Pistacia weinmannifolia seedlings were studied to see how their photosynthesis is affected by different levels of soil moisture. The researchers measured various photosynthetic and chlorophyll fluorescence parameters of the leaves. They found that as soil moisture decreased, the net photosynthetic rate, transpiration rate, and other key factors initially increased and then decreased. When soil moisture was extremely low, photosynthesis was significantly reduced, and the structure of the photosynthesis system was damaged.