**3.9 Protecting rare plants**

 Groundwater contained in a limestone or dolomite aquifer that discharges into a major river basin provides a calcium-, magnesium-, and bicarbonate-rich water that drives rare calciphile plant occurrence, converging streamlines of groundwater flow into valley fen. Shallow flow paths have short travel times based on anthropogenic chloride and sodium typically not found in the deeper flow paths of a carbonate aquifer. Thick calcite accumulations occur in the root zone at the water table.

There is a mixture of upwelling groundwater and water near the surface that can mix and then flow downslope from higher elevations into the fen or toward spring-fed lakes or directly to the river (**Figure 11**). Shallow groundwater decreases downgradient in the calcareous fen as older groundwater pushes up to discharge [28]. Komor [28] believes that encroachment of reed grasses and other invasive species into the calcareous fen may reflect human-caused disturbances in the valley. The land use in this riparian area requires special protection to limit invasive species and preserve the unique plant life. The Minnesota Department of Natural Resources has enacted rules to sustain and preserve calcareous fens in Minnesota.
