Composition and soil–environment analysis of prairies on Walpole Island, southwestern Ontario

Abstract

Extensive prairie communities on Walpole Island Indian Reserve in Lake St. Clair, southwestern Ontario, were sampled for vegetation and soil profile characteristics. Two hundred and fifty-two species were found in the 20 stands. Dominant grasses included Calamagrostis canadensis, Andropogon gerardii, Sorghastrum nutans, Panicum virgatum, Poa pratensis, and Spartina pectinata. Dominant forbs were Pycnanthemum virginianum, Liatris spicata, Fragaria virginiana, Lysimachia quadriflora, and Viola papilionacea. Stands were ordered along a recognized moisture–substrate gradient divided into four segments; dry-mesic sandy, mesic sandy loam, wet-mesic sandy loam, and wet loam. Many species showed preferences for certain regions of the gradient. Species richness ranged between 44 and 91 species per stand. The composition of the vegetation was summarized for the four segments, using prevalent species lists. Effectiveness of the direct gradient analysis was assessed by ordination using reciprocal averaging and polar ordination. Percent sand, percent organic matter, and depth of A horizon were significant correlates of the primary axis. Frequent burning of the prairie by the Indians has effectively maintained these prairies. The composition of the Walpole Island prairies is similar to those in Michigan, Illinois, and Wisconsin, forming part of the eastern tallgrass prairie.