Distribution of Cellular Slime Molds in Wisconsin Prairie Soils

Cellular slime molds were isolated from 75% of soil samples from 50 prairie remnants in southern Wisconsin. Total populations (cells per g of soil) were greatest in wet sites, intermediate in wet-mesic and mesic sites, and least in dry-mesic sites. Populations were slightly higher in dry than in dry-mesic sites, possibly because soils in dry sites had higher water-retaining capacities than soils in dry-mesic sites. Dominant species included Polysphondylium violaceum in wet prairies, Dictyostelium giganteum and P. violaceum in mesic prairies, and P. pallidum and D. sphaerocephalum in dry prairies. Dictyostelium sp. (YS) and P. pallidum both had greater populations at the two extremes of the moisture gradient than in mesic sites. Other species isolated included D. discoideum, D. lacteum, D. mucoroides, D. polycephalum, D. purpureum and D. rosarium. Average species diversity ranged from 3.2 species per site in dry-mesic prairies to 4.6 per site in wet-mesic prairies.