4:30 PM - 4:45 PM
[HQR03-15] Vegetation history of Lake Harutori in Hokkaido during the past 8,500 years based on pollen analysis
Keywords:Paleoenvironment, Pollen, Jomon transgression
The temperature during 7,500 to 5,000 years ago was estimated approximately 2℃ higher than at present in Japan (Matsushima, 2006). Because the sea level rose during this period, it is called the Jomon transgression, a warming phenomenon that serves as an analog for future global warming. In general, warming occurs earlier in colder regions. Therefore, paleoenvironmental reconstructions in Hokkaido are essential from a paleoenvironmental viewpoint as an analog for predicting future climate changes such as global warming.
In previous research, pollen analysis was used to study environmental changes (vegetation change) in the land area of Hokkaido, Japan (e.g., Igarashi et al., 2001; Morita, 2001). However, studies on the Holocene (especially the Jomon transgression) at high temporal resolution are scarce, and detailed vegetation change is not yet known. In this study, we reconstructed the paleoenvironment at high temporal resolution by pollen analysis using sediment core collected from Lake Harutori in Kushiro, located in southeastern Hokkaido. From the result of radiocarbon dating, it is known that the analysis of about 3,000 to 8,500 years ago is possible except for the upper part. According to the results of pollen analyses so far, the occurrence rate of Fagus pollen tends to be high in samples from the Jomon transgression. The current northern limit of the Fagus genus is the Kuromatsunai Lowland in Hokkaido, about 400 km west of Kushiro City. Therefore, from this occurrence trend, it is possible that the distribution of Fagus was expanding to the east during the Jomon transgression, suggesting that the area around Lake Harutori was also warming. However, it is necessary to carefully discuss whether Faguscan be an indicator of global warming, considering the possibility of flying pollen.
In this presentation, we will report the vegetation transition by pollen analysis with high temporal resolution of about 100 years interval.
In previous research, pollen analysis was used to study environmental changes (vegetation change) in the land area of Hokkaido, Japan (e.g., Igarashi et al., 2001; Morita, 2001). However, studies on the Holocene (especially the Jomon transgression) at high temporal resolution are scarce, and detailed vegetation change is not yet known. In this study, we reconstructed the paleoenvironment at high temporal resolution by pollen analysis using sediment core collected from Lake Harutori in Kushiro, located in southeastern Hokkaido. From the result of radiocarbon dating, it is known that the analysis of about 3,000 to 8,500 years ago is possible except for the upper part. According to the results of pollen analyses so far, the occurrence rate of Fagus pollen tends to be high in samples from the Jomon transgression. The current northern limit of the Fagus genus is the Kuromatsunai Lowland in Hokkaido, about 400 km west of Kushiro City. Therefore, from this occurrence trend, it is possible that the distribution of Fagus was expanding to the east during the Jomon transgression, suggesting that the area around Lake Harutori was also warming. However, it is necessary to carefully discuss whether Faguscan be an indicator of global warming, considering the possibility of flying pollen.
In this presentation, we will report the vegetation transition by pollen analysis with high temporal resolution of about 100 years interval.