Grant by the Coca-Cola foundation
Resilience of hydrological system maintained by forest ecosystem functions.
period: Jan 2018 to May 2022
PI: Yoshiko Kosugi, Professor, Graduate School of Agriculture, Kyoto University
CoI: Masanori Katsuyama, Professor, Graduate School of Life and Environmental
Sciences, Kyoto Prefectural University
CoI: Kenichirou Kosugi,Professor, Graduate School of Agriculture, Kyoto
University
Earth is the water planet. However, the amount of water that is cycling
in terrestrial system is limited to be less than 1% of total water. The
available water is also unevenly distributed. Recent technology produce
many kinds of new water resources, nevertheless we mostly depend on natural
terrestrial water resources. Every terrestrial life depend on water that
is re-produced during the hydrological cycle. Thus, to maintain the sustainability
of hydrological cycle is a critical concern for us terrestrial living things.
This project aims to conserve the sustainability of hydrological processes
and natural water resources by establishing a knowledge about forest ecosystem
functions maintaining the resilience of hydrological systems. We claim
that the most important point to achieve the sustainability of hydrological
processes is to make the society mature with knowledge that has scientific
background.
Global water cycle is now be exposed to the menace of change because of
human impact. Forest ecosystem functions are expected to play a significant
role on maintaining the sustainable hydrological cycle, and thus sustainable
society. The regulative function of forest on the hydrological cycle and
climate have been drastically elucidated from recent field studies. Recent
studies have revealed that to maintain evapotranspiration from forest ecosystems
is especially important for the resilience of terrestrial hydrological
system. The process of evapotranspiration is sometimes accused as the waste
of water in arid regions, but basically it re-produces new water in hydrological
cycle. Plenty of evapotranspiration from humid forests supports the rainfall
re-cycle in the continents. It also supports the carbon cycle, biomass
production, and every other ecosystem functions of forests. In Asian monsoon
humid region such as Japan, which is characterized with plenty of rainfall
and steep topography, regulating water cycle with the reservoirs, to keep
water to prevent the droughts and at the same time to mitigate the flood
disasters, is one of the most important issues for water management. Forests
act as natural water reservoirs with its function to prolong the residence
time. They also purify the water, which is another important issue for
water management in this region. Forest soil prevents overland flow and
help water to percolate into deeper layer. In Japan, forested mountain
cultivates most available natural water resources including deep-layer
groundwater. We must also know that sometimes these groundwater causes
deep layer erosion. Thus utilization of groundwater resources with sustainable
manor can rather help its resilience. In humid regions, the simple idea
of just saving water is not a wise solution. To know the scientific aspects
of forest functions and by them maintaining the resilience of natural hydrological
system are rather more important.
From these backgrounds, we challenge a project consisting of the following
subjects.
1) Evaluation of forest functions maintaining the resilience of hydrological
cycle
1.1) Monitoring the resilience of global water cycle
The water cycle is now changing due to various kinds of human impacts
including the green-house gas effects. The world-wide monitoring is required
for this purpose and the stable isotopic signal of bottled water can highly
contribute to this purpose. We continue the collaboration with Coca Cola
Company for the monitoring of the water cycle on the earth. Bottled water
is as ubiquitous as the spatial distribution of humankind, and its utility
as a monitoring tool for regulatory or geochemical applications has been
confirmed in many researches. Here, utilizing a global database of >
800 samples from more than 70 countries and 5 or more year continuous record
from Japanese bottled waters, this study demonstrate the important effects
of latitude, elevation, continentality, and orography on the isotopic signature
of bottled water. In addition to the spatial distribution, we investigate
time sequential variation of monthly samples from 5 sources in Japan offered
by Coca Cola Japan to know the stability, or vulnerability, of the groundwater
bodies for the years to the preceding climate change. The results of the
study provide the first global groundwater isoscape for use by scientists
and policymakers around the world and establish a baseline for the groundwater
isoscape to assess gradual changes in the status of water resources corresponding
with environmental change.
1.2) Monitoring the resilience of evapotranspiration and gas exchange
Monitoring of the evapotranspiration and greenhouse gas exchange between forest and the atmosphere using the tower. Evapotranspiration from forests has an important role to hydrological cycles, and also to the atmospheric environment. It also governs the photosynthesis by forests. Greenhouse gas exchange between forest and the atmosphere responds to the climate changes so delicately that a rude forest operation may eliminate the ecosystem resilience, giving unexpected feedback effects on the climate. A long-term, and careful monitoring is essential for the establishment of the proper prediction model and management plan. We examine how forests maintain the stability of evapotranspiration and gas exchange under long-term temporal variations of climate and vegetation.
1.3) Monitoring the resilience of water quality
Long-term transient of the forest dynamics will cause some kind of changes
on the water quality, and the change sometimes relate to the degradation
of water resources. For example, nitrate is an essential element for the
vegetation. However, the nitrogen saturation in river/stream water is recently
reported worldwide, and one of the important reasons of this phenomena
is forest dynamics and/or disturbance. Global environmental change may
also accelerate the disturbance through the changes of rainfall pattern,
extreme climate events, and consequent change of hydrological processes.
Here, we conduct the long-term monitoring of hydrological processes and
the groundwater and stream water quality as well as forest dynamics, and
consider the relationship among climate change, forest dynamics, and water
quality.
1.4) Monitoring the resilience of ground water resources
Deep layer ground water is an important resources for our future society.
The sustainable usage of these resources also contribute to prevent sediment
disasters caused by the deep-seated landslide. The forest soil acts as
the buffer zone to help water infiltrating to the base-rock to form deep
layer ground water. We examine how this forest function works at various
forested watersheds with different geological features.
These monitoring studies includes the process understanding of forest
functions for the prediction of future possible impacts. Because the relationship
between forest functions and water cycle and climate are very complex,
the modelling for the impact prediction should be based on insights into
the detailed onsite processes. Hence, the observations using new technologies
such as isotopic tracing and cutting-edge sensing methods are conducted
to develop realistic models including geophysical and biochemical processes
and considering the impacts of human disturbances.
2) Transmission of the practical scientific findings to the public
It is important to share the scientific findings with the public. Particularly
this should be emphasized for our final goal to conserve the sustainability
of hydrological processes and water resources. Hence, we operate a project
web-site, hold open educational programs, and publish textbooks for enlightening
the public based on our study findings.
Through these activities we aim our final goal, that is, to conserve the sustainability of hydrological processes and water resources by establishing a knowledge about forest functions maintaining the resilience of hydrological systems. This study can also contribute to the social planning necessary for solving the serious environmental problems in the Anthropocene and creating the sustainable nature system.
At this project, Coca Cola Japan provides bottled water ’IROHASU’ to Kyoto University to estimate the geographical distribution of stable
isotope signatures of ground water. Coca Cola Japan has been providing
bottled water to Kyoto University to estimate the geographical distribution
of stable isotopic information of ground water. The bottled water is a
useful tool for the long-term evaluation of possible change in water cycle
related with climate change, and to evaluate the resilience of the global
water cycle depending on the natural and/or human impacts on the atmospheric
environment.
Our previous project studies related with this project were supported
by Coca-Cola foundation from 1/2013 to 3/2017 (title: 'Evaluation Study
of Forest Impacts on the Water Cycle and Climate Change'), and also by
several other Grants-in-Aid for Scientific Research (KAKENHI) projects
by the Japan Society for the Promotion of Science (JSPS), and by a Core
Research for Evolutional Science and Technology (CREST) project by the
Japan Science and Technology Agency (JST).