Establishment and control of hay-scented fern: a native invasive species
Cretaz, L. & Kelty, M. J. (1999). Establishment and control of hay-scented fern: a native invasive species. Biological Invasions, 1(2-3), 223-236. PDF.
Summary
Hay scented fern (Dennstaedtia punctilobula), native to eastern North America, can act as an invasive species by creating a dense understory monoculture. It reduces native tree diversity by preventing germination, reducing available light, competing for water and nutrients, and possibly by releasing allelopathic chemicals. While increases in hay scented fern are linked to deer browsing and canopy thinning, it is unclear how these two factors interact to promote the fern invasion. While herbicide treatments have been successful in the past for reducing fern density, alternative mechanical methods may be preferential in some sensitive areas. Therefore, the Cretaz and Kelty (1999) investigated the roles of deer browsing and thinning in hay scented fern establishment by evaluating fern cover in six sites with various thinning and deer browsing history. They found that both high deer browsing and a history of thinning were necessary to produce dense fern monocultures and that one disturbance alone was not sufficient. The authors also explored three potential hay scented fern removal strategies, removal (full removal of fern fronds and mat), mixed (fronds were removed but mat was torn into pieces and replaced), and clipping (only fronds were removed). They found that both the fern mat and fronds interfere with tree seedling success. Both removal and clipping were more successful in aiding woody species germination and establishment than the mixed treatment.
Take home points
A combination of factors, high deer browsing and stand thinning, are necessary for hay scented fern to act as an invasive.
Native plants with traits similar to alien invasives (vegetative regeneration, hardiness), may act as invasive species under specific conditions.
Management implications
Mechanical removal of hay scented fern can yield successful results in its control. However, this may be difficult to produce at large scales.
Keywords
Impact Study; Observation; Invasive Plant; Terrestrial Habitat; Dennstaedtia punctilobula; Hay Scented Fern; Restoration