Assessing the Reintroduction Potential of the Endangered Huachuca Water Umbel in Southeastern Arizona

Abstract

The Huachuca water umbel (HWU, Lilaeopsis schaffneriana ssp. recurva) is a federally endangered aquatic perennial plant endemic to southeastern Arizona and northern Sonora, Mexico. The species was listed because of threats posed by the degradation and loss of wetlands throughout its limited range. Although the species is easily grown in a greenhouse, information regarding specific requirements that allow long-term persistence of HWU in natural habitats is lacking, and few efforts to reintroduce this species have been attempted. Using greenhouse-propagated material, we introduced 128 individual HWU plugs into four spring-fed wetland sites near Elgin, Arizona. The sites represent a range of habitat conditions. After two years, overall survival of transplanted plugs was 60% and the area occupied had increased by 845%. This study documented the response of transplanted HWU to periodic drying, disturbance due to scouring and trampling, and sediment deposition. We also examined the number of viable seeds incorporated into a seed bank at the study location in the first season after transplanting. This case study offers a model for watershedwide reintroduction efforts of endangered plants. It also illustrates the importance of low-level disturbance and the necessity of long-term monitoring and maintenance of competing plant species in establishing viable species reintroductions.