The Navasota Ladies’ Tress (Spiranthes parksii, referred to as NLT henceforth) is a federally listed endangered species which is endemic to the Brazos Valley of East Central Texas.  The continued existence of NLT is threatened by habitat loss and degradation.  We performed a series of experimental studies manipulating biotic and abiotic factors in order to determine their impact on NLT growth and establishment.  In one experiment, we assessed the effects of large herbivores and fire on NLT populations.  In another we factorially manipulated soil resources by adding nutrients and water to some plots and also simulated grazing by removing herbaceous plant biomass.
Results/Conclusions

Our data suggest that herbivore grazing of flowering stalks prior to seed development is extensive and potentially has a substantial impact on NLT establishment.  Additionally, phosphorus appears to be a limiting nutrient for NLT growth. There was not a strong response to increased light availability due to biomass removal for any of the nutrient treatments.  The information obtained from this suite of experiments regarding the environmental factors regulating NLT population dynamics is invaluable for successful long-term NLT conservation and habitat restoration.