Environmental Correlates and Reproductive Capacity of Guadalupe Fescue (Festuca ligulata), an Endangered Grass of the Northern Sierra Madre Oriental

ABSTRACT Guadalupe fescue (Festuca ligulata Swallen) is an endangered perennial grass species that is endemic to the Sky Island conifer-oak forests and piñonoak-juniper woodlands of the northern Sierra Madre Oriental. Little is known about the habitat requirements, population dynamics, or reproductive ecology of this species. We assessed aspects of the demography, habitat preferences, and germination rates of Guadalupe fescue in two Sky Island sites on each side of the US–Mexico border: the Chisos Mountains of Big Bend National Park (BIBE) in Texas, USA, and the Maderas del Carmen Protected Area (MCPA) in Coahuila, Mexico. Through field and greenhouse measurements, we evaluated the plant vigor, reproductive capacity, and environmental growing conditions of 422 plants (323 in BIBE and 99 in MCPA). Our results reveal that Guadalupe fescue is a very rare species growing within a narrow elevational range (2066–2394 m) on rocky microsites with relatively open canopy and forest floor conditions, compared to the range of available local habitats. For collected seeds, the mean fill rate was 54% (31% for BIBE and 61% for MCPA) and overall germination rate was 14% (8% at BIBE and 33% at MCPA). These results provide important baseline ecological data on Guadalupe fescue, which is critical for informing endangered species recovery planning and restoration activities aimed at bolstering this species' population size.