Fire resilience and altered competitive dynamics of the endangered forb Pectis imberbis show potential for prescribed fire as a conservation tool

Dryland managers face a dilemma balancing prescribed fire use with rare species conservation. In semi-arid grasslands and woodlands, managers often avoid burning habitats with threatened plants, though fire may reduce competition from invasive grasses and support native persistence. In the Madrean Sky Islands of southeastern Arizona, drought, altered fire regimes, and non-native species encroachment are transforming lower elevation grasslands and woodlands, home to the endangered forb, Pectis imberbis. These stressors interact in complex ways, yet cumulative effects on rare species like P. imberbis remain poorly understood. We conducted a fully factorial greenhouse experiment to test how fire, drought, and competition affect P. imberbis. Plants were grown from seed with intra- and interspecific competitors, then exposed to fire and drought. After 39 weeks, we measured above- and belowground biomass. Interspecific competition and drought reduced biomass, but burning appeared to ameliorate interspecific competition's negative effects. Pectis imberbis resprouted robustly after fire—even under drought and competition—though drought and intraspecific competition delayed resprouting. Our findings indicate prescribed fire may provide a safe and effective way to manage P. imberbis habitat while supporting broader goals such as invasive species control.