Assessing microsite and regeneration niche preferences through experimental reintroduction of the rare plant Tephrosia angustissima var. corallicola

Abstract

As the world’s biodiversity is increasingly threatened by destruction and/or climate change, rare species reintroductions may be necessary to conserve species threatened with extinction. When ecological processes change or a species’ range is heavily fragmented, it may be difficult to determine microsite characteristics needed for a successful reintroduction. In such cases, experimental reintroductions can be used to learn more about the species’ reproductive niche while establishing new self-sustaining populations. We reintroduced the Florida endangered species, Tephrosia angustissima var. corallicola, to examine native microsite requirements and feasibility of reintroduction into nearby suitable habitat. We transplanted Tephrosia into three microsites with varying light and substrate and characterized their wet and dry season soil moisture, soil bulk density, and light conditions. We monitored transplant and recruited seedling growth, reproduction, and survival and seedling germination in each microsite for 6 years. The microsite supporting greatest survival changed across developmental stages and time. Although no original transplants survived to 2009, the reintroduced population persists in 2015 through recruitment. Highest recruit growth, flowering, and survival occurred in shady, dry microsites. Recruits germinated more in the wettest microsite, reproduced most in the driest, and persisted longest in the wettest. Recruits germinated in shadier locations than where adults were planted. Although assessing whether a reintroduction is self-sustaining will require decades of monitoring, this experimental reintroduction elucidated the necessity for heterogeneous microsites at recipient sites and the efficacy of planting reproductive individuals for rapid next generation recruitment. Determining appropriate microsites for species requiring human assisted migration may also benefit from these techniques.