Echinecea laevigata (smooth coneflower) is a long-lived perennial endemic to forest glade with in the southeastern USA. Since it was federally listed as endangered in 1992 some population monitoring has continued but detailed work on demographics is largely lacking. Our goal was to explore the effects of life-stage transitions and reproduction on changes in population densities. We have monitored annually the size and reproductive status of approximately 1,200 marked plants across four populations since 2014. We assessed number of seeds per flower, performed lab and field germination tests, and measured seedling survival in the field. We used these data sets to develop demographic models for smooth coneflower.
Results/Conclusions
Smooth coneflower exhibit an iteroparous life history. About 10% of plants flowered in a year. After flowering, many plants (46-66%) remained small (<100cm2 leaf area) for up to three years. In that third year, only about 11% flowered, again. A higher proportion of plants regressed to smaller sizes than grew to larger sizes. Two stages that were most influential in population growth as measured with elasticity were 1) progressing from first to second year and 2) remaining in the small stage class from year to year. Our work suggests that management strategies such as removal of woody vegetation has the potential to promote small plant growth and survival which could effectively increase population sizes.