Aquatic plant communities are good indicators of lake conditions, and persistent changes to those communities are indicative of environmental change. Our study used historical and recent lake plant surveys to detect changes in Minnesota’s lake plant communities over the last century. We did not find taxa richness estimates useful for change detection and suggest that recent richness values were higher than historical due to increased search effort rather than real change. The primary signal of change was the failure to relocate taxa in lakes where they were historically common. In 55 % of the lakes, surveyors did not relocate at least one taxon that was reported in an historic survey. We found that emergent plant taxa were most likely to have been lost; for lakes where emergents were reported historically, 45% had at least one emergent taxon that was not redetected compared to 30% of lakes where at least one floating-leaf taxon was not redetected and 42% of lakes where at least one submerged taxon was not redetected. Lakes in the southwestern and central ecoregions of the state were most likely to have gross and persistent aquatic plant losses. Eutrophication was the most likely reason for losses, with substantial declines in the probability of presence of many taxa with greater increases in lake phosphorus concentrations. We identified limitations with these datasets and recommend survey method changes to improve future collection of lake plant lists.

水生植物群落是湖泊状况的良好指标，而这些群落的持续变化预示着环境的变化。我们的研究使用历史和最近的湖泊植物调查来发现上个世纪明尼苏达州湖泊植物群落的变化。我们没有找到分类单元丰富度估计值对更改检测有用，并且建议由于增加的搜索工作而不是实际更改，最近的丰富度值高于历史值。变化的主要信号是未能在历史上很常见的湖泊中重新安置分类单元。在55％的湖泊中，测量师没有迁移至少一个历史调查中报告的分类单元。我们发现，紧急植物分类群最有可能丢失。对于历史上曾报告有紧急事件的湖泊，45％的人至少没有发现一个紧急分类单元，而30％的湖泊中至少没有重新发现一个浮叶分类单元，而42％的湖泊中至少一个水下分类单元没有被识别。该州西南部和中部生态区的湖泊最有可能造成总的和持续的水生植物损失。富营养化是造成损失的最可能原因，许多类群存在的可能性大大降低，而湖中磷的浓度增加了。我们确定了这些数据集的局限性，并建议对调查方法进行更改，以改进将来收集的湖泊植物名单。该州西南部和中部生态区的湖泊最有可能造成总的和持续的水生植物损失。富营养化是造成损失的最可能原因，许多类群存在的可能性大大降低，而湖中磷的浓度增加了。我们确定了这些数据集的局限性，并建议对调查方法进行更改，以改进将来收集的湖泊植物名单。该州西南部和中部生态区的湖泊最有可能造成总的和持续的水生植物损失。富营养化是造成损失的最可能原因，许多类群存在的可能性大大降低，而湖中磷的浓度增加了。我们确定了这些数据集的局限性，并建议对调查方法进行更改，以改进将来收集的湖泊植物名单。