The researchers studied the levels of different plant compounds in Ginkgo biloba leaves over time. They found that carotenoid levels peaked in June and then decreased. Chlorophyll a was the main type of chlorophyll present, and its levels were closely related to total chlorophyll levels. The ratio of carotenoids to chlorophyll changed in the opposite direction to the chlorophyll a/b ratio. Flavonoids had negative correlations with chlorophyll, chlorophyll a, chlorophyll a/b ratio, and carotenoids. Only the relationship between flavonoids and chlorophyll a/b ratio was significant when considering other factors.