Vegetational analysis of the floodplain forests and a floristic survey of Van Loon wildlife area

Abstract

The floodplain forest of the Van Loon Wildlife Refuge is located on the bottomlands of the Black River in La Crosse County, Wisconsin. The composition of the tree, shrub and herb strata were surveyed. A total of twelve overstory species were encountered in the study. Acer saccharinum was the dominant species in all stands except one. In that stand, Acer saccharinum was slightly exceeded in importance by Quercus bicolor. Quercus bicolor, Ulmus rubra, Betula nigra and Fraxinus pennsylvanica were secondary dominants and considered important species. Each species was present in all stands. The average tree density in the bottomland forest was 367.8/ha. The 22 average basal area/ha and basal area/tree were 27.1 m and 0.08 m , respectively.

The shrub stratum did not appear to be important in the Van Loon Wildlife Refuge as indicated by low values for frequency and estimated percent cover for all species. Sambucus canadensis, Ilex verticillata and Zanthoxylum americanum were the most prominent shrubs encountered. Shrubs reached greatest importance in openings within the floodplain forest.

Ninety-two herbaceous species were encountered while sampling. Sixty species occurred with a frequency of at least 1%, and Laportea canadensis was the dominant herb. Viola papilionacea, Galium aparine, the family Gramineae and the genus Carex were also important.

A vascular flora of the Van Loon Wildlife Refuge was compiled during the ecological sampling and on reconnaissance trips to the different communities present in the bottomland habitats and areas adjacent to the Black River. Three hundred sixty-five species, representing 88 families, were collected. Two hundred thirty-eight species from 67 families were found in bottomland communities. The remaining species were found in upland communities adjacent to the Black River.