1:45 PM - 3:15 PM
[O03-P64] Hiraodai and Hirotani Wetland Research of soil hardness and water sources + Ramsar Convention
Keywords:Hiraodai karst, Hirotani Wetland, Soil hardness, Stable isotope, Biodiversity, Ramsar Convention
We are researching from the viewpoint of origin, increase and decrease, and regeneration of Hirotani Wetland which is the only karst plateau in Japan, located in Hiraodai. The research was conducted last year focusing on the following three points.
・ Quantification of wetland boundaries by soil hardness
・ Flow analysis of water by stable isotope
・ Ramsar Convention registration activities ... Conservation activities of Hiraodai + Hirotani Wetland
Hirotani Wetland, between 1994, when we started the survey, and 2010, more than 60% of its area was vanished. We think that artificial trail construction for conservation in 1998 lead devastation of the wetland. We thought it is human being' s responsibility to restore the damage done by human beings. We used Satoyama methods and started three restoration activities. First was maintenance of stone stackings to raise the underground water level. Second was adjustment of damming plate to make origin of underground water. Third was pulling up fallen reeds to revive seeds of wetland plants. By those activities, we succeeded to restore the wetland's area for 105% by 2017.
Wetlands are often considered from vegetation. However, the wetland boundary was quantified using soil hardness as a new wetland investigation method. I thought that the border between the grasslands and the wetlands in the Hirotani Wetland is about 7 mm, but in order to make it even more universal, surveys were also conducted in the Tadewara Marsh in Oita Prefecture and the Kushiro wetland in Hokkaido. The boundary value of the soil hardness of the grassland and the wetland is 8 to 9 mm, which proves the validity of the boundary value in the Hirotani Wetland. It is thought that wetland research by the geologic approach called surveying has made great progress.
Water was analyzed using stable isotopes to determine the origin of water in the Hirotani Wetland. From the results, a graph of the relative ratio between the celestial water line and the Hirotani Wetland was created, and when the approximate line of each measured point was taken, a straight line with almost the same slope as the celestial water line was found. Therefore, it turned out that the groundwater of the Hirotani Wetland originates from rainwater. Furthermore, from the intercept of the approximation line, it was considered that the water was seven months ago from March when it was sampled. However, for the first time to consider stable isotopes, we were taught by that who is studying stable isotopes at Tohoku University. It has been pointed out that dynamic classification is involved and complicated, and the width of this data can not be considered in detail. It seems that it was early to give concrete results. After all, I felt that it was difficult for high school students to study stable isotopes that could not handle analytical instruments.
In addition, as part of applied ecology, we are engaged in Ramsar Convention registration activities of Hiraodai and Hirotani Wetlands. The Ramsar Convention is a wide-ranging international treaty related to biodiversity, and Akiyoshidai in Yamaguchi Prefecture is also registered, etc. The Ramsar Convention registration is the most important condition that local approval is agreed. Therefore we made a petition to Kitakyushu city council in addition to the presentation of the company and event hosted by prefecture, city. The petition of a high school student was the first time, was taken up by media companies, and local people were able to have a broad understanding of registration activities. With this petition, Kitakyushu City and Fukuoka Prefecture have also officially launched for Ramsar Convention registration. We will continue various appealing activities in the future, and want to convey the wonderfulness of Hiraodai + Hirotani Wetlands to more people. The challenge of the international treaty by high school students, which was not dealt with by anyone, is likely to bear fruit. And the Hirotani wetlands are also likely to make great strides in their conservation.
・ Quantification of wetland boundaries by soil hardness
・ Flow analysis of water by stable isotope
・ Ramsar Convention registration activities ... Conservation activities of Hiraodai + Hirotani Wetland
Hirotani Wetland, between 1994, when we started the survey, and 2010, more than 60% of its area was vanished. We think that artificial trail construction for conservation in 1998 lead devastation of the wetland. We thought it is human being' s responsibility to restore the damage done by human beings. We used Satoyama methods and started three restoration activities. First was maintenance of stone stackings to raise the underground water level. Second was adjustment of damming plate to make origin of underground water. Third was pulling up fallen reeds to revive seeds of wetland plants. By those activities, we succeeded to restore the wetland's area for 105% by 2017.
Wetlands are often considered from vegetation. However, the wetland boundary was quantified using soil hardness as a new wetland investigation method. I thought that the border between the grasslands and the wetlands in the Hirotani Wetland is about 7 mm, but in order to make it even more universal, surveys were also conducted in the Tadewara Marsh in Oita Prefecture and the Kushiro wetland in Hokkaido. The boundary value of the soil hardness of the grassland and the wetland is 8 to 9 mm, which proves the validity of the boundary value in the Hirotani Wetland. It is thought that wetland research by the geologic approach called surveying has made great progress.
Water was analyzed using stable isotopes to determine the origin of water in the Hirotani Wetland. From the results, a graph of the relative ratio between the celestial water line and the Hirotani Wetland was created, and when the approximate line of each measured point was taken, a straight line with almost the same slope as the celestial water line was found. Therefore, it turned out that the groundwater of the Hirotani Wetland originates from rainwater. Furthermore, from the intercept of the approximation line, it was considered that the water was seven months ago from March when it was sampled. However, for the first time to consider stable isotopes, we were taught by that who is studying stable isotopes at Tohoku University. It has been pointed out that dynamic classification is involved and complicated, and the width of this data can not be considered in detail. It seems that it was early to give concrete results. After all, I felt that it was difficult for high school students to study stable isotopes that could not handle analytical instruments.
In addition, as part of applied ecology, we are engaged in Ramsar Convention registration activities of Hiraodai and Hirotani Wetlands. The Ramsar Convention is a wide-ranging international treaty related to biodiversity, and Akiyoshidai in Yamaguchi Prefecture is also registered, etc. The Ramsar Convention registration is the most important condition that local approval is agreed. Therefore we made a petition to Kitakyushu city council in addition to the presentation of the company and event hosted by prefecture, city. The petition of a high school student was the first time, was taken up by media companies, and local people were able to have a broad understanding of registration activities. With this petition, Kitakyushu City and Fukuoka Prefecture have also officially launched for Ramsar Convention registration. We will continue various appealing activities in the future, and want to convey the wonderfulness of Hiraodai + Hirotani Wetlands to more people. The challenge of the international treaty by high school students, which was not dealt with by anyone, is likely to bear fruit. And the Hirotani wetlands are also likely to make great strides in their conservation.