Facing an increasing number of threats, including the effects of climate change and species invasions, reintroduction has become a common method of recovery of imperiled plant species. The American hart’s-tongue fern (Asplenium scolopendrium var. americanum, AHTF) is a threatened evergreen fern with fragmented populations ranging from northern Alabama to the upper peninsula of Michigan. In New York, AHTF consists of sixteen populations between Onondaga and Madison counties and is associated with talus slope communities along the Niagara Escarpment. The objective of our research is to determine the best method of reintroduction of AHTF. Specifically, we examine the effects of life stage and acclimatization methods on the survival and growth of transplants. Approximately 2,000 total AHTF, grown from spores from six source populations in New York, were planted across three sites in Onondaga county. Sites were determined by GIS analysis of habitat, population connectivity potential and site quality. Over sixteen months, we recorded percent survival by life stage and used ANOVA to determine any differences in growth. We anticipated that larger, more advanced life stages with more rigorous acclimatization would produce greater survival and growth than earlier life stages.
Results/Conclusions
Transplanted gametophytes exhibited survival of 3.53% and 0.63% (N=1106) at four and sixteen months after transplanting, respectively. Gametophytes produced a total of five sporelings. Transplanted sporelings (<1 year old sporophytes) exhibited 38.18% and 4.31% survival (N=220) at four and sixteen months after transplanting, respectively. Immature sporophytes (1 to 5 years old) with only indoor acclimatization (IA) exhibited 34.65% and 5.94% survival (N=101) at four and sixteen months after transplanting, respectively. Immature sporophytes with indoor and outdoor acclimatization (IOA) exhibited 60.00% and 21.11% survival (N=90) at four and sixteen months after transplanting, respectively. Sporelings, IA and IOA immature sporophytes all decreased in mean number of fronds per transplant at twelve months after transplanting. The difference of means was significant between sporelings and IA sporophytes (p=0.004) and IA and IOA sporophytes (p=0.009). The average frond length of sporelings, IO and IOA sporophytes all increased at twelve months after transplanting, with IOA sporophytes exhibiting the largest growth. No significant differences between the three life stages were observed. Three IOA sporophytes developed sori after twelve months. The preliminary results of this research suggest that transplants of more advanced life stages with more rigorous acclimatization offer the greatest potential for AHTF reintroduction.