The study looked at how drought affects the photosynthesis of Abies koreana trees under different light conditions. They found that when the trees were not watered for 21 days, their photosynthetic rate decreased, and their ability to absorb and use light for photosynthesis was impaired, especially in full sunlight. The trees also took longer to recover after being re-watered in full sunlight compared to shaded conditions. This shows that drought has a greater negative impact on the photosynthesis of these trees when they are exposed to high light intensity.