Hiraoka is the created wetland that was constructed in 2000 in an urban park in Sapporo City. We introduced fen and bog plants and monitored the hydrochemical conditions and species assemblage composition four times during the 16 years after construction (YAC). The species richness indices of total, exotics, and annuals resembled those of the target fens within 11 YAC, but the species assemblages did not match the target fens even after 16 YAC, showing that species richness is a less effective way to measure success. The 0.1 m high artificial hummocks enhanced species richness 1.3 to 1.4 times more than the surrounding hollows and increased variety within species assemblages (although these hummocks collapsed before16 YAC). Water level from ground surface (WL) were stable at around 0.00 to +0.05 m, except during several-days floods, when a maximum WL of +0.4 to +0.5 m. Hydrological conditions were, therefore, similar to those natural fens nearby. Mean pH values (min and max) decreased from 6.9 (5.5–9.3) in 1 YAC to 6.2 (5.7–6.9) in 16 YAC and approached those of natural fens. The mean electrical conductivity (166–196 ${\mathrm{\mu S}\text{cm}}^{-1}$) and concentrations of major minerals (Ca²⁺, Mg²⁺, and K⁺) were consistently higher than those of Japanese fens, but dissolved phosphorus (0.00–0.04 mg l⁻¹) and nitrogen (0.12–0.48 mg l⁻¹) were lower. The trajectory of species assemblages quickly approached the target fen at least 5 YAC, but then changed between 5 and 11 YAC, before stagnating. Since mineral content in Hiraoka was near the lower limit of calcareous rich-fens, abundant minerals would be less effective in changing the species assemblage compositions. Due to the dominance of eight initially introduced fen species, the trajectory turned in a different direction. Species assemblages stagnated between initial and target communities before 16 YAC, since the five fen dominants introduced at 8 to 9 YAC had not yet dominated. Accordingly, initial introductions, including species combinations of target fen, can shorten the time required to achieve natural fens. At 16 YAC, large emerged macrophytes did not dominate and did not competitively exclude fen species, probably because the water was oligotrophic and the wetland design did not include open water.

平冈是在2000年在札幌市的城市公园内建造的人工湿地。在建设后的16年（YAC）中，我们引入了and和沼泽植物，并对水化学条件和物种组成组成进行了四次监测。总物种，外来物种和年度物种的物种丰富度指数与11 YAC内的目标fen相似，但即使在16 YAC之后物种组合也没有达到目标，表明物种丰富度是衡量成功与否的较无效方法。高度为0.1 m的人工山岗使物种丰富度比周围的空洞增加了1.3到1.4倍，并增加了物种集合中的物种多样性（尽管这些山岗在YAC16之前倒塌了）。除了在几天的洪水期间，地表水位（WL）稳定在0.00至+0.05 m左右，当最大WL为+0.4至+0.5 m时。因此，水文条件类似于附近的自然环境。平均pH值（最小和最大）从1个YAC中的6.9（5.5-9.3）降低到16个YAC中的6.2（5.7-6.9），并接近天然。平均电导率（166–196${\mathrm{微秒}\text{厘米}}^{--\mathrm{1个}}$）和主要矿物质（Ca 2 ⁺，Mg ²⁺和K ⁺）的浓度始终高于日本s，但溶解的磷（0.00–0.04 mg l ^-1）和氮（0.12–0.48 mg l ^-1）较低。物种集合的轨迹至少在5 YAC附近迅速接近目标点，但在停滞之前在5和11 YAC之间变化。由于平冈的矿物质含量接近钙质富rich的下限，因此丰富的矿物质在改变物种组成上的作用较小。由于最初引入的八种species的优势，其轨迹转向了不同的方向。在YAC 16之前，最初和目标社区之间的物种聚集停滞不前，因为在YAC 8至9引入的5个分统尚未主导。因此，最初的引入，包括目标initial的物种组合，可以缩短实现天然的时间。在YAC举行的第16届大会上，大型涌出的大型植物并未占优势，也没有竞争性地排除类，