Cattle Grazing Reduces Survival and Reproduction of the Western Prairie Fringed Orchid

Authors

Bonnie Warner Alexander, Valley City State University
Donald Kirby, North Dakota State UniversityFollow
Mario Biondini, North Dakota State University--Fargo
Edward Dekeyser, North Dakota State University--Fargo

Date of this Version

6-2010

Document Type

Article

Citation

The Prairie Naturalist· 42(1/2): June 2010, pp 45-49

Comments

This issue of The Prairie Naturalist contains a series of three papers on the western prairie fringed orchid by Dr. Bonnie Alexander and her colleagues. Dr. Alexander passed away in August, 2007, after a brief but hard fought battle with cancer and only a short while after completing her Doctorate in Natural Resources Management at North Dakota State University. Her research on this threatened orchid species adds greatly to the information needed by researchers, managers, and decision makers to assure its persistence into the future

Abstract

QuantifYing impacts of livestock grazing and prairie management strategies on the threatened western prairie' fringed orchid (Platanthera praeclara) is difficult due to the erratic appearance of the orchid above-ground. We monitored above-ground survival of orchids from flowering to mature seed capsule production, comparing plant height, flower numbers, and seed capsule numbers from 2002-2004 in rotationally grazed pastures and non-grazed sites. Orchid survival differed significantly between grazed and non-grazed pastures, with the proportion of plants surviving from flower to capsule production consistently lower in grazed pastures. Mean orchid survival in grazed and non-grazed areas was 40% and 87%, respectively. The proportion., of surviving plants producing capsules greater than 3 mm in diameter was significantly greater in non-grazed pastures. Flower and bud production did not differ between grazed and non-grazed areas, tlnd plant height was significantly greater in non-grazed) areas. High levels of above-ground plant mortality may reduce orchid tuber winter survival and robustness of above-ground; growth the following growing season. Creation of protected orchid nursery areas within grazed pastures is suggested to reduce high mortality of above-ground orchid plants.