VASCULAR FLORA AND PLANT COMMUNITY TYPES OF THE OTT BIOLOGICAL PRESERVE,CALHOUN COUNTY, MICHIGAN

摘要

The Harvey N. Ott Biological Preserve in Calhoun County, Michigan, comprises ca. 121 hectares (298 acres) of terrestrial plant communities that include oak-hickory forests, hardwood swamps, a prairie fen, and a highly disturbed remnant understory of former oak openings. This property, now owned by Calhoun County, was once owned by Albion College as its nature center. From September 2011 to November 2012, we conducted a floristic inventory of the area after having studied relevant herbarium specimens and an unpublished checklist of the area prepared by Dr. William Gilbert. Gilbert, who was a professor at Albion College, conducted an inventory of the vascular plants of the preserve from 1946 to 1954 and made 656 collections during this period. Based on current circumscriptions and names, Gilbert documented 460 different species, 63 (13.7%) of which were introduced, including 36 (7.8%) that are now considered invasive. We hypothesized that the percentages of introduced and invasive species of all taxa have increased since Gilbert's study. During our field work, we documented 290 species that Gilbert collected that could easily be identified and made 292 collections of graminoids and other species that were either difficult to identify in the field or were not documented by Gilbert. Of these collections, 136 represent newly-recorded species for the preserve, which, when added to Gilbert's total, makes a total of 596 species recorded for the preserve. Of this total, 124 (20.8%) are introduced and 73 (12.2%) are considered invasive, which supports our hypothesis. Of the three currently state-listed rare plants that were documented by Gilbert, only two were relocated in 2012: Geum virginianum L. and Amorpha canescens Pursh, both listed as special concern. The third species, Cypripedium candidum Muhl. ex Willd. (listed as threatened), was not observed. A route for a portion of the North Country Trail through the preserve was finalized during this study. We hope that our work will provide useful baseline data for preserve management and stimulate more botanical studies of the area.