Biederman L.A.,Iowa State University |
Beckman J.,Ecological and Water Resources |
Prekker J.,Ecological and Water Resources |
Anderson D.,Ecological and Water Resources |
And 2 more authors.
Natural Areas Journal
Western prairie fringed orchid (WPFO, Platanthera praeclara Sheviak & Bowles) is a federally threatened Great Plains forb incapable of regeneration if above-ground parts are damaged within a given growing season. The invasion of smooth brome (Bromus inermis Leyss) reduces diversity and alters resources in northern tall grass prairies, including those occupied by WFPO. Prescribed fire is most effective for brome reduction when it is timed to its phenology. This timing could also interfere with the growth of non-target species, including WPFO. Our objective was to document the emergence and growth of WPFO and to determine the degree of phenological overlap between WFPO and smooth brome. We monitored orchid phenology to detect emergence dates and tracked growth of flowering and non-flowering WFPO. We found that WFPO individuals likely to flower emerge earlier and their growth is more rapid than plants not destined to flower. We augmented orchid monitoring with observations of smooth brome for two years and found that the majority of reproductive orchids emerged before the dates when brome reached its reported stage of greatest susceptibility to fire. We conclude that late spring prescribed fires are likely to damage WPFO individuals most likely to reproduce. Fall burns may provide an alternative strategy for prairie management at WPFO sites. Source