Effects of climatic conditions on morphology, hydrochemical conditions, and plant species composition of Sphagnum hummocks

为了弄清北海道各地泥炭堆形状和大小的区域差异的原因，在控制雪压和其他植物遮阳的条件下，对生长在泥炭堆上的3种泥炭的生长情况进行了4公里的研究。富连川有圆柱形和极凸起型，Sarobetsu和Utasai有扁平和低型。Utonai为圆锥形和中高型，年生长量在Sarobetu和Utasai较大。在6月，由于蒸散量最大，雨水缺乏，丘面干燥，沙罗贝图的山棘生长受到明显抑制。遮荫的消除抑制了所有沼泽中泥炭草的生长，这可能是由于丘面蒸发蒸腾损失增加所致。雪压的减少导致深雪地区Sarobetu和Utasai的下一夏季生长减少，因为丘面与地下水位保持足够高，因此更容易遭受严重的干旱。研究了福连嘎瓦沼泽中一个凸起的泥沼的水平衡，并探讨了水在泥沼内部的运动规律。晴天时，表层通过补充下层蒸发蒸腾损失的等量水分保持恒定含水量，但由于深层供水量不足，下层含水量下降。当下雨时，从丘面供给的雨水通过表层迅速渗透而没有储存，而部分雨水则被储存到较深层。完整的表层泥炭结构优良，具有较高的保水和吸水能力。因此，当表层由于蒸散作用失去一些水分时，水能够从深层重新补给。与此相反，深层宏观结构崩塌的中度分解泥炭的水力导电性似乎相对较低，这导致了细水期含水率下降，深层降雨期雨水蓄积。雨水的储存机制会使站在微营养化地表水上的内丘形成一个营养化条件。此外，整个生长季节的湿润气候条件，如频繁的短间隔降雨和大的负净失水值，阻止了深层含水量的下降和下垫面水位的下降。少

In order to clarify the reasons of regional differences in shape and size of Sphagnum hummocks throughout Hokkaido, we examined the growth of 3 Sphagnum species growing on hummocks in 4 mires, with controlling the conditions of snow pressure and shading by other plants. Fuhrengawa has cylindrical and extremely raised type, Sarobetsu and Utasai have flat and low type. Utonai has conical and middle height type, The annual growth was larger in Sarobetu and Utasai. Remarkable suppression of the growth of S. papillosum at Sarobetu was observed in June, where hummock surface was desiccated owing to the highest evapotranspiration and a lack of rainwater. Removal of shading suppressed the growth of Sphagnum in the all mires, probably due to the enhanced evapotranspiration losses from hummock surface. Removal of snow pressure caused the decrease in the growth of next summer at Sarobetu and Utasai in deep snow region, because hummock surface were kept higher enough from underlying water table to … More suffer severe drought.We investigated the water balance of a raised hummock of Sphagnum fuscum in Fuhrengawa mire and consider how water moves interior hummock. In fine days, a surface layer kept a constant water content by re-supplying the same amount of water lost by evapotranspiration from a lower layer, but water content in the lower layer was decreasing because of an insufficient supply of water from deeper parts. When it was raining, rainwater supplied from the hummock surface percolated rapidly through the surface layer without storage, whereas some rainwater was stored into the deeper layer. Intact peat of surface layer has fine structure resulting high water retention and absorption capacity. Therefore, when some water was lost from the surface layer by evapotranspiration, water was able to re-supplied from the deeper layer. Contrary to this, it seemed that moderately decomposed peat with macrostructural collapse in deeper layer has relatively low hydraulic conductivity, resulting in decreasing water content during fine periods and storage of rainwater during rain periods in the deeper layer. The storage mechanism of rainwater would generate an ombrotrophic condition at inner hummocks standing on minerotrophic surface water. Furthermore, the humid climatic conditions throughout a growing season such as frequent rains with short intervals and large negative values of net water loss prevent from declining water content of the deeper layer and decreasing the level of underlying water surface. Less