Germinable soil seed and competitive relationships between a rare native species and exotics in a semi-natural pasture in the Midlands, Tasmania

Helipterum albicans, a disturbance-dependent, rare, native daisy, survives in a few semi-natural paddocks grazed by stock in the Tasmanian Midlands. The germinable soil seed bank in a basalt paddock with a large population of this daisy largely consisted of exotic and annual species. The peak germination for native species was in winter and early spring, while exotics dominated from late spring to autumn. The peak germination of H. albicans occurred soon after a similar peak of an exotic rosette herb, Hypochoeris radicata. An experiment with different mixtures of these two species demonstrated that H. radicata had a depressive effect on the growth of H. albicans while the reverse was not apparent. As both species colonize bare ground, a managed reduction in Hypochoeris density is likely to favour the rare native.