Growth responses of Chihuahua pine (Pinus leiophylla) over 128 years of warming and precipitation regime shifts

Climate warming is reshaping forest growth, mortality, and regeneration across the southwestern United States, yet uncertainty remains regarding how less abundant species at their range margins will respond to increasing temperature and hydroclimatic stress. Chihuahua pine ( Pinus leiophylla ) occupies a sparse and fragmented distribution at its northern leading edge. This study utilized dendrochronological data to assess relationships between growth and climate for Chihuahua pine (PILE) by compiling 16 tree ring chronologies throughout the U.S. extent of its range. We evaluated spatial and temporal patterns in climate–growth relationships to assess PILE’s sensitivity to temperature, precipitation, vapor pressure deficit (VPD), and competitive environment. We found that PILE growth was strongly influenced by high temperatures during the onset of the North American Monsoon (NAM) and increasing atmospheric moisture demand, with widening sensitivity to VPD over time. We found no evidence of cold limitation, suggesting that warming alone is unlikely to constrain persistence at the leading edge. The observed climate–growth relationships showed limited spatial differentiation along the monsoon gradient, and the effects of competition were confounded by site-level climate variation. Despite exhibiting traits consistent with drought tolerance and hydroclimatic responsiveness, the drivers of PILE’s sparse distribution remain unresolved, highlighting gaps in our understanding related to dispersal, regeneration, and demographic constraints. Our results suggest PILE may represent a viable candidate species for climate-resilient forest management in the southwest. Future research is needed to develop actionable guidelines for managers to support the health of understudied species and climate resilient landscapes.