Invasive exotic plants such as Canada thistle and leafy spurge, if not controlled, can choke out native vegetation. Aggressively invasive non-native plants are known as "noxious weeds."
Jewel Cave National Monument uses an integrated pest management (IPM) approach to control noxious weeds. IPM includes mechanical control (hand-pulling and cutting), chemical control (application of herbicides), and biocontrol (introducing insects which attack the plant).
To prevent contamination of water inside the cave, herbicide chemicals cannot be used in about half of the Monument. The Cave and Karst Management Plan / Environmental Assessment (2007) established pesticide use zones based on geology and hydrology, and discussed the potential environmental effects of chemical treatment.
Jewel Cave National Monument relies heavily on mechanical methods to control exotic plants. Hand-pulling removes part of the root system and stresses the plant. Cutting prevents the plant from producing seed.
Over seven acres of Canada thistle, leafy spurge, and spotted knapweed were mechanically treated at Jewel Cave in 2012.