The Blue Grass Army Depot (BGAD) is home to Kentucky’s largest concentration of the endangered perennial forb Running Buffalo Clover (Trifolium stoloniferum Muhl ex A. Eaton). The constituent element occurrences (E.O.s) at the BGAD have undergone both declines and increases in population (rooted crown count) since monitoring began in 1994; it is an area of active research as to whether management encourages population growth. A series of population viability analyses were performed for the 10 extant E.O.s using rooted crown counts from 2003, 2004, 2005, 2006, 2008, 2010, 2012, 2013, 2014, 2017 and 2018. The population viability analyses were performed in R using the popbio, lmtest, and XLConnect packages where the cumulative probability of extinction was projected over 50 years with a quasi-extinction threshold of 1.
Results/Conclusions
Despite a notable decline (45%) in rooted crown count at the BGAD from 2014 to 2017, 6 of the 10 E.O.s exhibit a positive average population growth over the past 11 surveys. PVA data suggests that most extant E.O.s should persist over the next 10 years, although 4 E.O.s have a cumulative probability of extinction over 20%. Additionally, 9 of the 10 E.O.s are “B,” “C,” or “D” ranked according to the United States Fish and Wildlife Service recovery plan. Observations from the field indicate that E.O.s are most at risk from invasive species such as Japanese stiltgrass (Microstegium vimineum (Trin.) A. Camus) which needs to be manually removed or treated with herbicide. In addition, further monitoring will strengthen predictions. Management will remain important to recovery of T. stoloniferum at the BGAD.