What can cause a change in aquatic plant communities?
Some species of aquatic plants tend to occur within a relatively narrow range of conditions that may include specific water nutrient levels, clarity, pH, and/or depth; while other plants may tolerate a wide range of these conditions. Annual variations in temperature or precipitation may cause one or more of the plant communities to temporarily expand or reduce its range. On some occasions, climate variations can result in long-lasting changes to a plant community. For example, during the drought in the 1930s, bulrush seeds that had been dormant on the lake bottoms for years were suddenly exposed to air as the lake levels dropped. Once exposed, these seeds germinated, forming many of the extensive bulrush beds we have in our lakes today. However, under the same low-water conditions, other species may experience high mortality due to exposure. Trends in abundance and diversity of aquatic plant species over several years that can not be explained by climate change are often the result of
