GERMINABLE SOIL SEED AND COMPETITIVE RELATIONSHIPS BETWEEN A RARE NATIVE SPECIES AND EXOTICS IN A SEMINATURAL PASTURE IN THE MIDLANDS, TASMANIA

Helipterum albicans, a disturbance-dependent, rare, native daisy, surv ives in a few semi-natural paddocks grazed by stock in the Tasmanian M idlands. The germinable soil seed bank in a basalt paddock with a larg e population of this daisy largely consisted of exotic and annual spec ies. The peak germination for native species was in winter and early s pring, while exotics dominated from late spring to autumn. The peak ge rmination of H. albicans occurred soon after a similar peak of an exot ic rosette herb, Hypochoeris radicata. An experiment with different mi xtures of these two species demonstrated that H. radicata had a depres sive effect on the growth of H. albicans while the reverse was not app arent. As both species colonize bare ground, a managed reduction in Hy pochoeris density is likely to favour the rare native.