Because of the differences of climate and weather, including the age of the wood type, the measured values, photosynthesis is different from the reference value.
Due to the different types of terrain and weather, including the age of the species. As a result, the photosynthesis measurements differed from the reference value.
Because of the difference of the image area, and the weather, including the age of the species Therefore, the photosynthesis measured different from the reference value.