Historical change in lake sedimentation in Lake Takkobu, Kushiro Mire, northern Japan over the last 300 years

Ahn, Young Sang; Mizugaki, Shigeru; Nakamura, Futoshi; Nakamura, Yugo

doi:10.1016/j.geomorph.2006.01.036

Cited by 28 publications

(32 citation statements)

References 52 publications

(65 reference statements)

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“…by sea-level regression (Kumano et al 1990). The main outflow from the lake is into the Kushiro River, and inflows to the lake are from the Takkobu River and the backflow of the Kushiro River, occurring at high water (Ahn et al 2006). The lake is bordered by wetland vegetation containing reed (Phragmites australis), carex (Carex spp.…”

Section: Study Areamentioning

confidence: 99%

“…The sediment core used in this study was one of the 15 cores analyzed by Ahn et al (2006). It was extracted from the center of Lake Takkobu (point C2, Fig.…”

Section: Coring and Dating Of Sedimentsmentioning

confidence: 99%

“…This core was selected for pollen analysis because lake sediments are likely to be best preserved in the center of the basin, where the water is usually deepest and disturbance by the movement of water and biological activity tends to be limited (Moore et al 1991). Ahn et al (2006) also estimated the age of the Lake Takkobu sediments at four depths, using three methods. First, 137 Cs dating was used to identify the 1963 surface in the sediments.…”

Section: Coring and Dating Of Sedimentsmentioning

confidence: 99%

“…This paper first aims to assess the impact of recent human activity on the vegetation in Takkobu, using fossil pollen, to compare with the previous study of soil erosion in the area by Ahn et al (2006). This study extracted Lake Takkobu sediments and measured sedimentation rates to analyze the last 300 years' history of soil erosion in the catchment.…”

Section: Introductionmentioning

confidence: 99%

“…The five-to sevenfold increase in sedimentation rates since the late 19th century confirmed the significance of Japanese land-use development. Here, the results of pollen analysis on one of the Lake Takkobu sediment cores will be presented and interpreted, along with documentary data and Ahn et al's (2006) findings. The reconstruction of past vegetation change in Takkobu then leads to the second aim of the paper, which is to determine the baseline state of Takkobu forests to be restored.…”

Section: Introductionmentioning

confidence: 99%

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Recent human impact on vegetation in Takkobu, northern Japan, reconstructed from fossil pollen in lake sediments

Kumagai

Ahn

Nakamura

2008

Journal of Forest Research

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The vegetation of Takkobu, northern Japan, has been significantly altered by land-use development following Japanese settlement at the end of the 19th century. In order to assess the impact of human activity on vegetation dynamics in Takkobu, changes in the vegetation composition over the last 300 years were reconstructed from fossil pollen in the sediments of Lake Takkobu. The pollen assemblage represented broadleaved forests on the surrounding hills and alder forests found on the margin of the wetland bordering the lake. Prior to Japanese settlement, the hillside forests consisted predominantly of oak. However, with the onset of land-use development, a significant decline in oak relative to increasing birch was apparent, particularly after the early 1960s. These results suggest that successive logging since the 1880s had gradually undermined the resilience of oak. An increase of Artemisia and birch pollen also indicates an expansion of disturbed land. Since the 1960s, a large part of the broadleaved forests in Takkobu has been converted to larch plantations, although this was not represented in the pollen data because of the underrepresentation of larch pollen. The results of the pollen analysis have implications for forest restoration in Takkobu. The use of long-term data allows the determination of the baseline (natural) vegetation to be restored, and also illustrates the factors affecting present-day vegetation and how it may change in the future.

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Section: Study Areamentioning

confidence: 99%

“…The sediment core used in this study was one of the 15 cores analyzed by Ahn et al (2006). It was extracted from the center of Lake Takkobu (point C2, Fig.…”

Section: Coring and Dating Of Sedimentsmentioning

confidence: 99%

Section: Coring and Dating Of Sedimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Recent human impact on vegetation in Takkobu, northern Japan, reconstructed from fossil pollen in lake sediments

Kumagai

Ahn

Nakamura

2008

Journal of Forest Research

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Elevated sedimentation in lake records linked to agricultural activities in the Ishikari River floodplain, northern Japan

Ahn

Nakamura

Kizuka

et al. 2009

Earth Surf Processes Landf

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The purpose of this study was to examine the historical change in sedimentation rates in lakes that have been impacted by river regulation and agricultural activities in the Ishikari River floodplain. We dated sediment cores using caesium-137 ( 137 Cs) dating and tephrochronology, and we estimated sediment sources from 137 Cs concentrations in the topsoil of representative land covers. We found that, between 1739 and 1963, the distance between the lake and the main river channel and whether or not the lake was connected to the river affected the sedimentation rates. After 1963, agricultural drainage systems were established in the Ishikari River floodplain. The average sedimentation rate before and after the construction of drainage ditches varied between 1-66 and 87-301 mg cm -2 a -1 , respectively. The increase in the sedimentation rate after 1963 was caused by the construction of a number of drainage networks, as well as extensive cultivation activity and/or fragmentation of the swamp buffers surrounding the lakes. The 137 Cs activities at the surfaces of the lake as well as the catchment-derived 137 Cs contributions and 137 Cs inventory in the lake profiles were used to examine the sediment influx from the various drainage areas after the establishment of the drainage system. Our results indicate that the majority of the lake sediments were derived from cultivated areas, and therefore the catchment-derived 137 Cs contribution in the lakes was strongly correlated with the sedimentation rate. The 137 Cs inventory across all of the lake profiles was also significantly greater than the atmospheric fallout. We identified a negative correlation between the 137 Cs lake profile inventory and the sedimentation rate. This is because the sediment originating from the drainage areas contained low 137 Cs concentrations, which diluted the overall concentration of 137 Cs in the lake sediment.

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2007

Hydrological Processes

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Historical change in lake sedimentation in Lake Takkobu, Kushiro Mire, northern Japan over the last 300 years

Cited by 28 publications

References 52 publications

Recent human impact on vegetation in Takkobu, northern Japan, reconstructed from fossil pollen in lake sediments

Recent human impact on vegetation in Takkobu, northern Japan, reconstructed from fossil pollen in lake sediments

Elevated sedimentation in lake records linked to agricultural activities in the Ishikari River floodplain, northern Japan

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