摘要

Within the United States, the Dakota Skipper now occurs only in Minnesota, North Dakota, and South Dakota. In these states it has been associated with margins of glacial lakes and calcareous mesic prairies that host warm-season native grasses. Preliminary geographic information system (GIS) analysis in North Dakota has indicated a close congruency between historic distribution of the Dakota Skipper and that of specific near-shore glacial lake features and related soil associations. This study analyzed humidity-related non-biotic microbabitat characteristics within three remaining occupied Dakota Skipper sites in each state during the larval growth period in 2000. Measured parameters included topographic relief, soil compaction, soil pH, moisture, and temperature at various depths, soil bulk density, soil texture, and temperature and humidity within the larval nest zone. Results of these efforts reveal two distinctive habitat substrates, one of relatively low surface relief with dense but relatively less compact soils, and another of relatively high relief with less dense but more compact soils. In the low-relief habitat, grazing appears to Compact soils unfavorably in otherwise similar prairies in the more xeric western portion of the range, potentially by affecting ground-water buffering of larval nest zone humidity.

  • 出版日期2008-5-6