Ecology of the endangered species Solidago shortii. VI. Effects of habitat type, leaf litter, and soil type on seed germination

Solidago shortii T. and G. (Asteraceae) is a federal-endangered species endemic to a small area in northeastern Kentucky. Seeds sown in December 1994 in a Festuca arundinacea-dominated meadow, in two Juniperus virginiana stands, and in an oak-hickory forest germinated to 39-59% in spring 1995; those sown in gaps of a J. virginiana stand and in the open germinated to 48-66%. Peak germination occurred before the oak-hickory canopy leafed-out and before F. arundinacea produced new (green) growth. Seeds covered with leaf litter either immediately after sowing (on 23 December 1994) or 40 d after sowing germinated to 79-87% in spring 1995; those kept free of litter or with litter removed 40 d after being covered with litter germinated to 58%. Only seeds continuously covered with litter from time of sowing germinated (3%) the second spring. In the laboratory, cold-stratified (nondormant) seeds germinated to 96-100% after 2 wk incubation at a 12/12 h daily thermoperiod of 30/15°C on soil derived from sandstone, black shale, dolomite, calcareous shale, and phosphatic limestone. These and previously-published results show that seeds of S. shortii germinate over a broad range of environmental conditions; thus, this phase of the life cycle probably does not contribute to the narrow endemism of the species.