thousands of years under water-saturated conditions. Consequently, tropical
peatlands play a role in sinks and stores of gigantic amounts of water and carbon on a
global scale.
Regarding the water storage function of peat, most tropical peatlands are located
in the tropical rain belt, i.e., the intertropical convergence zone (ITCZ), a narrow
band of rising air and intense precipitation, which is driven by moisture convergence
associated with the north-south trade winds that collide near the equator. The ITCZ
accounts for 32% of the global precipitation and plays an essential role in the global
water circulation system (Kang et al. 2018). The mass amount of precipitation in the
ITCZ consistently has a direct impact on the water storage function of the tropical
peatlands, resulting in large amounts of water storage by the tropical peatlands. It is
suggested that global peatlands store 10% of all freshwater even though the total area
of peatlands covers only 3% of the global land surface (Rezanezhad et al. 2016).
Nevertheless, there has been little research to determine the amount of the water
supply in peatlands worldwide.
In addition to the importance of the precipitation brought by the climate in the
ITCZ, the contribution of evapotranspiration to local area and remote precipitation
(i.e., moisture recycling) is crucial for sustaining water resources and ecosystems.
Approximately 60% of evapotranspiration returns as precipitation over land through
terrestrial moisture recycling (van der Ent et al. 2010). Moreover, approximately
40% of all terrestrial rainfall originates from evapotranspiration. Wang-Erlandsson
et al. (2014) estimated that tropical evergreen broadleaf forests occupy approximately 10% of the global land surface but contribute 22% of the global evapotranspiration. This argument may be accepted by scientists, but it is not being studied as
an important issue in the global water cycle, including the role of tropical peatlands.
Ellison et al. (2019) have focused on the role of forests in rainfall and the water
supply through water recycling, but there has been no mention of the role or
importance of tropical peatlands because information and data have been markedly
lacking to date. As mentioned above, the importance of tropical peatlands and their
90
T. Kato et al.
address biodiversity conservation at the landscape level; and (3) to provide
socioeconomic security to the people who are already making a livelihood on the
peatlands.
Keywords Carbon negative · Biodiversity conservation · Conservation planning ·
Drainage-based water management · Stock-based water management
3.1 Introduction
Tropical peatlands are widespread in the Amazon Basin, Congo Basin, Southeast
Asia, and New Guinea, covering areas of 54.5 Mha, 14.6 Mha, 24.8 Mha, and
10.1 Mha, respectively (Gumbricht et al. 2017; Dargie et al. 2017; Page et al. 2011).
Peat consists of dead, incompletely decomposed plant material that has accumulated
over thousands of years under water-saturated conditions. Consequently, tropical
peatlands play a role in sinks and stores of gigantic amounts of water and carbon on a
global scale.
Regarding the water storage function of peat, most tropical peatlands are located
in the tropical rain belt, i.e., the intertropical convergence zone (ITCZ), a narrow
band of rising air and intense precipitation, which is driven by moisture convergence
associated with the north-south trade winds that collide near the equator. The ITCZ
accounts for 32% of the global precipitation and plays an essential role in the global
water circulation system (Kang et al. 2018). The mass amount of precipitation in the
ITCZ consistently has a direct impact on the water storage function of the tropical
peatlands, resulting in large amounts of water storage by the tropical peatlands. It is
suggested that global peatlands store 10% of all freshwater even though the total area
of peatlands covers only 3% of the global land surface (Rezanezhad et al. 2016).
Nevertheless, there has been little research to determine the amount of the water
supply in peatlands worldwide.
In addition to the importance of the precipitation brought by the climate in the
ITCZ, the contribution of evapotranspiration to local area and remote precipitation
(i.e., moisture recycling) is crucial for sustaining water resources and ecosystems.
Approximately 60% of evapotranspiration returns as precipitation over land through
terrestrial moisture recycling (van der Ent et al. 2010). Moreover, approximately
40% of all terrestrial rainfall originates from evapotranspiration. Wang-Erlandsson
et al. (2014) estimated that tropical evergreen broadleaf forests occupy approximately 10% of the global land surface but contribute 22% of the global evapotranspiration. This argument may be accepted by scientists, but it is not being studied as
an important issue in the global water cycle, including the role of tropical peatlands.
Ellison et al. (2019) have focused on the role of forests in rainfall and the water
supply through water recycling, but there has been no mention of the role or
importance of tropical peatlands because information and data have been markedly
lacking to date. As mentioned above, the importance of tropical peatlands and their
90
T. Kato et al.