Factors to change two alternative systems, macrophyte-rich macrophyte-free in shallow lakes

2000年8月，我们调查了钏路沼泽3个不同植被覆盖度和养分浓度的浅湖的水生植物、水质、浮游植物生物量和物种组成。日本菜可以在各种营养水平下生存。它形成了一个光消退更陡、溶解有机碳（DOC）浓度较高、底部附近溶解氧（DO）浓度较低、硝酸盐+亚硝酸盐和可溶性活性磷（SRP）浓度较低的环境。水陆蓼群落的pH值要高得多，靠近底部的DO没有下降。叶绿素a与限制养分（TN: TP【大于等于】10时为TP， TN: TP < 10时为TN/10）的关系在有无淹没植被的湖泊间存在显著差异。在一定营养水平下，有植物水体的叶绿素a浓度显著低于无植物水体。对应分析表明，不同站点间浮游植物群落结构的差异很大程度上取决于沉水植物的存在与否，而有沉水植物的湖泊中浮游植物种类的排序可以用TN、叶绿素、pH和SRP的环境梯度来解释

We investigated aquatic macrophytes, water quality, and phytoplankton biomass and species composition in three shallow lakes with different levels of vegetation coverage and nutrient concentrations in Kushiro Moor during August 2000. Trapa japonica can live at a wide range of nutrient levels. It forms an environment with a steeper extinction of light, higher concentrations of dissolved organic carbon (DOC), lower concentrations of dissolved oxygen (DO) near the bottom, and lower concentrations of nitrate + nitrite, and soluble reactive phosphorus (SRP). The pH was much higher In a Polygonum amphibium community, and the DO near the bottom did not drop. The relationship between chlorophyll a and the limiting nutrient (TP when TN : TP 【greater than or equal】 10, and TN/10 when TN : TP < 10) significantly differed between lakes with and without submerged vegetation. The chlorophyll a concentrations at a given nutrient level were significantly lower in water with submerged macrophytes than in water without them. Correspondence analysis showed that the difference in phytoplankton community structure among sites is due largely to the presence or absence of submerged macrophytes, and the ordination of phytoplankton species in the lakes with submerged macrophytes is best explained by environmental gradients of TN, chlorophyll, pH, and SRP