Abstract
This study analyzed biological and microclimatic factors affecting the post-reintroduction survival and growth of laboratory-propagated American hart’s-tongue ferns (Asplenium scolopendrium var. americanum, AHTF), a rare and threatened fern species with a fragmented distribution across the eastern United States and Canada. In total, 1,925 AHTF transplants, representing four life history stages (protonemata, gametophytes, sporelings, and immature sporophytes) were reintroduced into three sites determined to be ideal habitats within Onondaga County, New York. Factors that resulted in higher rates of survival included more rigorous acclimatization of transplants, better transplant vigor at the time of transplanting, and higher humidity at reintroduction sites. Analysis of wind speed and direction provided implications of low spore dispersal, and therefore low gene flow, between extant AHTF populations. Insights from this research contribute to a growing, yet still understudied, body of knowledge regarding fern species reintroductions and inform best practices for future AHTF reintroductions.