Assessment of microhabitat differences between Drosera rotundifolia and Drosera intermedia in a northern Michigan bog.

Abstract

The purpose of this study was to investigate microhabitat differences between two species of sundews, Drosera rotundifolia and Drosera intermedia. I tested several hypotheses: D. rotundifolia density increases with increasing height above a fixed low point, while D. intermedia density decreases with height; D. rotundifolia grows primarily on red Sphagnum moss, while D. intermedia grows primarily on green Sphagnum; the densities of both Drosera species increase with decreasing pH; the density of neither Drosera species is affected by water conductivity or dissolved oxygen content. At Mud Lake Bog in Cheboygan County, Michigan, I recorded the species of Drosera plants, as well as the height of the plants above a fixed low point and the color of Sphagnum moss on which they were growing. I also measured the pH, conductivity, and dissolved oxygen content of the water in which the plants were growing. Densities of both Drosera species decreased with increasing height, though the trend was stronger for D. intermedia. D. rotundifolia grew significantly more on red Sphagnum than did D. intermedia, while D. intermedia grew significantly more on green Sphagnum than did D. rotundifolia. D. rotundifolia density varied significantly with neither pH, conductivity, nor dissolved oxygen. D. intermedia density increased significantly with decreasing pH and increasing conductivity, but not with dissolved oxygen. My results were consistent with past research, and conclusively illustrated the differences in microhabitat preferences between the two Drosera species.