Regeneration After Severe Wildfire: Hotter Microclimates Exceed Hydraulic and Thermal Tolerances in Sierra Nevada Conifer Seedlings.

Elevated leaf temperatures in post-fire environments significantly reduce conifer seedling thermal and hydraulic safety margins, threatening regeneration in Sierra Nevada forests.

• Why it matters: Understanding how drought and heat stress impact seedling survival is crucial for predicting forest recovery amid climate change, especially in fire-prone regions where regeneration determines long-term forest composition.
• What they did: Researchers combined field observations with a controlled drought-heat chamber experiment on five Sierra Nevada conifer species, measuring physiological thresholds like T crit, T50, and turgor loss point under elevated temperatures.
• The result: Findings reveal that heat stress, often decoupled from air temperature, dominates seedling vulnerability, with no trade-offs between drought and heat tolerance, highlighting the urgent need to incorporate microclimate and energy balance considerations into forest management.