Most conservation measures for pteridophytes involve occurrences in late succession or climax vegetation. There is a tendency to avoid those species that occur in disturbed sites.Also there is a custom of stopping prairie fires, filling in mine and quarry sites, and mitigating borrow pits. However, some very rare species flourish where disturbance has occurred. Some disturbances are produced under natural conditions, forming more or less permanent early stages in succession, as prairie fields, montane snow fields, floods, sand dunes, falling trees, natural pastures, and wetlands, including marshes, fens, and bogs. In the past two centuries, successional habitats have been created by human activity, including trails and roadsides, lumbering, fires, old pastures, orchards, baseball fields, sand and gravel mines and borrow pits, and cemeteries. Stages of early succession make it possible for "fugitive species" to become established and produce large populations.To be sure, such man-made openings are subject to entrance of Eurasian weeds and other invasives, but early-succession native species are ultimately able to compete with them. They will disappear nevertheless with succession to mature communities. These rarities cannot tolerate dominance of later-succession plants, especially trees and shrubs. A common change occurs from open herbaceous space to mature beech-sugar maple or northern hardwood forest, or to oak-hickory forest. Disturbance on acidic sites, may lead to mixed clones of lycopods, some very rare in Michigan, such as Diphasiastrum, sabinifolium, Lycopodiella subappressa, and Huperzia appalachiana. On circumneutral sites we find many rare moonworts, including the globally endangered Botrychium pseudopinnatum and B. acuminatum. Methods of turning back succession are now being explored, including fire, tree and shrub sapling removal, handpulling and raking of the herb layer, and bulldozing to re-expose the open soil surfaces.

Key words: Lycopodiaceae, conservation, disturbed habitats, endangered species, Ophioglossaceae, Pteridophytes