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尾瀬ヶ原の湿原植生分布を決めている泥炭土壌の理化学的要因
村上, 大樹;楊, 宗興
Permalink : http://hdl.handle.net/2115/84987
JaLCDOI : 10.14943/lowtemsci.80.269
KEYWORDS : 湿地;植生;降水涵養型;水質;泥炭;wetland;vegetation;ombrotrophic;water chemistry;peat
Abstract
泥炭湿地の植生分布と泥炭土壌の栄養性の関係を明らかにすることを目的として，日本における有数の泥炭湿地である尾瀬ヶ原において，河川から湿原中央部にかけて調査測線を設定し，植生分布と泥炭土壌の理化学性の調査を行った．その結果，尾瀬ヶ原の植生分布は，泥炭土壌の理化学性に基づいて明確に支配されていることが明らかとなった．地下水位の測定結果から，尾瀬ヶ原湿地の大部分は降水涵養型の泥炭湿地であると判断されたが，泥炭土壌の粒度分析結果から，尾瀬ヶ原の大部分では，洪水時に供給された土粒子がミネラル供給源となり，湿原植生の分布に影響を及ぼしていることがわかった．
The importance of pore water chemistry in the distribution of the mire vegetation was examined by chemical analysis of the peat interstitial water and peat soils of Ozegahara mire, Japan. Along a transect from a riverside to the center of the mire, dominant vegetation changed in an almost decreasing order of plant height from gallery forest, skunk cabbage, reed, sasa-bamboo, Moliniopsis japonica to Sphagnum mat, with sporadic appearance of cinnamon fern (Osmunda cinnamomea) with heights of around 100 cm on the transect way. These vegetations was found to have discrete (Ca2+ + Mg2+) concentration in peat interstitial waters and ash content of the peat soil，indicating a close association of the vegetation types with physico-chemical environment of the peat soils. Most of the survey sites along the transect were identified to be ombrotrophic, judging from the groundwater tables which were much higher than the river surface (up to 6.0 m). Nevertheless, elevated ash contents as high as more than 50% were detected in peat soil especially at the sites of cinnamon fern at deeper layers (15-20 cm and 20-25 cm), suggesting that soil particles had been transported onto the mire through river overflows. SiO2, Ca2+, Mg2+, and K+ concentrations in peat interstitial waters were significantly correlated with fine sand contents in the peat soils at 5-10 cm depth (p<0.05). Height of plants that grow in the ombrotrophic sites showed significant positive correlations with both K+ and Ca2+ concentrations (p<0.05). The survey results suggest that, in Ozegahara mire where is mostly ombrotrophic, soil particles derived from flooding serve as an important mineral source affecting the distribution of vegetation type on the mire.
The importance of pore water chemistry in the distribution of the mire vegetation was examined by chemical analysis of the peat interstitial water and peat soils of Ozegahara mire, Japan. Along a transect from a riverside to the center of the mire, dominant vegetation changed in an almost decreasing order of plant height from gallery forest, skunk cabbage, reed, sasa-bamboo, Moliniopsis japonica to Sphagnum mat, with sporadic appearance of cinnamon fern (Osmunda cinnamomea) with heights of around 100 cm on the transect way. These vegetations was found to have discrete (Ca2+ + Mg2+) concentration in peat interstitial waters and ash content of the peat soil，indicating a close association of the vegetation types with physico-chemical environment of the peat soils. Most of the survey sites along the transect were identified to be ombrotrophic, judging from the groundwater tables which were much higher than the river surface (up to 6.0 m). Nevertheless, elevated ash contents as high as more than 50% were detected in peat soil especially at the sites of cinnamon fern at deeper layers (15-20 cm and 20-25 cm), suggesting that soil particles had been transported onto the mire through river overflows. SiO2, Ca2+, Mg2+, and K+ concentrations in peat interstitial waters were significantly correlated with fine sand contents in the peat soils at 5-10 cm depth (p<0.05). Height of plants that grow in the ombrotrophic sites showed significant positive correlations with both K+ and Ca2+ concentrations (p<0.05). The survey results suggest that, in Ozegahara mire where is mostly ombrotrophic, soil particles derived from flooding serve as an important mineral source affecting the distribution of vegetation type on the mire.
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