For rare and endangered plants, the creation of ex situ populations is one strategy to reduce extinction risks. In Georgia, one of the most highly endangered plant species is Baptisia arachnifera (Fabaceae). Occurring only in a very small area of Southeast Georgia, the natural habitat of the species is highly restricted, with most populations now found in actively managed short-rotation timber plantings and under powerline right of ways. New populations can be established through a variety of mechanisms, including direct sowing of seeds without any treatment, planting of seeds with various treatments, planting of seedlings of various ages, or transplanting of living plants (either active or dormant). I present data on seed germination under field conditions and seedling establishment, survival, and growth. I also compare the survival, growth, and reproduction of existing adult plants and two planted seedling cohorts of different ages over a ten-year period (2004-2015). The ex situ population was located at the Lake Louise Biological Field Station of Valdosta State University in Lowndes County, GA.
Results/Conclusions
Seed germination under field conditions averaged 17%, but varied across years and treatments. Seedlings derived from germinated seeds had low cumulative survival (2.4%), grew very slowly over the study period and none were reproductive. In contrast, the two planted seedling cohorts had much higher growth rates than germinated seeds. Reproductive activity was achieved by the second year after planting for the older seedlings and the third year for the younger seedlings. Reproduction at least once during the study was also higher for older vs younger seedlings (93% vs 41%). The older seedlings had higher cumulative survival compared to the younger seedlings (61% vs 52%, with existing adults averaging 50%). A growing season fire in May 2013 induced significant mortality in both seedlings and adults and caused strong impacts on plant morphology. Dormant season fires in 2005 and 2010 did not induce either response. While the ex situ population has declined in total population size during the period, the rapid growth and reproductive activity indicates that ex situ populations may assist in the recovery of this endangered species. The use of planted seedlings is recommended over direct seeding due to their higher survival, growth, and reproduction.