Effects of a water-depth gradient on the germination of lakeshore plants

Abstract

The germination requirements of many wetland species commonly found in the seed bank are poorly understood. The purpose of this study is to explore the germination responses of lakeshore plant species to a water-depth gradient on each of two soil types normally found on shorelines and to test whether germination patterns predict field distributions of adults. Germination patterns were determined in a greenhouse by sowing seeds of 24 lakeshore species along an artificial water-depth gradient, using two soil types (sand and organic soil). Those species showing significant treatment effects were then tested for similar or different germination patterns, using Kendall's coefficient of concordance. Species had similar germination patterns (n = 5, P = 0.02) on sand. Species had different germination patterns (n = 7, P > 0.50) on the organic soil. Mean water-depth of germination was significantly correlated with the mean depth occupied by adults in the field for seven species (r = 0.81, P = 0.04). This study shows that germination requirements are important in controlling recruitment of wetland species after disturbance.