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Eastern Prairie Fringed Orchid
"Finding the Needle"
by Kristen Lundh
We spent the day looking for the proverbial needle in a haystack. The needle, emerging spears of eastern prairie fringed orchids in a sea of vegetation growing up after an early spring burn.
A spring burn was prescribed as the first step in managing invasive reed canary grass that had inundated this wet prairie in Iowa; a site that also supports a healthy population of eastern prairie fringed orchid (Platanthera leuchophaea). Controlling reed canary grass is complicated by the orchid population. A graduate student from Western Illinois University is studying the site to determine the impact of reed canary grass management and climate variability on this federally threatened orchid.
The graduate student and staff from the Rock Island Field Office, in cooperation with the County Conservation Board that owns the prairie, have been busy locating newly emerging orchids so the plants can be covered before herbicide is sprayed to control reed canary grass.
Numbers of eastern prairie fringed orchids within a population tend to naturally go up and down over time. At this site, the changes have been very drastic with a high of over 2,000 flowering plants in some years to a low of zero during other years. This current study may help site managers better understand what effect reed canary grass is having on the plants. The study will also help determine if changes in hydrology due to fluctuations in annual precipitation and water level management in the marsh correlate with changes in orchid numbers. Rock Island Field Office staff will continue annually surveying individual eastern prairie fringed orchids within the site and recording whether they are vegetative, flowering, juvenile, or possibly dormant in order to better understand the demographics of the population.
Remnant prairies like this site are increasingly rare across the Iowa landscape. Although a vast 30 million acre sea of tallgrass prairie once covered Iowa, today only 1/10th of 1 percent of the original prairies remain. Conversion of native Iowa prairie to plowed fields, pastures and development has left this once extensive ecosystem present as only a small collection of isolated patches of varying size and quality. Most prairie remnants are small and degraded by haying, grazing, dumping, fire suppression or encroaching shrubs and trees.
Prairie ecosystems are one of the most diverse in the world; comprised of hundreds of plants, animals, and insects. Loss of prairie has caused a concomitant decline of many species that make up these communities; some have become rare and some, extinct. Several prairie species in Iowa, like the eastern prairie fringed orchid, have received federal protection under the Endangered Species Act (ESA).
Kristen Lundh is the Endangered Species Coordinator at the Rock Island, Illinois Field Office
Last updated: October 15, 2015