Hydrological setting of infertile species-rich wetland——a case study in the warm temperate Japan  

作　　者：Kikuchi A. Nakagoshi  N. Onda  Y. 

机构地区：[1]Graduate School for International Development and Cooperation, Hiroshima University,Graduate School for International Development and Cooperation, Hiroshima University,Institute of Geoscience, University of Tsukuba Higashi-Hiroshima City, 739_8529 Japan,Higashi-Hiroshima City, 739_8529 Japan,Ibaraki 305_8571, Japan

出　　处：《Journal of Environmental Sciences》2003年第2期279-283,共5页环境科学学报（英文版）

摘　　要：The detailed groundwater flow and water chemistry to illustrate landscape structure of the infertile peatless mire by using piezometers and groundwater wells were measured. The instruments were installed in lines through a small spring-fed wetland underlying little peat from the hillslope to the valley bottom in southwestern Japan. Flow net and EC data clearly indicated that the wetland was situated in a high-EC groundwater upspring area. The low-productivity graminous vegetation was related with four hydrological factors such as: (1) high water level; (2) low-EC(<25 micro S/cm) groundwater; (3) weakly upward hydraulic gradient; and (4) overflowing of negatively pressured groundwater. In other words, the “old or deep groundwater” constructed the foundation of slope-wetland, and maintained the high groundwater level. In contrast, overflowing “youthful groundwater” is supplied from head of slope-wetland preferentially through the shallow substratum. The plant communities of the peatless mire in southwestern Japan are similar to those of raised bog in northern cool temperate Japan. There have been some reports verifying that the underlying mineral substrata of such wetlands were quartzile rocks such as granite, rhyolite, chart and well-leached sand. Results showed (1) low cation availability affects the water acidity; (2) upward seepage of high-EC groundwater composed the foundation of the investigated peatless mire; and (3) the poor mineral condition seems to play a similar role to northern ombrotrophic(rain-fed) condition.The detailed groundwater flow and water chemistry to illustrate landscape structure of the infertile peatless mire by using piezometers and groundwater wells were measured. The instruments were installed in lines through a small spring-fed wetland underlying little peat from the hillslope to the valley bottom in southwestern Japan. Flow net and EC data clearly indicated that the wetland was situated in a high-EC groundwater upspring area. The low-productivity graminous vegetation was related with four hydrological factors such as: (1) high water level; (2) low-EC(<25 micro S/cm) groundwater; (3) weakly upward hydraulic gradient; and (4) overflowing of negatively pressured groundwater. In other words, the “old or deep groundwater” constructed the foundation of slope-wetland, and maintained the high groundwater level. In contrast, overflowing “youthful groundwater” is supplied from head of slope-wetland preferentially through the shallow substratum. The plant communities of the peatless mire in southwestern Japan are similar to those of raised bog in northern cool temperate Japan. There have been some reports verifying that the underlying mineral substrata of such wetlands were quartzile rocks such as granite, rhyolite, chart and well-leached sand. Results showed (1) low cation availability affects the water acidity; (2) upward seepage of high-EC groundwater composed the foundation of the investigated peatless mire; and (3) the poor mineral condition seems to play a similar role to northern ombrotrophic(rain-fed) condition.

关 键 词：ECO-HYDROLOGY electrical conductivity groundwater flow plant community WETLAND 

分 类 号：X171[环境科学与工程—环境科学]