5:15 PM - 6:45 PM
[HQR05-P02] Spatial biome changes in Tohoku Region since the Last Glacial Maximum.
Keywords:Biomization, pollen analysis, temperate deciduous forest, Tohoku region
Pollen analytical studies have reconstructed vegetation changes in Japan (e.g., Yasuda and Miyoshi 2002). Gotanda et al. (2002) modified the Biomization method for Japan and succeeded in reconstructing biome distribution with 76% accuracy using modern pollen data. Modified Biomization method clarified the spatio-temporal biome changes in southwestern Japan over the past 20,000 years. In particular, they discuss the last glacial maximum escape sites of warm-temperate evergreen broad-leaved forests (Gotanda and Yasuda 2008).
In this study, I used the Biomization method to clarify the biome changes over the past 20,000 years in the Tohoku regions in order to clarify the change of deciduous broad-leaved forests.
Pollen diagrams for the past 20,000 years were quantified using a collection of published pollen analytical studies. Age models estimated using 14C dates and/or Tephrochronology (Machida and Arai, 2003) and then compiled to each millennial time slice. The Biomization method is the same as in Gotanda et al. (2002).
Pollen contribution rates were calculated for each age at each analyzed site and mapped by 1000 years.
I reconstructed and mapped past biome distribution each millennial time slice. During the Last Glacial Maximum, cool mixed forest appeared from high elevation to low elevation, suggesting a cold climate. The lack of occurrence of cool conifer forest despite the cold climate may be due to the poor reconstruction rate of cool conifer forests by the Biomization method.
After 10k yr BP, temperate deciduous forests have appeared widely, and warm-mixed/broadleaved evergreen forest has not appeared in the Tohoku region. Warm-mixed/broadleaved evergreen forest did not expand further north than the Kanto region. In particular, the lack of expansion even near the Pacific coastline may be due to the rate of vegetation movement. Since warm-mixed/broadleaved evergreen forest appeared at 6k yr BP based on the reconstruction results in the Kanto region (Gotanda 2012), it is likely that they did not expand into the Tohoku region.
The biome distribution over the past 20,000 years was reconstructed using the Biomization method based on pollen analysis data from the Tohoku region. During the Last Glacial Maximum, cool mixed conifer forest was widely distributed, and as the climate warmed, temperate deciduous forest moved northward, and by 8 kyr BP, the Northeastern region was widely covered with temperate deciduous forest. However, warm-mixed/broadleaved evergreen forest probably did not extend further north than the Kanto region. The low restoration rate of cool conifer forest by the Biomization method suggests that there is room for improvement in biome reconstruction in colder regions.
In this study, I used the Biomization method to clarify the biome changes over the past 20,000 years in the Tohoku regions in order to clarify the change of deciduous broad-leaved forests.
Pollen diagrams for the past 20,000 years were quantified using a collection of published pollen analytical studies. Age models estimated using 14C dates and/or Tephrochronology (Machida and Arai, 2003) and then compiled to each millennial time slice. The Biomization method is the same as in Gotanda et al. (2002).
Pollen contribution rates were calculated for each age at each analyzed site and mapped by 1000 years.
I reconstructed and mapped past biome distribution each millennial time slice. During the Last Glacial Maximum, cool mixed forest appeared from high elevation to low elevation, suggesting a cold climate. The lack of occurrence of cool conifer forest despite the cold climate may be due to the poor reconstruction rate of cool conifer forests by the Biomization method.
After 10k yr BP, temperate deciduous forests have appeared widely, and warm-mixed/broadleaved evergreen forest has not appeared in the Tohoku region. Warm-mixed/broadleaved evergreen forest did not expand further north than the Kanto region. In particular, the lack of expansion even near the Pacific coastline may be due to the rate of vegetation movement. Since warm-mixed/broadleaved evergreen forest appeared at 6k yr BP based on the reconstruction results in the Kanto region (Gotanda 2012), it is likely that they did not expand into the Tohoku region.
The biome distribution over the past 20,000 years was reconstructed using the Biomization method based on pollen analysis data from the Tohoku region. During the Last Glacial Maximum, cool mixed conifer forest was widely distributed, and as the climate warmed, temperate deciduous forest moved northward, and by 8 kyr BP, the Northeastern region was widely covered with temperate deciduous forest. However, warm-mixed/broadleaved evergreen forest probably did not extend further north than the Kanto region. The low restoration rate of cool conifer forest by the Biomization method suggests that there is room for improvement in biome reconstruction in colder regions.