2013 Volume 3 Pages 3-14
The spring-fed wetlands around Ise Bay contain components of the Tokai hilly land elements, namely, Berberis sieboldii, Drosera tokaiensis, Eriocaulon nudicuspe, Veratrum stamineum var. micranthum and 11 other species endemic to the Tokai hills. In order to develop sustainable environmental management plans and conservation initiatives for this area, we analyzed the characteristics of pH, electric conductivity (EC), and NO2- and NO2- concentrations in interstitial water of each habitat at every month from 2003 to 2007. Seven areas with exceptionally high densities of the Tokai hilly land element were selected for analysis; six in Ena, Gifu Prefecture, and one in Kasugai City, Aichi Prefecture, Japan. Interstitial water pH and EC (μS/cm) samples from areas dominated by specific species were as follows. In Ena City, in areas where V. stamineum var. micranthum was dominant, pH was 6.3 (5.4-7.4) [median (minimum-maximum)] and EC = 24 (8-75); E. nudicuspe, pH 6.1 (5.5-7.1), EC = 30 (11-58); B. sieboldii, pH 6.5 (5.7-7.1), EC = 34 (9-60). D. tokaiensis in Ena, pH 6.0 (5.3-7.0), EC = 57 (23-98) and in Kasugai, pH 5.5 (4.5-6.9), EC = 138 (105-188). Interstitial water samples in these areas ranged from acidic to neutral, and, except for areas inhabited by D. tokaiensis, EC values were 60 μS/cm. Interstitial water NO3- concentrations in different areas inhabited by species endemic to the Tokai hills were 1.1 (0-4.4) μM in areas of B. sieboldii, 0.5 (0-2.8) μM in areas of E. nudicuspe, and 2.9 (0-8.9) μM in areas of V. stamineum var. micranthum; these concentrations are considered typical of oligotrophic conditions. D. tokaiensis exhibited an ability to adapt to both oligotrophic and eutrophic conditions. For example, NO3- concentrations in areas where D. tokaiensis was dominant were 26.2 (0-148) μM in Ena and 13.1 (0-74) μM in Kasugai. The median NO2- concentrations in all areas ranged from 0.8 to 1.2 μM. The NO3- concentration in areas dominated by D. rotundifolia in Ena, which is not a Tokai hilly land element, was 0.8 (0-3.3) μM. In this study, we demonstrated that acidic and oligotrophic conditions are not always limiting factors for the Tokai hilly land element in wetlands.