DISTRIBUTIONS OF SPECIES OF BOTRYCHIUM (OPHIOGLOSSACEAE) IN NORTH-NORTHWESTERN MINNESOTA

摘要

From 2005 to 2020, we conducted targeted field surveys in northwestern Minnesota across those portions of Koochiching, Lake of the Woods, Roseau, Beltrami, Marshall, Polk, Pennington, and Kittson Counties that lie north of the 48th parallel for any ofthe fifteen species of Botrychium known to occur in Minnesota. Prior to 2005, there were only nine populations of Botrychium recorded from this area. During our 16-year survey, we took 640 collections. Vouchers were accessioned at the University of Minnesota Bell Museum Herbarium. Data were reported annually to the Minnesota Department of Natural Resources and entered into the Natural Heritage Information System database. All collections in this database from this area are accounted for in this report,666 in total. Twelve taxa are represented, some of them common, and others among the rarest species of Botrychium in Minnesota. Ten taxa are currently listed in Minnesota as rare, threatened, or endangered; an eleventh likely will be. Distributions areinfluenced by the landscape history from early post-glacial to present. Changes in vegetation from pre- to post-settlement have been influenced by logging practices, fire suppression, widespread drainage and agricultural conversion, and settlement history. Broad distribution patterns of Botrychium in pre-settlement times would likely have been similar to present, but the specific habitats suitable to Botrychium on this landscape have changed profoundly with the post-settlement changes in the vegetation.Micro-distributional observations in rich sites suggest a few possible associations that are unusually predictive.