# Stage‐Specific Responses to Warming in Trojan Fir Across Early Life Stages: Germination, Seedling Survival, and Seedling Growth

## TL;DR

This study shows how warming temperatures affect different early life stages of the endangered Trojan fir tree, with germination increasing but seedling survival decreasing at higher temperatures.

## Contribution

The study reveals stage-specific responses to warming in Trojan fir, emphasizing the need to consider both germination and seedling survival in conservation planning.

## Key findings

- Higher temperatures enhance germination but reduce seedling survival and root growth.
- Cold stratification improves germination across temperature regimes.
- Seedling survival declines at 30°C, indicating a thermal threshold for early growth.

## Abstract

Understanding the early life‐stage responses of tree species to climate change is critical for predicting forest regeneration success and guiding conservation and management efforts. We investigated the effects of temperature, cold stratification, and light on germination and early seedling performance of Abies nordmanniana subsp. equi‐trojani (Trojan fir), an endangered endemic tree from north‐western Anatolia (Türkiye). Germination was tested under fixed (10°C, 15°C, 20°C, 25°C, 30°C) and alternating (15°C/25°C, 20°C/30°C) incubation temperatures with and without cold stratification. Early seedlings were monitored for 10 days under controlled, nutrient‐free agar conditions. Our results show that while higher fixed and alternating temperatures enhance germination, early seedling survival declined at the warmest temperature (30°C), and root growth peaked at 20°C and decreased at higher temperatures. Cold stratification significantly improved germination across all temperature regimes, reducing the need for warmer incubation temperatures to achieve high germination. Light had a limited effect on overall germination. These findings indicate stage‐specific responses to warming, as warmer conditions favor germination, whereas cooler conditions favor early seedling survival and root allocation. Consequently, successful regeneration assessments and conservation planning should consider both germination and early seedling stages, alongside local thermal contexts, when evaluating the impacts of climate change on Trojan fir.

We investigated the effects of temperature, cold stratification, and light on germination and early seedling growth in Abies nordmanniana subsp. equi‐trojani (Trojan fir), an endangered endemic tree from northwestern Anatolia (Türkiye). Our results show that while higher fixed and alternating temperatures enhance germination, they also lead to increased seedling mortality and reduced root growth. Mediterranean high‐altitude tree species may exhibit complex responses to warming at their early life stages, highlighting the necessity of considering both germination and seedling stages in conservation planning under climate change.