Experimental reintroduction of the endangered Echinacea laevigata : comparison of planting methods and effects of light intensity on biomass and photosynthesis

by 1974- Alley, Heather

In an experimental reintroduction of the endangered species Echinacea laevigata, we tested several planting methods to determine the optimal method for establishing populations in the wild. High survival rates and comparable growth among plants from all planting methods suggests that reintroduction is a promising conservation strategy for the species and that there are various options for introducing populations. Plants performed well regardless of age at the time of planting, spacing, and presence or absence of soil amendment. Therefore, reintroduction practitioners may weigh logistical costs and benefits when choosing reintroduction methods for E. laevigata. Based on theoretical predictions and our findings, we suggest that an ideal method for establishing populations is to plant adult plants (older than one year) in the spring, without soil amendment. This recommendation is preliminary and contingent on the future survival and reproductive success of reintroduced individuals. In order to more effectively and efficiently manage E. laevigata populations, it is important to understand the role of the light environment in the species’ decline. While it is generally agreed that the species decline is in part due to the lack of fire-maintained, early successional habitat, the extent to which light limits population persistence has not been quantified. We compare the effects of high, medium and low developmental light levels on photosynthetic performance as described by light curves, and on biomass allocation. We found no significant difference in photosynthetic response among plants grown at different light levels. However, plants grown under low light (18 percent of full sun) had significantly lower root and flowering stem dry weight, and number of flower heads than plants grown in full sun or moderate shade (43 percent of full sun). Therefore, in order to optimize biomass and flower production, important factors in population persistence, light levels should be maintained above 43 percent of full sun for E. laevigata populations.